Investigation of cytotoxic and apoptotic effects of single and combined doses of (-)-gossypol (AT-101) and recombinant human apo2l/trail in breast cancer cell lines (MCF-7 and MDA-MB-231)

AT-101 is an (-)- enantiomer of gossypol with potent anticancer agent. Tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) induces apoptosis preferentially in cancer cells. The objective was to investigate the cytotoxic and apoptotic effects of single and combined doses of AT-101 and Apo2L/TRAIL on human breast cancer cell lines (MCF-7 and MDA-MB-231) and to find out what apoptotic molecules have been affected. The cells were incubated with AT-101 (0.5-10?M) and TRAIL (10-200ng/mL) for 72 hours. XTT-based viability assay was used to calculate the percentage cytotoxicity. Apoptosis was confirmed by measuring the histon-DNA fragmentation degree.The IC50 values of MCF-7 and MDA-MB-231 cells were 4.64 ?M, 3.99 ?M (AT-101) and 133 ng/mL, 93.2 ng/mL (TRAIL) respectively. The cytotoxicity for MCF-7 and MDA-MB-231 cells was 32.3, 36.6 % in AT-101(2.5 µM) and 36.8, 35.7 % in TRAIL (60 ng/mL) respectively.The synergistic cytotoxicity was 78.2 % (CI: 0.298) at MCF-7 cells while it was 83.2 % (CI: 0.256) at MDA-MB-231 cells at combination (60ng/mL TRAIL+2.5 ?M AT-101). In sequential treatment of 2.5 ?M AT-101 and 80 ng/mLTRAIL, cytotoxicity were 80.8 and 86.8 % for MCF-7 and MDA-MB-231 cell cultures respectively.The combined use of AT-101 and TRAIL resulted in an increase at Bax, Trail-R1, Caspase-3, Cytochrome C, proteins and a decrease in Pon2, Procaspase-3 , Bcl-x, Bcl-2 and Xiap proteins in MDA-MB-231 cell cultures. There was significant increase in Bad, Trail-R1, Pon2, Fadd, Smac/Diablo, Cytochrome C and a decrease in Ciap protein in MCF-7 cell cultures.The study is the first primary data on the synergistic apoptotic effects of AT-101 and TRAIL combination in MCF-7 and MDA-MB-231 cell lines.