Argeted therapies and tailored patient management. In the study, we elucidated a minimal deletion region of 1.4 Mb at chromosome 4q26 in sporadic CRC, consistent with the previous report 10781694 that the frequency of allelic deletion at 4q26 was increased in colorectalcarcinomas compared with adenomas [11]. Although numerous previous studies have suggested candidate TSG loci on chromosome 4 [14,15], here we identified, for the first time, NDST4 gene as a novel candidate TSG at 4q26. In addition, because LOH at polymorphic loci allows the expressivity of loss-of-function deletion in TSGs, this genetic study has potential diagnostic and prognostic relevance [21]. The LOH assay established in the study could be a cost-effective tool for providing a useful biomarker of adverse prognosis in CRC. NDST4 is one member of the N-deacetylase/N-sulfotransferase (heparan glucosaminyl) (NDST) family, which is responsible for heparan sulfate (HS) biosynthesis on a core protein to form heparan sulfate proteoglycans (HSPGs) [22,23]. HSPGs ubiquitously reside on the cell surface, inside the cell, and in the extracellular matrix [24]. The HS chains of HSPGs interact with a wide array of protein ligands such as growth factor families, and thus, contribute to the tissue structure and function during development and adult homeostasis [25,26]. Importantly, the content and distribution of HSPGs are altered during tumorigenesis, which have been implicated in positive or negative aspects of tumor progression. For example, HSPGs function as co-receptors for growth factors and their receptor tyrosine kinases to stabilize the signaling complexes during tumor proliferation and invasion [27]. In contrast, HSPGs promote cell-cell and cell-extracellular matrix interactions and build inhibitory barriers for tumor invasion. Therefore, the decreased levels of HSPGs correlate with tumor progression [28,29]. In the present study, the genetic loss of NDST4 was significantly associated with advanced pathological stage, which refers to the local tumor depth of invasion in CRC, suggesting that the loss of function of NDST4 gene might impair the modification of HS chains of specific HSPGs, leading to more Epigenetic Reader Domain invasive tumor cells through remodeling of the interaction of cell adhesion receptors and ligands. Four different isoforms of NDSTs are identified in vertebrates. Unlike the universal gene expression of NDST1 and NDST2, NDST3 and NDST4 transcripts are predominantly expressed during embryonic development [30,31]. Epigenetic Reader Domain However, the expression patterns of NDSTs have never been illustrated in the human colon. Using RT-PCR, we found that the transcripts of four NDSTs were readily detectable in normal colonic mucosa, whereas only NDST4 expression was downregulated in most of the tested CRC tumors (data not shown). According to the predicted structure of the sulfotransferase domain of NDSTs, the four different isoforms may exhibit varying substrate specificities [30]. Sheng et al. recently demonstrated that NDST1 performed the modification in a highly ordered manner to control the N-sulfation domains in HS, suggesting that initiated and followed N-sulfation could be conducted using different NDSTs [32]. With the relatively poor deacetylation activity of NDST4 on unmodified HS chains, NDST4 might prefer those with an initial modification by other isoforms [30]. In addition, NDSTs play a pivotal role in HS biosynthesis because NDSTs are the first participants in the sequential modification process [.Argeted therapies and tailored patient management. In the study, we elucidated a minimal deletion region of 1.4 Mb at chromosome 4q26 in sporadic CRC, consistent with the previous report 10781694 that the frequency of allelic deletion at 4q26 was increased in colorectalcarcinomas compared with adenomas [11]. Although numerous previous studies have suggested candidate TSG loci on chromosome 4 [14,15], here we identified, for the first time, NDST4 gene as a novel candidate TSG at 4q26. In addition, because LOH at polymorphic loci allows the expressivity of loss-of-function deletion in TSGs, this genetic study has potential diagnostic and prognostic relevance [21]. The LOH assay established in the study could be a cost-effective tool for providing a useful biomarker of adverse prognosis in CRC. NDST4 is one member of the N-deacetylase/N-sulfotransferase (heparan glucosaminyl) (NDST) family, which is responsible for heparan sulfate (HS) biosynthesis on a core protein to form heparan sulfate proteoglycans (HSPGs) [22,23]. HSPGs ubiquitously reside on the cell surface, inside the cell, and in the extracellular matrix [24]. The HS chains of HSPGs interact with a wide array of protein ligands such as growth factor families, and thus, contribute to the tissue structure and function during development and adult homeostasis [25,26]. Importantly, the content and distribution of HSPGs are altered during tumorigenesis, which have been implicated in positive or negative aspects of tumor progression. For example, HSPGs function as co-receptors for growth factors and their receptor tyrosine kinases to stabilize the signaling complexes during tumor proliferation and invasion [27]. In contrast, HSPGs promote cell-cell and cell-extracellular matrix interactions and build inhibitory barriers for tumor invasion. Therefore, the decreased levels of HSPGs correlate with tumor progression [28,29]. In the present study, the genetic loss of NDST4 was significantly associated with advanced pathological stage, which refers to the local tumor depth of invasion in CRC, suggesting that the loss of function of NDST4 gene might impair the modification of HS chains of specific HSPGs, leading to more invasive tumor cells through remodeling of the interaction of cell adhesion receptors and ligands. Four different isoforms of NDSTs are identified in vertebrates. Unlike the universal gene expression of NDST1 and NDST2, NDST3 and NDST4 transcripts are predominantly expressed during embryonic development [30,31]. However, the expression patterns of NDSTs have never been illustrated in the human colon. Using RT-PCR, we found that the transcripts of four NDSTs were readily detectable in normal colonic mucosa, whereas only NDST4 expression was downregulated in most of the tested CRC tumors (data not shown). According to the predicted structure of the sulfotransferase domain of NDSTs, the four different isoforms may exhibit varying substrate specificities [30]. Sheng et al. recently demonstrated that NDST1 performed the modification in a highly ordered manner to control the N-sulfation domains in HS, suggesting that initiated and followed N-sulfation could be conducted using different NDSTs [32]. With the relatively poor deacetylation activity of NDST4 on unmodified HS chains, NDST4 might prefer those with an initial modification by other isoforms [30]. In addition, NDSTs play a pivotal role in HS biosynthesis because NDSTs are the first participants in the sequential modification process [.
