miR-130b Promotes Sunitinib Resistance through Regulation of PTEN in Renal Cell Carcinoma

Abstract

Background: MicroRNAs are a class of small noncoding RNAs that play an important role in progression and drug resistance in cancer. Several reports have shown that miR-130b modulates cell growth and drug resistance in some cancers. However, the expression and biological role of miR-130b in renal cell carcinoma (RCC) remain poorly understood. This study aimed to examine the expression and functional role of miR-130b and to analyze the association between miR-130b and sunitinib resistance in RCC. Methods: The expression of miR-130b in 32 RCC tissues and their corresponding normal kidney tissues was determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). We performed a 4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT) assay in RCC cell lines transfected with miR-130b inhibitor or miR-130b mimics. We evaluated the relationship between miR-130b and PTEN and also analyzed the effect of miR-130b on sunitinib resistance. Results: qRT-PCR analysis showed that the expression of miR-130b was higher in RCC tissues than in corresponding normal kidney tissues. The MTT assay revealed that miR-130b modulated cell growth. qRT-PCR revealed an inverse correlation between miR-130b and PTEN in RCC. Western blotting demonstrated that miR-130b regulated the expression of PTEN in the RCC cell line. Additionally, miR-130b was associated with sunitinib resistance through regulation of PTEN. We established the sunitinib-resistant Caki-1 (Caki-1-SR) cells and observed that the expression of miR-130b was elevated in Caki-1-SR cells compared with parental Caki-1 cells. Knockdown of miR-130b improved sunitinib resistance in Caki-1-SR cells. Conclusion: The expression of miR-130b was upregulated in RCC. miR-130b promoted cell growth and was associated with sunitinib resistance through regulating PTEN expression. Collectively, these results suggest that miR-130b may play an oncogenic role and be a promising therapeutic target.