Fig. 4

HIF-1α is a 5-FU resistance and prognostic biomarker in CRC patients. a Images of IHC staining for GLUT1, HK2, PKM2, LDHA, MCT4, and HIF-1α on tumor sections in subcutaneous transplantation tumor models. Scale bar = 100 μm. b Images of IHC staining for GLUT1, HK2, PKM2, LDHA, MCT4, and HIF-1α on tumor sections in CRC patients. Scale bar = 100 μm. c Comparison of IHC staining for HIF-1α in CRC patients. The grayscale HIF-1α signal is the mean optical density (MOD) of staining. d Comparison of HIF1A mRNA expression in CRC patients as assessed by RT-qPCR. ACTB was used as the internal reference. e Representative images of Wright’s staining and HIF-1α immunofluorescence staining (green) of CTCs in the blood of peripheral veins and tumor reflux veins. Scale bar = 10 μm. f Histograms illustrating the detection of CTCs and the proportions of HIF-1α-positive CTCs in peripheral venous blood. g Histograms illustrating the detection of CTCs and the proportions of HIF-1α-positive CTCs in tumor reflux venous blood. h Kaplan-Meier estimates of DFS of CRC patients on fluorouracil analog-based chemotherapy with high (MOD ≥0.2, n = 11) or low (MOD < 0.2, n = 16) HIF-1α expression as assessed by the intensity of the grayscale signal of IHC images. i Kaplan-Meier estimates of DFS of CRC patients on fluorouracil analog-based chemotherapy who had either HIF-1α-positive CTCs (n = 8) or HIF-1α-negative CTCs (n = 19) in peripheral venous blood. j Kaplan-Meier estimates of DFS of CRC patients on fluorouracil analog-based chemotherapy who had either HIF-1α-positive CTCs (n = 9) or HIF-1α-negative CTCs (n = 18) in tumor reflux venous blood. Bar chart data were compared by ANOVA (ns = not significant, * p < 0.05, and ** p < 0.01), and results are shown as means ± SEM. Survival was compared by log rank (Mantel-Cox) testing