Effects of vitamin D3 on Survivin expression in human osteoblasts

Abstract

Introduction: Survivin is an antiapoptotic gene expressed in all phases of the nomal cell cycle but highest during the G2/M interphase. Survivin implication in cell proliferation has been the target of extensive cancer research. Objective: To investigate the in vitro effects of vitamin D3 On the expression of Survivin in normal human osteoblast cell cultures as well as in commercially obtained MG-63 osteosarcoma cells. Methods: Human alveolar bone explants were recovered from extraction sites of non-Carious molars and premolars of 8 healthy donors and laboratory cultivated to 2nd passage. MG-63 Osteosarcoma cells were purchased from ATCC. To assess the effect of vitamin D3, bone markers were confirmed using a I125-labeled Human Osteocalcin Kit (Nichols Diagnostics) and an Alkaline Phosphatase Assay (Sigma) Survivin levels were measured using an enzyme immunometric assay (Total Survivin TiterZyme[R], Assay Designs) after 7 and 20 days of culture in both experimental and control groups. Results: Higher levels of Survivin were detected in non vitamin D3 treated osteoblasts vs. osteosarcoma cells at 7 days (P[less than] 0.01). Survivin expression in osteoblasts decreased after vitamin D3 treatment at 7 (P[less than]0.05) and 20 days of culture (P=NS) (Fig. 1). There was no effect of vitamin D3 on Survivin expression in MG-63 cells at 7 or 20 days (P=NS) (Fig.2). The response to vitamin D3 in the osteoblast group was statistically significant at 7 and 20 days of culture when compared to the osteosarcoma group (P[less than]0.01). Conclusions: Expression of Survivin in cultured human osteoblast and MG-63 osteosarcoma cells was positively identified. Our findings suggest a positive correlation between higher expression of Survivin and less differentiated osteoblasts that still retain their proliferative ability. Strategic gene therapy to promote up-regulation of Survivin could potentially increase or maintain a higher proliferative stage in pre-osteoblastic cells prior to further differentiation.