Abstract
Heparanase (HPSE‐1) is an endo‐β‐d‐glucuronidase involved in the degradation of cell‐surface/extracellular matrix heparan sulfate (HS) in normal and neoplastic tissues. HPSE‐1 represents the first example of purification and cloning of a mammalian HS‐degradative enzyme. Elevated HPSE‐1 levels are known to be associated with metastatic cancers, directly implicating HPSE‐1 in metastatic events. The purpose of this study was to determine the role of cAMP response element‐binding protein (CREB) in modulating HPSE‐1‐mediated effects on human melanoma cell invasion. Highly invasive, brain‐metastatic melanoma cells (70W) were transfected with the dominant‐negative CREB (KCREB) and subsequently analyzed for changes in their HPSE‐1 content, functionality, and cell invasive properties. KCREB‐transfected cells showed a decrease in HPSE‐1 mRNA expression and activity. This correlated with a significantly decreased invasion of these cells through Matrigel™‐coated filters. Furthermore, adenoviral vectors containing the full‐length human HPSE‐1 cDNA in sense orientation (Ad‐S/hep) were constructed to investigate CREB effects on HPSE‐1. Restoration of HPSE‐1 expression and functionality following Ad‐S/hep infection of KCREB‐transfected 70W cells recovered melanoma cell invasiveness. These results demonstrate that KCREB inhibits HPSE‐1 and suggest that one of the roles CREB plays in the acquisition of melanoma cells metastatic phenotype is affecting HPSE‐1 activity. © 2004 Wiley‐Liss, Inc.