Effect of Rapamycin in Proliferation of Human Burkitt Lymphoma Cells

Objective To investigate rapamycin effects on growth inhibition and mTOR/p70S6K signaling pathway of human Burkitt lymphoma cell line Raji cells. Methods Proliferations of Raji cells under different of concentrations (0，1，5，10，20，40，50 and 100nmol/L) and different times (24，48 and 72 h) were investigated by MTT assay.Apoptosis and cell cycle were analyzed via flowcytometry.The morphological alterations were confirmed by the optical microscope.The expressions of mTOR，p70S6K，p-p70S6K proteins were examined by Western blot technique in the rapamycin-treated and untreated Raji cells. Results Rapamycin inhibited the proliferation of Raji cells at concentrations more than 5nmol/L(P＜0.05)，in a dose and time dependent manner.After treatment with rapamycin，the number of cells at S phase and G2/M phase was decreased gradually (P＜0.05)，but significantly increased at G0/G1 phase in dose and time dependent manners (P＜0.05).However，evident apoptosis did not observed in Raji cells.The expression of mTOR、p-p70S6K proteins was decreased gradually while the expression of p70S6K protein was increased in a concentration-dependent manner (P＜0.05). Conclusion mTOR/p70S6K signaling pathway was constitutively activated in Raji cells and Rapamycin inhibited Raji cell proliferation by arrest at G0/G1 phase and inhibition of mTOR/p70S6K signaling pathway.