Abstract: Objective To establish a bcl-2 transfected squamous cell carcinoma cell line SCL-1 which stably expresses bcl-2 protein,and to investigate the Fas signaling pathway in the apoptosis of SCL-1 cells.Methods SCL-1 cells were transfected by lipofection with bcl-2 cDNA-containing retrovirus expression vector pIRESneo(SCL-1/bcl-2)or plRESneo vector plasmid(SCL-1/vector)as control.The transfected cells were selected with G-418,and passaged.The protein and mRNA expression of bcl-2 was detected by immunofluorescence,Western blot and RT-PCR,respectively.Then,varying concentrations(0～120μmol)of C₂-ceramide,CH-11(a monoclonal antibody to Fas protein)were applied to induce the apoptosis of SCL-1/bcl-2 and SCL-1/vector cells.The apoptosis rate of these cells was measured by detection of soluble DNA-histone complexes with ELISA.Results Bcl-2 protein was found to be expressed in the SCL-1/bcl-2 cells,but not in the SCL-1/vector cells.The apoptosis rate of SCL-1/bcl-2 cells induced by C₂-ceramide was of no significant difference from the control cells without any stimulation,while statistical difference was observed in that of SCL-1/vector cells between the C₂-ceramide-stimulating group and the control without any stimulation.There was a significant difference in the apoptosis rate of both SCL-1/bcl-2 and SCL-1/vector cells induced by CH-11 from that of the control free of any stimulation.Conclusion s The SCL-1 cell clone expressing bcl-2 protein highly and stably,is established successfully by gene transfection technique.Bcl-2 could generally antagonize the apoptosis in SCL-1 cells induced by C₂-ceramide,but only partly inhibit that induced by CH-11,which may suggest that the apoptosis of SCL-1 cells could occur via death receptor pathway after the blockage of mitochondrial apoptosis pathway.

Key words: Carcinoma,squamous cell, Apoptosis, Antigens,CD95, Proto-oncogene proteins c-bcl-2, Ceramide