Ascorbic acid incerases 1,25-dihydroxyvitamin D(3) effect in human osteosaroma cell line MG63

We eximined the interaction between 1,25-dihydroxyvitamin D(3) and ascorbic acid in the human osteosarcoma cell MG63 by measuring alkaline phosphatase (ALP) activity. Both vitamins induced ALP activity in this cell line. Simultaneous addition of both ascorbic and 1,25-dihydroxyvitamin D(3) induced much higher ALP activity than each vitamin alone. Pretreatment of MG63 with ascorbic acid or type I collagen, increased the ALP activity induced by 1,25-dihydroxyvitamin D(3). Binding assay anf immunoblotting analysis showed that the number of vitamin D receptors was increased in MG63 pretreated with ascorbic acid. In conclusion,ascorbic acid stimulates collagen production of MG63, and collagen increases the vitamin D receptor content. The increase in vitamin D receptor content potentiates the activity of 1,25-dihydroxyvitamin D(3) in this cell line.