Fig. 4

cMYC mediates the miR-155-driven PTGES2 transactivation. a, b Promoter activity of PTGES2 gene in MDA-MB-436 (a) and Hs-578 T cells (b) with (miRZIP155) or without (control) miR-155 knockdown. PGL3 empty vector was used as negative control. c Schematic diagram showing the cMYC-binding site (E-box, marked in grey) on PTGES1 or PTGES2 gene promoter. Numbers indicate nucleotide positions counted from the transcription start site. d Chromatin immunoprecipitation result of cMYC in MDA-MB-436 control and knockdown (miRZIP155) cells. Promoters of PTGES1 and PTGES2 are tested. IgG was used as negative control. e, f Promoter activity of PTGES2 gene in MDA-MB-436(e) and Hs-578 T cells (f) with miR-155 knockdown (miRZIP), in combination with cMYC reconstitution (miRZIP155 + cMYC). Data on the right panels confirms cMYC protein overexpressed in the reporter assay.g Western blot results of cMYC in the miR-155-high and -low TNBC specimens (n = 20)