THE SYNERGISTIC EFFECT OF CO-ADMINISTRATION OF HMG-COA REDUCTASE INHIBITOR AND SELECTIVE COX-2 INHIBITOR AGAINST HEPATOCELLULAR CARCINOMA CELLS IS MEDIATED BY INHIBITION OF NF-KB/AKT PATHWAY

Abstract

Background and Aims: Both NS-398, a selective cyclo-oxygenase-2 (COX-2) inhibitor and simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor exert anti-cancer effect on HCC cells, but the effect of co-administration of two drugs is still unknown. NF-kB/Akt is connected with multiple aspect of oncogenesis, including cell cycle progression and apoptosis. The present study was undertaken to investigate the synergistic in vitro anti-cancer effects of co-administration of NS-398 and simvastatin and the role of NF-kB/Akt pathway.

Method: The human HCC cell lines, Hep3B and Huh7 were cultured. Both cells were treated with control, simvastatin, NS-398, and co- administration of simvastatin and NS-398 for 24 and 48 hours. Cell proliferation was measured by BrdU assay. Apoptosis was evaluated by flow cytometry. Expression of proteins including proapoptotic molecules, antiapoptotic molecules, cell cycle regulators, Akt and NF-kB were measured in Western blot analysis.

Results: In Hep3B cells, co-administration of simavastatin and NS-398 resulted in a greater effect on proliferation and apoptosis. Both NS-398 and simvastatin resulted in decrease of procaspase-3, Bcl-2, and increase of cleaved caspase-9, but co-administration of two drugs resulted in a greater decrease of procaspase-3 and Bcl-2 and increase of cleaved caspase-9 than monotherapy. NF-kB and Akt expression decreased by each drug alone, but more decreased when the two drugs were co-administered. In Huh7 cells, co-administration of simavastatin and NS-398 resulted in a greater effect on proliferation but not in apoptosis. Both NS-398 and simvastatin resulted in decrease of procaspase-3, cyclin D1 and increase of cleaved caspase-9. Co-administration of two drugs resulted in a greater decrease of procaspase-3 and cyclin D1 and increase of cleaved caspase-9. NF-kB and Akt expression were also more decreased when the two drugs were co-administered.

Conclusion: The co-administration of NS-398 and simvastatin produced greater anti-cancer effect against Hep3B cells and Huh 7 cells. The co-administration resulted in a greater increase of proapoptotic molecules and a decrease of antiapoptotic molecules. The mechanism of synergistic anti-cancer effect seems to be mediated through inhibition of NF-kB/Akt pathway.