Cancer stemness and osteosarcoma (OS) malignant progression are closely associated. However, the molecular mechanisms underlying this association have not been fully demonstrated. Long noncoding RNAs (lncRNAs) are an intriguing class of widely prevalent endogenous RNAs involved in OS progression, the vast majority of which have not been characterized functionally. Here, we identified tumor promoter lncRNA WAC-AS1 to be highly expressed in OS tumors and associated with worse survival. Further analysis revealed that WAC-AS1 increased tumorsphere formation of OS cells and promoted metastasis, as confirmed by cell proliferation, transwell and wound healing assays. MiR-5047 was identified as a downstream target of WAC-AS1. Subsequently, based on bioinformatics analysis, RIP assay and luciferase reporter assay, SOX2 mRNA was verified as a target of miR-5047. WAC-AS1 enhanced OS cell proliferation and stemness via acting as a ceRNA by binding to miR-5047, thereby increasing SOX2 expression. In addition, SOX2 bound to the promoter region of WAC-AS1 and promoted its transcription, thereby forming a positive feedback loop to regulate OS malignancy. Taken together, our findings show WAC-AS1 is a tumor promoter and a key regulator of OS cell stemness and metastasis via a miR-5047/SOX2 axis.

中文翻译：

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LncRNA WAC-AS1通过海绵miR-5047上调SOX2促进骨肉瘤转移和干性

癌症干性与骨肉瘤（OS）恶性进展密切相关。然而，这种关联背后的分子机制尚未得到充分证明。长非编码 RNA (lncRNA) 是一类有趣的广泛存在的内源性 RNA，参与 OS 进展，其中绝大多数尚未得到功能表征。在这里，我们发现肿瘤启动子 lncRNA WAC-AS1 在 OS 肿瘤中高表达，并且与较差的生存率相关。进一步的分析表明，WAC-AS1 增加了 OS 细胞的肿瘤球形成并促进了转移，细胞增殖、Transwell 和伤口愈合测定证实了这一点。MiR-5047 被确定为 WAC-AS1 的下游靶标。随后，基于生物信息学分析、RIP检测和荧光素酶报告基因检测，验证SOX2 mRNA是miR-5047的靶标。WAC-AS1 通过与 miR-5047 结合，充当 ceRNA，从而增强 OS 细胞增殖和干性，从而增加 SOX2 表达。此外，SOX2与WAC-AS1的启动子区域结合并促进其转录，从而形成正反馈环来调节OS恶性肿瘤。综上所述，我们的研究结果表明，WAC-AS1 是一种肿瘤启动子，也是通过 miR-5047/SOX2 轴调节 OS 细胞干性和转移的关键因子。