The influence of fluid shear stress on the expression of Cbfa1 in MG-63 cells cultured under different gravitational conditions

Purpose: This study was aimed to explore the effect of flow shear stress on the expression of Cbfa1 in human osteosarcoma cells and to survey its functional alteration in simulated microgravity. After culture for 48 h in two different gravitational environments, i.e. I G terrestrial gravitational condition and simulated microgravity condition, human osteosarcoma cells (MG-63) were treated with 0.5 or 1.5 Pa fluid shear stress (FSS) in a flow chamber for 15, 30, and 60 min, respectively. The total RNA in cells was isolated. RT-PCR analysis was made to examine the gene expression of Cbfa1. The total protein of cells was extracted and the expression of Cbfa1 protein was detected by means of Western blotting. Results: MG-63 cells cultured in I G condition reacted to FSS treatment with an enhanced expression of Cbfa1. Compared with no-FSS control group, Cbfa1 mRNA expression increased significantly at 30 and 60 min with the treatment of FSS (P < 0.01). And there was remarkable difference on the Cbfa1 mRNA expression between the treatments of 0.5 and 1.5 Pa FSS at 30 or 60 min (P < 0.01). Cbfa1 protein expressions had a trend to increase at 30 min with the treatment of FSS and they increased significantly at 60 min with the treatment of 0.5 or 1.5 Pa FSS (P < 0.05). As to the cells cultured in simulated microgravity by using clinostat, the expression of Cbfa1 was significantly different between I G and simulated microgravity conditions at each test time (P < 0.05). Compared with no-FSS control group cultured in simulated microgravity, Cbfa1 mRNA expression increased significantly at 30 and 60 min with the treatment of FSS (P < 0.05). And Cbfa1 protein expression increased significant at 60 min with the treatment of 1.5 Pa FSS under simulated microgravity conditions (P < 0.05). Conclusions: FSS can significantly increase the gene and protein expression of Cbfa1 in human osteosarcoma cells. And this inducible function of FSS was adversely affected by simulated microgravity. (C) 2008 COSPAR. Published by Elsevier Ltd. All rights reserved.