Previous studies have shown that cancer susceptibility candidate 5 (CASC5) plays important roles in several types of cancer. But its expression and clinical significance in human pan‐cancer remain largely unclear. In the present study, we comprehensively analysed the expression profile and prognostic values of CASC5 in pan‐cancer across 33 cancer types based on the online TCGA analysis databases. CASC5 was found to be abnormally expressed in 16 types of cancer. In addition, dysregulated expression of CASC5 was closely associated with patient overall survival (OS) in kidney renal papillary cell carcinoma (KIRP), lung adenocarcinoma (LUAD), pancreatic adenocarcinoma (PAAD) and thymoma (THYM). By comparative analysis, we found that CASC5 was significantly up‐regulated in LUAD and predicted poor patient OS. High CASC5 expression was closely correlated with tumour advanced stages of patients with LUAD. Through GSEA based on the KEGG database, CASC5 was found to be closely related to DNA replication and microRNA regulation in LUAD. Functionally, knockdown of CASC5 could inhibit cell proliferation of LUAD cells in vitro, rather than affecting cell migration and invasion. Mechanistically, CASC5 promoted proliferation of LUAD cells by targeting miR‐139‐5p. Collectively, our findings reveal that CASC5 is a novel oncogenic gene in LUAD and may be a potential clinical target and (or) biomarker for this human malignancy.

中文翻译：

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CASC5是肺腺癌中潜在的肿瘤驱动基因。

先前的研究表明，癌症易感候选物5（CASC5）在几种类型的癌症中起着重要作用。但是其在人全癌中的表达和临床意义仍不清楚。在本研究中，我们基于在线TCGA分析数据库全面分析了CASC5在33种癌症类型的全癌中的表达谱和预后价值。发现CASC5在16种癌症中异常表达。此外，CASC5表达失调与肾肾乳头状细胞癌（KIRP），肺腺癌（LUAD），胰腺腺癌（PAAD）和胸腺瘤（THYM）的患者总生存期（OS）密切相关。通过比较分析，我们发现CASC5在LUAD中明显上调，并预测患者OS较差。CASC5的高表达与LUAD患者的肿瘤晚期密切相关。通过基于KEGG数据库的GSEA，发现CASC5与LUAD中的DNA复制和microRNA调控密切相关。在功能上，敲除CASC5可以抑制LUAD细胞在体外的细胞增殖，而不是影响细胞的迁移和侵袭。从机理上讲，CASC5通过靶向miR-139-5p促进LUAD细胞的增殖。总的来说，我们的发现表明，CASC5是LUAD中的一种新型致癌基因，可能是该人类恶性肿瘤的潜在临床靶标和（或）生物标记物。抑制CASC5可以抑制LUAD细胞在体外的细胞增殖，而不影响细胞的迁移和侵袭。从机理上讲，CASC5通过靶向miR-139-5p促进LUAD细胞的增殖。总的来说，我们的发现表明，CASC5是LUAD中的一种新型致癌基因，可能是该人类恶性肿瘤的潜在临床靶标和（或）生物标记物。抑制CASC5可以抑制LUAD细胞在体外的细胞增殖，而不影响细胞的迁移和侵袭。从机理上讲，CASC5通过靶向miR-139-5p促进LUAD细胞的增殖。总的来说，我们的发现表明，CASC5是LUAD中的一种新型致癌基因，可能是该人类恶性肿瘤的潜在临床靶标和（或）生物标记物。