Functional corticotropin-releasing factor receptors in human neuroblastoma cells

The present study examined the presence of functional corticotropin-releasing factor (CRF) receptors in IMR-32 neuroblastoma cells. [I-125]Tyr(o)-ovine CRF binding was linear with increasing protein concentrations, saturable, reversible and of high affinity. Scatchard analysis indicated a K-d of similar to 0.8 nM and a B-max of similar to 32 fmol/mg protein. Competition studies with CRF and related peptides revealed a pharmacological profile characteristic of the CRF(1) receptor subtype. CRF stimulated cAMP production in a dose-dependent manner with an apparent EC(50) of similar to 4 nM. In addition, the putative CRF receptor antagonist alpha-helical CRF(9-41) dose-dependently inhibited CRF stimulated (10 nM) cAMP production with an IC50 of similar to 60 nM. CRF treatment down regulated its own receptor while treatment with the protein kinase C activator, phorbol 12-myristate 13-acetate (PMA), increased CRF binding in neuroblastoma cells. Taken together, these data demonstrate the utility of the human neuroblastoma cell line for functional studies on CRF receptors and suggest that CRF may play a regulatory role in the pathophysiology of human neuroblastoma.