The aim of the present study was to investigate the subcellular localization of estrogen receptors ERα and ERβ in androgen-independent prostate cancer cell line DU-145, and the possible role of exportin CRM1 on ERs distribution. In addition, we evaluated the ERs contribution to activation of ERK1/2 and AKT. Immunostaining of ERα and ERβ was predominantly found in the extranuclear regions of DU-145 cells. CRM1 inhibitor Leptomycin B reduced drastically the presence of ERα and ERβ in the extranuclear regions and increased in the nuclei, indicating the possible involvement of CRM1 on ERs nuclear-cytoplasmic shuttling. 17β-estradiol (E2), ERα-selective agonist PPT and ERβ-selective agonist DPN induced a rapid increase on ERK1/2 phosphorylation. E2-induced ERK1/2 activation was partially inhibited when cells were pretreated with ERα- or ERβ-selective antagonists, and blocked by simultaneous pretreatment with both antagonists, suggesting ERα/β heterodimers formation. Furthermore, E2 treatment did not activate AKT pathway. Therefore, we highlighted a possible crosstalk between extranuclear and nuclear ERs and their upstream and downstream signaling molecules as an important mechanism to control ER function as a potential therapeutic target in prostate cancer cells.
Keywords: AKT; CRM1; ERK1/2; ERα; ERβ; Prostate cancer cell.
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