Circular RNA circEVI5 functions as a miR-433 sponge to promote renal cell carcinoma progression via GBP2-mediated oncogenic signaling
TL;DR
The findings establish circEVI5 as a novel oncogenic driver that facilitates RCC progression through the miR-433/GBP2 regulatory axis and provides a framework for developing RNA-based therapies.
Abstract
Introduction Renal cell carcinoma (RCC) is a fatal urological malignancy with limited therapeutic options and poor prognosis. Emerging evidence has shown that a number of circular RNAs (circRNAs) exert crucial effects on carcinogenesis. Nevertheless, the biological role of circEVI5 in RCC remains poorly clarified. This study aimed to elucidate the clinical significance, biological functions, and molecular mechanisms of circEVI5 in RCC pathogenesis. Methods The expression profile of circEVI5 was first screened based on GEO and TCGA-KIRC datasets, and further verified in RCC cell lines (A498, 786-O, ACHN, CAKI-1, OSRC-2) and normal renal tubular epithelial HK-2 cells using qRT-PCR. Functional assays (CCK-8, Transwell) and a subcutaneous xenograft model were employed to assess circEVI5’s role in proliferation, migration, and invasion. RNA pull-down, RIP, and dual-luciferase reporter assays were conducted to validate interactions among circEVI5, miR-433, and GBP2. Clinical correlations were further analyzed based on TCGA datasets and immunohistochemical staining results. Results CircEVI5 was significantly upregulated in RCC tissues (median FC=6.619; P<0.05) and cell lines, correlating with advanced tumor stage (median FC=7.691; P<0.05) and poor survival (P=0.035). Knockdown of circEVI5 via small interfering RNA inhibited cell viability, migration, and invasion in vitro and suppressed tumor growth in vivo. Mechanistically, circEVI5 acted as a cytoplasmic molecular sponge for miR-433, which was downregulated in RCC and inversely correlated with GBP2 expression. RNA pull-down and RIP assays confirmed direct binding between circEVI5 and miR-433, while luciferase assays identified GBP2 as a miR-433 target. Rescue experiments demonstrated that miR-433 inhibition or recombinant GBP2 reversed the anti-tumor effects of circEVI5 knockdown. Clinically, GBP2 overexpression in RCC tissues predicted reduced survival, and miR-433 levels were inversely correlated with both circEVI5 (P<0.0001) and GBP2 (P=0.0003). Discussion Our findings establish circEVI5 as a novel oncogenic driver that facilitates RCC progression through the miR-433/GBP2 regulatory axis. The circEVI5/miR-433/GBP2 network represents a potential therapeutic target, and circEVI5 may serve as a prognostic biomarker for RCC patients. This study highlights the critical role of circRNA-mediated miRNA sponging in RCC pathogenesis and provides a framework for developing RNA-based therapies.