Effect on proliferation and apoptosis in RPM1-8226 human myeloma cells and regulation on steroid receptor coactivator-3 by deguelin

Abstract

Objective: To investigate the effects of deguelin on the proliferation inhibition and apoptosis induction in RPMI-8226 cells in vitro, as well as the regulation of steroid receptor coactivator-3 (SRC-3) to explore the relationship between them. Methods: The effect of deguelin on the growth of RPMI-8226 cells was studied by MTT assay. Apoptosis was detected through Hoechst 33258 staining and Annexin-V FITC/PI double-labeled cytometry. RT-PCR Technology was applied to assessment of the mRNA expression of SRC-3, whereas, SRC-3 protein expression and localization were determined by using immunohistochemistry method. Results: Deguelin presented striking proliferation inhibition potency on RPMI-8226 cells in vitro and apoptosis induction activity in a time- and dose-dependent manner. The IC50 value for 24 h was (54.55±0.40) nmol/L, (17.04±0.73)% RPMI-8226 cells went apoptotic when treated with 25 nmol/L deguelin for 24 h, with the dose of deguelin increasing to 100 nmol/L, (63.57±1.36)% cells were apoptotic. Over-expression of SRC-3 was found in RPMI-8226 cells, whereas the mRNA and protein expression levels of SRC-3 were significantly downregulated in RPMI-8226 cells induced by deguelin in a dose-dependent manner. The disposition of SRC-3 was situated mainly at the nuclear, occasionally in the cytoplasm. Conclusion: Deguelin exhibited potent proliferation inhibition to the human myeloma cell line RPMI-8226 cells, furthermore, deguelin might induce RPMI-8226 cells apoptosis in a dose-dependent manner, which might correspond to the regulation of the expression of SRC-3.