Quercetin and Methotrexate in Combination have Anticancer Activity in Osteosarcoma Cells and Repress Oncogenic MicroRNA-223.

Introduction: Osteosarcoma (OS) is one of the most common bone neoplasms in adolescents. Notable short- and long-term toxic effects of OS chemotherapy regimens have been reported. Hence, new chemotherapeutic agents with the ability to potentiate OS chemotherapy drugs and protect non-tumorous tissues are required.

Methods: Saos-2 cells were treated with Methotrexate (MTX) and Quercetin (Que) (a polyphenolic flavonoid with anti-tumor effects) alone and in combination. MTT assay was performed to investigate the cytotoxicity of the drugs. Moreover, apoptosis-involved genes, including miR- p53 BCL-2 CBX7, and CYLD expression were analyzed via qRT-PCR. Annexin V-FITC/PI kit was employed to assess the apoptosis rate.

Results: The MTT results showed that Que increases MTX cytotoxicity on OS cells. The measured IC50s are 142.3 µM for QUE and 13.7 ng/ml for MTX. A decline in MTX IC50 value was observed from 13.7 ng/ml to 8.45 ng/ml in the presence of Que. Moreover, the mRNA expression outcomes indicated that the combination therapy significantly up-regulates the tumor suppressor genes, such as p53, CBX7, and CYLD, and declines anti-apoptotic genes BCL-2 and miR-223, which can lead to proliferation inhibition and apoptosis inducement. Furthermore, the apoptosis rate increased significantly from 6.03% in the control group to 38.35% in Saos-2 cells that were treated with the combination of MTX and Que.

Conclusion: Que, with the potential to boost the anticancer activity of MTX on Saos-2 cancer cells through proliferation inhibition and apoptosis induction, is a good candidate for combination therapy.