Association between microRNA-125b expression in formalin-fixed paraffin-embedded tumor tissues and prognosis in patients with melanoma

Melanoma is an invasive and malignant type of tumor with unsatisfactory therapeutic outcomes. The present study aimed to detect the expression levels of microRNA (miR)-125b in formalin-fixed paraffin-embedded (FFPE) melanoma tissues and the association of its expression levels with the clinical features, diagnosis and prognosis of melanoma. Expression levels of miR-125b in 29 FFPE melanoma specimens (16 primary and 13 metastatic tumors), and 16 intradermal nevus (IDN) specimens as a control, were detected by reverse transcription-quantitative PCR. Associations among miR-125b expression and mortality, patient age and sex, tumor location and size, lymph node metastasis (LNM) and TNM stage were analyzed by t-test. The diagnostic value of miR-125b for melanoma was evaluated by receiver operating characteristic (ROC) curve analysis. Prognosis of patients in the microRNA-125b low- and high-expression groups was analyzed by Fisher's exact test. The association between miR-125b expression and the overall survival of patients with melanoma was assessed using Kaplan-Meier curve analysis and a Cox proportional hazards model. The results revealed that the expression levels of miR-125b in primary and metastatic melanomas were significantly lower than those in the IDN control group (P<0.05), and the expression levels of miR-125b in the metastatic group were significantly lower than those in the primary group (P<0.05). In addition, the expression levels of miR-125b were significantly associated with LNM (P=0.001) and TNM stage (P=0.004), but not with age, sex, tumor size or location (P>0.05). ROC curve analysis revealed that the area under the curve (AUC) was 0.880, with a 95% CI of 0.777–0.984 (P<0.05). The overall survival rate of the patients with a low expression level of miR-125b (20.0%) was lower than that of patients with a high expression level of miR-125b (64.3%) (P<0.05). miR-125b expression was an independent predictor of overall survival in patients with melanoma [hazard ratio (HR), 0.252; 95% CI, 0.087–0.729]. Overall, these findings indicated that a low expression level of miR-125b was associated with higher LNM and TNM stage in patients with melanoma, and that this has a certain diagnostic value. miR-125b may be used for the early screening of melanoma and determining the prognosis of patients with melanoma, and may be a potential target for the treatment of the disease.