Objective: To investigate the diagnostic value of serum miRNAlet-7a in laryngeal carcinoma and the effect of let-7a on proliferation and apoptosis of laryngeal carcinoma cells. Methods: Real-time quantitative PCR was used to determine the expression level of serum miRNAlet-7a. The miRNA let-7a mimetic was synthesized and transiently transfected into the laryngeal carcinoma Hep-2 cell line by cationic liposome method. The effects of up-regulation of let-7a expression on laryngeal cancer Hep-2 cells were detected by FCM and MTT assays,respectively. The association of let-7a levels with laryngeal cancer and the diagnostic value for laryngeal cancer were analyzed. Measurement data were taken by t test or analysis of variance; Counting data were analyzed by χ(2) test and Fisher exact probability method. The receiver operating characteristic curve was used to analyze the diagnostic value of let-7a for laryngeal cancer. Results: The relative expression of serum let-7a in healthy subjects was significantly higher than that in patients with laryngeal cancer (0.931±0.094) vs (0.380±0.113) (t=26.507,P<0.01). The relative expressions of serum let-7a in patients with laryngeal cancer before and after surgery were (0.380±0.113) vs(0.493±0.164),with significant difference (t=3.848,P<0.01).The relative expression of serum let-7a was related to lymph node metastasis (t=2.946, P<0.01). There was a positive correlation between the relative expression of let-7a in laryngeal carcinoma and that in serum (r=0.466,P=0.003). After transfection of let-7a mimics, Hep-2 cells showed an increased significant increase in the expression of let-7a (P<0.01), proliferation (P<0.01) and apoptosis (P<0.01). ROC curve analysis showed that the best critical value for relative expression of let-7a in the diagnosis of laryngeal carcinoma was 0.557 with a sensitivity of 0.794,a specificity of 0.727,an area under curve(AUC) of 0.859,and a 95%CI of 0.773-0.926. Conclusions: miRNA let-7a can inhibit the proliferation of laryngeal carcinoma Hep-2 cells and promote apoptosis. Serum let-7a is down-regulated in patients with laryngeal cancer and the level of let-7a is related to lymph node metastasis,which would help early diagnosis and postoperative disease monitoring of laryngeal cancer,but further research is needed.
目的： 探讨血清miRNA let-7a对喉鳞状细胞癌的诊断价值以及let-7a对喉癌细胞增殖与凋亡的影响。 方法： 选择湖南省人民医院2016年1月至2018年4月经病理确诊的喉癌患者为研究对象，实时定量PCR（qRT-PCR）测定50例患者的喉癌组织、癌旁组织和血清标本，以及50名健康体检者血清标本miRNA let-7a的表达水平。合成miRNA let-7a模拟体（let-7a mimics）并采用阳离子脂质体法瞬时转染入喉癌细胞株Hep-2内；流式细胞术、四甲基偶氮唑蓝法（MTT）分别检测let-7a表达上调后对喉癌Hep-2细胞凋亡、增殖的影响；分析血清let-7a与喉癌临床、病理指标的关联及对喉癌的诊断价值。计量资料采取t检验或方差分析；计数资料选择χ(2)检验及Fisher确切概率法；采用受试者工作特征（ROC）曲线分析let-7a对喉癌的诊断价值。 结果： 健康人和喉癌患者血清let-7a相对表达量分别为（0.931±0.094）和（0.380±0.113），差异有统计学意义（t=26.507，P<0.01）；喉癌患者术前和术后血清let-7a相对表达量分别为（0.380±0.113）和（0.493±0.164），差异有统计学意义（t=3.848，P<0.01）；血清let-7a相对表达量与淋巴转移有关（t=2.946, P<0.01）。let-7a在喉癌组织中的相对表达量与血清中相对表达量呈正相关（r=0.466，P=0.003）。转染let-7a mimics后Hep-2细胞中let-7a表达明显上升（P<0.01），Hep-2细胞的增殖受到抑制（P<0.01），Hep-2细胞凋亡率明显升高（P<0.01）。ROC曲线分析，以0.557为let-7a相对表达量的最佳临界值诊断早期喉癌（Ⅰ-Ⅱ期），其灵敏度为0.794，特异度为0.727，曲线下面积为0.859，95% CI为0.773~0.926。 结论： let-7a可抑制喉癌Hep-2细胞的增殖，促进其凋亡；喉癌患者血清let-7a出现下调，let-7a水平变化与淋巴转移有关，以上特点有助于喉癌的早期诊断与术后病情监测。.
Keywords: Laryngeal neoplasms; Serum; miRNAlet-7a.