C-Phycocyanin, a selective cyclooxygenase-2 inhibitor, induces apoptosis in lipopolysaccharide-stimulated RAW 264.7 macrophages

• Published in: Biochemical and biophysical research communications 2003-05, Vol.304 (2), p.385-392
• Main Authors: Reddy, Madhava C, Subhashini, J, Mahipal, S.V.K, Bhat, Vadiraja B, Srinivas Reddy, P, Kiranmai, G, Madyastha, K.M, Reddanna, P
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; C-Phycocyanin; Cell Division - drug effects; Cell Line; Cell Nucleus - ultrastructure; Cell Survival - drug effects; Cyanophyta; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors - pharmacology; Cytochrome c; Cytochrome c Group - metabolism; Dinoprostone - biosynthesis; DNA Fragmentation; Flow Cytometry; Isoenzymes - antagonists & inhibitors; Isoenzymes - metabolism; Lipopolysaccharides - pharmacology; Macrophages - cytology; Macrophages - drug effects; Macrophages - enzymology; Macrophages - metabolism; Membrane Proteins; Mice; Microscopy, Confocal; Mitochondria - metabolism; Phycocyanin - pharmacology; Poly(ADP-ribose) Polymerases - metabolism; Prostaglandin-Endoperoxide Synthases - metabolism; Proto-Oncogene Proteins c-bcl-2 - metabolism; RAW 264.7 cells; Spirulina platensis
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/S0006-291X(03)00586-2

C-Phycocyanin (C-PC) is one of the major biliproteins of Spirulina platensis, a blue green algae, with antioxidant and radical scavenging properties. It is also known to exhibit anti-inflammatory and anti-cancer properties. However, the mechanism of action of C-PC is not clearly understood. Previously, we have shown that C-PC selectively inhibits cyclooxygenase-2 (COX-2), an inducible isoform that is upregulated during inflammation and cancer. In view of the reported induction of apoptosis in cancer cells by cyclooxygenase-2 inhibitors, the present study is undertaken to test the effect of C-PC on LPS stimulated RAW 264.7 mouse macrophage cell line. These studies have shown a dose dependent reduction in the growth and multiplication of macrophage cell line by C-PC. This decrease in cell number appears to be mediated by C-PC induced apoptosis as evidenced by flow cytometric and confocal microscopic studies. Cells treated with 20 μM C-PC showed typical nuclear condensation and 16.6% of cells in sub-G o/G 1 phase. These cells also showed DNA fragmentation in a dose dependent manner. The studies on poly(ADP ribose) polymerase (PARP) cleavage showed typical fragmentation pattern in C-PC treated cells. This C-PC induced apoptosis in RAW 264.7 cells appears to be mediated by the release of cytochrome c from mitochondria and independent of Bcl-2 expression. These effects of C-PC on RAW 264.7 cells may be due to reduced PGE 2 levels as a result of COX-2 inhibition.