Abstract:

Objective To investigate the relationship between expression of active form of caspase-3 and cell cycle in Fas-mediated apoptosis of B lymphocytoma cell line MML-1. Methods MML-1 cells were incubated with agonistic anti-Fas antibody for different time, and cell apoptosis was induced. Cell apoptotic rates were analysed by flow cytometry, and sensitivity of MML-1 cells to apoptosis was determined. The expression of active form of caspase-3 was analysed by double staining with PI-Triton X and FITC-active caspase-3. Cyclin A, B₁ and E were selected as cell cycle markers for S, G₂/M and G1 phase of MML-1 cells, and the expression of active form of caspase-3 was detected by flow cytometry. Results The cell apoptotic rate reached 56% after induction by Fas for 6 h. After induction by Fas for 4 h, the active form of caspase-3 was mainly expressed in cells of G₁ phase, while rarely in cells of S and G₂/M phase. Cells with negative cyclin A and B₁ and positive cyclin E expressed active form of caspase-3. Conclusion The expression of active form of caspase-3 in MML-1 cells mediated by Fas might be cell cycle dependent. Cells entering into late G₁ and early S phase first express active form of caspase-3, and their sensitivity to Fas-mediated apoptosis is the highest.

Key words: apoptosis, caspase-3, cell cycle, Fas