The betulinic acid-induced human CIK cell cytotoxicity to gastric cancer cell line SGC-7901 and its mechanism

Objective To observe the effect of betulinic acid(BetA) on the growth of human cytokine induced killer(CIK) cells and the killing activity of CIK cells on the gastric cancer cells in vitro before and after induced by betulinic acid,explore its mechanism.Methods Peripheral blood mononuclear cell (PBMC) were separated form the healthy and were induced with various of cytokine to become CIK cells in vitro.CIK cells were collected on the tenth day and were induced with betulinic acid in different concentrations,followed by 48 h,the colorimetric methyl thiazolyl tetrazolium(MTT) method assay the proliferation rate of human CIK cells.Flow cytometry (FCM) was used to detect the expression changes of perforin,granzyme B and CD107a of human CIK cells before and after betulinic acid-induced.Lactate dehydrogenase (LDH) release assay was used to measure the influence on cytotoxic activity of CIK cells induced by betulinic acid against gastric cancer cell line SGC-7901 in vitro.Western blot assay was used to measure the extracellular signal-regulated kinase1/2 (ERK1/2),and adapter proteins SH2-domain containing leukocyte protein of 76KD(SLP-76) and linker for activative of T cells(LAT) expression changes of human CIK cells before and after drug-induced.Results Betulinic acid can promote CIK cells growth when the concentration were in 0.08-10 μg/ml,the expression of perforin,granzyme B and CD107a of CIK cells were significantly higher than control group(P＜0.05) when the concentration of betulinic acid were in 0.3 μg/ml.In the meanwhile,the cytotoxic activity of CIK cells in vitro against gastric cancer cell line SGC-7901 were also remarkably higher than the control group (P＜0.05).The expression of SLP-76,LAT and ERK1/2 were significantly increased to a certain extent than the control group( P＜0.05 ),when CIK cells were treated with betulinic acid.Conclusion These results suggest that betulinic acid can promote CIK cells growth in some concentrations and increase the cytotoxic activity of CIK cells against gastric cancer cell line SGC-7901,its mechanism may related with two factors,on the one hand,enhancing the activity of SLP-76,LAT and ERK1/2,on the other hand,increasing the expression of perforin,granzyme B and CD107a on the surface of CIK cells. Key words: Betulinic acid; Gastric cancer cell line; CIK cells