Inhibitory roles of miR-320 in osteosarcoma via regulating E2F1

Objectives: Osteosarcoma (OsC) is the most common primary bone malignant tumor with lower incidence and high degree of malignancy, but the exact mechanism remains unknown. More evidence demonstrated microRNAs (miRNAs) could contribute to tumor progression. In this study, we investigated the expression and functions of miR-320 in OsC cells. Materials and Methods: miR-320 expression levels in several human OsC cell lines and human normal osteoblastic cell line were tested by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). U2OS cells were transfected with miR-320 mimics or negative control oligos. MTT assay and cell flow cytometry assay by PI staining were performed to access the cell growth rate. Bioinformatic prediction and luciferase assays were used to identify the predicted target E2F1. qRT-PCR and Western blot were performed to access the molecular alteration of E2F1. Results: miR-320 was decreased in human OsC cell lines. Heterogeneous expression of miR-320 inhibited cell proliferation and induced cell cycle arrest. Besides, we proved that miR-320 could directly regulate the expression of E2F1 in U2OS cells. Conclusion: These data suggested that miR-320 regulates the proliferation and cell cycle by targeting E2F1 in human OsC progression.