[Diagnostic value of serum miRNA let-7a for laryngeal carcinoma and effects of let-7a on proliferation and apoptosis of laryngeal carcinoma cells].

ABSTRACT

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.