Cyclic AMP phosphodiesterase-4 in brain tumor biology: Immunochemical analysis

Cyclic AMP plays a significant role in the biology of brain tumors and represents an important therapeutic target. Intracellular levels of cAMP are regulated through its synthesis via adenylyl cyclases and its degradation by phosphodiesterases (PDEs). There are eleven families of PDEs (1 through 11) as well as multiple sub-families from which numerous isoforms are generated by alternate mRNA splicing. We, and others have found that specific PDE isoforms exhibit tumor promoting qualities and that PDE inhibitors possess potent anti-tumor activity. In order to investigate the molecular basis for PDE actions in brain tumor biology, we rigorously examined the patterns of PDE isoform expression. In the following chapter we focus on the PDE4 sub-family of cAMP specific hydrolases and discuss several challenges that arise when examining their patterns of expression by western blotting, immuno-histochemistry and immuno-fluorescence.