Regulation of FOXO3a/beta-catenin/GSK-3beta signaling by 3,3'-diindolylmethane contributes to inhibition of cell proliferation and induction of apoptosis in prostate cancer cells.
Previous studies from our laboratory have shown anti-proliferative and pro-apoptotic effects of 3,3'-diindolylmethane (DIM) through regulation of Akt and androgen receptor (AR) in prostate cancer cells. However, the mechanism by which DIM regulates Akt and AR signaling pathways has not been fully investigated. It has been known that FOXO3a and glycogen synthase kinase-3beta (GSK-3beta), two targets of activated Akt, interact with beta-catenin, regulating cell proliferation and apoptotic cell death. More importantly, FOXO3a, GSK-3beta, and beta-catenin are all AR coregulators and regulate the activity of AR, mediating the development and progression of prostate cancers. Here, we investigated the molecular effects of B-DIM, a formulated DIM with higher bioavailability, on Akt/FOXO3a/GSK-3beta/beta-catenin/AR signaling in hormone-sensitive LNCaP and hormone-insensitive C4-2B prostate cancer cells. We found that B-DIM significantly inhibited the phosphorylation of Akt and FOXO3a and increased the phosphorylation of beta-catenin, leading to the inhibition of cell growth and induction of apoptosis. We also found that B-DIM significantly inhibited beta-catenin nuclear translocation. By electrophoretic mobility shift and chromatin immunoprecipitation assays, we found that B-DIM inhibited FOXO3a binding to the promoter of AR and promoted FOXO3a binding to the p27(KIP1) promoter, resulting in the alteration of AR and p27(KIP1) expression, the inhibition of cell proliferation, and the induction of apoptosis in both androgen-sensitive and -insensitive prostate cancer cells. These results suggest that B-DIM-induced cell growth inhibition and apoptosis induction are partly mediated through the regulation of Akt/FOXO3a/GSK-3beta/beta-catenin/AR signaling. Therefore, B-DIM could be a promising non-toxic agent for possible treatment of hormone-sensitive but most importantly hormone-refractory prostate cancers.
Li
Yiwei
Y
Department of Pathology, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Wang
Zhiwei
Z
Kong
Dejuan
D
Murthy
Shalini
S
Dou
Q Ping
QP
Sheng
Shijie
S
Reddy
G Prem Veer
GP
Sarkar
Fazlul H
FH
D021581:Active Transport, Cell Nucleus; D016588:Anticarcinogenic Agents / Q000494:pharmacology; D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D008954:Models, Biological; D011471:Prostatic Neoplasms / Q000473:pathology; D015398:Signal Transduction; D051176:beta Catenin / Q000378:metabolism*
D016588:Anticarcinogenic Agents; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D007211:Indoles; D051176:beta Catenin; D050760:Cyclin-Dependent Kinase Inhibitor p27; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; C016392:3,3'-diindolylmethane