Triptolide reduces the viability of osteosarcoma cells by reducing MKP-1 and Hsp70 expression.

Osteosarcoma is the most common type of malignant bone tumor found in adolescents and young adults. The aim of the present study was to determine whether triptolide, a diterpene epoxide extracted from the Tripterygium plant, was able effectively decrease the viability of osteosarcoma cells. The underlying molecular mechanisms are also investigated. The human osteosarcoma cell lines U-2 OS and MG-63 were used in this study. The U-2 OS and MG-63 cells were treated with 0, 5, 10, 25 or 50 nM triptolide. Cells treated with dimethyl sulfoxide only were used as the no drug treatment control. A commercial MTT kit was used to determine the effects of triptolide on cells. Mitogen-activated protein kinase phosphatase-1 (MKP-1) is frequently overexpressed in tumor tissues, possibly related to the failure of a number of chemotherapeutics. Heat shock protein 70 (Hsp70) is a chaperone molecule that is able to increase drug resistance. The protein expression levels of MKP-1 and Hsp70 were determined using western blot analysis. The results indicate that triptolide effectively reduced the viability of the osteosarcoma cells. Furthermore, triptolide was found to effectively reduce MKP-1 expression and Hsp70 levels. Further analysis showed that triptolide reduced MKP-1 mRNA expression in the U-2 OS and MG-63 cells. Triptolide reduced Hsp70 mRNA expression levels in U-2 OS and MG-63 cells. These results suggest that triptolide effectively decreases the viability of osteosarcoma cells. These effects may be associated with the decreased expression of MKP-1 and Hsp70 levels. These results suggest that triptolide may be used in the treatments of osteosarcoma.