Over the last decade, work from a number of laboratories has established that mammalian cells depend on growth factor-dependent signaling to maintain their viability. We have demonstrated that this is true even for cells that lack the ability to initiate their own demise through the intrinsic apoptotic pathway. This finding led us to hypothesize that the essential function of survival signaling is to direct the cell to take up and metabolize sufficient nutrients to maintain mitochondrial integrity and cellular ATP production. The ability of cancer cells to survive in the absence of growth factor signaling depends on the cells acquiring mutations that stimulate sufficient nutrient uptake and metabolism to maintain cellular bioenergetics. Such signaling renders a cancer cell resistant to cell death by either apoptosis or necrosis. In the preceding five years of this grant, we established that Akt activation promotes cell survival by stimulating glucose uptake and metabolism. As a result, Akt-transformed cells become addicted to glycolytic metabolism for the support of ATP production. In addition, we have defined that glutamine represents a second essential metabolic substrate required for cell proliferation of transformed cells. In contrast to glucose, glutamine uptake and metabolism is not regulated by Akt-dependent signal transduction. In the ensuing five years, we plan to further investigate the regulation of glucose and/or glutamine uptake in normal and transformed cells. We believe a more complete characterization of the essential role of these nutrients in cancer cell growth and survival may lead to the development of new and safer cancer therapies.
Three Specific Aims are envisioned. We will: 1) Examine whether Akt-induced reprogramming of glucose metabolism can be exploited to selectively impair cancer cell growth and/or survival. 2) Define the molecular determinants of the glutamine dependence exhibited by some transformed cells. 3) Investigate the signaling pathways that can induce a transition from glucose-dependent mitochondrial metabolism to a glutamine-dependent mitochondrial metabolism during growth of normal and/or transformed cells.
Mammalian cells depend on extracellular signals to direct their nutrient uptake and metabolism. Recent evidence suggests that distinct oncogenic mutations control the cellular metabolism of glucose and glutamine, the two major nutrients used by cancer cells to fuel their growth and proliferation. This project seeks to determine whether oncogenic reprogramming of metabolism can be exploited to develop new cancer therapeutic strategies.
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