[Apoptosis of lymphocytes induced by Fas/FasL of colon cancer cells].

BACKGROUND & OBJECTIVE: It has been reported that apoptotic rate of tumor infiltrating lymphocytes(TIL) in Fas ligand(FasL) positive region was higher than in FasL negative region, which indicated that tumor cells could kill tumor infiltrating lymphocytes through high-expressed FasL. This study was designed to determine whether colon cancer cells SW480 could induce apoptosis of lymphocytes by Fas system in vitro. METHODS: Colon cancer cells SW480 were co-cultured with Jurkat cells with different effector-target(E-T) ratios of 20:1, 10:1, 5:1. Growth curve method, flow cytometry(FCM) analysis, fluorescence microscope were used to detect apoptosis of Jurkat cells. RESULTS: Flow cytometry revealed that the apoptotic rate of Jurkat cells were 1.8 +/- 0.21, 5.49 +/- 0.17, 11.18 +/- 0.14, and 18.22 +/- 0.11 with the SW480 planting concentrations at 0(control), 0.5 x 10(5)/ml, 1 x 10(5)/ml, 2 x 10(5)/ml, respectively. Fluorescence microscopy showed that the apoptotic rate of Jurkat cells were 1.58 +/- 0.12, 5.22 +/- 0.13, 9.74 +/- 0.21, and 19.33 +/- 0.18 with the SW480 planting concentrations at 0(control), 0.5 x 10(5)/ml, 1 x 10(5)/ml, and 2 x 10(5)/ml, respectively. Based on the three different E-T ratios, SW480 cell could all induce apoptosis of Jurkat. Furthermore, Jurkat cell apoptosis rate increased with the increase of planting concentration of SW480 and co-culture time. There were significant difference between each test group and control(All values P < 0.01). CONCLUSION: Colon cancer cells SW480 could induce apoptosis of lymphocytes throught Fas system, which providing theoretical foundation for metastasis and counterattack of colon cancer.