Effects of CD59 on antitumoral activities of phycocyanin from Spirulina platensis

The regulatory effect of phycocyanin (PC) from Spirulina platensis on cluster of differentiation 59 (CD59) gene expression of Hela cells and antitumoral mechanism of PC was investigated in this study. PC was purified by hydroxylapatite (HA) and sephacrylHR-200 gel-filtration columns chromatography. The molecular weight of PC was determined by SDS-PAGE electrophoresis. The CD59 cDNA was inserted into the eukaryotic expression plasmid pALTER-MAX, and the recombinant vector pALTER-MAX-CD59 was successfully constructed. By using cationic liposome (Lipfectamine-2000)-mediated transfection method, the recombinant plasmid pALTER-MAX-CD59 and the selective marker PcDNA were cotransfected into Hela cells and normal Chinese hamster ovary (CHO) cells. Stable positive cell clones were sorted out and disposed with different concentrates of PC. The expression of CD59 protein was determined by in situ hybridization, immunofluorescence and enzyme linked immunosorbent assay (ELISA). In addition, the effect of PC on the proliferation of Hela cells was determined by MTT method and the expression of Fas protein was by immunohistochemistry. Results showed that PC can promote the expression of CD59 protein in Hela cells, hold back it is reproductions of Hela cells, and moreover, a dosage effect was found between them. Namely, with the ascendance of PC concentration, the expression quantities of CD59 protein and apoptosis-inducing Fas protein increased and the multiplication activity of Hela cells declined, whereas PC was of no use to CD59 and Fas protein expression, and reproduction of normal CHO cells as well. Besides an imaginable antitumoral molecular immune mechanism of PC was brought forward and discussed.