Hsa_circ_0005320 affects cell proliferation and the cell cycle via the IGF2BP3/CDK2 axis in bladder cancer

Abstract

Background: Circular RNAs (circRNAs), which are covalently closed non-coding RNAs, are frequently dysregulated in cancer. However, their precise role in bladder cancer (BCa) remains largely unknown.

Methods: Expression of hsa_circ_0005320 in tissues and cell lines was detected using quantitative real-time PCR. Proliferation and colony forming capacity of BCa cells were assessed using Cell Counting Kit-8, ethynyl-labeled deoxyuridine, and colony formation assays. The cell cycle was analyzed using flow cytometry. Protein expression of insulin-like growth factor II mRNA-binding protein 3 (IGF2BP3) and cyclin dependent kinase 2 (CDK2) was examined using western blots. The binding of RNA and protein was validated using RNA immunoprecipitation. Additionally, xenograft tumor models were established to validate the function of hsa_circ_0005320 in vivo.

Results: We screened hsa_circ_0005320 from previous high-throughput sequencing and found that it was highly expressed in BCa tissues and associated with tumor differentiation and depth of invasion in BCa patients. Through functional experiments, we demonstrated that hsa_circ_0005320 promoted cell proliferation and regulated the cell cycle. Mechanistically, hsa_circ_0005320 interacted with and upregulated the expression of IGF2BP3, which binds to and enhances the stability of CDK2 mRNA. Furthermore, knockdown of hsa_circ_0005320 resulted in a reduction in tumor burden in vivo.

Conclusions: Collectively, these findings highlight the pro-oncogenic role of hsa_circ_0005320 in BCa through the IGF2BP3/CDK2 axis, providing valuable insights into the mechanism of circRNAs in tumor progression.

Keywords: Bladder cancer; Cell cycle; IGF2BP3; Proliferation; circRNA.