MicroRNA-33a-5p suppresses growth of osteosarcoma cells and is downregulated in human osteosarcoma.

A body of evidence has indicated that microRNAs (miRNAs) may have significant roles in cancer. Aberrant expression of miRNAs has frequently been observed in various human malignancies, including osteosarcoma (OS). However, the roles of miRNAs in OS remain poorly understood. In the present study, high-throughput deep sequencing was performed to screen for deregulated miRNAs in OS. Screening identified 310 miRNAs which were significantly overexpressed and 41 miRNAs which were significantly downregulated (>2-fold) in OS samples, compared with adjacent non-tumor bone tissues. Among these miRNAs, miR-33a-5p was notably downregulated. TaqMan reverse transcription-polymerase chain reaction analysis further verified that miR-33a-5p expression was significantly reduced in a large cohort of human OS samples. Enhancing miR-33a-5p expression via transfection with miR-33a-5p precursor significantly inhibited OS cell growth, suggesting potential antitumor properties of miR-33a-5p. The results of the present study provide novel insights into the miRNAs involved in OS, and suggest that miR-33a-5p may function as a tumor suppressor in OS. Therefore, miR-33a-5p may be able to serve as a diagnostic and therapeutic target for OS treatment.