Skip to main content
Download PDF

Long noncoding RNA AFAP1-AS1 acts as a competing endogenous RNA of miR-423-5p to facilitate nasopharyngeal carcinoma metastasis through regulating the Rho/Rac pathway

Journal of Experimental & Clinical Cancer Research volume 37, Article number: 253 (2018) Cite this article

Abstract

Background

Actin filament-associated protein 1 antisense RNA 1 (AFAP1-AS1), a long noncoding RNA, is significantly highly expressed and associated with metastasis and poor prognosis in many cancers, including nasopharyngeal carcinoma (NPC). In this study, we aim to identify the role of AFAP1-AS1 acting as an oncogenic lncRNA to promote NPC metastasis.

Methods

The role of AFAP1-AS1, miR-423-5p, and FOSL2 in NPC metastasis was investigated in vitro and in vivo. Bioinformatics analysis and luciferase activity assays were used to identify the interaction between AFAP1-AS1, miR-423-5p, and FOSL2. Additionally, real-time PCR and western blotting were used to assess the function of AFAP1-AS1 acting as an oncogenic lncRNA to promote NPC progression by regulating miR-423-5p and the downstream Rho/Rac pathway.

Results

In this study, we determined that AFAP1-AS1 functions as a competing endogenous RNA in NPC to regulate the Rho/Rac pathway through miR-423-5p. These interactions can mediate the expression of RAB11B, LASP1, and FOSL2 and accelerate cell migration and invasion via the Rho/Rac signaling pathway or FOSL2. AFAP1-AS1 and FOSL2 could competitively bind with miR-423-5p to regulate several molecules, including RAB11B and LASP1 of the Rho/Rac signaling pathway. AFAP1-AS1 can also regulate the expression of LASP1, which was transcriptionally regulated by FOSL2, resulting in increased migration and invasion of NPC cells via the Rho/Rac signaling pathway.

Conclusions

The observations in this study identify an important role for AFAP1-AS1 as a competing endogenous RNA (ceRNA) in NPC pathogenesis and indicate that it may serve as a potential target for cancer diagnosis and treatment.

Background

Nasopharyngeal carcinoma (NPC) is a head and neck epithelial malignancy that occurs frequently in Southern China [1,2,3,4,5]. Epstein-Barr virus exposure [6,7,8,9,10,11,12,13,14,15], diet, and genetic factors [16] are implicated in its etiology. Although radiotherapy is an effective treatment for NPC patients in the early stages of the disease [17,18,19,20], the majority (75–90%) of NPC cases are predisposed to metastasis at initial diagnosis [21,22,23,24], which hampers efficacious treatment and poses a high risk of disease recurrence. Enhancing our understanding of the molecular mechanisms underlying NPC may promote the development of effective metastasis-targeted therapy and improve the overall prognosis of patients with this disease.

Noncoding RNAs, including microRNAs (miRNAs), long noncoding RNAs (lncRNAs) [25,26,27,28,29,30,31,32,33] and circular RNAs (circRNAs) [34,35,36,37], have important roles in the regulation of gene expression and are involved in the development of a variety of human diseases, including cancer. The lncRNA actin filament associated protein 1 antisense RNA 1 (AFAP1-AS1) maps to the antisense DNA strand of AFAP1 and was first identified as highly expressed in esophageal cancer [38]. AFAP1-AS1 is also highly expressed in lung cancer and pancreas cancer, and hepatocellular carcinoma [39,40,41,42,43]. We previously discovered that AFAP1-AS1 was significantly highly expressed in NPC and associated with metastasis and poor prognosis [44, 45]. Numerous cytoskeleton proteins, including proteins in the small GTPase Rho/Rac signaling pathway, were identified and significantly regulated using the liquid chromatography-tandem mass spectrometry (LC-MS/MS) by siAFAP1-AS, suggesting that AFAP1-AS1 may regulate NPC migration and invasion through this pathway; however, as a newly identified lncRNA, the mechanism by which AFAP1-AS1 regulates the Rho/Rac signaling pathway remains unknown.

A new model of lncRNA involvement in gene regulation has recently been proposed, called competing endogenous RNA (ceRNA). This model proposes that lncRNAs and mRNA transcripts affect one another by competitively combining with miRNA response elements (MREs) to influence posttranscriptional regulation [46,47,48]. In this way, lncRNAs bind with miRNAs to modulate regulation of protein-coding gene expression and participate in the regulation of cell behavior. These interactions between mRNAs, miRNAs, and lncRNAs generate complex regulatory networks [49]. In this study, we found that AFAP1-AS1 acts as a ceRNA, competitively binding with miR-423-5p and directly regulating RAB11B and LASP1 genes in the Rho/Rac pathway. AFAP1-AS1 can also regulate the expression of FOSL2 and its downstream genes by competing with FOSL2 to bind miR-423-5p, resulting in increased migration and invasion of NPC through the Rho/Rac signaling pathway.

Methods

Tissues and cell lines, chemicals, plasmids, and transfection

Thirty-two nasopharyngeal carcinoma samples and 13 nontumor nasopharyngeal epithelium tissues were obtained from patients. All samples were collected with the consent of patients and the experiments were approved by the ethics committee of Hunan Cancer Hospital, Changsha, China. All fresh tissues were immersed in RNALater (Ambion, Austin, TX, USA). The tissue samples were stored in a − 80 °C laboratory freezer. RNA was isolated using TRIzol reagent (Invitrogen, Carlsbad, CA, USA) according to the manufacturer’s protocol. The NPC cell lines 5-8F and HNE2 were maintained in our laboratory in RPMI 1640 medium supplemented with 10% fetal bovine serum (FBS; Invitrogen), penicillin (100 U/ml, Sigma-Aldrich, St. Louis, MO, USA), and streptomycin (100 mg/ml, Sigma-Aldrich). All cell lines had been recently tested for mycoplasma contamination and identified no cross-contaminated cell lines or mycoplasma contamination.

The synthetic miR-423-5p mimics and inhibitors were supplied by Ruibo Co. (Guangzhou, China). siRNAs and nontargeting scrambled control siRNAs were provided by Invitrogen. The sequences of the AFAP1-AS1- and FOSL2-targeting siRNAs are listed in Additional file 1: Table S1. To construct the AFAP1-AS1 expression vector, the entire AFAP1-AS1 sequence was amplified by reverse transcription PCR (RT-PCR) and cloned into the pcDNA3.1 vector. The open reading frame of FOSL2 (NM_005253) was cloned into the pENTR vector and tagged with the C-terminal Flag and His peptide sequences was purchased from the Vigene Co. (Rockville, MD, USA). Transfection of cells with plasmids, siRNAs, and miRNAs was performed using Lipofectamine 3000 (Life Technologies, Grand Island, NY, USA) or HiPerFect (Qiagen, Hilden, Germany) transfection reagents, according to the manufacturer’s instructions.

Online expression profiles analysis

NPC data sets and the corresponding clinical data were downloaded from publicly available GEO databases. These included 62 patients with NPC and 6 non-NPC nasopharyngeal epithelial tissues from GSE73460 [50], 6 patients with NPC and 12 non-NPC epithelial tissues from GSE32906 [50] and 122 patients with NPC with survival status from GSE70970 [51].

Bioinformatics analysis, reporter plasmids, and luciferase activity assays

Five software tools, RNAhybrid, RNA22, PITA, TargetScan, and RegRNA, were used for miRNA target prediction in this study. For miRNA target validation assays, 58 bp fragments of the AFAP1-AS1 sequence, or the RAB11B, LASP1, RAC1, and FOSL2 3′-UTRs containing the wild-type (WT) and mutant (MT) binding sites for miR-423-5p, were cloned into the pMIR-REPORT vector. The sequences of these synthetic oligonucleotides are listed in Additional file 1: Table S1. Cells (5-8F and HNE2) were cotransfected with pMIR-REPORT vectors containing the WT sequences of the RAB11B, RAC1, LASP1, or FOSL2 3′-UTRs or their corresponding mutants, along with the pRL-TK control vector and miR-423-5p mimics, inhibitors, or negative control.

For the LASP1 promoter activity analysis, the Promoter 2.0 Prediction Server (http://www.cbs.dtu.dk/services/Promoter/) was used to predict potential AP1-binding sites in the LASP1 promoter sequence. Three tandem the wild type or mutant AP1-binding sites were inserted into the TA-luciferase vector as synthetic oligonucleotides encoding the wild type or mutant AP1-binding sites (Additional file 1: Table S1).

The AP-1 cis-element reporter plasmid (the AP-1 reporter), which contains multiple conserved AP1-binding sites for sensitive detection of AP-1 transcriptional activity, was purchased from Promega (pAP1-TA-luc; Promega, Fitchburg, WI, USA) to measure the AP-1 transcriptional activity. Plasmid transfection and luciferase assays were performed as described previously [52]. Cells were harvested 48 h posttransfection and assayed using a Dual Luciferase Assay (Promega) according to the manufacturer’s instructions. All transfection assays were carried out in triplicate.

Wound healing and transwell assays

For wound healing assays, 5-8F and HNE2 cells were seeded and grown to 90% confluence in 6-well culture plates, and a 200 μl pipet tip was used to create a scratch in the cell monolayer. Images were captured and measured with an ocular ruler to ensure that all wounds were the same width at the beginning of each experiment.

For transwell assays, 5-8F and HNE2 cells in 200 μl serum-free media were placed into upper transwell chambers (8.0 μl pore size, BD Biosciences, Franklin Lakes, NJ, USA) for invasion assays after transfection, according to the manufacturer’s protocol. Invaded cells were fixed and stained with methanol and 0.1% crystal violet, counted under a microscope, and imaged. Independent experiments were carried out in triplicate.

Western blotting

Proteins were extracted and separated according to previously described methods. Membranes were incubated overnight at 4 °C with primary anti-RHOA, anti-RHOC, anti-RAC2, anti-RAB10, anti-RAB11B, anti-RAB11A, anti-RHOGDI, anti-PFN1, anti-LASP1, or anti-FOSL2 antibodies (Proteintech, Wuhan, China). Blots were visualized by exposure to X-ray films using an enhanced chemiluminescence detection system (EMD Millipore, Burlington, MA, USA). Blots were probed with anti-GAPDH antibody (Cell Signaling Technology, Danvers, MA, USA) as an endogenous control for equal loading.

Real-time PCR

Total RNA was isolated with TRIzol reagent (Invitrogen) according to the manufacturer’s protocol. For miRNA real-time PCR, cDNA was synthesized using the miScript system (Ruibo) according to the manufacturer’s instructions. miR-423-5p expression levels were measured using a Ruibo miRNA primer assay (Ruibo) and a miDETECT Track miRNA qRT-PCR kit (Ruibo) according to the manufacturer’s instructions. Data were normalized to the small nuclear RNA RNU6B (U6 snRNA) expression level. For mRNAs and lncRNAs, real-time PCR expression analysis was carried out using a SYBR green real-time PCR kit (Applied Biological Materials, Inc., Richmond, BC, Canada). Data were normalized to the GAPDH expression level and further normalized to the negative control, unless otherwise indicated. The primers used for PCR are listed in Additional file 1: Table S1. Fold changes in expression were calculated using a relative quantification (2-ΔΔCt) method. All reactions were performed in triplicate and repeated in three independent experiments.

in vivo nude mouse models

Male BALB/C nude mice (5–6 weeks of age, 16–18 g) were maintained in the experimental animal center of Central South University in a pathogen-free facility. The Institutional Animal Ethics Committee of Central South University approved this animal study. Mice were divided into four groups, including the over-AFAP1-AS1, negative control (NC), miR-423-5p, and over-FOSL2 groups. For metastasis assay, 2 × 106 5-8F cells in a volume of 200 ml with corresponding treatment were tail-vein injected into five-week-old male BALB/c nude mice which were randomly divided into four groups (n = 10 for each group). 60 days later, the mice were killed, and all the lungs are surgically removed and the number of macroscopically visible pulmonary metastases nodules per mouse was counted by two experienced pathologists. Then, the lung tissues were fixed in 10% neutral phosphate-buffered formalin, followed by HE staining.

Statistical analysis

All continuous variables are presented as the means ± standard deviation (SD), and categorical data are expressed as percentages. GraphPad Prism 5.0 (GraphPad Software, Inc., La Jolla, CA, USA) was used for statistical analysis. Student’s t-test was performed to assess significant differences between two groups using p < 0.05 as the significance threshold. Survival analysis was performed by Kaplan-Meier curves and log-rank test for significance. A two-sided p-value of < 0.05 was considered statistically significant.

Results

Overexpression of AFAP1-AS1 accelerates NPC cell migration and invasion

We first confirmed the function of AFAP1-AS1 in NPC cells migration and invasion. The overexpressing AFAP1-AS1 vector was constructed and transfected into the NPC cell lines 5-8F and HNE2, and the expression of AFAP1-AS1 was confirmed by real-time PCR (Fig. 1a). Wound healing and transwell assays demonstrated that overexpression of AFAP1-AS1 accelerated 5-8F and HNE2 cell migration (Fig. 1b) and invasion (Fig. 1c).

Fig. 1
figure 1

Overexpression of AFAP1-AS1 stimulates NPC cells migration and invasion of in vitro. a. AFAP1-AS1 levels were detected by qRT-PCR in 5-8F and HNE2 cells after transfection with the pcDNA3.1-AFAP1-AS1 (AFAP1-AS1) vector and the empty pcDNA3.1 vector (NC). b. Wound healing assays using 5-8F and HNE2 cells transfected with the pcDNA3.1-AFAP1-AS1 (AFAP1-AS1) or the pcDNA3.1 (NC) vectors. The relative ratio of wound closure per field is shown on the right. Scale bars, 100 μm. *, p < 0.05; **, p < 0.01; ***, p < 0.001. c. Transwell analysis of 5-8F and HNE2 cells transfected with the pcDNA3.1-AFAP1-AS1 (AFAP1-AS1) or the pcDNA3.1 vectors (NC). The relative ratio of invasive cells per field is shown on the right. For all quantitative results, data are presented as the means and standard errors of the mean (± SEM) from three independent experiments. Scale bars, 100 μm. *, p < 0.05; **, p < 0.01; ***, p < 0.001

Full size image

AFAP1-AS1 physically interacts with miR-423-5p in NPC cells

To identify the mechanism of AFAP1-AS1 in NPC, we used four programs (PITA, RNAhybrid, RNA22, and RNAreg2.0) to predict potential lncRNA-miRNA interactions involving AFAP1-AS1. Among the results, miR-423-5p was selected for further investigation, since it was the only interacting miRNA proposed by all these four tools. Then, whether endogenous AFAP1-AS1 levels were affected by miR-423-5p was examined through transfection of miR-423-5p mimics or inhibitors into 5-8F and HNE2. Real-time PCR indicated that AFAP1-AS1 expression was reduced after transfection with miR-423-5p mimics (Fig. 2a) and induced after transfection with miR-423-5p inhibitors in 5-8F and HNE2 cells (Fig. 2b). These results indicated that AFAP1-AS1 was negatively regulated by miR-423-5p in NPC cells. A total of 2 binding sites for miR-423-5p were predicted in the AFAP1-AS1 sequence. One binding site between 5021 and 5043 bp of AFAP1-AS1 (NR_026892, Fig. 2c) with the lowest minimum free energy was selected, and its wild-type (WT) and mutant (MT) sequences were cloned into a pMIR-REPORT luciferase vector for luciferase activity assay. The result showed that transfection of miR-423-5p mimics into 5-8F and HNE2 cells reduced the luciferase activity generated by the wild-type AFAP1-AS1 reporter (WT), but not that of the empty vector or the reporter vector containing the mutant miR-423-5p binding site (Fig. 2d). Moreover, transfection with miR-423-5p inhibitors increased the luciferase activity of the wild type AFAP1-AS1 reporter (WT, Fig. 2e), suggesting that miR-423-5p binds with AFAP1-AS1 through this site.

Fig. 2
figure 2

miR-423-5p could bind with the AFAP1-AS1 sequence. a. The expression level of AFAP1-AS1 was reduced by miR-423-5p mimics compared with negative controls (NC) in NPC cells transfected with miR-423-5p mimics or negative controls using the qRT-PCR method. b. The expression level of AFAP1-AS1 was induced by miR-423-5p inhibitors (423-5p In) in 5-8F and HNE2 cells transfected with miR-423-5p mimics or negative controls. c. Sequence alignment of human miR-423-5p within the AFAP1-AS1 sequence. The seed sequence of miR-423-5p matches the AFAP1-AS1 sequence. Mutations within the AFAP1-AS1 sequence. AFAP1-AS1 in the mutant luciferase reporter constructs are as shown. d. The pMIR-reporter-AFAP1-AS1 vector was used for the luciferase assays. 5-8F and HNE2 cells were transfected with miR-423-5p mimics or control and luciferase reporters containing the wide type or mutant AFAP1-AS1 sequence, as indicated. Firefly luciferase activity was normalized with Renilla luciferase activity. Relative luciferase activities are presented. Data represent three independent experiments in triplicate. e. Luciferase activity was measured in 5-8F and HNE2 cells cotransfected with miR-423-5p inhibitors, negative control, and the luciferase reporter constructs containing the wide type or mutant AFAP1-AS1 sequence, as indicated. *, p < 0.05; **, p < 0.01; ***, p < 0.001

Full size image

miR-423-5p is expressed at low levels in NPC and suppresses cell migration and invasion

Based on the above findings, we screened online published miRNA datasets and found that miR-423-5p expression was low-expressed in NPC clinical samples compared with nontumor nasopharyngeal epithelium tissues in a gene expression profiling (GEP) dataset, GSE73460 (Additional file 2: Figure S1a), and another NPC GEP dataset, GSE32906 showed that the expression of miR-423-5p was tightly associated with the TNM stages of NPC patients (Additional file 2: Figure S1b). In the GSE70970 dataset, decreased miR-423-5p expression was also associated with poor overall survival and poor relapse-free survival (Additional file 2: Figure S1c) of NPC patients. Then, the expression of AFAP1-AS1 and miR-423-5p were examined in 32 NPC clinical samples and 13 nontumor nasopharyngeal epithelium biopsies by qRT-PCR. The results showed that miR-423-5p was lowly expressed in NPC tissues compared with that in nontumor nasopharyngeal epithelium tissues (Fig. 3a). Conversely, AFAP1-AS1 was highly expressed in the NPC tissues and tightly associated with the clinical TNM stages, neck lymph node metastasis, and the T stages of the patients (Fig. 3b). There was an inverse correlation between AFAP1-AS1 and miR-423-5p in the NPC tissues (Fig. 3c).

Fig. 3
figure 3

The expression of miR-423-5p was negatively correlated with AFAP1-AS1 in NPC biopsies and inhibited NPC cell migration and invasion in vitro. a. miR-423-5p was lowly expressed in 32 NPC tissues compared with 13 nontumor nasopharyngeal epithelial (NPE) tissues and correlated with the TNM stages of NPC patients as indicated. b. AFAP1-AS1 was highly expressed in the same 32 NPC tissues compared with 13 nontumor tissues and tightly correlated with the TNM stages, lymphoma metastasis, and the T stage of NPC patients, as indicated. c. The expression of miR-423-5p was tightly negatively correlated with that of AFAP1-AS1 in the same 32 NPC tissues and 13 nontumor tissues as indicated. d. The invasion ability was measured in 5-8F and HNE2 cells after treatment with miR-423-5p mimics or negative control using wound healing assays. The relative ratio of wound closure per field is shown at the bottom. Scale bars, 100 μm. e. Transwell assays were performed to measure the migration ability of miR-423-5p mimics in 5-8F and HNE2 cells after treatment with miR-423-5p mimics or negative control. The relative ratio of invasive cells per field is shown at the bottom. Scale bars, 100 μm. f. Wound healing assays of 5-8F and HNE2 cells after treatment with miR-423-5p inhibitors or negative control. The relative ratio of wound closure per field is shown to the bottom. Scale bars, 100 μm. g. Transwell assays were performed in 5-8F and HNE2 cells after treatment with miR-423-5p inhibitors or negative control. The relative ratio of invasive cells per field is shown on the bottom. Scale bars, 100 μm. *, p < 0.05; **, p < 0.01; ***, p < 0.001

Full size image

Next, we measured the cell migration and invasion capacity of miR-423-5p in NPC cells. Wound healing and transwell assays demonstrated that miR-423-5p overexpression using mimics inhibited cell migration and invasion compared with those of negative control (Fig. 3d and e), consistently with the functional effects of AFAP1-AS1 knockdown. Moreover, transfection with miR-423-5p inhibitors had a consequence similar to the function of AFAP1-AS1 overexpression in 5-8F and HNE2 cells (Fig. 3f and g). Taken together, these results indicated that AFAP1-AS1 might promote NPC cell migration and invasion via mutually regulated with miR-423-5p.

AFAP1-AS1 regulates the Rho/Rac signaling through miR-423-5p

We previously used a proteomics strategy to determine that AFAP1-AS1 regulates the expression of several small GTPase family members, and modulates cancer cell metastasis via regulation of actin filament integrity [44]. However, the mechanism by which AFAP1-AS1 regulates the GTPase family members expression remains unknown. Since AFAP1-AS1 interacts with miR-423-5p, we hypothesized that AFAP1-AS1 might act as a ceRNA to regulate the GTPase family members through miR-423-5p.

We first confirmed that AFAP1-AS1 regulates the small GTPase family members at the mRNA level. After AFAP1-AS1 knockdown (siRNA) or overexpression in 5-8F and HNE2 cells, multiple members of the Rho/Rac pathway were affected at the mRNA level, as determined by real-time PCR (Fig. 4a), and the expression of these molecules was also altered at the protein level, as revealed by western blotting (Additional file 2: Figure S2); these results were consistent with those of our previous proteomics analysis [44]. Similar results were obtained in 5-8F and HNE2 cells after transfection with miR-423-5p mimics and inhibitors (Fig. 4b and c). miR-423-5p regulated the expression of numerous molecules, including RAB10, RAB11A, RAC2, PFN1, RHOA, RAC1, RHOC, LASP1, and RAB11B, in the Rho/Rac signaling pathway at both the mRNA (Fig. 4b) and protein levels (Fig. 4c), suggesting that AFAP1-AS1 may regulate the Rho/Rac signaling via miR-423-5p.

Fig. 4
figure 4

miR-423-5p regulates the small GTPase Rho/Rac signaling pathway through AFAP1-AS1. a. Many molecules in the Rho/Rac signaling pathway, including RAB10, RAB11A, RAC2, PFN1, RHOA, RAC1, RHOC, LASP1 and RAB11B, were regulated at the mRNA level in 5-8F and HNE2 cells by AFAP1-AS1 overexpression or knockdown. b. Many molecules in the Rho/Rac signaling pathway, including RAB10, RAB11A, RAC2, PFN1, RHOA, RAC1, RHOC, LASP1 and RAB11B, were regulated at the mRNA level in 5-8F and HNE2 cells by overexpression or knockdown of miR-423-5p. c. Expression of Rho/Rac proteins, including RAB10, RAB11A, RAC2, PFN1, RHOA, RAC1, RHOC, LASP1 and RAB11B, was examined at the protein level in 5-8F and HNE2 cells after overexpression or knockdown of miR-423-5p.*, p < 0.05; **, p < 0.01; ***, p < 0.001

Full size image

miR-423-5p regulates the Rho/Rac signaling by directly targeting the 3′-UTRs of RAB11B and LASP1, but not that of RAC1

As shown in Fig. 4, we found that the expression of RAC1, RHOC, LASP1, and RAB11B was reduced by miR-423-5p mimics and induced by miR-423-5p inhibitors at both the mRNA and protein levels. We next investigated whether miR-423-5p directly targeted these molecules to regulate the Rho/Rac signaling pathway. First, the 3′-UTR sequences of these genes were analyzed using the TargetScan software. Interestingly, the 3′-UTRs of RAC1, LASP1, and RAB11B contained numerous elements exactly complementary to the miR-423-5p seed region. Next, the vectors containing the wild type or mutant (mutations targeting the seed miR-423-5p sequence) RAB11B, LASP1, and RAC1 3′-UTR sequences were constructed, and luciferase analysis showed that miR-423-5p mimics reduced luciferase activity in 5-8F and HNE2 when transfected with vectors containing the wild type RAB11B (Fig. 5a and b) and LASP1 (Fig. 5c and d) 3′-UTR sequences, but not in 5-8F and HNE2 transfected with the wild type RAC1 3′-UTR (pMIR-WT) (Additional file 2: Figure S3). The effect of miR-423-5p mimics on the luciferase activity of the vectors containing the mutant RAB11B and LASP1 sequence was abolished in 5-8F and HNE2 cells (Fig. 5). Transfection of miR-423-5p inhibitors in these cells had the opposite effect on the luciferase activity of the RAB11B and LASP1 3′-UTR reporter constructs (Fig. 5). These results suggested that miR-423-5p regulated the Rho/Rac signaling through direct binding the 3′-UTRs of RAB11B and LASP1.

Fig. 5
figure 5

miR-423-5p directly targets the 3′-UTRs of RAB11B and LASP1. a and c. Schematic diagrams of miR-423-5p binding sites in the 3′-UTRs of the RAB11B (a) and LASP1 (c) mRNAs predicted using RNAhybrid software. b and d. Luciferase activity was measured in 5-8F and HNE2 cells after cotransfection with miR-423-5p mimics or inhibitors and luciferase reporter constructs containing either wild-type or mutated miR-423-5p binding sites from the RAB11B (b) or LASP1 (d) 3′-UTRs. miR-423-5p mimics attenuated luciferase activity from RAB11B-WT and LASP1-WT constructs, but not from RAB11B-mutant and LASP1-mutant constructs. *, p < 0.05; **, p < 0.01; ***, p < 0.001

Full size image

AFAP1-AS1 acts AS a ceRNA regulating FOSL2 expression in NPC

The ceRNA hypothesis posits that specific lncRNA molecules function as sinks for pools of active miRNAs, functionally liberating mRNA transcripts targeted by certain miRNAs. Therefore, the expression of lncRNAs that act as ceRNAs is usually positively correlated with the expression levels of their affected mRNAs. To determine which mRNAs are regulated by AFAP1-AS1 through miR-423-5p via ceRNA, we first performed bioinformatics analysis to predict targets of miR-423-5p. The NPC gene expression omnibus (GEO) datasets were screened to identify mRNAs whose expression levels were positively correlated with those of AFAP1-AS1. The expression of FOSL2 was positively correlated with that of AFAP1-AS1 [53] (Additional file 2: Figure S4). Real-time PCR showed that FOSL2 was also overexpressed in those 32 NPC clinical samples compared with nontumor nasopharyngeal epithelial samples and tightly positively associated with the TNM stages, the T stages, and lymphoma metastasis in patients with NPC (Fig. 6a), positively correlated with the AFAP1-AS1 expression (Fig. 6b) while negatively correlated with miR-423-5p (Fig. 6c). The 3′-UTRs of FOSL2 were also predicted with several potential binding sites complementary to the miR-423-5p seed region (Fig. 6d). Transfection of miR-423-5p mimics or inhibitors into 5-8F and HNE2 cells reduced or induced the mRNA and protein levels of FOSL2, respectively (Fig. 6e). Luciferase assays also showed that miR-423-5p mimics decreased the luciferase activity of the wild type FOSL2 3′-UTR sequence (pMIR-WT), while no effect was observed on the luciferase activity from vectors containing the mutant miR-423-5p binding sites in 5-8F and HNE2 cells. Transfection with miR-423-5p inhibitors had the opposite effect on the luciferase activity generated from the FOSL2 3′-UTR (Fig. 6f).

Fig. 6
figure 6

AFAP1-AS1 acts as a ceRNA to regulate FOSL2 gene expression through miR-423-5p. a. The expression of FOSL2 and its correlation with the TNM stages, lymphoma metastasis, and T stages in the same 32 NPC tissues and 13 nontumor tissues as indicated. b. The expression of FOSL2 was tightly positively correlated with that of AFAP1-AS1 in 32 NPC tissues and 13 nontumor tissues as indicated. c. The expression of FOSL2 was tightly negatively correlated with that of miR-423-5p in 32 NPC tissues and 13 nontumor tissues as indicated. d. Prediction of miR-423-5p binding sites in the FOSL2 transcript. The red nucleotides are complementary to the miR-423-5p seed sequences. e. The expression of FOSL2 was regulated by miR-423-5p at the mRNA and protein levels after transfection of miR-423-5p mimics, miR-423-5p inhibitors, or negative control in 5-8F and HNE2 cells. f. Luciferase activity was measured in 5-8F and HNE2 cells cotransfected with miR-423-5p inhibitors, miR-423-5p mimics, or negative control, and luciferase reporters containing WT or MT FOSL2 sequences, as indicated. g. The expression of FOSL2 was examined at the mRNA and protein levels in 5-8F and HNE2 cells after transfection with AFAP1-AS1 overexpression vector, or siAFAP1-AS1

Full size image

We hypothesized that, as a ceRNA, AFAP1-AS1 competed with FOSL2 to bind miR-423-5p; therefore, we determined whether there was specific interplay among AFAP1-AS1, miR-423-5p, and FOSL2. We monitored both the mRNA and protein levels of FOSL2 after AFAP1-AS1 overexpression and knockdown in 5-8F and HNE2 cells. As expected, AFAP1-AS1 overexpression increased both the mRNA and protein levels of FOSL2, and siAFAP1-AS1 transfection reduced FOSL2 expression (Fig. 6g). Overall, these results suggested that the role of AFAP1-AS1 in modulating FOSL2 expression is mediated by its competitive binding with miR-423-5p in 5-8F and HNE2 cells. Together, these data indicated that AFAP1-AS1 functions as a ceRNA by competitively binding miR-423-5p, thereby relieving the suppression of FOSL2 expression by miR-423-5p in NPC.

FOSL2 accelerates NPC cell migration and invasion

To investigate the function of FOSL2 in NPC, a FOSL2 overexpression vector, including three Flag tags, was constructed and its expression confirmed in 5-8F and HNE2 cells (Fig. 7a). Wound healing and transwell assays demonstrated that overexpression of FOSL2 accelerated cell migration and invasion compared to those in negative control (Fig. 7b). Moreover, FOSL2 knockdown by siRNA (Fig. 7c) had the opposite effect (Fig. 7d). Taken together, these results indicated that FOSL2 induces NPC cell migration and invasion.

Fig. 7
figure 7

Functional analysis of FOSL2 in NPC cells. a. FOSL2 mRNA and protein levels were detected in 5-8F and HNE2 cells after transfection with the FOSL2 overexpression vector (FOSL2) or the empty vector (NC) by qRT-PCR and western blotting. b. Wound healing and transwell assays of 5-8F and HNE2 cells were conducted after transfection with pENTR-FOSL2 or pENTR empty vector. The relative ratio of wound closure per field is shown on the right. Scale bars, 100 μm. c. The expression of FOSL2 was examined at the mRNA and protein levels by qRT-PCR and western blotting in 5-8F and HNE2 cells after transfection with siFOSL2 or scrambled negative control siRNA. d. Wound healing and transwell assays were performed in 5-8F and HNE2 cells after treatment with siFOSL2 or scrambled siRNA control. The relative ratio of invasive cells per field is shown on the right. Scale bars, 100 μm. *, p < 0.05; **, p < 0.01; ***, p < 0.001

Full size image

FOSL2 activates transcription of LASP1 by binding its promoter

FOSL2 is a member of the Fos family of transcription factors that heterodimerize with the Jun family members to form the AP-1 complex, which is able to activate or suppress the expression of many genes involved in tumor growth and progression [54]. As a transcription factor, FOSL2 could modulate the expression of genes in the Rho/Rac pathway. Therefore, we determined whether FOSL2 could transcriptionally activate downstream genes in the Rho/Rac signaling pathway. Bioinformatics analysis indicated a potential FOSL2 binding site in the LASP1 promoter positioned at the − 322 to − 312 bp upstream of the transcription start site (Fig. 8a). Next, luciferase reporter constructs containing the wild-type and mutant LASP1 promoter sequences, including the potential FOSL2 binding site, were constructed (Fig. 8a). An AP-1 luciferase vector, containing multiple conserved AP1-binding sites for sensitive detection of the AP1 transcriptional activity, was used as a positive control. As shown in Fig. 8b, FOSL2 activated transcription from only the wild-type, but not the mutated LASP1 promoter in these two cell lines. AFAP1-AS1 also participated in regulation of the transcription activity of the AP-1 complex containing FOSL2. Overexpression of AFAP1-AS1 dramatically increased and knockdown decreased the AP-1 transcriptional activity from a synthetic promoter including the AP-1 consensus-binding site (pAP1-TA-luc) (Fig. 8c). FOSL2 knockdown also reduced LASP1 and AFAP1-AS1 expression (Fig. 8d). These results suggest that AFAP1-AS1 may regulate the Rho/Rac signaling pathway via the AP-1 transcriptional complex through modulating FOSL2 activity by competition with miR-423-5p.

Fig. 8
figure 8

FOSL2 modulates the transcription of LASP1 through binding its promoter. a. Prediction of potential FOSL2 binding sites in the LASP1 promoter. The nucleotides that are consensus FOSL2 binding sequences (WT) and mutated sequences (MT) are indicated. b. The luciferase activity of the LASP1 promoter and the AP-1 transcription factor was measured in 5-8F and HNE2 cells cotransfected with the FOSL2 overexpression vector or siFOSL2 and luciferase reporters containing the AP-1 luciferase plasmid (pAP1), or the WT or MT LASP1 promoter, as indicated. Overexpression of FOSL2 significantly induced the LASP1 and AP-1 transcription activity. *p < 0.05, **p < 0.01, compared with normal control (NC) group. c. The AP-1 transcription activity was examined through transfection of the AFAP1-AS1 overexpression vector or siAFAP1-AS1 and the AP-1 reporter plasmid containing the AP-1 consensus sequence. AP-1 transcriptional activity was induced through overexpressing AFAP1-AS1 or reduced after knockdown of AFAP1-AS1. d. The expression of LASP1 and AFAP1-AS1 was regulated by FOSL2 after knockdown or overexpression of FOSL2

Full size image

The function of AFAP1-AS1, miR-423-5p, and FOSL2 in NPC metastasis in vivo

The function of AFAP1-AS1, miR-423-5p, and FOSL2 in metastasis was confirmed in nude mice. AFAP1-AS1-, miR-423-5p-, and FOSL2-overexpressing 5-8F cell lines were used in this study. The cells were injected into the tail veins of nude mice; 5-8F-mock served as the control. After 60 days, the mice were sacrificed, and the lungs, livers, and lymph nodes were observed. Compared with the control, metastasis to the lungs of 5-8F cells transfected with AFAP1-AS1 and FOSL2 significantly increased, while metastasis of 5-8F transfected cells with miR-423-5p mimics were reduced (Fig. 9). These results indicated that AFAP1-AS1 and FOSL2 enhanced NPC metastasis and miR-423-5p reduced its metastasis.

Fig. 9
figure 9

The function of AFAP1-AS1, 423-5p, and FOSL2 in the metastasis of nasopharyngeal carcinoma 5-8F cells in vivo. a. Forty nude mice were randomly divided into 4 groups with 10 mice per group. Three experimental groups were injected with 5-8F cells transfected with the AFAP1-AS1 overexpression plasmid, miR-423-5p mimics, or the FOSL2 overexpression plasmid through the tail veins, and the control group was injected with 5-8F mock cells (NC). After 8 weeks, the nude mice were sacrificed, and the metastatic tumors were observed (upper panel). Representative lung tissue and metastatic nodes are indicated by arrows (lower panel). b. Metastatic nodes per lung in each group

Full size image

Discussion

A ceRNA hypothesis was proposed by Salmena et al. in 2011 [55]. The theory explains why mRNA, pseudogenes, lncRNA, and other molecules share miRNA response elements (MREs) and bind to identical miRNAs competitively to affect cell status [56]. miRNAs and MREs are two key elements in this hypothesis; miRNAs bind not only to MREs in mRNAs but also to pseudogenes and lncRNAs, influencing mRNA and lncRNA expression levels posttranscriptionally. For example, the tumor suppressor gene phosphatase and tensin homolog (PTEN), a negative regulator of the oncogenic phosphoinositide 3-kinase/Akt signaling pathway, provides the best evidence for disease-associated ceRNAs [57]. PTEN pseudogene 1 (PTENP1) can increase PTEN expression by binding to several miRNAs to suppress proliferation of cancer cells [58, 59]. Conversely, when PTENP1 is downregulated, more miRNAs are available to inhibit PTEN expression, facilitating tumor growth. Both PTEN and PTENP1 are controlled by ceRNA circuitry in many cancers [60]. LncRNAs interact with miRNAs and mRNAs as components of the cellular RNA language, which comprises a complex, finely controlled network.

AFAP1-AS1 is highly expressed and tightly associated with tumor progression in many cancers including NPC [43]. We previously showed that AFAP1-AS1 was associated with poor prognosis in NPC and it promoted cell migration and invasion via regulation of actin filament integrity and the Rho/Rac signaling [44]. In this study, we explored the detailed molecular mechanism of AFAP1-AS1 as a ceRNA in regulation of NPC cell migration and invasion. We hypothesized that AFAP1-AS1 may act as a ceRNA to regulate the Rho/Rac pathway; therefore, we employed bioinformatics methods to predict potential miRNAs regulated by AFAP1-AS1. miR-423-5p was the only miRNA predicted by all four tools used for these analyses and had the lowest minimum free energy, suggesting that AFAP1-AS1 is likely a direct target of miR-423-5p. Many reports have identified miR-423-5p as an oncogene in various cancers, including gastric cancer and hepatocellular carcinoma [61, 62]. In this study, we found that miR-423-5p was low-expressed in NPC and its expression was negatively correlated with the clinical TNM stages in NPC tumors. Overexpression of miR-423-5p inhibited NPC cells migration and invasion, and inhibition of miR-423-5p produced the opposite phenotype. The function of miR423-5p had an opposite effect to those of AFAP1-AS1 on migration and invasion. Luciferase assays confirmed that miR-423-5p regulated the 3’-UTR of AFAP1-AS1. These results suggested that AFAP1-AS1 may regulate downstream genes through binding of miR-423-5p, and that miR-423-5p may have a role as a tumor suppressor gene through its effects on different downstream genes in NPC.

We previously determined by the proteomic analysis that expression levels of at least 209 proteins were significantly altered after AFAP1-AS1 knockdown in NPC cells. Among these, the expression levels of many proteins involved in regulation of cytoskeletal dynamics were confirmed as significantly altered using liquid chromatography-tandem mass spectrometry (LC-MS/MS) after AFAP1-AS1 knockdown, including those in the small GTPase Rho/Rac signaling pathway: RAB10, RAB11A, RAC2, PFN1, RHOA, RAC1, RHOC, LASP1, and RAB11B [44]. The Rho/Rac signaling pathway is a well-established regulator of the actin cytoskeleton, as highlighted by the RAC1 dependence of membrane ruffling and RHOA-induced stress-fiber formation [63]. In this study, we focused on the role of AFAP1-AS1 as a noncoding RNA in regulation of the expression of these proteins. We investigated whether AFAP1-AS1 acted as a ceRNA through miR-423-5p to regulate the Rho/Rac pathway. miR-423-5p inhibited the expression of RAC1, RHOC, LASP1, and RAB11B and increased that of other molecules, including RAB10, RAB11A, RAC2, PFN1, and RHOA, consistently with the results after AFAP1-AS1 inhibition or overexpression [26]. These results implied that AFAP1-AS1 regulated the Rho/Rac signaling pathway through miR-423-5p. As a microRNA, miR-423-5p may directly regulate expression or translation of its target genes; therefore, we first examined whether some molecules including RAC1, RAB11B, RHOC, and LASP1 in the Rho/Rac pathway were direct target genes of miR-423-5p, since their expression levels were reduced by the specific miR-423-5p mimics. Bioinformatics analysis predicted the RAB11B and LASP1 genes as targets of miR-423-5p. Further experiments confirmed that miR-423-5p directly targeted these two genes and that AFAP1-AS1 acted as a ceRNA of RAB11B and LASP1, regulating their expression by competitively binding miR-423-5p, thus affecting the migration and invasion of NPC. As we know, LASP1 is an actin-binding phosphoprotein that is overexpressed in several cancers [64,65,66] and it is a cAMP- and cGMP-dependent signaling protein which binds to the actin cytoskeleton at extensions of the cell membrane [67, 68]. RAB11B belongs to the Rab family and regulates exocytotic and endocytotic pathways [69]. Our experiments confirmed the hypothesis that AFAP1-AS1 acts as a ceRNA to regulate the expression of key genes, such as LASP1 and RAB11B, by competitively binding miR-423-5p, resulting in dysregulation of the Rho/Rac1 signaling pathway and migration and invasion of human NPC cells [70,71,72].

The expression of RAB10, RAB11A, RAC2, PFN1, and RHOA were upregulated in 5-8F and HNE2 cells transfected with miR-423-5p mimics, which is consistent with the results of experiments using siAFAP1-AS1 and suggests that AFAP1-AS1 and miR-423-5p are tightly associated with the Rho/Rac signaling pathway. miR-423-5p may also indirectly regulate the expression of these proteins through its effects on other molecules. To identify other direct targets of miR-423-5p, we screened genes whose expression levels were highly correlated with those of AFAP1-AS1 in NPC tissues based on the results of previous microarray analyses and the ceRNA theory. FOSL2, a member of the Fos family [73], was analyzed using various prediction tools and found to contain several potential miR-423-5p binding sites in its 3′-UTR, while the expression of AFAP1-AS1 and FOSL2 was significantly correlated in NPC GEO datasets [53]. FOSL2 is a member of AP-1 transcription factor complexes. FOS and Jun protein family members can form homo- or heterodimers and bind to the promoters of specific genes to promote or inhibit their transcription in combination with other transcription and regulatory factors. In this study, we found that FOSL2 could regulate the LASP1 transcription by binding its promoter, suggesting that AFAP1-AS1 acts as a ceRNA in regulation of FOSL2 and the AP-1 transcription factor activation, thereby affecting the expression of small GTPase molecules. Whether AFAP1-AS1 also regulates the expression of other downstream genes through FOSL2 is worthy of further investigation.

In this study, we confirmed that AFAP1-AS1 functions as a ceRNA by adsorption of miR-423-5p and verified that LASP1, RAB11B, and FOSL2 are downstream target genes of miR-423-5p (Additional file 2: Figure S5). However, miRNAs can target multiple genes, and there may be other protein-encoding genes regulated by miR-423-5p among the 209 proteins regulated by AFAP1-AS1 in NPC cells using our previous proteomic approach; this is also worthy of further investigation.

Conclusions

AFAP1-AS1 may regulate a complex and sophisticated gene network through miR-423-5p as a ceRNA. Identification of the ceRNA network involving AFAP1-AS1 may contribute to a better understanding of NPC carcinogenesis and tumor progression. Our data also suggest that targeting AFAP1-AS1 and/or miR-423-5p have potential as a new therapeutic strategy and that these molecules are potential biomarkers in NPC.

Abbreviations

AFAP1-AS1 :

Actin filament-associated protein 1 antisense RNA 1

ceRNA:

Competing endogenous RNA

FBS:

Fetal bovine serum

GEO:

Gene expression omnibus

GEP:

Gene expression profiling

LC-MS/MS:

Liquid chromatography-tandem mass spectrometry

lncRNA:

Long Noncoding RNA

miRNAs:

MicroRNAs

MREs:

MiRNA response elements

MT:

Mutant

NC:

Negative control

NPC:

Nasopharyngeal carcinoma

PTEN:

Phosphatase and tensin homolog

PTENP1:

PTEN pseudogene 1

RT-PCR:

Reverse transcription PCR

SD:

Standard deviation

WT:

Wild-type

References

  1. Xiong W, Zeng ZY, Xia JH, Xia K, Shen SR, Li XL, Hu DX, Tan C, Xiang JJ, Zhou J, et al. A susceptibility locus at chromosome 3p21 linked to familial nasopharyngeal carcinoma. Cancer Res. 2004;64(6):1972–4.

    Article  CAS  Google Scholar 

  2. Zeng Z, Huang H, Zhang W, Xiang B, Zhou M, Zhou Y, Ma J, Yi M, Li X, Li X, et al. Nasopharyngeal carcinoma: advances in genomics and molecular genetics. Sci China Life Sci. 2011;54(10):966–75.

    Article  Google Scholar 

  3. Yi M, Cai J, Li J, Chen S, Zeng Z, Peng Q, Ban Y, Zhou Y, Li X, Xiong W, et al. Rediscovery of NF-kappaB signaling in nasopharyngeal carcinoma: how genetic defects of NF-kappaB pathway interplay with EBV in driving oncogenesis? J Cell Physiol. 2018;233(8):5537–49.

    Article  CAS  Google Scholar 

  4. Tu C, Zeng Z, Qi P, Li X, Guo C, Xiong F, Xiang B, Zhou M, Liao Q, Yu J, et al. Identification of genomic alterations in nasopharyngeal carcinoma and nasopharyngeal carcinoma-derived Epstein-Barr virus by whole genome sequencing. Carcinogenesis; 2018. https://doi.org/10.1093/carcin/bgy108. [Epub ahead of print]

  5. Wei F, Wu Y, Tang L, Xiong F, Guo C, Li X, Zhou M, Xiang B, Li X, Li G, et al. Trend analysis of cancer incidence and mortality in China. Sci China Life Sci. 2017;60(11):1271–5.

    Article  Google Scholar 

  6. Cai L, Ye Y, Jiang Q, Chen Y, Lyu X, Li J, Wang S, Liu T, Cai H, Yao K, et al. Epstein-Barr virus-encoded microRNA BART1 induces tumour metastasis by regulating PTEN-dependent pathways in nasopharyngeal carcinoma. Nat Commun. 2015;6:7353.

    Article  Google Scholar 

  7. Zou G, Ren B, Liu Y, Fu Y, Chen P, Li X, Luo S, He J, Gao G, Zeng Z, et al. INHBB suppresses anoikis resistance and migration through TGF-β signaling pathway in nasopharyngeal carcinoma. Cancer Sci; 2018. https://doi.org/10.1111/cas.13780. [Epub ahead of print]

  8. Zhao M, Luo R, Liu Y, Gao L, Fu Z, Fu Q, Luo X, Chen Y, Deng X, Liang Z, et al. miR-3188 regulates nasopharyngeal carcinoma proliferation and chemosensitivity through a FOXO1-modulated positive feedback loop with mTOR-p-PI3K/AKT-c-JUN. Nat Commun. 2016;7:11309.

    Article  CAS  Google Scholar 

  9. Song Y, Li X, Zeng Z, Li Q, Gong Z, Liao Q, Li X, Chen P, Xiang B, Zhang W, et al. Epstein-Barr virus encoded miR-BART11 promotes inflammation-induced carcinogenesis by targeting FOXP1. Oncotarget. 2016;7(24):36783–99.

    PubMed  PubMed Central  Google Scholar 

  10. Yan Q, Zeng Z, Gong Z, Zhang W, Li X, He B, Song Y, Li Q, Zeng Y, Liao Q, et al. EBV-miR-BART10-3p facilitates epithelial-mesenchymal transition and promotes metastasis of nasopharyngeal carcinoma by targeting BTRC. Oncotarget. 2015;6(39):41766–82.

    Article  Google Scholar 

  11. Zeng Z, Huang H, Huang L, Sun M, Yan Q, Song Y, Wei F, Bo H, Gong Z, Zeng Y, et al. Regulation network and expression profiles of Epstein-Barr virus-encoded microRNAs and their potential target host genes in nasopharyngeal carcinomas. Sci China Life Sci. 2014;57(3):315–26.

    Article  CAS  Google Scholar 

  12. He B, Li W, Wu Y, Wei F, Gong Z, Bo H, Wang Y, Li X, Xiang B, Guo C, et al. Epstein-Barr virus-encoded miR-BART6-3p inhibits cancer cell metastasis and invasion by targeting long non-coding RNA LOC553103. Cell Death Dis. 2016;7(9):e2353.

    Article  CAS  Google Scholar 

  13. Tu C, Zeng Z, Qi P, Li X, Yu Z, Guo C, Xiong F, Xiang B, Zhou M, Gong Z, et al. Genome-wide analysis of 18 Epstein-Barr viruses isolated from primary nasopharyngeal carcinoma biopsy specimens. J Virol. 2017;91(17). https://doi.org/10.1128/JVI.00301-17.

  14. Fan C, Tang Y, Wang J, Xiong F, Guo C, Wang Y, Xiang B, Zhou M, Li X, Wu X, et al. The emerging role of Epstein-Barr virus encoded microRNAs in nasopharyngeal carcinoma. J Cancer. 2018;9(16):2852–64.

    Article  Google Scholar 

  15. Zeng Z, Fan S, Zhang X, Li S, Zhou M, Xiong W, Tan M, Zhang W, Li G. Epstein-Barr virus-encoded small RNA 1 (EBER-1) could predict good prognosis in nasopharyngeal carcinoma. Clin trans oncol. 2016;18(2):206–11.

    Article  CAS  Google Scholar 

  16. Zeng Z, Zhou Y, Zhang W, Li X, Xiong W, Liu H, Fan S, Qian J, Wang L, Li Z, et al. Family-based association analysis validates chromosome 3p21 as a putative nasopharyngeal carcinoma susceptibility locus. Genet med. 2006;8(3):156–60.

    Article  CAS  Google Scholar 

  17. Wei F, Tang L, He Y, Wu Y, Shi L, Xiong F, Gong Z, Guo C, Li X, Liao Q, et al. BPIFB1 (LPLUNC1) inhibits radioresistance in nasopharyngeal carcinoma by inhibiting VTN expression. Cell Death Dis. 2018;9(4):432.

    Article  Google Scholar 

  18. He Y, Jing Y, Wei F, Tang Y, Yang L, Luo J, Yang P, Ni Q, Pang J, Liao Q, et al. Long non-coding RNA PVT1 predicts poor prognosis and induces radioresistance by regulating DNA repair and cell apoptosis in nasopharyngeal carcinoma. Cell Death Dis. 2018;9(2):235.

    Article  Google Scholar 

  19. Tang L, Wei F, Wu Y, He Y, Shi L, Xiong F, Gong Z, Guo C, Li X, Deng H, et al. Role of metabolism in cancer cell radioresistance and radiosensitization methods. J exper clin cancer res. 2018;37(1):87.

    Article  Google Scholar 

  20. Yang Y, Liao Q, Wei F, Li X, Zhang W, Fan S, Shi L, Li X, Gong Z, Ma J, et al. LPLUNC1 inhibits nasopharyngeal carcinoma cell growth via down-regulation of the MAP kinase and cyclin D1/E2F pathways. PLoS One. 2013;8(5):e62869.

    Article  CAS  Google Scholar 

  21. Wei F, Wu Y, Tang L, He Y, Shi L, Xiong F, Gong Z, Guo C, Li X, Liao Q, et al. BPIFB1 (LPLUNC1) inhibits migration and invasion of nasopharyngeal carcinoma by interacting with VTN and VIM. Br J Cancer. 2018;118(2):233–47.

    Article  CAS  Google Scholar 

  22. Wang W, Yi M, Zhang R, Li J, Chen S, Cai J, Zeng Z, Li X, Xiong W, Wang L, et al. Vimentin is a crucial target for anti-metastasis therapy of nasopharyngeal carcinoma. Mol Cell Biochem. 2018;438(1–2):47–57.

    Article  CAS  Google Scholar 

  23. Yang L, Tang Y, Xiong F, He Y, Wei F, Zhang S, Guo C, Xiang B, Zhou M, Xie N, et al. LncRNAs regulate cancer metastasis via binding to functional proteins. Oncotarget. 2018;9(1):1426–43.

    PubMed  Google Scholar 

  24. Zhou Y, Liao Q, Li X, Wang H, Wei F, Chen J, Yang J, Zeng Z, Guo X, Chen P, et al. HYOU1, regulated by LPLUNC1, is up-regulated in nasopharyngeal carcinoma and associated with poor prognosis. J Cancer. 2016;7(4):367–76.

    Article  CAS  Google Scholar 

  25. Wang JP, Tang YY, Fan CM, Guo C, Zhou YH, Li Z, Li XL, Li Y, Li GY, Xiong W, et al. The role of exosomal non-coding RNAs in cancer metastasis. Oncotarget. 2018;9(15):12487–502.

    PubMed  Google Scholar 

  26. Tang Y, He Y, Zhang P, Wang J, Fan C, Yang L, Xiong F, Zhang S, Gong Z, Nie S, et al. LncRNAs regulate the cytoskeleton and related rho/ROCK signaling in cancer metastasis. Mol Cancer. 2018;17(1):77.

    Article  Google Scholar 

  27. Yu J, Liu Y, Guo C, Zhang S, Gong Z, Tang Y, Yang L, He Y, Lian Y, Li X, et al. Upregulated long non-coding RNA LINC00152 expression is associated with progression and poor prognosis of tongue squamous cell carcinoma. J Cancer. 2017;8(4):523–30.

    Article  CAS  Google Scholar 

  28. Yu J, Liu Y, Gong Z, Zhang S, Guo C, Li X, Tang Y, Yang L, He Y, Wei F, et al. Overexpression long non-coding RNA LINC00673 is associated with poor prognosis and promotes invasion and metastasis in tongue squamous cell carcinoma. Oncotarget. 2017;8(10):16621–32.

    Article  Google Scholar 

  29. Yang L, Tang Y, He Y, Wang Y, Lian Y, Xiong F, Shi L, Zhang S, Gong Z, Zhou Y, et al. High expression of LINC01420 indicates an unfavorable prognosis and modulates cell migration and invasion in nasopharyngeal carcinoma. J Cancer. 2017;8(1):97–103.

    Article  CAS  Google Scholar 

  30. Fan C, Tang Y, Wang J, Xiong F, Guo C, Wang Y, Zhang S, Gong Z, Wei F, Yang L, et al. Role of long non-coding RNAs in glucose metabolism in cancer. Mol Cancer. 2017;16(1):130.

    Article  Google Scholar 

  31. Wang Y, Xue D, Li Y, Pan X, Zhang X, Kuang B, Zhou M, Li X, Xiong W, Li G, et al. The long noncoding RNA MALAT-1 is a novel biomarker in various cancers: a meta-analysis based on the GEO database and literature. J Cancer. 2016;7(8):991–1001.

    Article  CAS  Google Scholar 

  32. Gong Z, Zhang S, Zeng Z, Wu H, Yang Q, Xiong F, Shi L, Yang J, Zhang W, Zhou Y, et al. LOC401317, a p53-regulated long non-coding RNA, inhibits cell proliferation and induces apoptosis in the nasopharyngeal carcinoma cell line HNE2. PLoS One. 2014;9(11):e110674.

    Article  Google Scholar 

  33. Zhang W, Huang C, Gong Z, Zhao Y, Tang K, Li X, Fan S, Shi L, Li X, Zhang P, et al. Expression of LINC00312, a long intergenic non-coding RNA, is negatively correlated with tumor size but positively correlated with lymph node metastasis in nasopharyngeal carcinoma. J Mol Histol. 2013;44(5):545–54.

    Article  CAS  Google Scholar 

  34. Zhou R, Wu Y, Wang W, Su W, Liu Y, Wang Y, Fan C, Li X, Li G, Li Y, et al. Circular RNAs (circRNAs) in cancer. Cancer Lett. 2018;425:134–42.

    Article  CAS  Google Scholar 

  35. Zhong Y, Du Y, Yang X, Mo Y, Fan C, Xiong F, Ren D, Ye X, Li C, Wang Y, et al. Circular RNAs function as ceRNAs to regulate and control human cancer progression. Mol Cancer. 2018;17(1):79.

    Article  Google Scholar 

  36. Wang Y, Mo Y, Gong Z, Yang X, Yang M, Zhang S, Xiong F, Xiang B, Zhou M, Liao Q, et al. Circular RNAs in human cancer. Mol Cancer. 2017;16(1):25.

    Article  CAS  Google Scholar 

  37. He R, Liu P, Xie X, Zhou Y, Liao Q, Xiong W, Li X, Li G, Zeng Z, Tang H. circGFRA1 and GFRA1 act as ceRNAs in triple negative breast cancer by regulating miR-34a. J Exp Clin Cancer Res. 2017;36(1):145.

    Article  Google Scholar 

  38. Wu W, Bhagat TD, Yang X, Song JH, Cheng Y, Agarwal R, Abraham JM, Ibrahim S, Bartenstein M, Hussain Z, et al. Hypomethylation of noncoding DNA regions and overexpression of the long noncoding RNA, AFAP1-AS1, in Barrett's esophagus and esophageal adenocarcinoma. Gastroenterology. 2013;144(5):956–66 e954.

    Article  CAS  Google Scholar 

  39. Deng J, Liang Y, Liu C, He S, Wang S. The up-regulation of long non-coding RNA AFAP1-AS1 is associated with the poor prognosis of NSCLC patients. Biomed pharmacot. 2015;75:8–11.

    Article  CAS  Google Scholar 

  40. Lu X, Zhou C, Li R, Liang Z, Zhai W, Zhao L, Zhang S. Critical role for the long non-coding RNA AFAP1-AS1 in the proliferation and metastasis of hepatocellular carcinoma. Tumour biol. 2016;37(7):9699–707.

    Article  CAS  Google Scholar 

  41. Zeng Z, Bo H, Gong Z, Lian Y, Li X, Li X, Zhang W, Deng H, Zhou M, Peng S, et al. AFAP1-AS1, a long noncoding RNA upregulated in lung cancer and promotes invasion and metastasis. Tumour biol. 2016;37(1):729–37.

    Article  CAS  Google Scholar 

  42. Fu XL, Liu DJ, Yan TT, Yang JY, Yang MW, Li J, Huo YM, Liu W, Zhang JF, Hong J, et al. Analysis of long non-coding RNA expression profiles in pancreatic ductal adenocarcinoma. Sci Rep. 2016;6:33535.

    Article  CAS  Google Scholar 

  43. Wang Y, Mo Y, Yang X, Zhou R, Wu Z, He Y, Yang X, Zhong Y, Du Y, Zhou H, et al. Long non-coding RNA AFAP1-AS1 is a novel biomarker in various cancers: a systematic review and meta-analysis based on the literature and GEO datasets. Oncotarget. 2017;8(60):102346–60.

    PubMed  PubMed Central  Google Scholar 

  44. Bo H, Gong Z, Zhang W, Li X, Zeng Y, Liao Q, Chen P, Shi L, Lian Y, Jing Y, et al. Upregulated long non-coding RNA AFAP1-AS1 expression is associated with progression and poor prognosis of nasopharyngeal carcinoma. Oncotarget. 2015;6(24):20404–18.

    Article  Google Scholar 

  45. Tang Y, He Y, Shi L, Yang L, Wang J, Lian Y, Fan C, Zhang P, Guo C, Zhang S, et al. Co-expression of AFAP1-AS1 and PD-1 predicts poor prognosis in nasopharyngeal carcinoma. Oncotarget. 2017;8(24):39001–11.

    PubMed  PubMed Central  Google Scholar 

  46. Cesana M, Cacchiarelli D, Legnini I, Santini T, Sthandier O, Chinappi M, Tramontano A, Bozzoni I. A long noncoding RNA controls muscle differentiation by functioning as a competing endogenous RNA. Cell. 2011;147(2):358–69.

    Article  CAS  Google Scholar 

  47. Tay Y, Kats L, Salmena L, Weiss D, Tan SM, Ala U, Karreth F, Poliseno L, Provero P, Di Cunto F, et al. Coding-independent regulation of the tumor suppressor PTEN by competing endogenous mRNAs. Cell. 2011;147(2):344–57.

    Article  CAS  Google Scholar 

  48. Lian Y, Li X, Tang Y, Yang L, Li X, Xiong W, Li G, Zeng Z. Long non-coding RNAs function as competing endogenous RNAs to regulate cancer progression. Prog Biochem Biophys. 2016;43(3):219–25.

  49. Gong Z, Yang Q, Zeng Z, Zhang W, Li X, Zu X, Deng H, Chen P, Liao Q, Xiang B, et al. An integrative transcriptomic analysis reveals p53 regulated miRNA, mRNA, and lncRNA networks in nasopharyngeal carcinoma. Tumour biol. 2016;37(3):3683–95.

    Article  CAS  Google Scholar 

  50. Luo Z, Zhang L, Li Z, Li X, Li G, Yu H, Jiang C, Dai Y, Guo X, Xiang J, et al. An in silico analysis of dynamic changes in microRNA expression profiles in stepwise development of nasopharyngeal carcinoma. BMC Med Genet. 2012;5:3.

    CAS  Google Scholar 

  51. Bruce JP, Hui AB, Shi W, Perez-Ordonez B, Weinreb I, Xu W, Haibe-Kains B, Waggott DM, Boutros PC, O'Sullivan B, et al. Identification of a microRNA signature associated with risk of distant metastasis in nasopharyngeal carcinoma. Oncotarget. 2015;6(6):4537–50.

    Article  Google Scholar 

  52. Liao Q, Zeng Z, Guo X, Li X, Wei F, Zhang W, Li X, Chen P, Liang F, Xiang B, et al. LPLUNC1 suppresses IL-6-induced nasopharyngeal carcinoma cell proliferation via inhibiting the Stat3 activation. Oncogene. 2014;33(16):2098–109.

    Article  CAS  Google Scholar 

  53. Sengupta S, den Boon JA, Chen IH, Newton MA, Dahl DB, Chen M, Cheng YJ, Westra WH, Chen CJ, Hildesheim A, et al. Genome-wide expression profiling reveals EBV-associated inhibition of MHC class I expression in nasopharyngeal carcinoma. Cancer Res. 2006;66(16):7999–8006.

    Article  CAS  Google Scholar 

  54. Shaulian E, Karin M. AP-1 as a regulator of cell life and death. Nat Cell Biol. 2002;4(5):E131–6.

    Article  CAS  Google Scholar 

  55. Salmena L, Poliseno L, Tay Y, Kats L, Pandolfi PP. A ceRNA hypothesis: the Rosetta stone of a hidden RNA language? Cell. 2011;146(3):353–8.

    Article  CAS  Google Scholar 

  56. Tay Y, Rinn J, Pandolfi PP. The multilayered complexity of ceRNA crosstalk and competition. Nature. 2014;505(7483):344–52.

    Article  CAS  Google Scholar 

  57. Poliseno L, Pandolfi PP. PTEN ceRNA networks in human cancer. Methods. 2015;77-78:41–50.

    Article  CAS  Google Scholar 

  58. Wang L, Zhang N, Wang Z, Ai DM, Cao ZY, Pan HP. Pseudogene PTENP1 functions as a competing endogenous RNA (ceRNA) to regulate PTEN expression by sponging miR-499-5p. Biochemistry Biokhimiia. 2016;81(7):739–47.

    Article  CAS  Google Scholar 

  59. Yi M, Wang W, Chen S, Peng Y, Li J, Cai J, Zhou Y, Peng Q, Ban Y, Zeng Z, et al. Dual-functionality of RASSF1A overexpression in A375 cells is mediated by activation of IL-6/STAT3 regulatory loop. Mol Biol Rep. 2018;45(5):1277–87.

    Article  CAS  Google Scholar 

  60. Yu G, Yao W, Gumireddy K, Li A, Wang J, Xiao W, Chen K, Xiao H, Li H, Tang K, et al. Pseudogene PTENP1 functions as a competing endogenous RNA to suppress clear-cell renal cell carcinoma progression. Mol Cancer Ther. 2014;13(12):3086–97.

    Article  CAS  Google Scholar 

  61. Stiuso P, Potenza N, Lombardi A, Ferrandino I, Monaco A, Zappavigna S, Vanacore D, Mosca N, Castiello F, Porto S, et al. MicroRNA-423-5p promotes autophagy in Cancer cells and is increased in serum from Hepatocarcinoma patients treated with Sorafenib. Molecular therapy Nucleic acids. 2015;4:e233.

    Article  CAS  Google Scholar 

  62. Liu J, Wang X, Yang X, Liu Y, Shi Y, Ren J, Guleng B. miRNA423-5p regulates cell proliferation and invasion by targeting trefoil factor 1 in gastric cancer cells. Cancer Lett. 2014;347(1):98–104.

    Article  CAS  Google Scholar 

  63. Nobes CD, Hall A. Rho, rac, and cdc42 GTPases regulate the assembly of multimolecular focal complexes associated with actin stress fibers, lamellipodia, and filopodia. Cell. 1995;81(1):53–62.

    Article  CAS  Google Scholar 

  64. Grunewald TG, Kammerer U, Schulze E, Schindler D, Honig A, Zimmer M, Butt E. Silencing of LASP-1 influences zyxin localization, inhibits proliferation and reduces migration in breast cancer cells. Exp Cell Res. 2006;312(7):974–82.

    Article  CAS  Google Scholar 

  65. Wang H, Li W, Jin X, Cui S, Zhao L. LIM and SH3 protein 1, a promoter of cell proliferation and migration, is a novel independent prognostic indicator in hepatocellular carcinoma. Eur J Cancer. 2013;49(4):974–83.

    Article  CAS  Google Scholar 

  66. Lin X, Liu X, Fang Y, Weng X. LIM and SH3 protein 1 promotes tumor proliferation and metastasis in lung carcinoma. Oncol Lett. 2016;12(6):4756–60.

    Article  CAS  Google Scholar 

  67. Butt E, Gambaryan S, Gottfert N, Galler A, Marcus K, Meyer HE. Actin binding of human LIM and SH3 protein is regulated by cGMP- and cAMP-dependent protein kinase phosphorylation on serine 146. J Biol Chem. 2003;278(18):15601–7.

    Article  CAS  Google Scholar 

  68. Zhang Y, Xia M, Jin K, Wang S, Wei H, Fan C, Wu Y, Li X, Li X, Li G, et al. Function of the c-met receptor tyrosine kinase in carcinogenesis and associated therapeutic opportunities. Mol Cancer. 2018;17(1):45.

    Article  Google Scholar 

  69. Tarafder AK, Bolasco G, Correia MS, Pereira FJ, Iannone L, Hume AN, Kirkpatrick N, Picardo M, Torrisi MR, Rodrigues IP, et al. Rab11b mediates melanin transfer between donor melanocytes and acceptor keratinocytes via coupled exo/endocytosis. J invest dermatol. 2014;134(4):1056–66.

    Article  CAS  Google Scholar 

  70. Wang M, Zhao J, Zhang L, Wei F, Lian Y, Wu Y, Gong Z, Zhang S, Zhou J, Cao K, et al. Role of tumor microenvironment in tumorigenesis. J Cancer. 2017;8(5):761–73.

    Article  CAS  Google Scholar 

  71. Tang Y, Wang J, Lian Y, Fan C, Zhang P, Wu Y, Li X, Xiong F, Li X, Li G, et al. Linking long non-coding RNAs and SWI/SNF complexes to chromatin remodeling in cancer. Mol Cancer. 2017;16(1):42.

    Article  Google Scholar 

  72. Xu K, Xiong W, Zhou M, Wang H, Yang J, Li X, Chen P, Liao Q, Deng H, Li X, et al. Integrating ChIP-sequencing and digital gene expression profiling to identify BRD7 downstream genes and construct their regulating network. Mol Cell Biochem. 2016;411(1–2):57–71.

    Article  CAS  Google Scholar 

  73. Wang J, Sun D, Wang Y, Ren F, Pang S, Wang D, Xu S. FOSL2 positively regulates TGF-beta1 signalling in non-small cell lung cancer. PLoS One. 2014;9(11):e112150.

    Article  Google Scholar 

Download references

Availability of data and supporting materials

Additional file 2: Figures S1–S5 and Additional file 1: Table S1 can be found at Journal of Experimental & Clinical Cancer Research online.

á…Ÿ

Funding

This study was supported by grants from the Overseas Expertise Introduction Project for Discipline Innovation (111 Project, No. 111–2-12), the National Natural Science Foundation of China (81572787, 81672683, 81672993, 81772928, 81702907 and 81772901) and the Natural Science Foundation of Hunan Province (2016JC2035, 2017SK2015, 2018JJ3704 and 2018JJ3815).

Author information

Author notes

  1. Yu Lian and Fang Xiong contributed equally to this work.

Authors and Affiliations

  1. The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha, Hunan, China

    Yu Lian, Fang Xiong, Liting Yang, Fang Wei, Ming Zhou, Bo Xiang, Xiaoling Li, Xiang Chen, Guiyuan Li, Can Guo, Zhaoyang Zeng & Wei Xiong

  2. Department of Reproductive medicine, Ganzhou Hospital Affiliated to Nanchang University, NanChang, Jiangxi, China

    Yu Lian, Yanyan Tang, Qianjin Liao, Xu Wu & Yong Li

  3. The Key Laboratory of Carcinogenesis and OCancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Central South University, Changsha, Hunan, China

    Yu Lian, Fang Xiong, Liting Yang, Hao Bo, Zhaojian Gong, Yumin Wang, Fang Wei, Ming Zhou, Bo Xiang, Xiaoling Li, Guiyuan Li, Can Guo, Zhaoyang Zeng & Wei Xiong

  4. Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, the Third Xiangya Hospital, Central South University, Changsha, Hunan, China

    Xiayu Li

  5. Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China

    Yanyan Tang, Qianjin Liao & Hui Wang

  6. Department of Chemistry, University of North Dakota, Grand Forks, North Dakota, USA

    Xu Wu

  7. Department of Cancer Biology, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA

    Yong Li

Authors
  1. Yu Lian
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Fang Xiong
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Liting Yang
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Hao Bo
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Zhaojian Gong
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Yumin Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Fang Wei
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Yanyan Tang
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Xiayu Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Qianjin Liao
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Hui Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Ming Zhou
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Bo Xiang
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. Xu Wu
    View author publications

    You can also search for this author in PubMed Google Scholar

  15. Yong Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  16. Xiaoling Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  17. Xiang Chen
    View author publications

    You can also search for this author in PubMed Google Scholar

  18. Guiyuan Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  19. Can Guo
    View author publications

    You can also search for this author in PubMed Google Scholar

  20. Zhaoyang Zeng
    View author publications

    You can also search for this author in PubMed Google Scholar

  21. Wei Xiong
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

ZZ and WX conceived the experiments. YL, FX, LY, HB, ZG, YW, FW, YT, XL and QL conducted the experiments. HW, MZ, BX and XW analyzed and interpreted the data. YL, XL, CX, GL, CG, ZZ and WX wrote the manuscript. YL, WX and ZZ prepared the figures. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Zhaoyang Zeng or Wei Xiong.

Ethics declarations

Ethics approval and consent to participate

This study was approved by the Ethics Committee of Hunan Cancer Hospital and in accordance with the ethical standards formulated in the Declaration of Helsinki. Informed consent was obtained from all patients included in the study. All animal studies were approved by the Institutional Animal Care and Use Committee (IACUC) of Central South University. Standard animal care and laboratory guidelines were followed according to the IACUC protocol.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Additional files

Additional file 1:

Table S1. Primers used for PCR and sequences of synthetic oligonucleotides. (PDF 8 kb)

Additional file 2:

Figure S1. Relative miR-423-5p expression levels as determined from GEO datasets. a. miR-423-5p was downregulated in NPC biopsies (T; n = 62) when compared with nontumor NPE tissues (N; n = 6) in the GSE73460 miRNA array, p = 0.0008. b. miR-423-5p expression was tightly associated with the TNM stage of NPC tumors in the GSE32906 miRNA array. N, n = 6; I-II, n = 4; III, n = 4; IV, n = 4; N vs IV, p = 0.02; N vs III, p = 0.04. c. Kaplan-Meier curve analysis of overall survival (OS) and relapse-free survival (RFS) of patients with low and high miR-423-5p expression using data from the GSE70970 dataset. HR, hazard ratio. Figure S2. Expression of some Rho/Rac proteins, such as RAB10, RAB11A, RAC2, PFN1, RHOA, RAC1, RHOC, LASP1 and RAB11B, was examined in 5-8F and HNE2 cells after overexpression of AFAP1-AS1. Figure S3. miR-423-5p could not target the 3′-UTR of RAC1. a. The schematic model showing the putative binding sites for miR-423-5p on 3′-untranslated regions (3′-UTR) of RAC1. b. Luciferase activities were measured in 5-8F and HNE2 cells cotransfected with miR-423-5p mimics, miR-423-5p inhibitors, or negative control, and the luciferase reporters containing the WT or MT RAC1 3′-UTR. Transfection of miR-423-5p mimics or inhibitors into 5-8F and HNE2 cells could not significantly reduce or increase the luciferase activity generated by the WT and the reporter vector containing the MT miR-423-5p binding site of the RAC1 3′-UTR reporter (pMIR-WT). Figure S4. Pearson correlation analysis was performed to evaluate the correlation between the expression of FOSL2 and AFAP1-AS1 using the GSE64634 dataset (r = 0.5256, p = 0.0365). Figure S5. A schematic model of AFAP1-AS1 competitively binding miR-423-5p to upregulate RAB11B or LASP1 or FOSL2 transcription factor signaling and accelerate NPC metastasis. (PDF 199 kb)

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Lian, Y., Xiong, F., Yang, L. et al. Long noncoding RNA AFAP1-AS1 acts as a competing endogenous RNA of miR-423-5p to facilitate nasopharyngeal carcinoma metastasis through regulating the Rho/Rac pathway. J Exp Clin Cancer Res 37, 253 (2018). https://doi.org/10.1186/s13046-018-0918-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1186/s13046-018-0918-9

Keywords

Journal of Experimental & Clinical Cancer Research

ISSN: 1756-9966

Contact us