Role of promoter methylation in regulation of the mammalian heparanase gene

Abstract

Mammalian heparanase (endo-b-glucuronidase) degrades heparan sulfate proteoglycans and is an important modulator of the extracellular matrix and associated factors. The enzyme is preferentially expressed in neoplastic tissues and contributes to tumour metastasis and angiogenesis. To investigate the epigenetic regulation of the heparanase locus, methylation-specific and bisulfite PCR were performed on a panel of 22 human cancer cell lines. Cytosine methylation of the heparanase promoter was associated with inactivation of the affected allele. Despite lack of sequence homology, extensively methylated CpG islands were found both in human choriocarcinoma (JAR) and rat glioma (C-6) cells which lack heparanase activity. Treatment of these cells with demethylating agents (5-azacytidine, 5-aza-2 0 -deoxycytidine) resulted in stable dose-and time-dependant promoter hypomethylation accompanied by reappearance of heparanase mRNA, protein and enzymatic activity. An inhibitor of histone deacetylase, Trichostatin A, failed to induce either of these effects. Upregulation of heparanase expression and activity by demethylating drugs was associated with a marked increase in lung colonization by pretreated C-6 rat glioma cells. The increased metastatic potential in vivo was inhibited in mice treated with laminaran sulfate, a potent inhibitor of heparanase activity. We propose a model wherein expression of mammalian heparanase gene is modulated by the interplay between trans-activating genetic and cis-inhibitory epigenetic elements in its promoter.

Heparanase-neutralizing antibodies attenuate lymphoma tumor growth and metastasis

“…This is best demonstrated in Raji cells that lack intrinsic heparanase activity ( Fig. 1E) (20), whereas tumor xenografts produced by these cells exhibit typical heparanase activity. The ability of mAbs 9E8 and H1023 to attenuate the growth of these tumors (Figs.…”

“…Despite the lack of heparanase activity in Raji cells (Fig. 1E, Upper, Raji cells) because of gene methylation (20), tumor xenografts produced by Raji cells exhibit typical heparanase activity (Fig. 1E, Upper, Raji tumor), suggesting that heparanase-positive cells derived from the host populate the tumor microenvironment.…”

Promoter CpG hypomethylation and transcription factor EGR1 hyperactivate heparanase expression in bladder cancer

“…Heparanase expression in bladder cancer T Ogishima et al treatment, suggesting that promoter methylation could be involved in the transcriptional regulation of the heparanase gene (Shteper et al, 2003). Based on the functional promoter sequence of heparanase gene (De Mestre et al, 2003), MSP and USP primers were specifically designed to analyse the difference in promoter CpG methylation between normal bladder and bladder cancer.…”

“…Also, the prevalence of genome-wide hypomethylation has been described in several cancers (Kaneda et al, 2004) and site-specific hypomethylation of the promoter region has been shown to upregulate the expression of cancer-promoting genes (Ehrlich, 2002). Recently, promoter methylation has been associated with the regulation of heparanase expression in cancer cell lines (Shteper et al, 2003). In addition to the active involvement of promoter methylation in heparanase regulation, early growth response 1 (EGR1), a member of the zinc-finger family of transcription factors, has been shown to be important in the inducible transcription of the heparanase gene (De Mestre et al, 2003).…”

Heparanase Uptake Is Mediated by Cell Membrane Heparan Sulfate Proteoglycans

“…Induced heparanase expression under pathological conditions suggests a transcriptional regulation. Heparanase gene expression has been shown to involve promoter methylation (22), eukaryotic initiation factor 4E (23), and the Ets (24) and Egr1 (25) transcription factors. Recently, estrogen has been shown to induce heparanase promoter activation in estrogen receptor-positive breast cancer cells (26).…”