Abstract
Sorafenib is tyrosine kinase inhibitor used for the treatment of hepatocellular and renal carcinomas but suffers from resistance in some tumors such as colorectal cancer. Colorectal cancer multi-drug resistance might be attributed to over-expressionover-activation of P-glycoprotein (P-gp) efflux pump andor intracellular metabolism. Gingerol, paradol and shogaol are naturally occurring major compounds within the family Zingiberaceae. Gingerol and its related hydroxyphenylalkanones are known for their potential interference with P-gp function as well as intracellular drug metabolism. In the present study, we investigated the influence of gingerol, paradol and shogaol on the cytotoxic profile of sorafenib in colorectal cancer cell lines (HT-29, HCT-116, LS-174T and CaCo-2) via their influence on sorafenib cellular accumulation and intracellular metabolism. Sorafenib alone showed considerable cytotoxic activity against all testes colorectal cell lines with IC50 ranging from 2.00.3 to 11.100.8 M. Gingerol, paradol and shogaol significantly enhanced the cytotoxicity of sorafenib against HT-29 cells and decreased its IC50 from 9.20.4 M to 6.60.7, 3.80.4 and 4.7 0.4 M, respectively. Similarly in HCT-116, gingerol, paradol and shogaol significantly decreased sorafenib IC50 from 11.30.8 M to 5.70.7, 5.90.4 and 7.7 0.5 M, respectively. Using DNA cytometric analysis, combination of gingerol, paradol or shogaol with sorafenib significantly decreased the proliferating cell fractions from 16.91.1 to 11.61.1, 14.71.1 and 9.161.8, respectively. In parallel, combination of gingerol, paradol or shogaol with sorafenib significantly increased the c-PARP concentration from 60.020.0 pgcell to 256.525.8, 24461.4, and 202.937.2 pgcell, respectively. Gingerol and paradol, but not shogaol increased the intracellular accumulation of the P-gp probe, rhodamine at concentration range (3-100 M). However, using recombinant ATPase attached p-gp molecules, shogaol and paradol significantly inhibited the ATPase activity. Gingerol, paradol and shogaol increased sorafenib uptake and decreased its extracellular concentration from 1491.7132.0 ngml to 511.016.0, 216.039.0 and 256.415.6 ngml, respectively. Only gingerol and paradol increased sorafenib intracellular accumulation and increased its level from 239.016.0 pgcell to 297.032.6 and 327.012.0 pgcell, respectively. Both paradol and shogaol enhanced the intracellular metabolism of sorafenib to its N-oxide active metabolite and entrapped it within cellular compartment. In conclusion, gingerol, paradol and shogaol significantly enhanced the anti-cancer profile of sorafenib via influencing its cellular pharmacokinetics.