Department of Urology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301 Middle Yan Chang Road, Shanghai, 200072, P. R. China.
Shanghai Clinical College, Anhui Medical University, 81 Meishan Road, Hefei, 230032, P. R. China.
J Exp Clin Cancer Res. 2021 Oct 25;40(1):336. doi: 10.1186/s13046-021-02138-8.
Circular RNAs (circRNAs) have been shown to play vital biological functions in various tumors, including prostate cancer (PCa). However, the roles of circRNAs in the metastasis of PCa remain unclear. In the present study, differentially expressed circRNAs associated with PCa metastasis were screened using high-throughput RNA sequencing, from which hsa_circ_0004296 was identified.
Quantitative real-time PCR (qRT-PCR) was used to detect the expression of circ_0004296 in PCa tissues and adjacent normal tissues as well as in blood and urine. Gain and loss of function experiments were performed to investigate the function of circ_0004296 in PCa. Bioinformatics analyses, RNA pull-down assay, and mass spectrometry were conducted to identify RNA-binding proteins. RNA immunoprecipitation and RNA and protein nuclear-cytoplasmic fractionation were performed to investigate the underlying mechanism. A xenograft mouse model was used to analyze the effect of circ_0004296 on PCa growth and metastasis in vivo.
The expression of circ_0004296 was decreased in PCa tissues, blood, and urine, which was negatively associated with metastasis. Furthermore, gain and loss of function experiments in vitro and in vivo showed that circ_0004296 inhibited the proliferation, migration, invasion, and epithelial-mesenchymal transition of PCa cells. Mechanistically, circ_0004296 regulated host gene ETS1 expression at the post-transcriptional level. EIF4A3 was identified and confirmed as the downstream binding protein of circ_0004296. EIF4A3 expression was significantly upregulated in PCa tissues and associated with PCa metastasis. Silencing EIF4A3 suppressed PCa cell proliferation, migration, invasion, and EMT.
Circ_0004296 overexpression efficiently inhibited ETS1 mRNA nuclear export by promoting EIF4A3 retention in the nucleus, leading to the downregulation of ETS1 expression and suppression of PCa metastasis; thus, circ_0004296 might be a potential biomarker and therapeutic target for patients with PCa.
环状 RNA（circRNAs）已被证明在多种肿瘤中发挥重要的生物学功能，包括前列腺癌（PCa）。然而，circRNAs 在 PCa 转移中的作用仍不清楚。在本研究中，我们使用高通量 RNA 测序筛选与 PCa 转移相关的差异表达 circRNAs，从中鉴定出 hsa_circ_0004296。
使用实时定量 PCR（qRT-PCR）检测 PCa 组织及相邻正常组织、血液和尿液中 circ_0004296 的表达。通过 gain 和 loss of function 实验研究 circ_0004296 在 PCa 中的功能。通过生物信息学分析、RNA 下拉实验和质谱分析鉴定 RNA 结合蛋白。通过 RNA 免疫沉淀和 RNA 及蛋白核质分离实验研究其潜在机制。通过异种移植小鼠模型分析 circ_0004296 对体内 PCa 生长和转移的影响。
circ_0004296 在 PCa 组织、血液和尿液中的表达降低，与转移呈负相关。此外，体外和体内的 gain 和 loss of function 实验表明，circ_0004296 抑制了 PCa 细胞的增殖、迁移、侵袭和上皮间质转化。机制上，circ_0004296 在转录后水平调控宿主基因 ETS1 的表达。鉴定并证实 EIF4A3 是 circ_0004296 的下游结合蛋白。ETS1 在 PCa 组织中表达上调，并与 PCa 转移相关。沉默 EIF4A3 可抑制 PCa 细胞的增殖、迁移、侵袭和 EMT。
circ_0004296 的过表达通过促进 EIF4A3 在核内的保留，有效地抑制 ETS1 mRNA 的核输出，导致 ETS1 表达下调，抑制 PCa 转移；因此，circ_0004296 可能是 PCa 患者的潜在生物标志物和治疗靶点。
