Identification of a four-miRNA signature predicts the prognosis of papillary thyroid cancer

BACKGROUND In recently diagnosed patients with thyroid cancer, papillary thyroid cancer(PTC), as the most common histological subtype, accounts for 90% of all cases. Although PTC is known as a relatively adolescent malignant disease, there still is a high possibility of recurrence in PTC patients with a poor prognosis. Therefore, new biomarkers are necessary to guide more effective stratification of PTC patients and personalize therapy to avoid overtreatment or inadequate treatment. Accumulating evidence demonstrates that microRNAs(miRNAs) have broad application prospects as diagnostic biomarkers in cancer.AIM To explore novel markers consisting of miRNA-associated signatures for PTC prognostication.METHODS We obtained and analyzed the data of 497 PTC patients from The Cancer Genome Atlas. The patients were randomly assigned to either a training or testing cohort.RESULTS We discovered 237 differentially expressed miRNAs in tumorous thyroid tissues compared with normal tissues, which contained 172 up-regulated and 65 downregulated miRNAs. The evaluation of differently expressed miRNAs was conducted using our risk score model. We then successfully generated a fourmiRNA potential prognostic signature [risk score =(-0.001 × hsa-miR-181a-2-3p) +(0.003 × hsa-miR-138-5p) +(-0.018 × hsa-miR-424-3p) +(0.284 × hsa-miR-612)], which reliably distinguished patients from high and low risk with a significant difference in the overall survival(P < 0.01) and was effective in predicting the five-year disease survival rate with the area under the receiver operating characteristic curve of 0.937 and 0.812 in the training and testing cohorts, respectively. Additionally, there was a trend indicated that high-risk patients had shorter relapse-free survival, although statistical significance was not reached(P = 0.082) in our sequencing cohort.CONCLUSION Our results indicated a four-miRNA signature that has a robust predictive effect on the prognosis of PTC. Accordingly, we would recommend more radical therapy and closer follow-ups for highrisk groups.