Biotechnology studies of Sulfatase 2 as a novel target for the treatment of hepatocellular carcinoma

Abstract

Hepatocellular carcinoma (HCC) often arises on the background of chronic liver disease, and effective systemic treatments for HCC are limited. The disease is common globally and the majority of those affected survive less than 1 year. Expression of Sulfatase 2 (SULF2), an extracellular heparan sulfate 6-O-endosulfatase which modulates growth factor/receptor tyrosine kinase and Wnt signalling, has been reported to be increased at the mRNA level in advanced HCC. This thesis has explored the potential of SULF2 as a candidate for targeted anti-cancer therapy. Expression of SULF2 was compared at the mRNA and protein levels in 6 HCC cell lines. The impact of SULF2 silencing on signalling pathways and cell growth was assessed in vitro and in vivo using shRNA. Three of the 6 HCC cell lines showed high SULF2 expression at both the mRNA and protein level. The effect of SULF2 gene silencing in HCC cells was cell line-dependent, with inhibition of Wnt-3a-induced β-catenin-dependent transcriptional activity in the HuH-7 cell line and inhibition of FGF-1/2-stimulated phosphorylation of ERK, and IGF-II-stimulated phosphorylation of AKT, in the SNU-182 cell line. SULF2 suppression significantly reduced cell growth and proliferation in both cell lines. Xenograft implantation using HuH-7 cells was completely abrogated by silencing of SULF2. Microarray gene expression analysis of HuH-7 cell lines showed that SULF2 suppression dramatically upregulated catalytically active angiotensin converting enzyme 2 (ACE2) at the mRNA and protein level. The level of the ACE2 product, the hepta-peptide angiotensin 1-7 that has been reported to have anti-proliferative and anti-angiogenic activities, was also increased. Recombinant SULF2 enzyme was produced and purified, and commercially available sulfatases were characterised, for screening of potential small-molecule inhibitors of SULF2. Together, the studies described in this thesis have shown that SULF2 is an attractive and tractable target for the treatment of HCC.