In oral squamous cell carcinoma (OSCC), abnormal expression of microRNAs has been extensively reported. MiR-let-7a has been validated as a critical regulator of multiple cancers, but the biological process involved and its potential role in OSCC remain unknown.We first analyzed the differential expression of miR-let-7a in cancer tissues, adjacent noncancerous tissues and cell lines. The functional role of miR-let-7a in OSCC cell lines was evaluated by using colony formation assays, cell proliferation and transwell invasion assays in vitro. In addition, subcutaneous xenotransplantation of miR-let-7a transfected cells into nude mouse model was carried out to explore the potential function of miR-let-7a in vivo.miR-let-7a levels were found to be significantly downregulated in OSCC tissues compared with matched normal tissues (n = 60), and lower expression of miR-let-7a was related to poor prognosis in OSCC patients. Overexpression of MiR-let-7a induced a suppression in proliferation, invasion and migration and inhibited tumourigenesis in the nude mouse model. We also determined that c-Myc may serve as a direct target of miR-let-7a; furthermore, upregulated c-Myc expression could partially rescue the effects caused by miR-let-7a overexpression. miR-let-7a is low expression in OSCC, and promotes tumor development by directly targeting c-Myc. Our results may provide a potential therapeutic role for miR-let-7a in human OSCC.

在口腔鳞状细胞癌（OSCC）中，microRNA 的异常表达已被广泛报道。 MiR-let-7a已被证实是多种癌症的关键调节因子，但其所涉及的生物学过程及其在OSCC中的潜在作用仍不清楚。我们首先分析了miR-let-7a在癌组织、癌旁非癌组织和癌组织中的差异表达。细胞系。通过体外集落形成测定、细胞增殖和 Transwell 侵袭测定评估 miR-let-7a 在 OSCC 细胞系中的功能作用。此外，将转染miR-let-7a的细胞皮下异种移植到裸鼠模型中，以探讨miR-let-7a在体内的潜在功能。发现与相比，miR-let-7a在OSCC组织中的水平显着下调与匹配的正常组织 (n = 60) 相比，miR-let-7a 的低表达与 OSCC 患者的不良预后相关。在裸鼠模型中，MiR-let-7a 的过表达可抑制增殖、侵袭和迁移，并抑制肿瘤发生。我们还确定 c-Myc 可能作为 miR-let-7a 的直接靶标；此外，上调的c-Myc表达可以部分缓解miR-let-7a过表达引起的影响。 miR-let-7a 在 OSCC 中低表达，通过直接靶向 c-Myc 促进肿瘤发展。我们的结果可能为 miR-let-7a 在人类 OSCC 中发挥潜在的治疗作用。