Phycocyanin-mediated apoptosis in AK-5 tumor cells involves down-regulation of Bcl-2 and generation of ROS.
C-phycocyanin, which is a major biliprotein of the blue-green algae, has been shown to possess cyclooxygenase-2 inhibitory activity. We have studied the effect of phycocyanin on a rat histiocytic tumor line. AK-5 cells are induced into apoptotic death program when treated with phycocyanin, which involves the activation of caspase-3. Phycocyanin-mediated apoptotic death is induced through the generation of reactive oxygen radicals. Free radical scavengers inhibited phycocyanin-induced apoptotic death in AK-5 cells. Bcl-2, an inhibitor of apoptosis, is shown to regulate ROS generation. Bcl-2 gene-transfected AK-5 cells are resistant to phycocyanin-induced death. Overexpression of Bcl-2 inhibited the production of ROS in phycocyanin-treated AK-5 cells. Thus, our observations demonstrate phycocyanin-induced apoptotic death in AK-5 cells, which is inhibited by Bcl-2 expression through the regulation of free radical generation. Phycocyanin, a natural product, could therefore be a possible chemotherapeutic agent through its apoptotic activity against tumor cells.
Pardhasaradhi
Bobbili V V
BV
Centre for Cellular and Molecular Biology, Hyderabad 500 007, India.
Ali
A Mubarak
AM
Kumari
A Leela
AL
Reddanna
Pallu
P
Khar
Ashok
A
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D000458:Cyanobacteria; D051546:Cyclooxygenase 2; D053938:DNA Fragmentation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D007527:Isoenzymes / Q000378:metabolism; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology*; D010798:Phycocyanin / Q000494:pharmacology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D007527:Isoenzymes; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D010798:Phycocyanin; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases