Loss of Tuberous Sclerosis Complex-2 Function and Activation of Mammalian Target of Rapamycin Signaling in Endometrial Carcinoma

作者：Karen H. Lu, Weiguo Wu, Bhuvanesh Dave, Brian M. Slomovitz, Thomas W. Burke, Mark F. Munsell, Russell R. Broaddus, Cheryl L. Walker · 发表于：Clinical Cancer Research · 年份：2008 · DOI：10.1158/1078-0432.ccr-07-0321 · 被引用次数：73 · 研究领域：Tuberous Sclerosis Complex Research、PI3K/AKT/mTOR signaling in cancer、Vascular Tumors and Angiosarcomas

PURPOSE: The involvement of phosphatase and tensin homologue deleted on chromosome ten (PTEN) in endometrial carcinoma has implicated phosphatidylinositol 3-kinase signaling and mammalian target of rapamycin (mTOR) activation in this disease. Understanding the extent of mTOR involvement and the mechanism responsible for activation is important, as mTOR inhibitors are currently being evaluated in clinical trials for endometrial carcinoma. Although tuberous sclerosis complex 2 (TSC2) is the "gatekeeper" for mTOR activation, little is known about defects in the TSC2 tumor suppressor or signaling pathways that regulate TSC2, such as LKB1/AMP-activated protein kinase, in the development of endometrial carcinoma. EXPERIMENTAL DESIGN: We determined the frequency of mTOR activation in endometrial carcinoma (primary tumors and cell lines) and investigated PTEN, LKB1, and TSC2 defects as underlying cause(s) of mTOR activation, and determined the ability of rapamycin to reverse these signaling defects in endometrial carcinoma cells. RESULTS: Activation of mTOR was a consistent feature in endometrial carcinomas and cell lines. In addition to PTEN, loss of TSC2 and LKB1 expression occurred in a significant fraction of primary tumors (13% and 21%, respectively). In tumors that retained TSC2 expression, phosphorylation of tuberin at S939 was observed with a high frequency, indicating that mTOR repression by TSC2 had been relieved via AKT phosphorylation of this tumor suppressor. In PTEN-nul...