Rat sciatic nerve Schwann cells either do not proliferate, or proliferate very slowly, in medium containing 10% fetal bovine serum (FBS). They were previously shown to respond only to a limited number of mitogens associated with cells of central and peripheral nervous systems, which appeared to be distinct from FGFs and PDGF, and to agents that raise intracellular cAMP levels. In a basal medium consisting of 75% DMEM, 25% Ham's F-12, 5 nM sodium selenite, 50 microM 2-amino ethanol, and 2 mM histidine, supplemented with 5% FBS, we showed that aFGF, bFGF, and PDGF were all capable of stimulating Schwann cell growth and the stimulation was greatly potentiated by forskolin and dibutyryl-cAMP. In addition, pretreating culture surface with purified matrix proteins such as laminin, fibronectin, or type 1 collagen, was necessary for obtaining a better cellular response to the mitogenesis of these growth factors even in 10% FBS. Our results clearly indicated that providing a suitable medium and substratum, aFGF, bFGF and PDGF are mitogens for rat sciatic nerve Schwann cells in medium with and without forskolin or dibutyryl-cAMP.

Abstract. Our previous study revealed that estrogen regulates nm23-H1 expression thus promoting cell migration-invasion via activating PIK3/Akt pathway. In this study, we explored the effect of hormone on hypoxia-inducible factor-1 (HIF-1·), a key factor in cancer invasion and metastasis, via activation of Akt signaling transduction pathway. We treated two ovarian cancer cell lines ES-2 and SKOV3 with 17ß-estradiol, methoxyprogesterone acetate (MPA) only, or hormone combined with and Akt, MAPK pathway inhibitor, or transefected with siRNA targeting Akt sequenced with hormone. Expression of HIF-1· was measured by Western blotting. We observed the effect of hormone on nm23-H1 expression after the cells were transfected by siRNA targeting HIF-1· or treated with CoCl 2 to induce HIF-1· overexpression. The 17ß-estradiol increased HIF-1· expression in ovarian cancer cells, and this upregulatory effect was abrogated by Akt inhibitor LY294002 (P<0.05) and Akt siRNA interference (P<0.05), but not affected by MAPK inhibitor PD980059 (P>0.05). MPA had the opposite effect. Nm23-H1 protein expression in ES-2 and SKOV3 cells were decreased after treatment with 17ß-estradiol (P<0.05), whereas MPA had the opposite effect. The effect was attenuated by HIF-1· siRNA (P<0.05) and enhanced by HIF-1· overexpression after CoCl 2 treatment (P<0.05). Our data suggest that estrogen and progestin regulate HIF-1· expression via Akt signaling pathway, affecting nm23-H1 expression in influencing cell metastasis.