Nongenomic estrogen action in human lung myofibroblasts

Recent studies have suggested that the antiproliferative effects of E2 may be mediated through a nongenomic action, Herein, we asked whether nongenomi c estrogen action regulates phosphorylation of Raf1 and ERK1/2 mitogen-acti vated protein (MAP) kinase in lung myofibroblasts. We demonstrated that lun g myofibroblasts, incubated in the presence of E2, showed a rapid phosphory lation on serine-259 of Raf1 and tyrosine-204 of ERK1/2 MAP kinase at 15 mi n, by approximately 3- and 5-fold, respectively. This phosphorylation was f ollowed by dephosphorylation between 30 and 60 min. Western blot analysis s howed that E2 regulates tyrosine phosphorylation of four main cytoplasmic p roteins in lung myofibroblasts, of 42, 44, 70 and 100 kDa, Furthermore, our results indicated that E2 inhibits cell proliferation (BrdU index) in lung myofibroblasts by approximately 30% (P < 0.01). These data provide evidenc e that nongenomic action of E2, regulates both serine and tyrosine phosphor ylation of cytoplasmic proteins in lung myofibroblasts, including Raf1 and ERK1/2 MAP kinase, which may regulate proliferation in lung myofibroblasts. (C) 2001 Academic Press.