Abstract
Excision repair cross-complementary gene 1 (ERCC1) is a downstream regulatory target of fibroblast growth factor receptor 2 (FGFR2); however, the mechanism of its action has not been elucidated. The cascades downstream of FGFR2 include the PKC, Ras/Raf/MEK/ERK, JAK/STAT and PI3K pathways. ERCC1 is considered to be a closely related downstream target gene of extracellular signal-regulated kinase (ERK)1/2, since ERCC1 mRNA and protein levels may be inhibited by the ERK inhibitor U0126. It was hypothesized that FGFR2, which specifically binds with fibroblast growth factor 7 (FGF7), may regulate ERCC1 gene expression through the ERK signaling pathway. The aim of the present study was to explore the association between the regulatory effect of FGFR2 on ERCC1 gene expression and the p-ERK1/2 signaling pathway in a drug-resistant hepatocellular carcinoma (HCC) cell line. The drug-resistant cell line HepG2/OXA and its parental cell line HepG2 were transfected with Bek shRNA in the logarithmic growth phase. Transfected and untransfected HepG2 and HepG2/OXA cells were then stimulated with FGF7 and changes in the protein expression of FGFR2, p-ERK1/2 and ERCC1 was detected with western blot analysis. Following transfection, HepG2/T and HepG2/OXA/T cells were observed to grow stably in a screening medium containing puromycin. The western blot analysis demonstrated a significant decrease in the protein expressions of FGFR2, p-ERK1/2 and ERCC1 in HepG2/T and HepG2/OXA/T cells as compared to untransfected cells. Expression of FGFR2, p-ERK1/2 and ERCC1 in HepG2/OXA cells was significantly increased compared to the parental HepG2 cells. Following stimulation with FGF7, the expression of FGFR2, p-ERK1/2 and ERCC1 was increased, with significant differences between HepG2 and HepG2/OXA cells in the expression of p-ERK1/2 and ERCC1. No differences were detected in the protein levels following Bek shRNA transfection in HepG2/T and HepG2/OXA/T cells. In conclusion, the FGFR2-mediated ERK1/2 signaling pathway in HCC cells plays an important role in the regulation of ERCC1 expression.