BACKGROUND Accumulating evidence indicates that long non-coding RNAs (lncRNAs) are potential biomarkers and key regulators of tumour development and progression. SOX2 overlapping transcript (SOX2OT) is a novel lncRNA that acts as a potential biomarker and is involved in the development of cancer and cancer stem cells. However, the clinical significance and molecular mechanism of SOX2OT in bladder cancer are still unknown. METHODS The expression level of SOX2OT was determined by RT-qPCR in a total of 106 patients with urothelial bladder cancer and in different bladder cancer cell (BCC) lines. Bladder cancer stem cells (BCSCs) were isolated from BCCs using flow cytometry based on the stem cell markers CD44 and ALDH1. Loss-of-function experiments were performed to investigate the biological roles of SOX2OT in the stemness phenotype of BCSCs. Comprehensive transcriptional analysis, RNA FISH, dual-luciferase reporter assays and western blots were performed to explore the molecular mechanisms underlying the functions of SOX2OT. RESULTS SOX2OT was highly expressed in bladder cancer, and increased SOX2OT expression was positively correlated with a high histological grade, advanced TNM stage and poor prognosis. Further experiments demonstrated that knockdown of SOX2OT inhibited the stemness phenotype of BCSCs. Moreover, inhibition of SOX2OT delayed xenograft tumour growth and decreased metastases in vivo. Mechanistically, we found that SOX2OT was mainly distributed in the cytoplasm and positively regulated SOX2 expression by sponging miR-200c. Furthermore, SOX2 overexpression reversed the SOX2OT silencing-induced inhibition of the BCSC stemness phenotype. CONCLUSION This study is the first to demonstrate that SOX2OT plays an important regulatory role in BCSCs and that SOX2OT may serve as a potential diagnostic biomarker and therapeutic target in bladder cancer.

中文翻译：

---

长非编码RNA SOX2OT通过调节SOX2促进膀胱癌细胞的干性表型。

背景越来越多的证据表明，长非编码RNA（lncRNA）是肿瘤发生和进展的潜在生物标志物和关键调节因子。SOX2重叠转录本（SOX2OT）是一种新型lncRNA，可作为潜在的生物标志物，参与癌症和癌症干细胞的发育。然而，SOX2OT在膀胱癌中的临床意义和分子机制仍不清楚。方法 通过 RT-qPCR 测定 106 例膀胱尿路上皮癌患者和不同膀胱癌细胞 (BCC) 系中 SOX2OT 的表达水平。使用基于干细胞标记 CD44 和 ALDH1 的流式细胞术从 BCC 中分离膀胱癌干细胞 (BCSC)。进行功能丧失实验以研究 SOX2OT 在 BCSC 干性表型中的生物学作用。进行综合转录分析、RNA FISH、双荧光素酶报告基因测定和蛋白质印迹来探索 SOX2OT 功能的分子机制。结果 SOX2OT在膀胱癌中高表达，SOX2OT表达升高与组织学分级高、TNM分期晚、预后差呈正相关。进一步的实验表明，SOX2OT 的敲除抑制了 BCSC 的干性表型。此外，抑制 SOX2OT 可以延迟异种移植肿瘤的生长并减少体内转移。从机制上讲，我们发现SOX2OT主要分布在细胞质中，并通过海绵miR-200c正向调节SOX2的表达。此外，SOX2 过表达逆转了 SOX2OT 沉默诱导的 BCSC 干细胞表型抑制。结论 这项研究首次证明 SOX2OT 在 BCSC 中发挥重要的调节作用，并且 SOX2OT 可能作为膀胱癌的潜在诊断生物标志物和治疗靶点。