ABSTRACT

Bladder cancer (BLCA) is a common malignant urothelial cancer in the world. Although circular RNAs (circRNAs) involve in regulating BLCA progression, the role of a novel circular RNA circSETD3 in regulating BLCA pathogenesis has not been studied. The expression of circSETD3, miR-641, PTEN mRNA in BLCA tissues and cell lines were measured using RT-qPCR. The gain-of-function experiments were performed in vitro and in vivo to detect the effects of circSETD3 on cell proliferation, migration, EMT, and stemness maintenance. Besides, rescue experiments were performed to demonstrate the regulatory mechanism of circSETD3/miR-641/PTEN in BLCA cell malignant phenotypes in vitro. CircSETD3 was remarkably downregulated in the cancerous clinical tissues and cell lines, in contrast with their normal counterparts, and circSETD3 tended to be deficient in BLCA patients with larger tumor size, advanced clinical stages, positive lymph metastasis and worse prognosis. In addition, circular isoforms of circSETD3 were more resistant to RNase R+ and actinomycetes D treatment compared to their linear isoforms, and circSETD3 mainly distributed in the cytoplasm of the BLCA cells. Further gain-of-function experiments showed that circSETD3 acted as a tumor suppressor to suppress BLCA cell proliferation, migration, EMT and stemness, and the underlying mechanisms had also been elucidated. Mechanistically, circSETD3 sponged miR-641 to upregulate PTEN, resulting in the blockage of BLCA progression. Our findings indicated that circSETD3 acted as a vital tumor suppressor in BLCA via regulating the miR-641/PTEN axis.

摘要

膀胱癌（BLCA）是世界上常见的恶性尿路上皮癌。尽管环状 RNA (circRNA) 参与调节 BLCA 进展，但尚未研究新的环状 RNA circSETD3 在调节 BLCA 发病机制中的作用。使用 RT-qPCR 测量 BLCA 组织和细胞系中 circSETD3、miR-641、PTEN mRNA 的表达。在体外和体内进行了功能获得实验，以检测 circSETD3 对细胞增殖、迁移、EMT 和干性维持的影响。此外，还进行了拯救实验，证明了circSETD3/miR-641/PTEN在体外对BLCA细胞恶性表型的调控机制。. 与正常对应物相比，CircSETD3在癌性临床组织和细胞系中显着下调，并且在肿瘤较大、临床分期晚期、淋巴结转移阳性和预后较差的BLCA患者中往往缺乏circSETD3。此外，circSETD3的环状异构体比其线性异构体更能抵抗RNase R+和放线菌D的处理，并且circSETD3主要分布在BLCA细胞的细胞质中。进一步的功能增益实验表明，circSETD3作为肿瘤抑制因子抑制BLCA细胞增殖、迁移、EMT和干性，其潜在机制也已阐明。从机制上讲，circSETD3 吸收 miR-641 上调 PTEN，导致 BLCA 进展受阻。