2-Methoxyestradiol-induced Apoptosis in Prostate Cancer Cells Requires Smad7

• Published in: The Journal of biological chemistry Vol. 280; no. 15; pp. 14773 - 14779
• Main Authors: Davoodpour, Padideh, Landström, Maréne
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15-04-2005; American Society for Biochemistry and Molecular Biology
• Subjects: 2-Methoxyestradiol; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; beta Catenin; Blotting, Western; Carrier Proteins - metabolism; Cell Line, Tumor; Cell Nucleus - metabolism; Cytoskeletal Proteins - metabolism; DNA-Binding Proteins - metabolism; Estradiol - analogs & derivatives; Estradiol - metabolism; Estradiol - pharmacology; Humans; Male; Membrane Proteins - metabolism; Neovascularization, Pathologic; p38 Mitogen-Activated Protein Kinases - metabolism; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; Proto-Oncogene Proteins - metabolism; RNA - metabolism; RNA, Small Interfering - metabolism; Signal Transduction; Smad7 Protein; Time; Time Factors; Trans-Activators - metabolism; Transforming Growth Factor beta - metabolism
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.M414470200

Prostate cancer is the second most common cause of death related to cancer in Western society. 2-Methoxyestradiol (2-ME), an endogenous metabolite of estradiol-17β, inhibits tumor angiogenesis while also exerting potent cytotoxic effects on various cancer cells. 2-ME has been shown to activate the p38 MAPK and JNK pathways and to induce apoptosis in cells, although the underlying molecular mechanisms for this are unknown. Here we report that the expression of Smad7, an adaptor molecule required to activate p38 MAPK in the transforming growth factor β signaling pathway, is also required for 2-ME-induced p38 activation and apoptosis in human prostate cancer cells (PC-3U). PC-3U/AS-S7 cells stably transfected with an antisense Smad7 construct, or PC-3U cells transiently transfected with short interfering RNA for Smad7, were protected against 2-ME-induced apoptosis. 2-ME-induced apoptosis was found to involve p38 MAPK and JNK, because simultaneous treatments with 2-ME and a specific p38 inhibitor (SB203580) or an inhibitor of JNK (L-JNK1) prevented 2-ME-induced apoptosis. Most interestingly, Smad7 was shown by both antisense and short interfering RNA techniques to affect levels of β-catenin, which has been implicated previously in the regulation of apoptosis. Moreover, Smad7 was found to be important for the basal expression of Bim, a pro-apoptotic Bcl-2 family member, and for 2-ME-induced expression of Bim. These results suggest that expression of Smad7 is crucial for 2-ME-induced apoptosis in human prostate cancer cells.