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]