Use of Saikosaponin D and JNK inhibitor SP600125, alone or in combination, inhibits malignant properties of human osteosarcoma U2 cells.

Saikosaponin D (Ssd) is a major active ingredient derived from the traditional Chinese medicinal herb Bupleurum falcatum, and SP600125 is a specific inhibitor of JNK that competes with adenosine triphosphate. In this study, we co-analyzed cell proliferation, apoptosis, migration, and invasion in U-2OS osteosarcoma cells treated with Ssd and SP600125 alone or in combination. Cell death and signaling were analyzed using western blotting and flow cytometry. We observed dramatic inhibition of cellular proliferation, invasion, and migration in cells treated with Ssd alone or in combination with SP600125. Ssd, alone or in combination with SP600125, enhanced Cytochrome C release, increased the Bax/Bcl-2 ratio, and activated caspase-3, -8 and -9, indicating that cellular apoptosis was induced via both the mitochondrial and death receptor pathways. The effect of SP600125 alone on U2 cells was not significant. Additional evaluation of Mcl-1, Akt, p-Akt, ERK, and p-ERK supported an anti-tumor effect of Ssd, which was enhanced in combination with SP600125. This study provides a theoretical basis for the treatment of osteosarcoma with Ssd alone or in combination with SP600125.