Silencing of hHS6ST2 inhibits progression of pancreatic cancer through inhibition of Notch signalling

Abstract

Many of the ligands involved in developmental processes require HS (heparan sulfate) to modulate signal transduction. hHS6ST2 (human heparan sulfate D-glucosaminyl 6-O-sulfotransferase-2) is a Golgi-resident enzyme that usually acts on GlcA/IdoA(2S)-GlcNAc/NS disaccharide-6-sulfate modifications within the HS sequence. Emerging evidence indicates the importance of 6-O-sulfation in a number of developmental processes. However, any correlation with cancer-related events remains largely unexplored. In the present study, we found that hHS6ST2, but not other variants, was activated in human PC (pancreatic cancer). shRNA (short hairpin RNA)-mediated silencing of endogenous hHS6ST2 expression in the PC cell line PANC-1 inhibited cell invasion and migration. hHS6ST2 knockdown also resulted in markedly reduced tumorigenesis in immunocompromised mice. To specifically explore the molecular alterations resulting from depletion of hHS6ST2-generated 6-O-sulfation, we employed two-dimensional gel electrophoresis technology followed by nano-HPLC-ESI (electrospray ionization)-tandem MS to separate and identify total proteins from PC cells. Our data suggest that hHS6ST2 potentiates Notch signalling in PC cells. We also identified a role for hHS6ST2 in the growth and tumorigenicity of these cells which, at least in part, acts through Notch-mediated EMT (epithelial-mesenchymal transition) and angiogenesis. The results of the present study suggest that hHS6ST2 could be an attractive target for PC therapy.

Overexpression of HS6ST2 is associated with poor prognosis in patients with gastric cancer

“…EMT is an important mechanism which induces tumor-related epithelial cells to acquire mesenchymal features; including increased motility and reduced cell-cell contact in the early stage of tumorigenesis (33). Song et al (13) revealed that the activation of HS6ST2, in pancreatic cancer (PC), participated in EMT and angiogenesis in the progression of this disease. The potential mechanism by which HS6ST2 potentiates PC carcinogenesis is mainly attributed to the activation of the notch-signaling pathway, which mediates EMT and angiogenesis (13).…”

“…Song et al (13) revealed that the activation of HS6ST2, in pancreatic cancer (PC), participated in EMT and angiogenesis in the progression of this disease. The potential mechanism by which HS6ST2 potentiates PC carcinogenesis is mainly attributed to the activation of the notch-signaling pathway, which mediates EMT and angiogenesis (13). The notch-signaling pathway is involved in the processes of tumor cell proliferation, invasion, and the establishment of a mesenchymal phenotype (33,34).…”

“…By way of this mechanism, HSPGs subsequently participate in diverse biological functions including blood clotting, cell recognition, adhesion, proliferation, and differentiation by interactions with diverse cytokines (8,9). Previous studies have revealed that HS6ST2 is associated with the progression of malignant tumors, and is upregulated in various tumor types including thyroid (10,11), colorectal (12), pancreatic (13), ovarian (14), breast cancer (15), and chondrosarcomas (16). However, to the best of our knowledge, the involvement of HS6ST2 in GC has not yet been elucidated.…”

Reprogrammed Cellular Metabolism and O -GlcNAc Modification in Cancer

“…Moreover, as UDP-GlcNAc, the product of HBP is not only required for OGT mediated O-GlcNAc modification of cytosolic and nuclear proteins but also in the glycosylation of membrane proteins, it is possible that high GlcNAc levels may contribute in EMT by changing the topology of cell surface proteins. Alternatively, O-GlcNAc effect could be mediated through altered O-GlcNAc modification of transcription factors that have been implicated in EMT [38].…”

“…Moreover, as UDP-GlcNAc, the product of HBP is not only required for OGT mediated O-GlcNAc modification of cytosolic and nuclear proteins but also in the glycosylation of membrane proteins, it is possible that high GlcNAc levels may contribute in EMT by changing the topology of cell surface proteins. Alternatively, O-GlcNAc effect could be mediated through altered O-GlcNAc modification of transcription factors that have been implicated in EMT [38].Given an emerging role of O-GlcNAc modification as a fundamental regulatory mechanism involved in the various cellular processes it is highly unlikely that global approaches such as RNAi mediated knockdown of OGT and OGA or their overexpression, inhibiting OGT and OGA activity by small molecule inhibitors would provide a definite answer regarding protein specific role of O-GlcNAc modification in cancer cell metabolism or cancer phenotype. It would be very challenging to distinguish the target specific effect from nontarget effect of such global approaches.…”