Inhibition of isoform D of phosphodiesterase type 4 reduces cell proliferation and survival in hepatocarcinoma cell lines

Abstract

Cyclic AMP phosphodiesterases (PDEs) are enzymes that regulate intracellular levels of cAMP by controlling its rate of degradation, in contrast to adenylyl cyclases that synthesize cAMP from intracellular ATP. PDEs are classified in 11 families (PDE1-PDE11). Some of these control the intracellular levels of both cyclic nucleotides, while others (PDE4, 7, 8) are specific for cAMP degradation. Previous experiments showed that isoform D of cAMP specific PDE4 (PDE4D) was aberrantly up-regulated in HCC cells, in particular in the highly tumorigenic Hep3B and Huh7 cell lines, which also showed increased PDE4 activity.