miR-874 suppresses the proliferation and metastasis of osteosarcoma by targeting E2F3

Increasing evidence indicates that microRNAs (miRNAs) play critical roles in osteosarcoma (OS) occurrence and development. MicroRNA-874 (miR-874) has proven to be dysregulated in several human cancers. However, the biological function and underlying molecular mechanism of miR-874 in OS remain unclear. In this study, we aimed to investigate the biological role and potential mechanism of miR-874 in OS. Here, we found that miR-874 expression was significantly decreased in OS cell lines and tissues by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), and its expression was correlated with tumor-node-metastasis (TNM) stage, tumor size, and lymph node metastasis (all P<0.01). Functional study revealed that overexpression of miR-874 in OS cells could remarkably inhibit proliferation, migration, and invasion and induce cell apoptosis. In addition, E2F transcription factor 3 (E2F3) was confirmed as a target of miR-874 in OS cells. E2F3 mRNA expression was upregulated and was inversely correlated with the level of miR-874 in OS tissues. Importantly, downregulation of E2F3 mimicked the effect of overexpression miR-874 in OS cells, and E2F3 overexpression partially attenuated the tumor-suppressive effects of miR-874 in OS cells. Taken together, these findings suggested that miR-874 might suppress the growth and metastasis of OS cells partially by targeting E2F3.