MicroRNA-30a suppresses papillary thyroid cancer cell proliferation, migration and invasion by directly targeting...

microRNA (miRNA/miR)-30a, a tumor-associated miRNA, has been implicated in the tumorigenesis and progression of different types of human cancer. Thyroid cancer is a common endocrine malignancy, of which papillary thyroid cancer (PTC) accounts for ~80-90% of all TC. However, the effect of miR-30a in PTC is yet to be fully elucidated. The TPC-1 human PTC cell line, as well as the normal human thyroid cell line (HT-ori3), were utilized in the current study. The PTC cell line was transfected with a miR-30a mimic. Subsequently, reverse transcription-quantitative polymerase chain reaction was performed to detect the expression of miR-30a and E2F transcription factor 7 (E2F7). Cell proliferation was assessed via a MTT assay and transwell migration and invasion assays were performed to detect the migration and invasion of PTC cells. A dual-luciferase reporter assay was also utilized to clarify the association between miR-30a and E2F7. The results of the current study revealed that miR-30a was significantly downregulated in TPC-1 cells compared with HT-ori3 cells and that the expression of E2F7 was significantly upregulated in PTC cells. The upregulation of miR-30a also inhibited the proliferation, migration and invasion of PTC cells. Furthermore, the luciferase assay revealed that miR-30a binds to the 3'-UTR of E2F7. Additionally, the overexpression of miR-30a decreased E2F7 levels in TPC-1 cells. These results indicate that miR-30a functions as a tumor suppressor in PTC by direct targeting E2F7 and that miR-30a may be a novel therapeutic target for patients with PTC.