| Objective:To explore the effects and mechanism of m TOR inhibitor rapamycin on proliferation,cell cycle and apoptosis in Burkitt Lymphoma cell line RAJI and CA46 cells,so as to provide the experimental evidence for a therapeutic target of Burkitt Lymphoma in the clinical work.Methods:3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay was performed to assess cell proliferation in Burkitt Lymphoma cell line RAJI and CA46 cells.The cell cycle distribution of Burkitt Lymphoma cell line RAJI and CA46 cells was analyzed by propidium iodide staining Flow cytometry(FCM) assay.The cell apoptosis of Burkitt Lymphoma cell line RAJI and CA46 cells was analyzed by FITC Annexin V staining Flow cytometry assay.The expression of RPS6,p-RPS6,survivin,and caspase-3 proteins was detected by Western blot after treated with rapamycin.Results:(1)Rapamycin markedly inhibited the proliferation of both RAJI and CA46 cells in a time- and concentration-dependent manner.It showed good biological activity that the cell proliferation inhibition rate reached about 20% after treated with 1 nmol/L rapamycin.(2)After treated with different concentrations of rapamycin for 24 hours and 48 hours,the proportion of both cells in G1/G0 phase in treated groups was significantly increased in a time- and concentration-dependent manner,compared with that in solvent control group.With regard to S and G2/M phase cells, the decreased population was accompanied with the increase of G1/G0 phase cells.(3)After treated with 100nmol/L rapamycin for 48 hours, both cells demonstrated apparent apoptosis,especially late apoptosis by FITC Annexin V staining Flow cytometry assay.(4)After treatment with rapamycin,the expression of p-RPS6 and survivin of Burkitt Lymphoma cell line RAJI and CA46 cells was obviously down-regulated,the expression of caspase-3 was obviously up-regulated in a time- and dose-dependent manner.However,rapamycin did not obviously affect the expression of RPS6.Conclusion:Our data suggests that rapamycin can effectively inhibit cell proliferation,arrest at G1/G0 phase in Burkitt Lymphoma cell line RAJI and CA46 cells,and this effect is achieved by inhibiting the activation of m TOR/RPS6 signal pathway through down-regulating the expression of phosphorylated RPS6 that is downstream effector of m TOR signal pathway.It also can induce apoptosis by down-regulating of the expression of anti-apoptotic protein survivin and activating the intrinsic pro-apoptotic protein caspase-3.Therefore,m TOR inhibitor rapamycin might be an attracting therapeutic approach for Burkitt Lymphoma. |
