Role of phospholipase D in tumorigenesis

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DESCRIPTION (provided by applicant): Elevated phospholipase D (PLD) activity has been reported in several types of human cancer including breast, kidney, colon and gastric cancer. Recent work has revealed that elevated PLD activity in human breast cancer cells can suppress apoptosis and promote cell migration - two critical steps in progression to a malignant cancer. The survival and migration signals generated by PLD are mediated - at least in part - by mTOR (the mammalian target of rapamycin), which has been widely implicated in cancer survival signals. While it is clear that PLD is capable of contributing to tumorigenesis and that PLD activity is elevated in a large number of human cancers, it is not known how and in what context elevated PLD activity contributes to the transformation of human cells or tumorigenesis in an animal. There is also much to be learned about the signaling pathways that activate PLD in human cancer cells. The Central Hypothesis of the proposal is that: PLD generates signals that suppress apoptosis and enhance cell migration in human cancer cells. Specifically, we propose to: 1) Characterize signals regulating PLD activity in human cancer cell lines and to evaluate targeting these signals pharmacologically both in vitro and in vivo; 2) Investigate a role for PLD survival signals in cell migration and metastasis; and 3) Evaluate the ability of PLD to cooperate with oncogenes to transform human cells in culture and to stimulate cell migration. The ability of PLD to both suppress apoptosis and enhance cell migration makes PLD an ideal target for the development of therapeutic strategies. As the era of molecular medicine and pathology evolves and individual tumors are examined at the molecular level, elevated PLD activity could be easily determined and the signals generated by PLD activity could then be targeted specifically. The studies proposed here will provide a conceptual framework for rational targeting of the apparent large number of human cancers with elevated PLD activity.