MicroRNAs (miRNAs/miRs) are widely studied as key regulators of gene expression and are involved in various diseases by affecting the miRNA-mediated regulatory function. BRAF is an important oncogene in the regulation of cell proliferation and apoptosis. In the present study, reverse transcription-quantitative polymerase chain reaction was used to determine the expression levels of miR-9-5p and BRAF mRNA in patients with papillary thyroid cancer (PTC). Western blotting was used to detect BRAF protein level. A luciferase assay was used to verify the miR-9-5p target site in BRAF. Cell Counting Kit-8 and flow cytometry were used to assess cell proliferation, and apoptosis, respectively. In the present study, it was demonstrated that miR-9-5p is downregulated in malignant PTC. Using bioinformatics analysis, miR-9-5p was predicted to target the human BRAF 3'-untranslated region (3'-UTR). A dual-luciferase assay demonstrated that miR-9-5p downregulated BRAF expression by directly targeting its 3'-UTR. Mutations in the 3'-UTR of BRAF completely abolished its interaction with miR-9-5p. Expression of exogenous miRNA that mimics miR-9-5p miRNA decreased BRAF protein and mRNA levels, while suppression of endogenous miR-9-5p resulted in an increase in BRAF protein, and mRNA levels. Furthermore, regulation of miR-9-5p was observed to suppress the viability of PTC cells by inducing apoptosis. Consistently, downregulation of miR-9-5p promoted proliferation of PTC cells by inhibiting the apoptosis of cells. In conclusion, the present study demonstrated that miR-9-5p may perform an important role in PTC prognosis and therapy.

The aim of the present study was to examine the interrelations between MEG-A3 gene and incidence of breast cancer. The expression of MEG-A3 gene in the tissue samples of patients with breast cancer and normal controls at RNA and protein levels was determined. Subsequently, the relative expression of RNA for the same patient was measured at different time-points (1, 3, 6, 8, 12 and 24 months), and the protein expression levels were determined using western blotting. The results showed that, the mRNA level in MEG-A3 gene of samples of patients with breast cancer was significantly higher than that of normal women (p<0.05). The MEG-A3 gene expression increased apparently with the prolongation and aggravation of the disease. In conclusion, there is a close correlation between MEG-A3 gene and the incidence of breast cancer; thus, MEG-A3 gene contributes to the occurrence and deterioration of breast cancer to some extent. It provides a theoretical basis for later disease treatment.