RESUMEN

Placental abnormalities cause impaired fetal growth and poor pregnancy outcome (e.g. preeclampsia [PE]) with long-lasting consequences for the mother and offspring. The molecular dialogue between the maternal niche and the developing placenta is critical for the function of this organ. Galectin-1 (gal-1), a highly expressed glycan-binding protein at the maternal-fetal interface, orchestrates the maternal adaptation to pregnancy and placenta development. Down-regulation or deficiency of gal-1 during pregnancy is associated with the development of PE; however, the maternal- and placental-derived gal-1 contributions to the disease onset are largely unknown. We demonstrate that lack of gal-1 imposes a risk for PE development in a niche-specific manner, and this is accompanied by a placental dysfunction highly influenced by the absence of maternal-derived gal-1. Notably, differential placental glycosylation through the Sda-capped N-glycans dominates the invasive trophoblast capacity triggered by maternal-derived gal-1. Our findings show that gal-1 derived from the maternal niche is essential for healthy placenta development and indicate that impairment of the gal-1 signaling pathway within the maternal niche could be a molecular cause for maternal cardiovascular maladaptation during pregnancy.

RESUMEN

The structure Siaα2,3(GalNAcß1,4)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(GalNAcß1,4)Galß1,4Glc-Cer]. The Sda synthase ß1,4 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 Siaα2,3Galß1,3/4(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.

Asunto(s)

Antígenos de Grupos Sanguíneos , Neoplasias del Colon , Humanos , Antígenos del Grupo Sanguíneo de Lewis , Fucosiltransferasas/metabolismo , Neoplasias del Colon/patología

RESUMEN

Terminal carbohydrate structures are particularly relevant in oncology because they can serve as cancer markers and alter the phenotype of cancer cells. The Sda antigen and the sialyl Lewisx and sialyl Lewisa (sLex and sLea) antigens are terminal structures whose biosynthesis is mutually exclusive. In this review, we describe the main features of the Sda antigen in cancer and its relationship with sLex/a antigens. Information was obtained from an extensive literature search and from The Cancer Genome Atlas (TCGA) public database. The Sda 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 sLea/sLex and reduced malignancy and stemness in cells constitutively expressing sLex/a antigens. However, consistent effects were observed upon B4GALNT2 forced expression and in cells not expressing sLex/a antigens. Thus, B4GALNT2 and the Sda antigen exert a tumor-restraining activity in CRC and probably other gastrointestinal cancers, independently of sLex/a antigens.

RESUMEN

BACKGROUND: glycosyltransferase B4GALNT2 and its cognate carbohydrate antigen Sda 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.

Asunto(s)

Neoplasias Colorrectales/enzimología , Regulación Neoplásica de la Expresión Génica , MicroARNs/metabolismo , N-Acetilgalactosaminiltransferasas/genética , Biomarcadores de Tumor , Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/metabolismo , Metilación de ADN , Epigénesis Genética , Glicosiltransferasas/genética , Humanos , Pronóstico

RESUMEN

BACKGROUND: The Sda 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 (sLex) antigen in normal and cancerous colon is mediated by fucosyltransferase 6 (FUT6) and is mutually exclusive from that of Sda. It is thought that the reduced malignancy associated with high B4GALNT2 was due to sLex 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 sLex or the Sda antigens. Transfectants were analyzed for growth in poor adherence, wound healing, stemness and gene expression profile. RESULTS: B4GALNT2/Sda expression down-regulated all malignancy-associated phenotypes in SW620 but only those associated with stemness in SW480. FUT6/sLex 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/Sda inhibits the stemness-associated malignant phenotype, independently of sLex inhibition. The impact of glycosyltransferases on the phenotype and the transcriptome is highly cell-line specific.

Asunto(s)

Neoplasias del Colon/metabolismo , N-Acetilgalactosaminiltransferasas/metabolismo , Antígeno Sialil Lewis X/metabolismo , Línea Celular , Línea Celular Tumoral , Neoplasias del Colon/genética , Fucosiltransferasas/genética , Fucosiltransferasas/metabolismo , Glicosiltransferasas/metabolismo , Humanos , Antígeno Lewis X/metabolismo , N-Acetilgalactosaminiltransferasas/genética , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/fisiología , Oligosacáridos/genética , Oligosacáridos/inmunología , Oligosacáridos/metabolismo , Antígeno Sialil Lewis X/fisiología , Transfección , Células Tumorales Cultivadas

RESUMEN

Rat small intestinal goblet cell mucins reacting with monoclonal antibody HCM31 increase significantly during regeneration from experimental mucosal damage and at the period of expulsion of parasitic nematode, Nippostrongylus brasiliensis (N.b). The reduction in reactivity of HCM31 with mucin upon neuraminidase treatment, suggested that HCM31 recognizes sialylated oligosaccharide on mucin. HCM31-reactive sialomucins are therefore considered to play an important role in the physiological and pathological changes in the gastrointestinal mucosa. To determine the epitope for HCM31, oligosaccharide-alditols reacted with HCM31 were obtained from the small intestinal mucins of N.b-infected rats and purified by ion-exchange chromatography followed by normal-phase HPLC. Two HCM31-reactive oligosaccharide-alditols were obtained. Analyses using tandem mass spectrometry and NMR spectroscopy showed that these oligosaccharides were core 4 mucin-type oligosaccharides having a common tetrasaccharide sequence, NeuAcα2-3(GalNAcß1-4)Galß1-4GlcNAcß- (Sd(a) blood group antigen). These structures were not found in the small intestinal mucin oligosaccharides from uninfected rats. This epitope specificity of HCM31 was also confirmed using previously established anti-GM2 and anti-Sd(a) antibodies. Taken together, these results strongly suggest that HCM31 specifically recognizes mucin-type oligosaccharides with the Sd(a) tetrasaccharide sequence. Immunohistochemical examination of human gastrointestinal tracts showed that HCM31 site-specifically stained the goblet cells in normal sigmoid colon and normal rectum, but the goblet cells stained with HCM31 were reduced in the corresponding cancer tissues. HCM31 seems to be useful for diagnosis of colonic cancer and for examining the function of secretory-type mucin with Sd(a) antigen.