Role of AKT1 in Mammary Tumorigenesis and Transformation.

摘要

AKT1 belongs to the AKT/PKB protein-serine kinase family and is the cellular homolog of the v-akt oncogene. Gene amplification and overexpression of AKT are associated with adenocarcinomas of the stomach, breast, ovary and pancreas. AKT1 is coupled to growth factor dependent proliferation and resistance to apoptosis, but these processes have not been studied in either mammary epithelial cells or in breast cancer. The broad objectives of this proposal are to determine the role of the AKT1 in the proliferation, survival and transformation of mammary epithelial cells using two transgenic mouse strains in which expression of either AKT1 or a constitutively active form of AKT1 is directed to the mammary gland under the control of a mammary gland- specific promoter. The use of these two transgenic models will allow determination of the role of AKT1 in mammary gland hyperplasia, dysplasia and tumorigenesis, and will address the hypothesis that AKT1 is involved in the growth, survival and transformation of mammary epithelial cells. This hypothesis will be tested using two experimental approaches. First, transgenic mice will be generated with mammary gland-directed expression of mild-type AKT1 or constitutively active myristoylated AKT1 (myrAKT1) to determine their effects on mammary hyperplasia and tumorigenesis. Second, primary mouse mammary epithelial cells will be transduced with ecotropic retroviruses expressing either AKT1 or myrAKT1 to determine their impact on growth factor-dependent proliferation, susceptibility to apoptosis induced by serum deprivation or the PI3K inhibitor, LY294002, as well as transformation determined by anchorage-independent growth in soft agar and tumor formation in nude mice. Gene arrays or suppression subtractive hybridization will be used to identify genes modulated by AKT1 that are involved in its anti-apoptotic and proliferative activities.