Abstract SY29-01: mTOR, metabolism, and cell growth control

Abstract

Abstract The mTOR complex 1 (mTORC1) is a ser/thr protein kinase complex and critical regulator of cellular metabolism, protein synthesis, autophagy and cell growth. This signaling system is normally carefully controlled by the integration of inputs from growth factors, nutrients, cellular energy status, oxygen availability and stress. A variety of loss-of-function or gain-of-function alterations in key mTORC1 regulatory proteins, very often results in inappropriate regulation of this signaling system. Uncontrolled mTORC1 activation contributes on its own or in combination with other pathways to metabolic diseases ranging from diabetes and obesity, cardiac hypertrophy, neurodegeneration, aging, benign tumor syndromes to highly malignant cancers. Mechanistically, uncontrolled mTORC1 activation leads to a constant positive input into anabolic processes and suppression of many catabolic processes. As a result, these cells require increased energy and carbon sources to meet their high metabolic needs for cell growth. To meet this demand, we have found in cells that are PTEN or TSC1/2 null, that activated mTORC1 uses distinct mechanisms to increase glutamine consumption (glutaminolysis) by elevating the expression of glutaminase and the activity of glutamate dehydrogenase. Furthermore, under nutrient-rich conditions, these tumor cells sense the increased energy production and in a positive feedback loop, promote more mTORC1 assembly via an AMP kinase (AMPK)-dependent, and a novel AMPK-independent mechanism. This acquired addiction to glutamine provides a novel therapeutic strategy for treating patients with activated mTORC1. Indeed, by acutely blocking the ability of energetically stressed cells with hyperactive mTORC1 to metabolize glutamine, we can selectively kill some tumor cells without damaging normal cells. We anticipate that these studies will lead to the development of “synthetic-lethal” drugs useful in the treatment of patients with diseases linked to inappropriate activation of mTORC1. Research supported by NIH RO1-GM51405 and the LAM Foundation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr SY29-01. doi:1538-7445.AM2012-SY29-01