Inhibition of MG-63 cell proliferation and PDGF-stimulated cellular processes by inhibitors of phosphatidylinositol 3-kinase

✍ Scribed by James E. Thomas; Murali Venugopalan; Rachelle Galvin; Yan Wang; Gary M. Bokoch; Chris J. Vlahos

• Book ID: 101260269
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 289 KB
• Volume: 64
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/(sici)1097-4644(199702)64:2<182::aid-jcb2>3.0.co;2-t

✦ Synopsis

Studies on a platelet-derived growth factor (PDGF) responsive osteosarcoma cell line, MG-63, were initiated to determine the effects of phosphatidylinositol (PtdIns) 3-kinase inhibitors on serum-stimulated cell proliferation and PDGF-stimulated DNA replication, actin rearrangements, or PtdIns 3-kinase activity. In a dose-dependent manner, the fungal metabolite wortmannin and a quercetin derivative, LY294002 (2-(4-morpholinyl)-8-phenyl-4H-1benzopyran-4-one), inhibited serum-stimulated MG-63 cell proliferation. The mitogenic effects of PDGF on MG-63 cells, as determined by incorporation of [ 3 H]-thymidine, were also substantially inhibited in the presence of 0.10 µM wortmannin or 10 µM LY294002. Furthermore, MG-63 cells stimulated by PDGF form distinct actin-rich, finger-like membrane projections which are completely inhibited by either 0.10 µM wortmannin or 10 µM LY294002. At these same concentrations, wortmannin and LY294002 were also effective at reducing levels of phosphatidylinositol 3-phosphate in PDGF-stimulated MG-63 cells. Treatment of these cells with increasing concentrations of wortmannin reduced the level of PDGF stimulated tyrosine phosphorylation of the PDGF receptor but did not significantly affect the amount of the PtdIns 3-kinase regulatory subunit, p85, associated with the receptor. Additionally, pretreatment of cells with 0.250 µM wortmannin followed by stimulation with PDGF resulted in a slightly reduced level of receptor autokinase activity; however, similar treatment with 50 µM LY294002 did not affect the level of autokinase activity. These results demonstrate the effects of two different PtdIns 3-kinase inhibitors on serum-and PDGF-stimulated MG-63 cell proliferation and PDGF-stimulated morphological changes and suggest a greater role for PtdIns 3-kinase in these processes.