Hu Jun, Xu Jun-Feng, Ge Wei-Li
Department of Prosthodontics, Hospital of Stomatology Affiliated to Zhejiang University Hangzhou 310006, China.
Department of Stomatology, Tongde Hospital of Zhejiang Province Hangzhou 310012, China.
Am J Transl Res. 2016 Jul 15;8(7):3023-31. eCollection 2016.
SMAD7 is a key inhibitor of transforming growth factor β (TGFβ) receptor signaling, which regulates the alteration of cancer cell invasiveness through epithelial-mesenchymal cell conversion. Since microRNAs (miRNAs) play a potential role in the tumorigenesis, cancer cell growth and metastases of oral squamous cell carcinoma (OSCC), determination of the involved miRNAs that may regulate SMAD7-mediated OSCC cell invasion appears to be one important question. Here, we found that the levels of miR-497 were significantly increased and the levels of SMAD7 were significantly decreased in OSCC specimens, compared to the paired adjacent non-tumor tissue. Moreover, miR-497 and SMAD7 inversely correlated in OSCC specimens. The 5-year survival of the patients with higher miR-497 levels in the resected OSCC was worse than those high miR-497 levels. Bioinformatics analyses showed that miR-497 targeted the 3'-UTR of SMAD7 mRNA to inhibit its translation, which was proved by luciferase reporter assay. Furthermore, miR-497 overexpression increased SMAD7-suppressed cell invasion, while miR-497 depletion decreased SMAD7-suppressed cell invasion in OSCC cells, in both a transwell cell invasion assay and a scratch would healing assay. Together, our data suggest that suppression of miR-497 in OSCC cells may promote cancer cell invasion via suppression of SMAD7, and highlight miR-497 as an intriguing therapeutic target to prevent OSCC metastases.
SMAD7是转化生长因子β(TGFβ)受体信号传导的关键抑制剂,其通过上皮-间充质细胞转化调节癌细胞侵袭性的改变。由于微小RNA(miRNA)在口腔鳞状细胞癌(OSCC)的肿瘤发生、癌细胞生长和转移中发挥潜在作用,确定可能调节SMAD7介导的OSCC细胞侵袭的相关miRNA似乎是一个重要问题。在此,我们发现与配对的相邻非肿瘤组织相比,OSCC标本中miR-497水平显著升高,而SMAD7水平显著降低。此外,在OSCC标本中miR-497与SMAD7呈负相关。在切除的OSCC中,miR-497水平较高的患者的5年生存率低于miR-497水平较低的患者。生物信息学分析表明,miR-497靶向SMAD7 mRNA的3'-UTR以抑制其翻译,荧光素酶报告基因检测证实了这一点。此外,在transwell细胞侵袭试验和划痕愈合试验中,miR-497过表达增加了SMAD7抑制的细胞侵袭,而miR-497缺失则降低了OSCC细胞中SMAD7抑制的细胞侵袭。总之,我们的数据表明,OSCC细胞中miR-497的抑制可能通过抑制SMAD7促进癌细胞侵袭,并突出了miR-497作为预防OSCC转移的一个有趣的治疗靶点。