ABSTRACT
[ ABSTRACT] AIM:To investigate the effect of phycocyanin on the apoptosis of human laryngeal cancer HEP-2 cells and to explore the inhibitory mechanism of phycocyanin to tumor.METHODS:Highly purified phycocyanin was ex-tracted from spirulina.The effects of phycocyanin at different concentrations on the growth of human laryngeal cancer HEP-2 cells were detected by MTT assay.In addition, the cell structures were observed under electron microscope.The cell ap-optosis was analyzed by flow cytometry.The production of reactive oxygen species ( ROS) was measured by flow cytometry. Enzymatic activities of caspase-3,-8 and-9 were measured by chemical colorimatry.The expression of Bax, Bcl-2, Fas, P53, caspase-3 and caspase-9 at mRNA and protein levels was determined by RT-PCR and Western blot.RESULTS:MTT test confirmed that phycocyanin inhibited the cell activity of HEP-2 cells with time and dose dependent manners.The result of electron microscope observation and flow cytometry indicated that phycocyanin induced the apoptosis of HEP-2 cells.The intracellular content of ROS was increased.The activities of caspase-3, -8 and -9 were increased.RT-PCR showed that the mRNA expression of Bax, Fas, P53, caspase-3, caspase-9 was increased and Bcl-2 was decreased.The results of Western blot were consistent with the results of RT-PCR.CONCLUSION:Phycocyanin might induce apoptosis of HEP-2 cells by down-regulating Bcl-2, up-regulating Bax, Fas and P53, and the transduction of apoptotic signals in the human laryngeal cancer cells.