Abstract: Objective To investigate the direct effects of carboxyamidotriazole(CAI)on the survival and apoptosis of colon cancer cells(MC38 and C26)and its indirect effects through enhancing the anticancer effects of spleen lymphocytes in mice. Methods MC38 and C26 cells were cultured in vitro,spleen lymphocytes of mice were isolated,MC38 and C26 cells were co-cultured with spleen lymphocytes of mice,and the cells were treated with different concentrations of CAI. CCK-8 method was used to detect cell survival,flow cytometry was used to detect cell apoptosis and the proportion of CD4⁺CD3⁺ T cells and CD8⁺CD3⁺ T cells in spleen lymphocytes of mice. Results The number of living cells of MC38 and C26 cells decreased(P＜0.05,P＜0.01 and P＜0.001)and the apoptosis rate was increased(P＜0.01 and P＜0.001)after being treated with different concentrations of CAI. The number of living cells of MC38 and C26 cells was decreased(P＜0.001)upon being co-cultured with spleen lymphocytes of mice for 48 h, and the apoptosis rate was increased(P＜0.001). The number of living cells of MC38 and C26 cells in co- culture groups treated with different concentrations of CAI for 48 h further decreased(P＜0.001)and the apoptosis rate increased(P＜0.05 and P＜0.001)as compared with those co-cultured with spleen lymphocytes of mice without CAI. The proportion of CD4⁺CD3⁺ T cells and CD8⁺CD3⁺ T cells in spleen lymphocytes of mice was significantly increased(P＜0.05 and P＜0.01)after 48 h treatment with different concentrations of CAI. Conclusions CAI can inhibit the survival and promote apoptosis of MC38 and C26 cells,and enhance the effects of spleen lymphocytes in mice on inhibiting the survival and promoting apoptosis of MC38 and C26 cells through a potential mechanism of increasing the proportion of CD4⁺CD3⁺ T cells and CD8⁺CD3⁺ T cells in spleen lymphocytes of mice.

Key words: carboxyamidotriazole, spleen lymphocytes of mice, colon cancer, apoptosis