Novel circular RNA, hsa_circ_0025039 promotes cell growth, invasion and glucose metabolism in malignant melanoma via the miR-198/CDK4 axis

Malignant melanoma, a tumor derived from melanocytes, shows severe drug resistance and prompt metastasis, causing a serious threat to human health. Circular RNAs (circRNAs) are widely expressed in mammals and have been indicated to play important roles in tumorigenesis. In the present study, we analyzed the variability of circRNAs in malignant melanoma by microarray and identified six differentially expressed circRNAs. In particular, we found that hsa_circ_0025039, which is formed by FOXM1 exons, is significantly upregulated in melanoma. In vitro, the knockdown of circ_0025039 inhibited cell proliferation, colony formation ability, invasion and glucose metabolism in melanoma cells. Additionally, we identified miR-198 as a direct target of hsa_circ_0025039. Furthermore, we demonstrated that hsa_circ_0025039 regulates CDK4 expression by sponging miR-198. In vivo study indicated that the silencing of hsa_circ_0025039 inhibits melanoma tumor formation and downregulates miR-198 and CDK4 expression. Taken together, our data showed that circ_0025039 promotes cell growth, invasion and glucose metabolism in malignant melanoma by sponging miR-198 and regulating CDK4.