| Summary: | 碩士 === 國立成功大學 === 藥理學研究所 === 92 === Eps8 (EGF receptor pathway substrate NO.8) is a common substrate of various receptor tyrosine kinases and cytoplasmic tyrosine kinase Src. It exists in two isoforms, p97Eps8 and p68Eps8 in many cell lines. Our previous studies have indicated that C3H10T1/2 fibroblast overexpressing p97Eps8 not only exhibits the ability of focus formation in cell culture but also promotes the tumor formation in mice as compared to the control cells. Since both tyrosyl phosphorylation and protein expression of Eps8 are elevated in v-Src transformed cell IV5, we wonder whether Eps8 may participate in v-Src-mediated transformation. By utilizing small interference RNA (siRNA) technology, we have generated IV5 cell lines with reduced Eps8 (both 97-kDa and 68-kDa proteins) expression. The cell growth (in both culture dish and animal) of these cell lines is significantly slower than the control cells. Furthermore, we have generated p97eps8-specific siRNA cell lines. Similarly, p97eps8 siRNA cells have slower growth rate than control cells. We also have demonstrated that the remarkable effect was not result form down–regulation of v-Src kinase activity. FACS analysis indicitated that these cells exhibit retardation of G1 phase progresssion as compared to the control cells. Finally, We have demonstrated that inhibition of v-Src-mediated transformation in p97eps8 siRNA cells may result form down-regulation of AKT activation. Thus, p97Eps8 may play an important role in v-Src-mediated cell cycle progression and transformation.
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