Kumamoto Tomohiro, Seki Naohiko, Mataki Hiroko, Mizuno Keiko, Kamikawaji Kazuto, Samukawa Takuya, Koshizuka Keiichi, Goto Yusuke, Inoue Hiromasa
Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8520, Japan.
Department of Functional Genomics, Chiba University Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
Int J Oncol. 2016 Nov;49(5):1870-1880. doi: 10.3892/ijo.2016.3690. Epub 2016 Sep 13.
The development of targeted molecular therapies has greatly benefited patients with lung adenocarcinomas. In contrast, these treatments have had little benefit in the management of lung squamous cell carcinoma (lung SCC). Therefore, new treatment options based on current genomic approaches are needed for lung SCC. Aberrant microRNA (miRNA) expression has been shown to promote lung cancer development and aggressiveness. Downregulation of microRNA-218 (miR-218) was frequently observed in our miRNA expression signatures of cancers, and previous studies have shown an antitumor function of miR-218 in several types of cancers. However, the impact of miR-218 on lung SCC is still ambiguous. The present study investigated the antitumor roles of miR-218 in lung SCC to identify the target genes regulated by this miRNA. Ectopic expression of miR-218 greatly inhibited cancer cell migration and invasion in the lung SCC cell lines EBC-1 and SK-MES-1. Through a combination of in silico analysis and gene expression data searching, tumor protein D52 (TPD52) was selected as a putative target of miR-218 regulation. Moreover, direct binding of miR-218 to the 3'-UTR of TPD52 was observed by dual luciferase reporter assay. Overexpression of TPD52 was observed in lung SCC clinical specimens, and knockdown of TPD52 significantly suppressed cancer cell migration and invasion in lung SCC cell lines. Furthermore, the downstream pathways mediated by TPD52 involved critical regulators of genomic stability and mitotic checkpoint genes. Taken together, our data showed that downregulation of miR-218 enhances overexpression of TPD52 in lung SCC cells, promoting cancer cell aggressiveness. Identification of tumor-suppressive miRNA-mediated RNA networks of lung SCC will provide new insights into the potential mechanisms of the molecular pathogenesis of the disease.
靶向分子疗法的发展使肺腺癌患者受益匪浅。相比之下，这些治疗方法在肺鳞状细胞癌（肺鳞癌）的治疗中收效甚微。因此，需要基于当前基因组方法的新治疗方案来治疗肺鳞癌。异常的微小RNA（miRNA）表达已被证明可促进肺癌的发展和侵袭性。在我们的癌症miRNA表达特征中经常观察到微小RNA-218（miR-218）的下调，并且先前的研究表明miR-218在几种类型的癌症中具有抗肿瘤功能。然而，miR-218对肺鳞癌的影响仍不明确。本研究调查了miR-218在肺鳞癌中的抗肿瘤作用，以确定受该miRNA调控的靶基因。miR-218的异位表达极大地抑制了肺鳞癌细胞系EBC-1和SK-MES-1中的癌细胞迁移和侵袭。通过计算机分析和基因表达数据搜索相结合，肿瘤蛋白D52（TPD52）被选为miR-218调控的假定靶标。此外，通过双荧光素酶报告基因测定观察到miR-218与TPD52的3'-UTR直接结合。在肺鳞癌临床标本中观察到TPD52的过表达，并且在肺鳞癌细胞系中敲低TPD52可显著抑制癌细胞的迁移和侵袭。此外，TPD52介导的下游途径涉及基因组稳定性的关键调节因子和有丝分裂检查点基因。综上所述，我们的数据表明，miR-218的下调增强了肺鳞癌细胞中TPD52的过表达，促进了癌细胞的侵袭性。鉴定肺鳞癌的肿瘤抑制性miRNA介导的RNA网络将为该疾病分子发病机制的潜在机制提供新的见解。
