The aim of the present study was to investigate the expression of cold-inducible RNA-binding protein (CIRP) in renal cell carcinoma (RCC) and to determine the effects of downregulation of CIRP on cell proliferation and chemosensitivity to gemcitabine. The expression of CIRP was detected by western blot analysis, quantitative polymerase chain reaction and immunohistochemistry (IHC) in 17 RCC and peri-cancerous tissue samples. Subsequently, the RCC 786-0 cell line was selected in order to investigate the function of CIRP using RNA interference (RNAi) technology, which was able to inhibit the expression of CIRP in vitro. Furthermore, the chemosensitivity to gemcitabine of each group [CIRP small interfering RNA (siCIRP), negative control small interfering RNA (siNC) and blank control] was compared. There were marked differences between the RCC and peri-cancerous tissues. IHC demonstrated that the CIRP expression in 13/17 (76.50%) tumor samples was markedly positive compared with that in the peri-cancerous tissues and the most common pathological type was clear cell RCC (92.30%). This observation was further confirmed through western blot analysis of protein expression levels. CIRP downregulation by RNAi in the RCC 786-0 cell line significantly decreased RCC proliferation. Additionally, when RNAi was coupled with gemcitabine treatment, there was a significant increase in apoptosis in the siCIRP group. CIRP was overexpressed in RCC tissues and in the 786-0 cell line. Downregulation of CIRP by siRNA inhibited the proliferation of the 786-0 cell line and enhanced the chemosensitivity of the cells to gemcitabine. Therefore, CIRP downregulation may provide a novel pathway for the treatment of metastatic RCC.
Keywords: chemosensitivity; cold-inducible RNA-binding protein; gemcitabine; renal cell carcinoma.