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

mTOR/p70S6K pathway is considered a central regulator in various malignant tumors, but its roles in esophageal squamous cell carcinoma (ESCC), which is a common cause of mortality in China, remain unknown. Here, we identify that the mTOR/p70S6K pathway is activated in ESCC; rapamycin and siRNA against mTOR rapidly inhibited expression of mTOR and the phosphorylation of its major downstream effectors, p70S6K and 4E-BP1, arrested cells in the G(0)/G(1) phase and induced apoptosis of ESCC cells. The findings may lay a foundation for making further investigations on the mTOR/p70S6K pathway as a potential target for ESCC therapy. (c) 2007 Elsevier Ireland Ltd. All rights reserved.