[Effects of mTOR siRNA on mTOR/p70S6K signaling pathway in esophageal squamous cell carcinoma cells and the growth of transplanted tumor in nude mice]

Abstract

Objective: To investigate the effects of mTOR siRNA on mTOR-p70S6K signaling pathway in esophageal squamous cell carcinoma (ESCC) cells in vitro,and growth and apoptosis in transplanted tumor in nude mice.

Methods: mTOR siRNA was transfected into ESCC cell line EC9706 cells. The expressions of factors of the mTOR/p70S6K signaling pathway were detected by RT-PCR and Western blot. DNA contents and cell apoptosis were determined by flow cytometry, and cell proliferation was measured by CCK-8 assay. The effects of mTOR siRNA on the transplanted tumor growth were assessed in nude mice.

Results: The levels of mTOR and p-p70S6K were significantly decreased (P < 0.05) while the level of p70S6K was increased (P < 0.05) in the cells transfected with mTOR siRNA, compared with that in untransfected cells and cells transfected with control siRNA. After being interfered by mTOR siRNA, the number of apoptotic cells was increased, cell proliferation became slower and cell cycle was arrested in G(1) phase compared with that in control cells. Also, mTOR siRNA inhibited the growth of transplanted tumor in vivo.

Conclusions: mTOR siRNA can effectively interfere in mTOR-p70S6K signaling pathway, induce cell apoptosis and inhibit cell proliferation and tumor growth, suggesting that mTOR-p70S6K signaling pathway plays an important role in the carcinogenesis and development of esophageal squamous cell carcinoma.