mTOR/p70S6K signaling pathway constitutively activated in esophageal squamous cell carcinona cell lines and inhibition of the pathway by rapamycin and siRNA against mTOR

5351 The mammalian target of rapamycin (mTOR)/ribosomal protein S6 kinase (p70S6K) signaling pathway is considered a central regulator of protein synthesis, and of cell proliferation, differentiation and survival. Some inhibitors of mTOR as anticancer reagents have been evaluated in various malignant tumors. However, the role of the mTOR/p70S6K signaling pathway in esophageal squamous cell carcinoma (ESCC), which is a common cause of mortality in China, and the sensitivity of ESCC to rapamycin, a mTOR inhibitor, remain unknown. In the present study, mTOR/p70S6K signaling pathway, and mRNA and protein expressions of mTOR/p70S6K signaling pathway in the ESCC cells treated with rapamycin and siRNA against mTOR were respectively investigated using immunocytochemistry, Western blots and reverse transcription polymerase chain reaction (RT-PCR). The result showed that mTOR /p70S6K signaling pathway was activated in the two ESCC cell lines, EC9706 and Eca109, and mRNA and protein levels of mTOR in EC9706 was higher than in Eca109 cells(P