THE EGYPTIAN JOURNAL OF IMMUNOLOGY Vol. 16 (1), 2009 Page: 00-00 C-Phycocyanin Inhibits Cell Proliferation and May Induce Apoptosis in Human HepG2 Cells 1 Osama M. Basha, 2 Raghda A. Hafez, 3 Yassin M. El-Ayouty, 4 Karima F. Mahrous, 5 Mohammed H. Bareedy, 3 Ahmed M. Salama 1 Department of Internal Medicine, Faculty of Medicine, Zagazig University, Zagazig, 2 Department of Microbiology, Faculty of Medicine, Zagazig University, Zagazig, 3 Department of Botany, Faculty of Science, Zagazig University, Zagazig, 4 National Research Center, Division of Genetic Engineering & Biotechnology, Department of Cell Biology, Cairo, 5 Department of Histology & Cytology, Faculty of Veterinary Medicine, Zagazig University, Egypt. C-Phycocyanin (C-PC) is one of the major biliprotein pigments of unicellular cyanbacterium of Spirulina platenesis, it has nutritional, medicinal, and hepatoprotectant application. The growth and multiplication of human hepatoma cell lines (HepG2) under the effect of different concentrations of C-PC (0.8, 1.75, 3.5 and 7.0 µg/ml) against untreated cells as control for 24h were investigated. The results showed that the proliferating cells in presence of C-PC reached 70, 51, 44, and 39%, respectively. The results revealed that the greatest reduction in proliferation of cells was recorded at 7.0 µg/ml and LC 50 at 1.75 µg/ml of C-PC. In parallel, to the previous results HCl-denatured MG-P revealed that in mass of cells there is a pattern of apoptosis because the expanded cytoplasmic area (bluish-green) reduced and appeared faintly red as C-PC concentration increased. Moreover, the cells lost all the nuclear entities then, become fragmented and having no nuclear remnants. The C-PC may be a new potential anti-cancer drug for therapy of human hepatoma cells. n recent years, there is an increasing awareness that certain naturally occurring compounds in plants and other sources, have protective effects against environmental mutagens/carcinogens and endogenous mutagens (Abraham, 2001). Dietary intake of such chemo preventive compounds has been suggested as an effective strategy for minimizing the deleterious effects of genotoxins and carcinogens. Spirulina is one of blue green microalgae, that has been used since ancient times as a source of food because of its high protein and nutritional values and it is gaining attention as a source of potential pharmaceuticals. Recent studies have demonstrated that C-PC, extracted from Spirulina, has several effects including antioxidant (Miranda et al., 1998), antimutagenic (Chamorro et al., 1996), antiviral (Ayehunie et al., 1998), anticancer (Chen et al., 1995; Schwartz et al., 1988), anti-allergic (Kim et al., 1998), immune enhancing (Qureshi et al., 1996), hepato- protective (Gonzalez et al., 1993), blood vessel relaxing (Paredes-Carbajal et al., 1997) and blood lipid-lowering effects (Iwata et al., 1990). The biological and pharmacological properties of Spirulina were attributed mainly to calcium-spirulan and (C-PC). C-PC, a water-soluble non-toxic biliproteins pigment isolated from Spirulina platenesis, has significant antioxidant and radical scavenging properties (Vadiraja et al., 2000). C-PC is one of the major biliproteins of Spirulina platenesis, this water soluble protein pigment was shown to be hepatoprotective (Vadiraja et al., 1998), antiarthritic (Remirez et al., 1999), and anti-inflammatory (Romay et al., 2000; Romay et al., 1998) in both in vitro and in vivo experimental models. However, little is known about its mechanism of action. Earlier, Reddy et al., 2000, showed that C-PC selectively inhibits cyclooxygenase-2 (COX- 2), the inducible isoform of cyclooxygenase, implicated in the mediation of inflammation, and arthritis. C-PC is used for the treatment of I