Cyclic Adenosine 3‘: 5’-Monophosphate-binding Protein, a Biochemical Marker of Neuroblastoma Differentiation

Mouse neuroblastoma tumors show reduced amounts of cyclic adenosine 3‘:5’-monophosphate (cAMP) binding protein. However, the levels of cAMP-binding protein were increased by 2-fold when the tumor cells were established in tissue culture, and these levels were comparable to that found in mouse brain. This binding protein is a free cAMP-binding protein that is not associated with protein kinase. The reduced amounts of free cAMP-binding protein in tumors are not a consequence of a defective gene, but the synthesis of this protein is regulated at the transcriptional and/or translational levels. The free cAMP-binding protein like the neurotransmitter-synthesizing enzymes can be used as a biochemical marker of differentiation, and this protein may play a role in neuronal differentiation.