Suppression of the growth of subcutaneous transplanted human liver cancer and lung metastasis in nude mice treated by sorafenib combined with fluorouracil

Abstract

The aim of this study was to explore the inhibitory effect of sorafenib and 5-Fu on transplanted human liver cancer in nude mice, and to investigate the synergistic effect and mechanism between sorafenib and 5-Fu. The nude mouse model of human liver cancer was made by transplantation of human highly metastatic liver cancer cell line HCCLM3 cells, and the tumor-bearing nude mice were treated with sorafenib, 5-Fu or both, respectively, and mock-treated tumor-bearing nude mice as negative control. To assess the anti-tumor effect of sorafenib and the synergistic effect of sorafenib combined with 5-Fu by measuring the tumor weight and number of lung metastases. Moreover, the expressions of phosphorylated extracellular signal-regulated kinase (p-ERK), P-glycoprotein (P-gp) and topoisomerase 2-alpha (Topo IIa) in the nude mice were assayed by immunocytochemistry and Western blot. The tumor weights and numbers of lung metastases were: (2.7 ± 0.825) g and 12.714 ± 6.317 in the negative control group, (0.933 ± 0.333) g and 4.333 ± 3.983 in the sorafenib group, (0.786 ± 0.212) g and 5.429 ± 4.315 in the Sorafenib + 5-Fu combination group, and (2.438 ± 0.793) g and 10.429 ± 6.241 in the 5-Fu group. Statistically, the tumor weights and numbers of lung metastases in the sorafenib group and combination group were significantly decreased, compared with that in the control group (P < 0.05). There was no significant difference in the tumor weight and number of lung metastases between the sorafenib group and the combination treatment group (P > 0.05). The expression levels of p-ERK, P-gp and Topo IIa proteins in the tumors after normalization were: negative control (0.017 ± 0.010, 0.085 ± 0.012, 0.103 ± 0.093), sorafenib group (0.010 ± 0.008, 0.044 ± 0.020, 0.020 ± 0.018), combination group (0.011 ± 0.007, 0.043 ± 0.023, 0.062 ± 0.026), and 5-Fu group (0.018 ± 0.009, 0.063 ± 0.032, 0.065 ± 0.034), respectively. Statistically, the expression of p-ERK, P-gp and Topo IIa in the Sorafenib group was significantly reduced compared with that of the control group (P < 0.05), and there was no significant difference in the expression of p-ERK, P-gp and Topo IIa between the sorafenib group and the combination treatment group (P > 0.05). Sorafenib can inhibit not only the tumor growth and lung metastsis in the nude mouse models, but also reduce the expression of multidrug resistance proteins P-gp and Topo IIa as well. There is no significant advantage for the sorafenib + 5-Fu combination treatment than Sorafenib alone in inhibiting the expression of p-ERK, P-gp and Topo IIa.