Effect of mir-129 on the SensitivityEnhancement of Methotrexate and Migration Inhibition in Osteosarcoma Cancer Cells

MicroRNAs have been recently declared to be contributed to the various aspects of osteosarcoma cells, including growth and survival, apoptosis, invasion, and chemoresistance.

The present study aimed to investigate the potentiating effects of miR-129 on the chemosensitivity of Saos-2 osteosarcoma cells to methotrexate (MTX) and underlying mechanisms.

Saos-2 cells were transfected with miR-129 mimics for 48 h. The cytotoxic effects of miR-129 and MTX on Saos-2 cells were measured using MTT assay. Moreover, a scratch wound healing assay was used to evaluate cell migration, and the apoptosis rateof cancer cells was also measured using ELISA Cell Death Assay and flow cytometry. Eventually, the mRNA expression levels of target genes were measured using quantitative RT-PCR.

The findings of the study revealed that miR-129 mimic transfection significantly increased the expression levels of this miRNA in Saos-2 cells (P<0.05) and that the combination of MTX with miR-129 transfection led to the enhanced cytotoxic effects of MTX in lower concentrations. miR-129 significantly increased MTX-induced apoptosis levels and decreased the invasivebehavior of Saos-2 cells. Eventually, the mRNA expression levels of c-Myc, K-Ras, CXCR4, MMP9, and ADAMTS, as the main genes involved in chemoresistance and cell invasion, were downregulated in miR-129 transfected cells.

The obtained results revealed the important role miR-129 plays in the sensitivity of osteosarcoma cells to MTX and its underlying mechanisms. Therefore, miR-129 might be an appropriate candidate for reversing MTX resistance in osteosarcoma cells.