Hydroxyurea induces fetal hemoglobin expression by activating cAMP signaling pathways in a cAMP- and cGMP-dependent manner

Abstract

Here we show that hydroxyurea (HU) induces fetal hemoglobin (HbF) expression by activating the cAMP pathway through two independent mechanisms. Although HU increased both cAMP and cGMP levels in CD34+-derived erythroblasts, only the cAMP pathway was found to be activated. However, HU-induced HbF expression was affected by the activities of both adenylate cyclase (AC) and soluble guanylate cyclase (sGC). HU decreased the expression of cGMP-inhibitable phosphodiesterase (PDE) 3B in a sGC-dependent manner, resulting in activation of the cAMP pathway. Second, HU induced the expression of cyclooxygenase-1 (COX-1) and increased the production of prostaglandin E2 (PGE2), which resulted in activation of the cAMP signaling pathway through AC. HU therapy elevated plasma PGE2 levels in sickle cell patients. These results demonstrate that HU induces HbF expression by activating the cAMP pathway via dual signaling mechanisms.