Tumor suppressor miR-33b-5p regulates cellular function and acts a prognostic biomarker in RCC.

Background: Renal cell carcinoma (RCC) is a renal parenchyma neoplasm with a 30% recurrence rate even when treated properly. MicroRNAs are noncoding small RNAs that are involved in cellular communication and may participate in cancer development. This study aimed to explore the relationship between miR-33b-5p expression and RCC progression and prognosis.

Method: RT-qPCR, CCK-8 assay, wound scratch assay, transwell assay and flow cytometry assay were used to evaluate the expression and function of miR-33b-5p in RCC. Additionally, RCC samples and survival data from The Cancer Genome Atlas were used to analyze the prognostic functions of miR-33b-5p.

Results: miR-33b-5p expression in RCC tissues and cell lines (786-O, ACHN) were found to be significantly downregulated, compared with normal tissues and cell lines (P<0.001). The miR-33b-5p mimic transfected cells showed a slower proliferation rate (P<0.01), while its invasion ability decreased by 38.16% (786-O, P<0.001) and 49.19% (ACHN, P<0.05), compared with the negative control (NC). The migration ability of both RCC lines were found to be as follows: miR-33b-5p inhibitor > NC or NC inhibitor > miR-33b-5p mimic. Additionally, TCGA and RCC samples reveal that low miR-33b-5p expression is related to poor survival outcomes (univariate analysis, P=0.029; multivariate analysis, P=0.024; Kaplan-Meier survival curves, P=0.014). Target genes prediction suggests that miR-33b-5p performs its tumor-suppressive effects and prognostic role through targeting TBX15, SLC12A5, and PTGFRN.

Conclusions: miR-33b-5p may function as a tumor-suppressive regulator and prognostic biomarker in RCC.