Hydroxyflutamide affects connexin 43 via the activation of PI3K/Akt-dependent pathway but has no effect on the crosstalk between PI3K/Akt and ERK1/2 pathways at the Raf-1 kinase level in primary rat Sertoli cells

We investigated the effects of 2-hydroxyflutamide (HF), an active metabolite of the anti-androgen flutamide, on the activation of the phosphoinositide-3 kinase/protein kinase B (PI3K/Akt) in rat Sertoli cells. Sertoli cells, isolated from 20-day-old rat testes, were cultured in vitro and treated with HF, testosterone, or HF+testosterone. Studies by western blotting demonstrated that HF inhibited the testosterone-mediated increase in c-Src activity (p<0.05). In contrast, Akt phosphorylation was augmented within 5 min after HF treatment (p<0.01). This effect was accompanied by a rapid upregulation in PTEN phosphorylation (p<0.001). Despite no changes in Raf-1 phosphorylation, HF increased extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation (p<0.001), indicating that the effect of the anti-androgen on ERK1/2 was independent of PI3K/Akt-pathway activation at this level. Since HF inhibited the testosterone-mediated increase in c-Src activity, it is likely that activation of both Akt and ERK1/2 occurred in a p-Src independent manner. Activation of PI3K/Akt-pathway by HF resulted in the reduced level of Sertoli cell functional marker, connexin 43 (p<0.01). Collectively, these data provide evidence that HF rapidly and transiently affects the protein kinase-dependent signaling pathways, acting both as an antagonist and agonist. Moreover, using testes of flutamide-treated rats for 7 days, we demonstrated that the anti-androgen can modulate the protein kinase-dependent pathways in long term by enhancing Akt and ERK1/2 protein expression (p<0.05).