1α, 25‐Dihydroxyvitamin D3 specific regulation of growth, morphology, and fibronectin in a human osteosarcoma cell line

Abstract

The ability of the hormonally active vitamin D metabolite, lα,25-dihydroxyvitamin D₃, to affect cell growth, morphology and fibronectin production has been examined using the MG-63 human osteosarcoma cell line. Hormone treatment reduced cell growth rate, saturation density and [³H]thymidine incorporation. Inhibition was specific for lα,25-dihydroxyvitamin D₃ relative to other vitamin D metabolites (lα,25-dihydroxyvitamin D₃ > 25-dihydroxyvitamin D₃ > 24R,25-dihydroxyvitamin D₃D₃), antagonized by high concentrations of serum and readily reversed by removal of lα,25-dihydroxyvitamin D₃ from the culture medium. Hormone treatment also increased cell associated alkaline phosphatase activity up to twofold and altered morphology such that treated cells were more spread out on the culture dish and contained more cytoplasmic processes. Significantly, lα,25-dihydroxyvitamin D₃ increased cellular and medium concentrations of fibronectin, a glycoprotein known to be involved in cellular adhesiveness. MG-63 cells contain a specific lα,25-dihydroxyvitamin D₃ receptor which may mediate these responses.