Long non-coding RNAs (lncRNAs) cancer susceptibility candidate 2 (CASC2) has been characterized as a tumor suppressor in glioma. Although CASC2 may predict the prognosis of glioma patients, the role and mechanism of CASC2 in human glioblastoma remain to be fully illuminated. Expression of CASC2 and miR-18a was detected using RT-qPCR. Cell growth was evaluated by MTT assay, colony formation assay, and flow cytometry; metastasis and epithelial-mesenchymal transition (EMT) were determined with transwell assay and Western blot, respectively. The target binding between CASC2 and miR-18a was predicted on Starbase software, and confirmed by luciferase reporter assay and RNA immunoprecipitation. Xenograft experiment measured tumor growth. As a result, CASC2 was downregulated and miR-18a was upregulated in glioblastoma tumor tissues and cells (T98 and A172). Overexpression of CASC2 promoted apoptosis rate and E-cadherin expression, but suppressed cell viability, colony-forming ability, migration, invasion, and expression of N-cadherin and Vimentin in T98 and A172 cells, accompanied with tumor growth inhibition in vivo; whereas, silencing of CASC2 exerted the opposite effect on cell growth, metastasis and EMT of T98 and A172 cells in vitro. However, reintroduction of miR-18a could reverse CASC2 upregulation-mediated suppression on above cell behaviors in vitro. More importantly, miR-18a was a downstream target for CASC2, and was negatively regulated by CASC2. Collectively, this study demonstrated that CASC2 served as tumor suppressor in glioblastoma by inhibiting cell growth, metastasis and EMT both in vitro and in vivo partially via CASC2-miR-18a axis.

中文翻译：

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靶向 miR-18a 的长链非编码 RNA CASC2 在体外和体内抑制胶质母细胞瘤细胞的生长、转移和 EMT

长链非编码 RNA (lncRNAs) 癌症易感性候选 2 (CASC2) 已被表征为胶质瘤中的肿瘤抑制因子。尽管 CASC2 可以预测胶质瘤患者的预后，但 CASC2 在人类胶质母细胞瘤中的作用和机制仍有待充分阐明。使用 RT-qPCR 检测 CASC2 和 miR-18a 的表达。通过MTT测定、集落形成测定和流式细胞术评估细胞生长；转移和上皮间质转化 (EMT) 分别用 transwell 测定和蛋白质印迹测定。CASC2 和 miR-18a 之间的靶标结合在 Starbase 软件上预测，并通过荧光素酶报告基因测定和 RNA 免疫沉淀证实。异种移植实验测量肿瘤生长。因此，CASC2在胶质母细胞瘤组织和细胞（T98和A172）中下调，miR-18a上调。CASC2的过表达促进了T98和A172细胞的凋亡率和E-cadherin的表达，但抑制了T98和A172细胞的细胞活力、集落形成能力、迁移、侵袭以及N-cadherin和Vimentin的表达，并伴有体内肿瘤生长抑制；而CASC2的沉默对体外T98和A172细胞的细胞生长、转移和EMT产生相反的影响。然而，重新引入 miR-18a 可以逆转 CASC2 上调介导的对上述细胞行为的体外抑制。更重要的是，miR-18a 是 CASC2 的下游靶标，受 CASC2 的负调控。总的来说，这项研究表明 CASC2 通过抑制细胞生长在胶质母细胞瘤中起到了肿瘤抑制作用，