Primary human osteoblasts and bone cancer cells as models to study glycodynamics in bone

Bone cells produce many glycoproteins potentially involved in the maintenance of healthy bone tissues. Two cytokines produced in inflamed joints, tumor necrosis factor (TNF)alpha and transforming growth factor (TGF)beta, have previously been shown to alter cellular glycosylation which may potentially affect the expression and function of glycoproteins. In order to evaluate models to study the glycodynamics of bone cells, we examined primary human osteoblastic cells from osteoarthritis patients, and compared these to human osteosarcoma cells MG63 and SJSA-1. We showed here for the first time that all of the human osteoblastic cells actively synthesize complex N- and O-glycan chains of bone cell glycoproteins, with quantitative differences between cell types. TNFalpha-induced apoptosis or TGFbeta-induced cell differentiation and proliferation had significant effects on both cell surface carbohydrates and glycosyltransferase activities of osteoblasts and osteosarcoma cells. The results indicate that cultured human bone-derived osteoblastic cells are good models to examine the glycodynamics of osteoblasts under conditions of cell growth and cell death. The changes induced by cytokines can result in altered cell surface functions which may be of importance in osteoarthritis, osteoporosis and other bone diseases.