Endo-sulfatase Sulf-1 protein expression is down-regulated in gastric cancer

Validation of Novel Molecular Imaging Targets Identified by Functional Genomic mRNA Profiling to Detect Dysplasia in Barrett's Esophagus

Barrett’s esophagus (BE) is the precursor of esophageal adenocarcinoma (EAC). Dysplastic BE (DBE) has a higher progression risk to EAC compared to non-dysplastic BE (NDBE). However, the miss rates for the endoscopic detection of DBE remain high. Fluorescence molecular endoscopy (FME) can detect DBE and mucosal EAC by highlighting the tumor-specific expression of proteins. This study aimed to identify target proteins suitable for FME. Publicly available RNA expression profiles of EAC and NDBE were corrected by functional genomic mRNA (FGmRNA) profiling. Following a class comparison between FGmRNA profiles of EAC and NDBE, predicted, significantly upregulated genes in EAC were prioritized by a literature search. Protein expression of prioritized genes was validated by immunohistochemistry (IHC) on DBE and NDBE tissues. Near-infrared fluorescent tracers targeting the proteins were developed and evaluated ex vivo on fresh human specimens. In total, 1976 overexpressed genes were identified in EAC (n = 64) compared to NDBE (n = 66) at RNA level. Prioritization and IHC validation revealed SPARC, SULF1, PKCι, and DDR1 (all p < 0.0001) as the most attractive imaging protein targets for DBE detection. Newly developed tracers SULF1-800CW and SPARC-800CW both showed higher fluorescence intensity in DBE tissue compared to paired non-dysplastic tissue. This study identified SPARC, SULF1, PKCι, and DDR1 as promising targets for FME to differentiate DBE from NDBE tissue, for which SULF1-800CW and SPARC-800CW were successfully ex vivo evaluated. Clinical studies should further validate these findings.

Gastric Cancer Heterogeneity and Clinical Outcomes

Gastric adenocarcinoma is a highly aggressive disease with poor overall survival. The aggressive nature of this disease is in part due to the high intra and inter tumoral heterogeneity and also due to the late diagnosis at presentation. Once progression occurs, treatment is more difficult due to the adaptation of tumors, which acquires resistance to commonly used chemotherapeutics. In this report, using publicly available data sets and pathway analysis, we highlight the vast heterogeneity of gastric cancer by investigating genes found to be significantly perturbed. We found several upregulated genes in the diffuse gastric cancer subtypes share similarity to gastric cancer as a whole which can be explained by the increase in this subtype of gastric cancer throughout the world. We report significant downregulation of genes that are underrepresented within the literature, such as ADH7, GCNT2, and LIF1, while other genes have not been explored within gastric cancer to the best of our knowledge such as METTL7A, MAL, CWD43, and SLC2A12. We identified gender to be another heterogeneous component of this disease and suggested targeted treatment strategies specific to this heterogeneity. In this study, we provide an in-depth exploration of the molecular landscape of gastric cancer in order to shed light onto novel areas of gastric cancer research and explore potential new therapeutic targets.

Sulfatase-1 knockdown promotes in vitro and in vivo aggressive behavior of murine hepatocarcinoma Hca-P cells through up-regulation of mesothelin

Our previous study (Oncotarget 2016; 7:46) demonstrated that the over-expression of sulfatase-1 in murine hepatocarcinoma Hca-F cell line (a murine HCC cell with lymph node metastatic [LNM] rate of >75%) downregulates mesothelin and leads to reduction in lymphatic metastasis, both in vitro and in vivo. In current work, we investigated the effects of Sulf-1 knockdown on mesothelin (Msln) and it's effects on the in vitro cell proliferation, migration, invasion, and in vivo tumor growth and LNM rate for Hca-P cells (a murine HCC cell with LNM rate of <25%). Western blotting and qRT-PCR assay indicated that both in vitro and in vivo Sulf-1 was down-regulated by 75% and 68% and led to up regulation of Msln by 55% in shRNA-transfected-Sulf-1-Hca-P cells compared with Hca-P and nonspecific sequence control plasmid transfected Hca-P cell (shRNA-Nc-Hca-P). The in vitro proliferation, migration and invasion potentials were significantly enhanced following Sulf-1 stable down-regulation. In addition, Sulf-1 knock-down significantly promoted tumor growth and increased LNM rates of shRNA-Sulf-1-Hca-P-transplanted mice by 78.6% (11 out of 14 lymph nodes were positive of cancer). Consistent with our previous work, we confirmed that Sulf-1 plays an important role in hepatocarcinoma cell proliferation, migration, invasion and metastasis. The interaction between Sulf-1 and Msln is a potential therapeutic target in the development of liver cancer therapy.

Enhanced tumorigenic potential of colorectal cancer cells by extracellular sulfatases

Heparan sulfate endosulfatase-1 and -2 (SULF1 and SULF2) are two important extracellular 6-O-endosulfatases that remove 6-O sulfate groups of N-glucosamine along heparan sulfate (HS) proteoglycan chains often found in the extracellular matrix. The HS sulfation pattern influences signaling events at the cell surface, which are critical for interactions with growth factors and their receptors. SULFs are overexpressed in several types of human tumors, but their role in cancer is still unclear because their molecular mechanism has not been fully explored and understood. To further investigate the functions of these sulfatases in tumorigenesis, stable overexpression models of these genes were generated in the colorectal cancer cells, Caco-2 and HCT-116. Importantly, mimicking overexpression of these sulfatases resulted in increased viability and proliferation, and augmented cell migration. These effects were reverted by shRNA-mediated knockdown of SULF1 or SULF2 and by the addition of unfractionated heparin. Detailed structural analysis of HS from cells overexpressing SULFs showed reduction in the trisulfated disaccharide UA(2S)-GlcNS(6S) and corresponding increase in UA(2S)-GlcNS disaccharide, as well as an unexpected rise in less common disaccharides containing GlcNAc(6S) residues. Moreover, cancer cells transfected with SULFs demonstrated increased Wnt signaling. In summary, SULF1 or SULF2 overexpression contributes to colorectal cancer cell proliferation, migration, and invasion.

IMPLICATIONS

This study reveals that sulfatases have oncogenic effects in colon cancer cells, suggesting an important role for these enzymes in cancer progression.

The Role of Heparanase and Sulfatases in the Modification of Heparan Sulfate Proteoglycans within the Tumor Microenvironment and Opportunities for Novel Cancer Therapeutics

Heparan sulfate proteoglycans (HSPGs) are an integral and dynamic part of normal tissue architecture at the cell surface and within the extracellular matrix. The modification of HSPGs in the tumor microenvironment is known to result not just in structural but also functional consequences, which significantly impact cancer progression. As substrates for the key enzymes sulfatases and heparanase, the modification of HSPGs is typically characterized by the degradation of heparan sulfate (HS) chains/sulfation patterns via the endo-6-O-sulfatases (Sulf1 and Sulf2) or by heparanase, an endo-glycosidase that cleaves the HS polymers releasing smaller fragments from HSPG complexes. Numerous studies have demonstrated how these enzymes actively influence cancer cell proliferation, signaling, invasion, and metastasis. The activity or expression of these enzymes has been reported to be modified in a variety of cancers. Such observations are consistent with the degradation of normal architecture and basement membranes, which are typically compromised in metastatic disease. Moreover, recent studies elucidating the requirements for these proteins in tumor initiation and progression exemplify their importance in the development and progression of cancer. Thus, as the influence of the tumor microenvironment in cancer progression becomes more apparent, the focus on targeting enzymes that degrade HSPGs highlights one approach to maintain normal tissue architecture, inhibit tumor progression, and block metastasis. This review discusses the role of these enzymes in the context of the tumor microenvironment and their promise as therapeutic targets for the treatment of cancer.