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 where calcium phosphate, produced by bone-forming cells, were 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, including the Phospholipase C (PLC) enzymes. Methods: we analysed the PLC enzymes in human osteoblasts and osteosarcoma cell lines MG-63 and SaOS-2. We compared the 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 4 and PLC  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  and PLC  isoforms. Conclusion: MG-63 and SaOS-2 osteosarcoma cell lines probably do not represent the appropriate experimental model for studies about the analysis of signal transduction in osteoblasts.