Spirulina phycocyanin induces differential protein expression and apoptosis in SKOV-3 cells.

The present study was designed to determine the effects of phycocyanin (PC) on Human ovarian cancer SKOV-3 cells and the underlying molecular mechanisms of action. The inhibitory effects of PC on the cell proliferation were detected by MTT assay. The IC50 values of PC were 182.0μM and 133.6μM for 24h and 48h exposure, respectively. PC induced apoptosis in SKOV-3 cells was observed by electron microscopy and flow cytometry. The apoptosis rate was increased from 1.6% to 19.8% after PC exposure. The fluorescence intensity of ROS and the activities of Caspase-3, Caspase-8, and Caspase-9 were increased. Differentiated expression protein spots were selected and identified using proteomic techniques. There were 698±73 and 683±79 protein spots resolved in untreated and PC-treated cells, respectively. Forty five differential protein spots were analyzed by MALDI-TOF-MS, including mtSSB, PSME3, and nucleolin. The mRNA expression profiles determined by RT-PCR were consistent with that of the two-dimensional electrophoresis. The decreased proteins such as HSP60, nucleolin, PPase, peroxiredoxin-4 and the increased protein (mtSSB) were identified in SKOV-3 cells after PC treatment, indicating that the effects of PC on tumor cell apoptosis may be relate to multiple target proteins. And the mitochondrial pathway may be the main pathway for PC-induced apoptosis.