Contrary influence of clinically applied sorafenib concentrations among hepatocellular carcinoma patients

The treatment responses of sorafenib in hepatocellular carcinoma are modest which may be due to different characteristics of cancer cells or insufficient therapeutic concentrations. This study was to clarify this issue. The anti-proliferative effects and differential expressions of 8 genes related to sorafenib anti-cancer mechanisms (tyrosine kinase receptor genes: KDR, PDGFRB; RAF cascade: RAF1, BRAF, MAP2K1, MAP2K2, MAPK1, MAPK3) were investigated in primary cultured hepatocellular carcinoma cells collected from 8 patients using clinically applied sorafenib concentrations (5, 10 μg/mL). The anti-proliferative effects of sorafenib at either 5 or 10 μg/mL, which were related to down-regulations of KDR, PDGFRB and/or genes in the RAF cascade, were achieved only in one patient (HCC38/KMUH). However, either 5 or 10 μg/mL sorafenib promoted proliferation in 4 patients (HCC29/KMUH, HCC62/KMUH, HCC87/KMUH, HCC98/KMUH). Among them, the RAF cascade, PDGFRB and/or KDR were up-regulated in 3 patients but no gene was differentially expressed in the remaining one patient (HCC87/KMUH). Increase the sorafenib concentration to 10 μg/mL paradoxically up-regulated and/or obliterated the previously down-regulated genes in the RAF cascade and/or KDR in 4 patients (HCC29/KMUH, HCC76/KMUH, HCC87/KMUH, HCC98/KMUH). Significant down-regulations of the RAF cascade and PDGFRB by sorafenib but without anti-proliferative effects were detected in one patient (HCC54/KMUH). In conclusion, influence of sorafenib on proliferation is not simply through the RAF cascade. The responses of KDR, PDGFRB and the RAF cascade to sorafenib among patients are diverse or even contrary. Increase the sorafenib concentration has potential to up-regulate genes favored angiogenesis and proliferation.