Control of TGF-Beta/Smad Signaling by mTOR in Prostate Cancer

mTOR 对前列腺癌中 TGF-β/Smad 信号传导的控制

• 批准号: 8234139
• 负责人: DAVID DANIELPOUR
• 金额: $ 31.6万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8234139
• 关键词: Address; Androgen Receptor; Androgens; Apoptosis; Binding; Binding Proteins; Biological; Cell Death; Cell Line; Complex; Cytostatics; Data; Development; Disease; Disease Progression; Dominant-Negative Mutation; Epithelial; Epithelial Cells; Germ Lines; Goals; Growth; Human; In Vitro; Insulin-Like Growth Factor I; Intercept; Investigation; Knockout Mice; Laboratories; Malignant - descriptor; Malignant Epithelial Cell; Malignant Neoplasms; Malignant neoplasm of prostate; Mediating; Mediation; Mediator of activation protein; Modeling; Molecular; Mullerian-inhibiting substance receptor; Nude Mice; Oncogenic; PC3 cell line; PTEN Gene Inactivation; PTEN gene; Pathway interactions; Patients; Phosphorylation; Phosphotransferases; Play; Prostate; Prostate carcinoma; Prostatic Neoplasms; Proteins; Proto-Oncogenes; Publishing; Raptors; Receptor Activation; Receptor Signaling; Regulation; Reporting; Research; Research Proposals; Role; Signal Pathway; Signal Transduction; Sirolimus; Staging; Stream; System; Testing; Therapeutic; Therapeutic Intervention; Tissues; Transforming Growth Factor beta; Tumor Promoters; Tumor Suppressor Proteins; Withdrawal; analog; base; bone morphogenetic protein receptors; bone morphogenic protein; cancer cell; cell growth; in vivo; inhibitor/antagonist; insight; interest; mTOR protein; mouse model; prostate carcinogenesis; receptor; receptor binding; receptor function; research study; response; retroviral transduction; tumor growth

Project Summary: Control of TGF-¿/Smad Signaling by mTOR in Prostate Cancer Transforming growth factor-beta (TGF-¿) is well recognized to function as a potent tumor suppressor of the prostate, where it is believed to play a pivotal role in activation of cell death following androgen withdrawal. The function of TGF-¿ is lost during carcinogenesis of the prostate; however, the underlying mechanisms for this loss of TGF-¿ receptor function remain poorly studied. Studies conducted in Dr. David Danielpour's laboratory in the past several years have demonstrated that both the insulin-like growth factor-I (IGF-I) and the androgen receptor (AR) signaling pathways, which appear to be constitutively activated in a sizable proportion of prostate tumors, can block multiple steps in the TGF-¿ signaling pathway and thus contribute to loss of the ability of TGF-¿ to function as a tumor suppressor. The IGF-I/PI3K/Akt signaling pathway is commonly activated in prostate cancer through loss of PTEN function and/or elevation of IGF-I levels. We published the first reports that the IGF-I/PI3K/Akt pathway suppresses phospho-activation of Smads 2 and 3 through a mechanism that is dependent on the mammalian inhibitor of rapamycin (mTOR). However, the mechanism by which mTOR mediates such suppression is not known, and will be investigated as detailed in Aims 1 and 2 of this proposal. These aims will test our hypothesis that an mTOR complex (TORC1) directly interacts with TGF-¿ receptors and intercepts the TGF-¿ signaling pathway. Aim 2 will develop substantial mechanistic insight at the molecular level of how mTOR interacts with TGF-¿ receptors and is able to modulate TGF-¿ receptor signaling. Recent data from our laboratory suggests that inhibition of mTOR by rapamycin activates Smads 1, 3, 5 or 8 through their c- terminal phosphorylation in prostate cancer cell lines. Aim 3 will validate the identity of the phospho-Smads that are phosphorylated by rapamycin, and test our hypothesis that Smads 1, 3, 5 or 8 are critical to mediation of the cytostatic effects of rapamycin on prostate cancer cells in culture and in growth of prostate tumor xenographs in athymic mice.. Understanding the how PI3K/Akt/mTOR cross-talks with those TGF-¿ and BMP signaling will likely have substantial therapeutic potential in prostate cancer.

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