Polymorphism in the GALNT1 gene and epithelial ovarian cancer in non-Hispanic white women: the Ovarian Cancer Association Consortium

An unusual dual sugar-binding lectin domain controls the substrate specificity of a mucin-type O-glycosyltransferase

N-acetylgalactosaminyl-transferases (GalNAc-Ts) initiate mucin-type O-glycosylation, an abundant and complex posttranslational modification that regulates host-microbe interactions, tissue development, and metabolism. GalNAc-Ts contain a lectin domain consisting of three homologous repeats (α, β, and γ), where α and β can potentially interact with O-GalNAc on substrates to enhance activity toward a nearby acceptor Thr/Ser. The ubiquitous isoenzyme GalNAc-T1 modulates heart development, immunity, and SARS-CoV-2 infectivity, but its substrates are largely unknown. Here, we show that both α and β in GalNAc-T1 uniquely orchestrate the O-glycosylation of various glycopeptide substrates. The α repeat directs O-glycosylation to acceptor sites carboxyl-terminal to an existing GalNAc, while the β repeat directs O-glycosylation to amino-terminal sites. In addition, GalNAc-T1 incorporates α and β into various substrate binding modes to cooperatively increase the specificity toward an acceptor site located between two existing O-glycans. Our studies highlight a unique mechanism by which dual lectin repeats expand substrate specificity and provide crucial information for identifying the biological substrates of GalNAc-T1.

GALNT12 promotes fibrosarcoma growth by accelerating YAP1 nuclear localization

Fibrosarcoma is a highly malignant type of soft tissue sarcoma that currently lacks effective treatment options. Polypeptide N-acetylgalactosaminyltransferase 12 (GALNT12) belongs to the uridine diphosphate N-acetylgalactosamine gene family, which is involved in numerous biological processes of diseases, such as tumor progression. Its upregulated expression is closely associated with the development of colorectal cancer. However, research on the role of GALNT12 in fibrosarcoma is currently limited. The present study aimed to assess the expression and biological function of GALNT12 in fibrosarcoma. Patient data and tissue samples were collected and public datasets were obtained from the Gene Expression Omnibus (GSE24369 and GSE21124). Immunofluorescence assays were performed to observe the cellular localization of GALNT12. GALNT12 expression was measured using reverse transcription-quantitative PCR, western blotting and immunohistochemistry. Small interfering RNAs were constructed to knock down GALNT12 expression in HT-1080 cells. Cell Counting Kit-8 and EdU assays were used to assess fibrosarcoma cell proliferation. Wound healing and Transwell assays were used to detect migration. Gene set enrichment analysis was performed to identify key pathways. Paired and unpaired Student's t-test, Fisher's exact test and one-way ANOVA (followed by Tukey's Honest Significant Difference test) were used to analyze the data. It was demonstrated that GALNT12 expression was upregulated in both fibrosarcoma cell lines and tissue samples and predicted poor patient prognosis. In vitro experiments demonstrated that high GALNT12 expression levels significantly increased HT-1080 cell proliferation and migration. Furthermore, it was demonstrated that high GALNT12 expression levels were closely associated with the yes1 associated transcriptional regulator (YAP1) signaling pathway. Knockdown of GALNT12 inhibited YAP1 nuclear translocation, which affected activation of key downstream genes including AMOTL2, BIRC5 and CYR61. Therefore, the present study demonstrated that GALNT12 promoted fibrosarcoma progression. GALNT12 could be a potential biomarker for this disease and may potentially provide new ideas for targeted therapy of fibrosarcoma in the future.

The association between single nucleotide polymorphisms and ovarian cancer risk: A systematic review and network meta-analysis

BACKGROUND

The relationship between single nucleotide polymorphisms (SNPs) and ovarian cancer (OC) risk remains controversial. This systematic review and network meta-analysis was aimed to determine the association between SNPs and OC risk.

METHODS

Several databases (PubMed, EMBASE, China National Knowledge Infrastructure, Wanfang databases, China Science and Technology Journal Database, and China Biology Medicine disc) were searched to summarize the association between SNPs and OC published throughout April 2021. Direct meta-analysis was used to identify SNPs that could predict the incidence of OC. Ranking probability resulting from network meta-analysis and the Thakkinstian's algorithm was used to select the most appropriate gene model. The false positive report probability (FPRP) and Venice criteria were further tested for credible relationships. Subgroup analysis was also carried out to explore whether there are racial differences.

RESULTS

A total of 63 genes and 92 SNPs were included in our study after careful consideration. Fok1 rs2228570 is likely a dominant risk factor for the development of OC compared to other selected genes. The dominant gene model of Fok1 rs2228570 (pooled OR = 1.158, 95% CI: 1.068-1.256) was determined to be the most suitable model with a FPRP <0.2 and moderate credibility.

CONCLUSIONS

Fok1 rs2228570 is closely linked to OC risk, and the dominant gene model is likely the most appropriate model for estimating OC susceptibility.

Exosome-derived SNHG16 sponging miR-4500 activates HUVEC angiogenesis by targeting GALNT1 via PI3K/Akt/mTOR pathway in hepatocellular carcinoma

Accumulating evidence suggests cancer-derived exosomes play an important role in promoting angiogenesis. Long noncoding RNA small nucleolar RNA host gene 16 (SNHG16) is known to aggravate hepatocellular carcinoma (HCC) progression. However, the function of exosomal SNHG16 in HCC angiogenesis remains unclear. In this study, the expression of SNHG16 was significantly upregulated in HCC tissues and cell lines. The proliferative, migratory, and angiogenic abilities of HUVECs were enhanced after exposure to exosomes derived from HCC cells by transmitting SNHG16. In addition, SNHG16 was validated to promote the biological function of HUVECs directly. Exosomal SNHG16 increased GALNT1 expression to promote angiogenesis via sponging miR-4500. SNHG16/miR-4500/GALNT1 axis played an important role in exosome-mediated angiogenesis and tumor growth in vitro and vivo. Furthermore, SNHG16 activated PI3K/Akt/mTOR pathway via competing endogenous miR-4500 and GALNT1. Meanwhile, the expression of plasma exosomal SNHG16 upregulated in the plasma of HCC patients. These data elucidated the essential role of exosomal SNHG16 in communication between HCC cells and endothelial cells. Exosomal SNHG16 could be utilized as a therapeutic target for anti-angiogenesis in HCC progression.

High Throughput Multiplex SNP-analysis in Chronic Obstructive Pulmonary Disease and Lung Cancer

Background:

A number of human inflammatory diseases and tumors have been shown to cause alterations in the glycosylation pattern of plasma proteins in a specific manner. These highly variable and versatile post-translational modifications finetune protein functions by influencing sorting, folding, enzyme activity and subcellular localization. However, relatively little is known about regulatory factors of this procedure and about the accurate causative connection between glycosylation and disease.

Objective:

The aim of the present study was to investigate whether certain single nucleotide polymorphisms (SNPs) in genes encoding glycosyltransferases and glycosidases could be associated with elevated risk for chronic obstructive pulmonary disease (COPD) and lung adenocarcinoma.

Methods:

A total of 32 SNPs localized in genes related to N-glycosylation were selected for the association analysis. Polymorphisms with putative biological functions (missense or regulatory variants) were recruited. SNPs were genotyped by a TaqMan OpenArray platform. A single base extension-based method in combination with capillary gel electrophoresis was used for verification.

Results:

The TaqMan OpenArray approach provided accurate and reliable genotype data (global call rate: 94.9%, accuracy: 99.6%). No significant discrepancy was detected between the obtained and expected genotype frequency values (Hardy–Weinberg equilibrium) in the healthy control sample group in case of any SNP confirming reliable sampling and genotyping. Allele frequencies of the rs3944508 polymorphism localized in the 3’ UTR of the MGAT5 gene significantly differed between the sample groups compared.

Conclusion:

Our results suggest that the rs34944508 SNP might modulate the risk for lung cancer by influencing the expression of MGAT5. This enzyme catalyzes the addition of N-acetylglucosamine (GlcNAc) in beta 1-6 linkage to the alpha-linked mannose of biantennary N-linked oligosaccharides, thus, increasing branching that is the characteristic of invasive malignancies.

Long non-coding RNA-SNHG7 acts as a target of miR-34a to increase GALNT7 level and regulate PI3K/Akt/mTOR pathway in colorectal cancer progression

Background

Colorectal cancer (CRC) arises in a multistep molecular network process, which is from either discrete genetic perturbation or epigenetic dysregulation. The long non-coding RNAs (lncRNAs), emerging as key molecules in human malignancy, has become one of the hot topics in RNA biology. Aberrant O-glycosylation is a well-described hallmark of many cancers. GALNT7 acts as a glycosyltransferase in protein O-glycosylation, involving in the occurrence and development of CRC.

Methods

The microarrays were used to survey the lncRNA and mRNA expression profiles of primary CRC cell line SW480 and metastatic CRC cell line SW620. Cell proliferation, migration, invasion, and apoptosis were assayed. Xenograft mouse models were used to determine the role of lncRNA-SNHG7 in CRC in vivo. In addition, CNC analysis and competing endogenous analysis were used to detect differential SNHG7 and relational miRNAs expression in CRC cell lines.

Results

SNHG7 expression showed a high fold (SW620/SW480) in CRC microarrays. The CRC patients with high expression of SNHG7 had a significantly poor prognosis. Furthermore, SNHG7 promoted CRC cell proliferation, metastasis, mediated cell cycle, and inhibited apoptosis. SNHG7 and GALNT7 were observed for co-expression by CNC analysis, and a negative correlation of SNHG7 and miR-34a were found by competing endogenous RNA (ceRNA) analysis. Further results indicated that SNHG7 facilitated the proliferation and metastasis as a competing endogenous RNA to regulate GALNT7 expression by sponging miR-34a in CRC cell lines. SNHG7 also played the oncogenic role in regulating PI3K/Akt/mTOR pathway by competing endogenous miR-34a and GALNT7.

Conclusion

The CRC-related SNHG7 and miR-34a might be implicated in CRC progression via GALNT7, suggesting the potential usage of SNHG7/miR-34a/GALNT7 axis in CRC treatment.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0632-2) contains supplementary material, which is available to authorized users.

LncRNA SNHG7 sponges miR-216b to promote proliferation and liver metastasis of colorectal cancer through upregulating GALNT1

Accumulating evidence suggests long noncoding RNAs (lncRNAs) play an important role in cancer progression. However, the function of lncRNA SNHG7 in colorectal cancer (CRC) remains unclear. In this study, SNHG7 expression was significantly upregulated in CRC tissues, especially in aggressive cases. In accordance, high level of SNHG7 was observed in CRC cell lines compared to normal colon cells. Furthermore, SNHG7 overexpression promoted the proliferation, migration, and invasion of CRC cell lines, while SNHG7 depletion inhibited invasion and cell viability in vitro. Mechanistically, knockdown of SNHG7 inhibited GALNT1 and EMT markers (E-cadherin and Vimentin). Importantly, SNHG7 directly interacted with miR-216b and downregulation of miR-216b reversed efficiently the suppression of GALNT1 induced by SNHG7 siRNA. Moreover, overexpression of SNHG7 significantly enhanced the tumorigenesis and liver metastasis of SW480 cells in vivo. SNHG7 positively regulated GALNT1 level through sponging miR-216b, and played an oncogenic role in CRC progression. Together, our study elucidated the role of SNHG7 as an miRNA sponge in CRC, and shed new light on lncRNA-directed diagnostics and therapeutics in CRC.

N-acetylgalactosaminyltransferases in cancer

Aberrant mucin-type O-glycosylation by glycosyltransferases is a well-described hallmark of many cancers and is also associated with additional non-cancerous developmental and metabolic disorders. The current review focuses on N-acetylgalactosaminyltransferase genes (GALNTs) and proteins (GalNAcTs) to illustrate their importance in cancer biology. Aberrant O-glycosylation by GalNAcTs activates a wide range of proteins that carry out interactions of sessile and motile cells affecting organogenesis, responses to agonists and stimulating hyperproliferation and metastatisation of neoplastic cells. As genome-wide analyses have provided abundant clues regarding under- or over-expressed genes that characterize different types of cancers, GALNTs and their transferase products have attracted attention by being unexpected actors in neoplastic contexts. We intend to review the current knowledge on GALNTs and their encoded transferases in cancer and suggest what could be the significance of such information in cancer pathogenesis and management.

Simple sugars to complex disease--mucin-type O-glycans in cancer

Mucin-type O-glycans are a class of glycans initiated with N-acetylgalactosamine (GalNAc) α-linked primarily to Ser/Thr residues within glycoproteins and often extended or branched by sugars or saccharides. Most secretory and membrane-bound proteins receive this modification, which is important in regulating many biological processes. Alterations in mucin-type O-glycans have been described across tumor types and include expression of relatively small-sized, truncated O-glycans and altered terminal structures, both of which are associated with patient prognosis. New discoveries in the identity and expression of tumor-associated O-glycans are providing new avenues for tumor detection and treatment. This chapter describes mucin-type O-glycan biosynthesis, altered mucin-type O-glycans in primary tumors, including mechanisms for structural changes and contributions to the tumor phenotype, and clinical approaches to detect and target altered O-glycans for cancer treatment and management.

The Cosmc connection to the Tn antigen in cancer

The Tn antigen is a tumor-associated carbohydrate antigen that is not normally expressed in peripheral tissues or blood cells. Expression of this antigen, which is found in a majority of human carcinomas of all types, arises from a blockage in the normal O-glycosylation pathway in which glycans are extended from the common precursor GalNAcα1-O-Ser/Thr (Tn antigen). This precursor is generated in the Golgi apparatus on newly synthesized glycoproteins by a family of polypeptide α-N-acetylgalactosaminyltransferases (ppGalNAcTs) and then extended to the common core 1 O-glycan Galβ1-3GalNAcα1-O-Ser/Thr (T antigen) by a single enzyme termed the T-synthase (core 1 β3-galactosyltransferase or C1GalT). Formation of the active form of the T-synthase requires a unique molecular chaperone termed Cosmc, encoded by Cosmc on the X-chromosome (Xq24 in humans, Xc3 in mice). Cosmc resides in the endoplasmic reticulum (ER) and prevents misfolding, aggregation, and proteasome-dependent degradation of newly synthesized T-synthase. Loss of expression of active T-synthase or Cosmc can lead to expression of the Tn antigen, along with its sialylated version Sialyl Tn antigen as observed in several cancers. Both genetic and epigenetic pathways, in addition to potential metabolic regulation, can result in abnormal expression of the Tn antigen. Engineered expression of the Tn antigen by disruption of either C1GalT (T-syn) or Cosmc in mice is associated with a tremendous range of pathologies and engineered expression of the Tn antigen in mouse embryos leads to embryonic death. Studies indicate that many membrane glycoproteins expressing the Tn antigen and/or truncated O-glycans may be dysfunctional, due to degradation and/or misfolding. Thus, expression of normal O-glycans is associated with health and homeostasis whereas truncation of O-glycans, e.g. the Tn and/or Sialyl Tn antigens is associated with cancer and other pathologies.

Identification and expression analysis of zebrafish polypeptide α-N-acetylgalactosaminyltransferase Y-subfamily genes during embryonic development

Mucin-type glycosylation is one of the most common posttranslational modifications of secretory and membrane proteins and has diverse physiological functions. The initial biosynthesis of mucin-type carbohydrates is catalyzed by UDP-GalNAc: polypeptide α-N-acetylgalactosaminyltransferases (GalNAc-Ts) encoded by GALNT genes. Among these, GalNAc-T8, -T9, -T17, and -T18 form a characteristic subfamily called "Y-subfamily" and have no or very low in vitro transferase activities when assayed with typical mucin peptides as acceptor substrates. Although the Y-subfamily isozymes have been reported to be possibly involved in various diseases, their in vivo functions have not been reported. Here, we isolated zebrafish Y-subfamily galnt genes, and determined their spatial and temporal expressions during the early development of zebrafish. Our study demonstrated that all the Y-subfamily isozymes were well conserved in zebrafish with GalNAc-T18 having two orthologs, galnt18a and galnt18b, and with the other three isozymes each having a corresponding ortholog, galnt8, galnt9, and galnt17. The galnt8 was expressed in the cephalic mesoderm and hatching gland during early developmental stages, and differently expressed in the head, somatic muscles, and liver in the later stages. The other three orthologs also exhibited the characteristic expression patterns, although their expressions were generally strong in the nervous systems. In addition to the expression in the brain, galnt17 and galnt18a were expressed in the somitic muscles, and galnt18a and galnt18b in the notochord. These expression patterns may contribute to the functional analysis of the Y-subfamily, whose physiological roles still remain to be elucidated.

Genome-wide association study identifies new susceptibility loci for epithelial ovarian cancer in Han Chinese women

Ovarian cancer is the leading cause of death from gynaecological malignancies worldwide. Here we perform a three-stage genome-wide association study (GWAS) in Han Chinese women to identify risk genetic variants for epithelial ovarian cancer (EOC). We scan 900,015 single-nucleotide polymorphisms (SNPs) in 1,057 EOC cases and 1,191 controls in stage I, and replicate 41 SNPs (P(meta)<10(-4)) in 960 EOC cases and 1,799 controls (stage II), and an additional 492 EOC cases and 1,004 controls (stage III). Finally, we identify two EOC susceptibility loci at 9q22.33 (rs1413299 in COL15A1, P(meta) = 1.88 × 10(-8)) and 10p11.21 (rs1192691 near ANKRD30A, P(meta) = 2.62 × 10(-8)), and two consistently replicated loci at 12q14.2 (rs11175194 in SRGAP1, P(meta) = 1.14 × 10(-7)) and 9q34.2 (rs633862 near ABO and SURF6, P(meta) = 8.57 × 10(-7)) (P<0.05 in all three stages). These results may advance our understanding of genetic susceptibility to EOC.

First comprehensive in silico analysis of the functional and structural consequences of SNPs in human GalNAc-T1 gene

GalNAc-T1, a key candidate of GalNac-transferases genes family that is involved in mucin-type O-linked glycosylation pathway, is expressed in most biological tissues and cell types. Despite the reported association of GalNAc-T1 gene mutations with human disease susceptibility, the comprehensive computational analysis of coding, noncoding and regulatory SNPs, and their functional impacts on protein level, still remains unknown. Therefore, sequence- and structure-based computational tools were employed to screen the entire listed coding SNPs of GalNAc-T1 gene in order to identify and characterize them. Our concordant in silico analysis by SIFT, PolyPhen-2, PANTHER-cSNP, and SNPeffect tools, identified the potential nsSNPs (S143P, G258V, and Y414D variants) from 18 nsSNPs of GalNAc-T1. Additionally, 2 regulatory SNPs (rs72964406 and #x26; rs34304568) were also identified in GalNAc-T1 by using FastSNP tool. Using multiple computational approaches, we have systematically classified the functional mutations in regulatory and coding regions that can modify expression and function of GalNAc-T1 enzyme. These genetic variants can further assist in better understanding the wide range of disease susceptibility associated with the mucin-based cell signalling and pathogenic binding, and may help to develop novel therapeutic elements for associated diseases.

Polymorphisms of MUC16 (CA125) and MUC1 (CA15.3) in relation to ovarian cancer risk and survival

Objective

To examine single nucleotide polymorphism (SNPs) in MUC16 (CA125) and MUC1 (CA15.3) in relation to ovarian cancer risk and survival.

Methods

We genotyped germline variants of MUC16 (rs2547065, rs1559168, rs12984471, rs2121133) and MUC1 (rs2070803, rs4072037, rs1045253) using samples collected from 758 ovarian cancer cases and 788 controls enrolled in the New England Case-Control Study between 2003 and 2008. We calculated age-adjusted odds ratios (OR) and 95% confidence intervals (CIs) for disease risk using unconditional and polytomous logistic regression and hazard ratios (HR) for survival using Cox proportional hazard ratios. In a subset of cases, we compared log-normalized CA125 values by genotype using generalized linear models.

Results

Cases homozygous for the variant allele of MUC16 SNP, rs12984471, had poorer overall survival (log-rank p = 0.03) and higher CA125 levels, especially cases over age 65 (p = 0.01). For MUC1 SNP, rs4072037, women homozygous for the G variant had a non-significantly decreased risk for serous invasive types but elevated risk for serous borderline tumors, mucinous borderline and invasive tumors, and endometrioid tumors. Women with the variant allele of MUC16 SNP, rs2547065, especially those who were homozygous had an elevated risk for ovarian cancer; but this association was not confirmed in an independent dataset.

Conclusion

This targeted screen of seven polymorphisms of MUC16 and MUC1 genes failed to identify and confirm effects on ovarian cancer risk overall. However, there may be effects of MUC16 rs12984471 on survival and MUC1 rs4072037 on risk for histologic types of ovarian cancer other than invasive serous. Further study is warranted.

Clinically significant missense variants in human GALNT3, GALNT8, GALNT12, and GALNT13 genes: intriguing in silico findings

Aberrant glycosylation by N-acetylgalactosaminyl transferases (GALNTs) is a well-described pathological alteration that is widespread in hereditary diseases, prominently including human cancers, familial tumoral calcinosis and hyperostosis-hyperphosphatemia. In this study, we integrated different computational tools to perform the in silico analysis of clinically significant mutations (nsSNPs/single amino acid change) at both functional and structural levels, found in human GALNT3, GALNT8, GALNT12, and GALNT13 genes. From function and structure based insights, mutations encoding R162Q, T359K, C574G, G359D, R297W, D303N, Y396C, and D313N substitutions were concordantly predicted highly deleterious for relevant GALNTs proteins. From intriguing findings, T359K-GALNT3 was simulated with high contribution for disease susceptibility (tumor calcinosis) as compared to its partner variant T272K (Ichikawa et al. [2006] J. Clin. Endocrinol. Metab. 91:4472-4475). Similarly, the prediction of high damaging behavior, evolutionary conservation and structural destabilization for C574G were proposed as major contributing factors to regulate metabolic disorder underlying tumor calcinosis and hyperostosis-hyperphosphatemia syndrome. In case of R297W-GALNT12, prediction of highly deleterious effect and disruption in ionic interactions were anticipated with reduction in enzymatic activity, associated with bilateral breast cancer and primary colorectal cancers. The second GALNT12 mutation (D303N)-known splice variant-was predicted with disease severity as a result of decrease in charge density and buried behavior neighboring the catalytic B domain. In the lack of adequate in silico data about systematic characterization of clinically significant mutations in GALNTs genes, current study can be used as a significant tool to interpret the role of GALNTs reaction chemistry in disease-association risks in body.

Site-specific protein O-glycosylation modulates proprotein processing - deciphering specific functions of the large polypeptide GalNAc-transferase gene family

BACKGROUND

Posttranslational modifications (PTMs) greatly expand the function and regulation of proteins, and glycosylation is the most abundant and diverse PTM. Of the many different types of protein glycosylation, one is quite unique; GalNAc-type (or mucin-type) O-glycosylation, where biosynthesis is initiated in the Golgi by up to twenty distinct UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts). These GalNAc-Ts are differentially expressed in cells and have different (although partly overlapping) substrate specificities, which provide for both unique functions and considerable redundancy. Recently we have begun to uncover human diseases associated with deficiencies in GalNAc-T genes (GALNTs). Thus deficiencies in individual GALNTs produce cell and protein specific effects and subtle distinct phenotypes such as hyperphosphatemia with hyperostosis (GALNT3) and dysregulated lipid metabolism (GALNT2). These phenotypes appear to be caused by deficient site-specific O-glycosylation that co-regulates proprotein convertase (PC) processing of FGF23 and ANGPTL3, respectively.

SCOPE OF REVIEW

Here we summarize recent progress in uncovering the interplay between human O-glycosylation and protease regulated processing and describes other important functions of site-specific O-glycosylation in health and disease.

MAJOR CONCLUSIONS

Site-specific O-glycosylation modifies pro-protein processing and other proteolytic events such as ADAM processing and thus emerges as an important co-regulator of limited proteolytic processing events.

GENERAL SIGNIFICANCE

Our appreciation of this function may have been hampered by our sparse knowledge of the O-glycoproteome and in particular sites of O-glycosylation. New strategies for identification of O-glycoproteins have emerged and recently the concept of SimpleCells, i.e. human cell lines made deficient in O-glycan extension by zinc finger nuclease gene targeting, was introduced for broad O-glycoproteome analysis.

Mucin 21 in esophageal squamous epithelia and carcinomas: analysis with glycoform-specific monoclonal antibodies

Monoclonal antibodies (mAbs) against mucin 21 (MUC21), a human counterpart of mouse epiglycanin/Muc21, were prepared using human embryonic kidney 293 cells transfected with MUC21 as the immunogen. The specificity of these mAbs was examined by flow cytometry, immunoprecipitation and western blotting focusing on the differential glycosylation of MUC21 expressed in variant Chinese hamster ovary (CHO) cells (ldlD cells and Lec2 cells) and CHO-K1 cells. One of these mAbs, heM21D, bound to both the unmodified core polypeptide of MUC21 and MUC21 attached with N-acetylgalactosamine (Tn-MUC21). Six antibodies, including mAb heM21C, bound to MUC21 with Tn, T or sialyl-T epitopes but not the unmodified core polypeptide of MUC21. Esophageal squamous carcinomas and adjacent squamous epithelia were immunohistochemically examined for the binding of these mAbs. MUC21 was expressed in esophageal squamous epithelial cells, and its O-glycan extended forms were observed in the luminal portions of squamous epithelia. As revealed by the binding of mAb heM21D and the absence of reactivity with mAb heM21C, esophageal squamous carcinoma cells produce MUC21 without the attachment of O-glycans. This is the first report to show that there is a change in the glycoform of MUC21 that can be used to differentiate between squamous epithelia and squamous carcinoma of the esophagus. Thus, these antibodies represent a useful tool to characterize squamous epithelial differentiation and carcinogenesis.

Role of common genetic variants in ovarian cancer susceptibility and outcome: progress to date from the Ovarian Cancer Association Consortium (OCAC)

In this article, we review the current knowledge of the inherited genetics of epithelial ovarian cancer (EOC) susceptibility and clinical outcome. We focus on recent developments in identifying low-penetrance susceptibility genes and the role of the Ovarian Cancer Association Consortium (OCAC) in these discoveries. The OCAC was established to facilitate large-scale replication analyses for reported genetic associations for EOC. Since its inception, the OCAC has conducted both candidate gene and genome-wide association studies (GWAS); the latter has identified six established loci for EOC susceptibility, most of which showed stronger association with the serous histological subtype. Future GWAS and sequencing studies are likely to result in the discovery of additional susceptibility loci and may result in established associations with clinical outcome. Additional rare and uncommon ovarian cancer loci will likely be uncovered from high-throughput next-generation sequencing studies. Applying these novel findings to establish improved preventative and clinical intervention strategies will be one of the major challenges of future work.

Polypeptide N-acetylgalactosaminyltransferase 6 expression in pancreatic cancer is an independent prognostic factor indicating better overall survival

BACKGROUND

The family of polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts) is responsible for the altered glycosylation in cancer. The purpose of our study was to investigate the clinical significance of two isoforms, GalNAc-T6 and -T3, and their correlation with the prognosis of pancreatic cancer.

METHODS

Immunohistochemistry was used to analyse GalNAc-T6 and -T3 expressions in 70 clinicopathologically characterised pancreatic cancer cases.

RESULTS

Positive expressions of GalNAc-T6 and -T3 were immunohistochemically identified in 51% (36 of 70) and in 77% (54 of 70) of patients, respectively. A close relationship was noted between GalNAc-T6 positive expression and pathological well/moderate differentiated type (P=0.001), small tumour size (P=0.044), absence of vascular invasion (P=0.009), and low stage of the American Joint Committee on Cancer systems (P=0.043). The expression of GalNAc-T3 significantly correlated with good differentiation (P=0.001), but not with other clinicopathologic features. Furthermore, univariate and multivariate analyses revealed that GalNAc-T6 expression was an independent prognosis indicator for the disease, whereas GalNAc-T3 expression had no impact on clinical outcome, even though 33 of 36 GalNAc-T6-positive cases also had a positive expression of GalNAc-T3 (P=0.001, r=0.356).

CONCLUSION

Both GalNAc-T6 and -T3 expressions correlated significantly with tumour differentiation, whereas only GalNAc-T6 expression predicted prognosis in pancreatic cancer.

A polymorphism in the GALNT2 gene and ovarian cancer risk in four population based case-control studies

Recent epidemiologic evidence supports a role for MUC1 in ovarian carcinogenesis; therefore, we hypothesized that common genetic variation in the genes responsible for glycosylation of MUC1 may influence ovarian cancer risk. In a genome-wide association study of ovarian cancer, we observed an association between a non-synonymous SNP (rs2271077) in the UDP-N-acetyl-alpha-d-galactosamine: polypeptide N-acetylgalactosainyltransferase 2 (GALNT2) gene and ovarian cancer risk (p=0.005). We sought to validate the association in four population based ovarian cancer case-control studies collaborating through the Ovarian Cancer Association Consortium. Although rs2271077 was associated with a significantly increased risk (Odds Ratio (OR) = 1.37, 95% Confidence Interval (CI) = 1.06-1.77) in one study with 961 cases and 922 controls, we observed no association in the remaining three studies including 1452 cases and 1954 controls (OR=0.83, 95% CI= 0.66-1.04). Therefore, there appears to be no strong evidence of association between GALNT2 SNP rs2271077 and ovarian cancer risk.