Suppression of the expression of multidrug resistance protein in liver cancer cells by sorafenib and the growth of subcutaneous tumor in nude mice model treated by a combination of sorafenib and fluorouracil

Abstract

Objective To explore the inhibitory effect of sorafenib on the expression of multidrug resistance proteins in HCCLM3,a human hepatocellular carcinoma cell line with high metastatic potential,and to investigate the synergistic effects of sorafenib and fluorouracil (5-Fu).Methods The HCCLM3 cells were treated with sorafenib plus 5-Fu or alone,respectively,and mock-treated as negative control.The expression of phosphorylated extracellular signal-regulated kinase ( pERK),P-glycoprotein (P-gp) and topoisomerase 2α(TOP-2α) in these cells was analyzed by immunocytochemistry and Western blotting.Moreover,nude mice were subcutaneously inoculated with HCCLM3 cells,and drug intervention was conducted similarly in four groups as described above.The changes in tumor volume were monitored.3 treatment groups and I control group were established in both cell and nude mice experiment:negative control (C),sorafenib (S),sorafenib and 5-Fu (SF),5-Fu (F).Results In the cell experiment,the quantified protein expression levels of pERK,P-gp and TOP-2α after normalization were as follows:C group (0.061 ± 0.026,0.076 ± 0.033,0.075 ± 0.022),S group (0.024 0.011,0.027 ± 0.006,0.025 ±0.024),SF group (0.027 ±0.015,0.022 ±0.019,0.038 ±0.020),F group (0.080 ± 0.036,0.047± 0.005,0.059 ± 0.025 ).Statistically,the cellular expression of pERK,P-gp and TOP-2α in S and SF groups was significantly reduced as compared with C group (P ＜ 0.05 ).In the nude mice experiment,the volume ( cm3 ) of tumors was as follows:C group ( 5.292 ± 1.523),S group ( 1.620 ± 0.784),SF group ( 1.110 ±0.402),F group (4.327± 1.709).Statistically,the volume of tumors in S and SF groups was significantly less than that in C group (P ＜ 0.05 ).Conclusion Sorafenib or the combination of sorafenib and 5-Fu can reduce not only the expression of pERK,P-gp and TOP-2α in HCCLM3 cells significantly,but also the volume of tumors in nude mice as well. Key words: Carcinoma, hepatocellular; Sorafenib; Fluorouracil; Extracellular signal-regulated kinase