2,3-Diaryl-2H-1-benzopyran derivatives interfere with classical and non-classical estrogen receptor signaling pathways, inhibit Akt activation and induce apoptosis in human endometrial cancer cells

Objectives: The present study was undertaken to explore the mechanism of anti-proliferative action of benzopyran compound D1 (2-[piperidinoethoxyphenyl]-3-phenyl-2H-benzopyran) and its hydroxy-(D2) and methoxy-(D3) derivatives in Ishikawa and human primary endometrial adenocarcinoma cells. Methods: Transcriptional activation assays were performed using luciferase reporter system and cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MU). The stage of cell cycle was determined by flow-cytometry and real time analysis of cyclinE1 and cdc2 genes. The apoptotic effects were measured by AnnexinV/PI staining and TUNEL The expression of PCNA, cyclin-D1, pAkt, XIAP, cleaved caspase-9, -3, PARP, Bax and Bcl2 were determined by immunoblotting. The caspase-3 activity and mitochondrial membrane potential were measured by colorimetric assay. Results: All three compounds inhibited E-2-induced ERE- and AP-1-mediated transactivation and proliferation in endometrial adenocarcinoma cells dose-dependently. Compound D1 caused the arrest of cells in the G(2) phase while D2 and D3 caused arrest in G, phase of the cell cycle. All compounds interfered with Akt activation, decreased XIAP expression leading to an increased cleavage of caspase-9, -3, PARP, increased Bax/Bcl2 ratio and caspase-3 activity. Conclusion: Findings suggest that benzopyran derivatives inhibit cellular proliferation via modulating ER-dependent classical and non-classical signaling mechanisms, interfere with Akt activation and induce apoptosis via intrinsic pathway in endometrial adenocarcinoma cells. (C) 2011 Elsevier Ireland Ltd. All rights reserved.