High Expression of the Sda Synthase B4GALNT2 Associates with Good Prognosis and Attenuates Stemness in Colon Cancer

Transcription factor FOXD1 and miRNA-204-5p play a major role in B4GALNT2 downregulation in colon cancer

The β1,4-N-acetylgalactosaminyltransferase 2 (B4GALNT2) which synthesizes the histo-blood group antigen Sda is highly expressed by normal colon, but it is dramatically down-regulated in colorectal cancer (CRC). High B4GALNT2 expression in CRC tissues is a marker of longer survival. The molecular bases of B4GALNT2 inhibition in CRC are largely obscure. A key role may be played by transcription factors and miRNA. Through an in silico analysis of The Cancer Genome Atlas and of the Cancer Cell Line Encyclopedia, we identified the transcription factors FOXD1, FOXF2 and PGR as well as mir-204-5p as potential inhibitory agents. Their transient transfection in the cell line GP2d, whose B4GALNT2 is closer to that of a normal mucosa, confirmed their inhibitory activity with a crucial role for FOXD1. The latter inhibited B4GALNT2 also in the middle B4GALNT2 expresser cell line Caco2. Deletion experiments of the putative FOXD1 binding sites in the ~ 2800 bp sequence upstream of the B4GALNT2 transcriptional start site cloned in frame with the luciferase reporter gene, confirmed the regulatory role of FOXD1. Finally, FOXD1 knock down in the non-B4GALNT2 expresser cell line SW948 stimulated B4GALNT2. Thus, FOXD1 and miR-204-5p emerged as crucial new player of B4GALNT2 down-regulation in CRC.

Guanylate cyclase-C Signaling Axis as a theragnostic target in colorectal cancer: a systematic review of literature

Introduction

Colorectal cancer (CRC) is a devastating disease that affects millions of people worldwide. Recent research has highlighted the crucial role of the guanylate cyclase-C (GC-C) signaling axis in CRC, from the early stages of tumorigenesis to disease progression. GC-C is activated by endogenous peptides guanylin (GU) and uroguanylin (UG), which are critical in maintaining intestinal fluid homeostasis. However, it has been found that these peptides may also contribute to the development of CRC. This systematic review focuses on the latest research on the GC-C signaling axis in CRC.

Methods

According to the aim of the study, a systematic literature search was conducted on Medline and PubMed databases. Ultimately, a total of 40 articles were gathered for the systematic review.

Results

Our systematic literature search revealed that alterations in GC-C signaling compartments in CRC tissue have demonstrated potential as diagnostic, prognostic, and therapeutic markers. This research highlights a potential treatment for CRC by targeting the GC-C signaling axis. Promising results from recent studies have explored the use of this signaling axis to develop new vaccines and chimeric antigen receptors that may be used in future clinical trials.

Conclusion

The findings presented in this review provide compelling evidence that targeting the GC-C signaling axis may be an advantageous approach for treating CRC.

The story of the Sda antigen and of its cognate enzyme B4GALNT2: What is new?

The structure Siaα2,3(GalNAcβ1,4)Gal- is the epitope of the Sda antigen, which is expressed on the erythrocytes and secretions of the vast majority of Caucasians, carried by N- and O-linked chains of glycoproteins, as well as by glycolipids. Sda is very similar, but not identical, to ganglioside GM2 [Siaα2,3(GalNAcβ1,4)Galβ1,4Glc-Cer]. The Sda synthase β1,4 N-acetylgalactosaminyl transferase 2 (B4GALNT2) exists in a short and a long form, diverging in the aminoterminal domain. The latter has a very long cytoplasmic tail and displays a Golgi- as well as a post-Golgi localization. The biosynthesis of Sda is mutually exclusive with that of the cancer-associated sialyl Lewis antigens, whose structure is Siaα2,3Galβ1,3/4(Fucα1,4/3)GlcNAc-. B4GALNT2 is down-regulated in colon cancer but patients with higher expression survive longer. In experimental systems, B4GALNT2 inhibits colon cancer progression,not only through inhibition of sialyl Lewis antigen biosynthesis. By contrast, in breast cancer B4GALNT2 is associated with malignancy. In colon cancer, the B4GALNT2 gene is regulated by multiple mechanisms, which include miRNA and transcription factor expression, as well as CpG methylation. In addition, Sda/B4GALNT2 regulates the susceptibility to infectious agents, the protection from muscle dystrophy, the activity of immune system in pregnancy and the immune rejection in xenotransplantation.

Specific (sialyl-)Lewis core 2 O-glycans differentiate colorectal cancer from healthy colon epithelium

Cells are covered with a dense layer of carbohydrates, some of which are solely present on neoplastic cells. The so-called tumor-associated carbohydrate antigens (TACAs) are increasingly recognized as promising targets for immunotherapy. These carbohydrates differ from those of the surrounding non-cancerous tissues and contribute to the malignant phenotype of the cancer cells by promoting proliferation, metastasis, and immunosuppression. However, due to tumor tissue heterogeneity and technological limitations, TACAs are insufficiently explored. Methods: A workflow was established to decode the colorectal cancer (CRC)-associated O-linked glycans from approximately 20,000 cell extracts. Extracts were obtained through laser capture microdissection of formalin fixed paraffin embedded tissues of both primary tumors and metastatic sites, and compared to healthy colon mucosa from the same patients. The released O-glycans were analyzed by porous graphitized carbon liquid chromatography-tandem mass spectrometry in negative ion mode. Results: Distinctive O-glycosylation features were found in cancerous, stromal and normal colon mucosal regions. Over 100 O-linked glycans were detected in cancerous regions with absence in normal mucosa. From those, six core 2 O-glycans were exclusively found in more than 33% of the cancers, carrying the terminal (sialyl-)LewisX/A antigen. Moreover, two O-glycans were present in 72% of the analyzed cancers and 94% of the investigated cancers expressed at least one of these two O-glycans. In contrast, normal colon mucosa predominantly expressed core 3 O-glycans, carrying α2-6-linked sialylation, (sulfo-)LewisX/A and Sda antigens. Conclusion: In this study, we present a novel panel of highly specific TACAs, based upon differences in the glycomic profiles between CRC and healthy colon mucosa. These TACAs are promising new targets for development of innovative cancer immune target therapies and lay the foundation for the targeted treatment of CRC.

Glycosyltransferases in Cancer: Prognostic Biomarkers of Survival in Patient Cohorts and Impact on Malignancy in Experimental Models

Background: Glycosylation changes are a main feature of cancer. Some carbohydrate epitopes and expression levels of glycosyltransferases have been used or proposed as prognostic markers, while many experimental works have investigated the role of glycosyltransferases in malignancy. Using the transcriptomic data of the 21 TCGA cohorts, we correlated the expression level of 114 glycosyltransferases with the overall survival of patients. Methods: Using the Oncolnc website, we determined the Kaplan−Meier survival curves for the patients falling in the 15% upper or lower percentile of mRNA expression of each glycosyltransferase. Results: Seventeen glycosyltransferases involved in initial steps of N- or O-glycosylation and of glycolipid biosynthesis, in chain extension and sialylation were unequivocally associated with bad prognosis in a majority of cohorts. Four glycosyltransferases were associated with good prognosis. Other glycosyltransferases displayed an extremely high predictive value in only one or a few cohorts. The top were GALNT3, ALG6 and B3GNT7, which displayed a p < 1 × 10−9 in the low-grade glioma (LGG) cohort. Comparison with published experimental data points to ALG3, GALNT2, B4GALNT1, POFUT1, B4GALT5, B3GNT5 and ST3GAL2 as the most consistently malignancy-associated enzymes. Conclusions: We identified several cancer-associated glycosyltransferases as potential prognostic markers and therapeutic targets.

Adaptation of the Golgi Apparatus in Cancer Cell Invasion and Metastasis

The Golgi apparatus plays a central role in normal cell physiology by promoting cell survival, facilitating proliferation, and enabling cell-cell communication and migration. These roles are partially mediated by well-known Golgi functions, including post-translational modifications, lipid biosynthesis, intracellular trafficking, and protein secretion. In addition, accumulating evidence indicates that the Golgi plays a critical role in sensing and integrating external and internal cues to promote cellular homeostasis. Indeed, the unique structure of the mammalian Golgi can be fine-tuned to adapt different Golgi functions to specific cellular needs. This is particularly relevant in the context of cancer, where unrestrained proliferation and aberrant survival and migration increase the demands in Golgi functions, as well as the need for Golgi-dependent sensing and adaptation to intrinsic and extrinsic stressors. Here, we review and discuss current understanding of how the structure and function of the Golgi apparatus is influenced by oncogenic transformation, and how this adaptation may facilitate cancer cell invasion and metastasis.

B4GALNT2 Controls Sda and SLex Antigen Biosynthesis in Healthy and Cancer Human Colon

The Sd^a carbohydrate antigen and the corresponding biosynthetic enzyme B4GALNT2 are primarily expressed in human normal colonic mucosa and are down‐regulated to variable degrees in colon cancer. On the other hand, the tumor associated antigen SLe^x is not detected in the healthy colon and is upregulated in colon cancer. High level of B4GALNT2 gene expression appears to be a good marker of prognosis in colon cancer; however, the molecular mechanisms regulating these carbohydrate antigens’ expression are still poorly understood. We review here the most recent progress made towards understanding this balanced expression of blood group carbohydrate epitopes Sd^a and SLe^x. In particular in recent years, we have attained a better understanding of genetic and epigenetic regulation of the B4GALNT2 gene and of the subcellular fate of B4GALNT2 isoforms.

Analysis of the proximal promoter of the human colon-specific B4GALNT2 (Sda synthase) gene: B4GALNT2 is transcriptionally regulated by ETS1

BACKGROUND

The Sda antigen and corresponding biosynthetic enzyme B4GALNT2 are primarily expressed in normal colonic mucosa and are down-regulated to a variable degree in colon cancer tissues. Although their expression profile is well studied, little is known about the underlying regulatory mechanisms.

METHODS

To clarify the molecular basis of Sda expression in the human gastrointestinal tract, we investigated the transcriptional regulation of the human B4GALNT2 gene. The proximal promoter region was delineated using luciferase assays and essential trans-acting factors were identified through transient overexpression and silencing of several transcription factors.

RESULTS

A short cis-regulatory region restricted to the -72 to +12 area upstream of the B4GALNT2 short-type transcript variant contained the essential promoter activity that drives the expression of the human B4GALNT2 regardless of the cell type. We further showed that B4GALNT2 transcriptional activation mostly requires ETS1 and to a lesser extent SP1.

CONCLUSIONS

Results presented herein are expected to provide clues to better understand B4GALNT2 regulatory mechanisms.

The Cancer-Associated Antigens Sialyl Lewisa/x and Sda: Two Opposite Faces of Terminal Glycosylation

Simple Summary

The glycosyltransferase β1,4-N-acetylgalactosaminyltransferae 2 (B4GALNT2), product of the B4GALNT2 gene is responsible for the biosynthesis of the carbohydrate antigen Sd^a. Both the enzyme and its cognate antigen display a restricted pattern of tissue expression and modulation in colorectal, gastric, and mammary cancers. In colorectal cancer, B4GALNT2 is generally downregulated, but patients displaying higher expression survive longer. The sialyl Lewis^a and sialyl Lewis^x antigens are associated with malignancy. Their biosynthesis and that of Sd^a are mutually exclusive. Forced expression of B4GALNT2 in colorectal cancer cell lines modulates the transcriptome towards lower malignancy, reducing stemness. These effects are independent of B4GALNT2-induced sLe^a/sLe^x inhibition. Thus, B4GALNT2 is a marker of better prognosis and a cancer-restraining enzyme in colorectal cancer, with a therapeutic potential.

Abstract

Terminal carbohydrate structures are particularly relevant in oncology because they can serve as cancer markers and alter the phenotype of cancer cells. The Sd^a antigen and the sialyl Lewis^x and sialyl Lewis^a (sLe^x and sLe^a) antigens are terminal structures whose biosynthesis is mutually exclusive. In this review, we describe the main features of the Sd^a antigen in cancer and its relationship with sLe^x/a antigens. Information was obtained from an extensive literature search and from The Cancer Genome Atlas (TCGA) public database. The Sd^a biosynthetic enzyme B4GALNT2 undergoes downregulation in colorectal (CRC) and stomach cancer, while it is ectopically expressed by a minority of breast cancer (BRCA) patients. High expression of B4GALNT2 is associated with better prognosis and a less malignant gene expression profile in CRC, while the opposite occurs in BRCA. The regulation of B4GALNT2 expression in CRC is multifactorial, involving gene methylation and miRNA expression. Forced expression of B4GALNT2 inhibited sLe^a/sLe^x and reduced malignancy and stemness in cells constitutively expressing sLe^x/a antigens. However, consistent effects were observed upon B4GALNT2 forced expression and in cells not expressing sLe^x/a antigens. Thus, B4GALNT2 and the Sd^a antigen exert a tumor-restraining activity in CRC and probably other gastrointestinal cancers, independently of sLe^x/a antigens.

B4GALNT2 Gene Promotes Proliferation, and Invasiveness and Migration Abilities of Model Triple Negative Breast Cancer (TNBC) Cells by Interacting With HLA-B Protein

B4GALNT2 gene encodes the enzyme β1,4-N-acetylgalactosaminyltransferase 2 that biosynthesizes the histo-blood group antigen Sda, which is expressed on the surface of erythrocytes and in body secretions. Analysis of The Cancer Genome Atlas (TCGA) database revealed that this gene was highly expressed in breast cancer tissues in comparison with adjacent healthy ones. In-vitro lentivirus-assisted B4GALNT2 gene knockdown experiments in model triple negative breast cancer (TNBC) cell lines (HCC1937 and MDA-MB-231) showed inhibition in cell proliferation, decrease in cell viability, promotion of cell apoptosis and inhibitions in cell migration and invasiveness abilities in comparison with empty lentivirus transfectant controls. Also, in cell cycle tests, the number of cells in the G1 phase increased, in the S phase decreased and did not change in the G2/M phase (indicative of the presence of a block in the G1 phase). In-vivo tumor formation experiments in mice revealed that knockdown of the B4GALNT2 gene in MDA-MB-231 cells inhibited their proliferation. Using co-immunoprecipitation (Co-IP) mass spectroscopy-assisted analysis, it was found that HLA-B protein [a product of the human leukocyte antigen (HLA) class I gene] interacts with B4GALNT2 protein. In-vitro overexpression of HLA-B in B4GALNT2-knocked down MDA-MB-231 cell lines significantly recovered the cell proliferation, viability and migration ability of B4GALNT2 gene. These indicate that HLA-B is one of the interaction proteins in the downstream pathway of the B4GALNT2 gene.

Comparative Gene Signature of (-)-Oleocanthal Formulation Treatments in Heterogeneous Triple Negative Breast Tumor Models: Oncological Therapeutic Target Insights

Triple negative breast cancer (TNBC) heterogeneity and limited therapeutic options confer its phenotypic aggressiveness. The discovery of anti-TNBC natural products with valid molecular target(s) and defined pharmacodynamic profile would facilitate their therapeutic nutraceutical use by TNBC patients. The extra-virgin olive oil (EVOO) is a key Mediterranean diet ingredient. S-(−)-Oleocanthal (OC) leads the bioactive anti-tumor EVOO phenolic ingredients. A previous study reported the solid dispersion formulated OC with (+)-xylitol (OC-X) suppressed the in vivo progression and recurrence of the TNBC MDA-MB-231 cells. This study investigates the ability of OC-X formulation to suppress the in vivo heterogeneous BC initiation and progression utilizing advanced preclinical transgenic MMTV-PyVT and TNBC PDX mouse models. Furthermore, the clustering of the gene expression profiles in MMTV-PyVT and PDX mouse tumors treated with OC-X acquired by a Clariom S microarray analysis identified the distinctly affected genes. Several affected novel signature genes identified in response to OC-X treatments and proved overlapped in both mouse and human tumor models, shedding some lights toward understanding the OC anticancer molecular mechanism and assisting in predicting prospective clinical outcomes. This study provides molecular and preclinical evidences of OC-X potential as a nutraceutical suppressing heterogeneous TNBC model and offers preliminary gene-level therapeutic mechanistic insights.

Glycosyltransferase B4GALNT2 as a Predictor of Good Prognosis in Colon Cancer: Lessons from Databases

BACKGROUND

glycosyltransferase B4GALNT2 and its cognate carbohydrate antigen Sd^a are highly expressed in normal colon but strongly downregulated in colorectal carcinoma (CRC). We previously showed that CRC patients expressing higher B4GALNT2 mRNA levels displayed longer survival. Forced B4GALNT2 expression reduced the malignancy and stemness of colon cancer cells.

METHODS

Kaplan-Meier survival curves were determined in "The Cancer Genome Atlas" (TCGA) COAD cohort for several glycosyltransferases, oncogenes, and tumor suppressor genes. Whole expression data of coding genes as well as miRNA and methylation data for B4GALNT2 were downloaded from TCGA.

RESULTS

the prognostic potential of B4GALNT2 was the best among the glycosyltransferases tested and better than that of many oncogenes and tumor suppressor genes; high B4GALNT2 expression was associated with a lower malignancy gene expression profile; differential methylation of an intronic B4GALNT2 gene position and miR-204-5p expression play major roles in B4GALNT2 regulation.

CONCLUSIONS

high B4GALNT2 expression is a strong predictor of good prognosis in CRC as a part of a wider molecular signature that includes ZG16, ITLN1, BEST2, and GUCA2B. Differential DNA methylation and miRNA expression contribute to regulating B4GALNT2 expression during colorectal carcinogenesis.

The role of the blood group-related glycosyltransferases FUT2 and B4GALNT2 in susceptibility to infectious disease

The glycosylation profile of the gastrointestinal tract is an important factor mediating host-microbe interactions. Variation in these glycan structures is often mediated by blood group-related glycosyltransferases, and can lead to wide-ranging differences in susceptibility to both infectious- as well as chronic disease. In this review, we focus on the interplay between host glycosylation, the intestinal microbiota and susceptibility to gastrointestinal pathogens based on studies of two exemplary blood group-related glycosyltransferases that are conserved between mice and humans, namely FUT2 and B4GALNT2. We highlight that differences in susceptibility can arise due to both changes in direct interactions, such as bacterial adhesion, as well as indirect effects mediated by the intestinal microbiota. Although a large body of experimental work exists for direct interactions between host and pathogen, determining the more complex and variable mechanisms underlying three-way interactions involving the intestinal microbiota will be the subject of much-needed future research.

The Sda Synthase B4GALNT2 Reduces Malignancy and Stemness in Colon Cancer Cell Lines Independently of Sialyl Lewis X Inhibition

Background: The Sd^a antigen and its biosynthetic enzyme B4GALNT2 are highly expressed in healthy colon but undergo a variable down-regulation in colon cancer. The biosynthesis of the malignancy-associated sialyl Lewis x (sLe^x) antigen in normal and cancerous colon is mediated by fucosyltransferase 6 (FUT6) and is mutually exclusive from that of Sd^a. It is thought that the reduced malignancy associated with high B4GALNT2 was due to sLe^x inhibition. Methods: We transfected the cell lines SW480 and SW620, derived respectively from a primary tumor and a metastasis of the same patient, with the cDNAs of FUT6 or B4GALNT2, generating cell variants expressing either the sLe^x or the Sd^a antigens. Transfectants were analyzed for growth in poor adherence, wound healing, stemness and gene expression profile. Results: B4GALNT2/Sd^a expression down-regulated all malignancy-associated phenotypes in SW620 but only those associated with stemness in SW480. FUT6/sLe^x enhanced some malignancy-associated phenotypes in SW620, but had little effect in SW480. The impact on the transcriptome was stronger for FUT6 than for B4GALNT2 and only partially overlapping between SW480 and SW620. Conclusions: B4GALNT2/Sd^a inhibits the stemness-associated malignant phenotype, independently of sLe^x inhibition. The impact of glycosyltransferases on the phenotype and the transcriptome is highly cell-line specific.