The Effect Of Low Extracellular Magnesium On The Growth Of Osteosarcoma Cells
Almuzayyen, Ahmed Abdullatif
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Introduction: Osteosarcoma is the most common bone sarcoma in children and adolescents. It is an aggressive primary bone cancer recognized by abnormal cell proliferation and function. The expression of platelet-derived growth factor (PDGF) and its receptor is demonstrated in 86% of osteosarcoma sample cells. PDGF is a potent mitogen for cells of mesenchymal origin. It plays a central role in regulating cell proliferation, chemotaxis and survival in normal cells as well as in osteosarcoma. In a study, investigating the role of extracellular magnesium on the PDGF induced proliferation in an osteosarcoma cell line (MG63) has shown that concentrations of Magnesium (Mg) below 0.8 mM gradually reduced basal cell proliferation compared with the control condition. Moreover, the stimulatory effects of PDGF were significantly abolished by cells incubation in concentrations of Mg below 0.8 mM. Aim of the study: To evaluate the growth rate of the osteosarcoma cell line (G-292) with or without PDGF in physiological versus low concentrations of extracellular Mg. Material and Methods: The MTT assay was used to assess the growth activity of G292 (Clone A141B1) human osteosarcoma cells. Growth activity was analyzed after various periods of incubation in media with 0.01mM Mg vs 0.8mM Mg, FBS free vs FBS (10%) containing media. The effects of human recombinant PDGF on cell growth at final concentrations of 50 ng/ml and 250 ng/ml were also evaluated. Result: Our experimental results show consistently at different time points of incubation that the Mg extracellular concentration plays a significant role on the growth of G292 osteosarcoma cells, where the low Mg level of 0.01 mM significantly reduced growth compared to the control group with normal Mg level of 0.8mM. No significant changes in cell growth were reflected when the media was supplemented with 50ng/ml of PDGF with either low (0.01mM) or normal (0.8mM) Mg concentrations. However, significant increases of metabolic activity with PDGF (250 ng/ml) were observed in both low and physiological concentrations of extracellular media in media with no added FBS. When the media containing low concentrations of Mg was supplemented with 10% FBS, no effects of PDGF (250 ng/ml) were observed in comparison to cells incubated under the same conditions but without added PDGF. Conclusions: Low extracellular Mg levels appear to significantly inhibit the growth of G292 osteosarcoma cells. However, under conditions of no other added growth factors via serum supplementation, effects of exogenous PDGF on cell growth can be observed as with physiological Mg level.