N-3 Fatty Acid-Induced Akt Suppression: Chemoprevention for Pancreatic Neoplasia

点击翻译按钮获取中文摘要

DESCRIPTION (provided by applicant): Several cancers and a few preinvasive lesions respond to w-3 fatty acids, which serves to promote apoptosis while blocking cellular proliferation. A similar response has been demonstrated in pancreatic cancer, although the suppressive nature of w-3 fatty acids in normal and/or neoplastic cells of the pancreas remains speculative. With the advent of modalities for earlier detection of pancreatic cancer, earlier diagnosis will soon be a reality. Hence, novel approaches to fighting these precancerous conditions must evolve, including chemoprevention, where dietary intake of fats and inhibition of key signaling pathways may reduce production of early cancer before it spreads. To examine this possibility, human pancreatic ductal epithelial (HPDE) cells with and without expression of activated Kras and mice with normal pancreas and those that develop mutant Kras-induced pancreatic precancer will be exposed to high levels of polyunsaturated fatty acids (PUFAs), w-3 and w-6. Observing cellular changes, cell proliferation, and apoptosis in normal tissue and during disease progression along with specific molecular events (activation of Akt, effects of PGE3-bound EP2 on Akt activation, phosphorylation of various proteins like Akt, Foxo, and Bad,) will determine the mechanisms of action for w-3 fatty acids in these modeling systems. The premise of this work is that w-3 fatty acids will function by generating increased levels of PGE3 which will lead to decreased pAkt in an EP2-dependent manner. Subsequent downstream events including dephosphorylation of Foxo and Bad will promote an increase in cell death and reduced cell division. Part of these evaluations will include employing w-6 fatty acids as controls but will also elucidate their potential mechanism in these modeling systems. In vitro manipulation will employ chemical inhibition or activation, siRNA technology, and transfection of expression vectors to suppress or enhance various signals in a stepwise manner through this pathway. In vivo, this work will be done in mutant Kras expressing mouse pancreas void of EP2, PI3K, Cox-2, Akt, Foxo, or Bad. In this manner, a systematic and stepwise analysis can be done at each step in the pathway to demonstrate a direct and critical link between w-3 fatty acids, the Akt pathway, and downstream events altering cell proliferation and inducing apoptosis in normal and precancerous cells of the pancreas. Understanding these processes in human cultured and mouse pancreas cells will illuminate similar dietary effects on human pancreatic precancer and cancer development while potentially providing a more effective means of inhibiting early disease processes in the human population.