Anti-tumorigenic action of 2-[piperidinoethoxyphenyl]-3-[4-hydroxyphenyl]-2H-benzo(b)pyran: evidence for involvement of GPR30/EGFR signaling pathway.

OBJECTIVE: The aim of the present study was to investigate the effect of non-steroidal, pure antiestrogenic benzopyran derivative i.e., 2-[piperidinoethoxyphenyl]-3-[4-hydroxyphenyl]-2H-benzo(b)pyran (K-1) on the growth of human endometrial cancer cells in vivo and in vitro and to elucidate its mechanism of action.

METHODS: Cell proliferation was assayed by measuring the incorporation of 5'-bromo-2'-deoxyuridine in Ishikawa and primary endometrial cancer cells. The expression of proliferation and apoptotic markers was analyzed by immunoblotting. The effect of K-1 on GPR30-regulated proteins was analyzed by ELISA and by immunoblotting. Nude mice bearing subcutaneous implanted-Ishikawa tumors, were treated for 14days with K-1 (200μg/kg body weight/day/orally). The proliferation markers, GPR30-regulated proteins and apoptotic markers were analyzed by immunoblotting in tumor xenograft. The apoptotic effect of compound K-1 was determined by TUNEL assay.

RESULTS: Compound K-1 inhibited proliferation of endometrial adenocarcinoma cells and decreased the expression of proliferation markers. It caused apoptosis by increasing the expression of apoptotic markers (NOXA, PUMAα) and reducing the expression of p-CREB and BclxL. Compound interfered with GPR30-regulated-EGFR activation, decreased p-ERK, p-c-jun, c-fos, cyclinD1 and c-myc expression. Treatment of tumor-bearing mice with K-1 resulted in a significant decrease in tumor volume and weight. Decreased expression of p-ERK and its downstream molecules and increased expression of apoptotic markers were observed in tumor in K-1 treated animals.

CONCLUSION: Findings suggest the potent inhibitory effect of compound K-1 on endometrial cancer cellular growth (in-vitro) and on tumor size (in-vivo) which is mediated at least, in part, by interference with GPR30-signaling.