Different Expression and Localization of Phosphoinositide Specific Phospholipases C in Human Osteoblasts, Osteosarcoma Cell Lines, Ewing Sarcoma and Synovial Sarcoma

Background: bone hardness and strength depends on mineralization, which involves a complex process in which calcium phosphate, produced by bone-forming cells, was shed around the fibrous matrix. this process is strictly regulated, and a number of signal transduction systems were interested in calcium metabolism, such as the phosphoinositide (pi) pathway and related phospholipase c (plc) enzymes. objectives: our aim was to search for common patterns of expression in osteoblasts, as well as in es and ss. methods: we analysed the plc enzymes in human osteoblasts and osteosarcoma cell lines mg-63 and saos-2. we compared the obtained results to the expression of plcs in samples of patients affected with ewing sarcoma (es) and synovial sarcoma (ss). results: in osteoblasts, mg-63 cells and saos-2 significant differences were identified in the expression of plc δ4 and plc η subfamily isoforms. differences were also identified regarding the expression of plcs in es and ss. most es and ss did not express plcb1, which was expressed in most osteoblasts, mg-63 and saos-2 cells. conversely, plcb2, unexpressed in the cell lines, was expressed in some es and ss. however, plch1 was expressed in saos-2 and inconstantly expressed in osteoblasts, while it was expressed in es and unexpressed in ss. the most relevant difference observed in es compared to ss regarded plc ε and plc η isoforms. conclusion: mg-63 and saos-2 osteosarcoma cell lines might represent an inappropriate experimental model for studies about the analysis of signal transduction in osteoblasts.