Harada K, Miyake H, Kusuda Y, Fujisawa M
Division of Urology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan.
Clin Transl Oncol. 2014 Sep;16(9):801-6. doi: 10.1007/s12094-013-1151-9. Epub 2013 Dec 20.
The objective of this study was to investigate the mechanism mediating the acquisition of a resistant phenotype to sorafenib in renal cell carcinoma (RCC).
A parental mouse RCC cell line, RenCa (RenCa/P), was continuously exposed to increasing doses of sorafenib, and a cell line resistant to sorafenib (RenCa/R), showing an approximately sixfold higher IC(50) than that of RenCa/P, was established. Changes in the expression of several molecules in these cell lines following sorafenib treatment were evaluated by western blotting, and the effects of sorafenib treatment on the in vivo growth patterns were compared.
There were no significant differences in sensitivities to potential agents against RCC between RenCa/P and RenCa/R. Among several apoptosis-related proteins, the expression of clusterin in RenCa/R was significantly greater than that in RenCa/P. Following treatment with sorafenib, the expression level of phosphorylated p44/42 mitogen-activated protein kinase (MAPK) in RenCa/P, but not that in RenCa/R, was significantly decreased. Furthermore, additional treatment with a specific inhibitor of the MAPK signaling pathway significantly increased the sensitivity of RenCa/R to sorafenib, but not that of RenCa/P. There was no significant difference between the in vivo growth patterns of RenCa/P and RenCa/R in mice without sorafenib treatment; however, the growth inhibitory effect of sorafenib on the RenCa/P tumor was significantly greater than that on the RenCa/R tumor.
These findings suggest that the upregulation of clusterin and continuous activation of the MAPK pathway during sorafenib treatment may be involved in the acquisition of a resistance to sorafenib in RCC.
本研究的目的是探讨肾细胞癌（RCC）对索拉非尼获得耐药表型的介导机制。
将亲本小鼠肾癌细胞系RenCa（RenCa/P）持续暴露于递增剂量的索拉非尼中，建立了对索拉非尼耐药的细胞系（RenCa/R），其半数抑制浓度（IC50）比RenCa/P高约6倍。通过蛋白质印迹法评估索拉非尼处理后这些细胞系中几种分子表达的变化，并比较索拉非尼处理对体内生长模式的影响。
RenCa/P和RenCa/R对潜在的肾细胞癌治疗药物的敏感性没有显著差异。在几种凋亡相关蛋白中，RenCa/R中簇集素的表达明显高于RenCa/P。用索拉非尼处理后，RenCa/P中磷酸化的p44/42丝裂原活化蛋白激酶（MAPK）的表达水平显著降低，而RenCa/R中则没有。此外，用MAPK信号通路的特异性抑制剂进行额外处理显著增加了RenCa/R对索拉非尼的敏感性，但没有增加RenCa/P的敏感性。在未用索拉非尼处理的小鼠中，RenCa/P和RenCa/R的体内生长模式没有显著差异；然而，索拉非尼对RenCa/P肿瘤的生长抑制作用明显大于对RenCa/R肿瘤的作用。
这些发现表明，索拉非尼治疗期间簇集素的上调和MAPK通路的持续激活可能参与了肾细胞癌对索拉非尼的耐药获得。
