Inducible overexpression of Bak sensitizes HCC-9204 cells to apoptosis induced by doxorubicin

AIM: To investigate the role of overexpression of Bak in apoptotic pathways and drug susceptibility using doxorubicin and vinorelbine in human HCC-920 4 cells. METHODS: An inducible system, MT-II regulatory system which allowe d controlled expression of protein upon addition of ZnSO4(100 mu mol/L) as an external inducer was used. Stable transfection of pMD-Bak gene was perfo rmed on HCC-9204? cells. Apoptotic cells were measured by morphological cri teria, as well as by TUNEL assay and flow cytometry. The ability of Bak to decrease clonogenic cell survival was studied by colony-forming assays, whi le decrease in cell viability was assessed by MTT assay. RESULTS: Cells ove rexpressing Bak showed extensive cell death with nucleus fragmentation dete cted by TUNEL assay. FAGS analyses showed that Bak could induce significant G(1) accumulation and apoptosis in 19.29 % cells 24 h after induction. Bak significantly decreased the clonogenic survival following exposure to adri amycin, but not vinorelbine. Furthermore, the time-course of cell viability rates following exposure of HCC-9204/Bak cells to adriamycin and vinorelbi ne was in agreement with the above findings. Bak selectively sensitized HCC -9204 cells to death induced by adriamycin while resisted to vinorelbine. C ONCLUSION: Bak may prolong cell cycle in G(1) phase, leading to apoptosis a nd decrease clonogenic survival of HCC-9204 cells in a drug-specific manner .