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22 avril 2011 5 22 /04 /avril /2011 18:10
Eur J Pharmacol. 2010 Dec 15;649(1-3):74-83. Epub 2010 Sep 19.

C-Phycocyanin inhibits MDR1 through reactive oxygen species and cyclooxygenase-2 mediated pathways in human hepatocellular carcinoma cell line.


School of Life Sciences, University of Hyderabad, Hyderabad-500046, India.


The effects of C-Phycocyanin (C-PC), a biliprotein from Spirulina platensis on the regulation of multidrug resistance-1 (MDR1), a poly glycoprotein in human hepatocarcinoma cell line, HepG2 were reported.


The results revealed that a significant down regulation of MDR1 expression in C-PC treated HepG2 cells was through reactive oxygen species and cyclooxygenase-2 (COX-2) mediated pathways.


C-PC in a concentration dependent manner increased the accumulation of doxorubicin in HepG2 cells and enhanced sensitivity of the cells to doxorubicin by 5 folds.


The induction of MDR1 expression by PGE₂ and its down regulation by C-PC and DPI (Diphenylene iodonium, NADPH oxidase inhibitor) or by COX-2 knockdown suggest that the enhanced sensitivity of HepG2 cells to doxorubicin by C-PC is mediated by the down regulation of MDR1 expression.


Further studies reveal the involvement of NF-κB and AP-1 in the C-PC induced down regulation of MDR1. Also the inactivation of the signal transduction pathways involving Akt, ERK, JNK and p38 by C-PC was observed.


The present study thus demonstrates the efficacy of C-PC in overcoming the MDR1 mediated drug resistance in HepG2 cells by the down regulation of reactive oxygen species and COX-2 pathways via the involvement of NF-κB and AP-1.


[PubMed - indexed for MEDLINE]

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