The extended cytoplasmic tail of the human B4GALNT2 is critical for its Golgi targeting and post‐Golgi sorting

Ferreira

Orlandani

et al. 2020

Cells

Background: The carbohydrate antigen Sda and its biosynthetic enzyme B4GALNT2 are highly expressed in normal colonic mucosa but are down-regulated to a variable degree in colon cancer tissues. Here, we investigated the clinical and biological importance of B4GALNT2 in colon cancer. Methods: Correlations of B4GALNT2 mRNA with clinical data were obtained from The Cancer Genome Atlas (TCGA) database; the phenotypic and transcriptomic changes induced by B4GALNT2 were studied in LS174T cells transfected with B4GALNT2 cDNA. Results: TCGA data indicate that patients with high B4GALNT2 expression in cancer tissues display longer survival than non-expressers. In LS174T cells, expression of B4GALNT2 did not affect the ability to heal a scratch wound or to form colonies in standard growth conditions but markedly reduced the growth in soft agar, the tridimensional (3D) growth as spheroids, and the number of cancer stem cells, indicating a specific effect of B4GALNT2 on the growth in poor adherence and stemness. On the transcriptome, B4GALNT2 induced the down-regulation of the stemness-associated gene SOX2 and modulated gene expression towards an attenuation of the cancer phenotype. Conclusions: The level of B4GALNT2 can be proposed as a marker to identify higher- and lower-risk colorectal cancer patients.

Section: Introductionmentioning

confidence: 99%

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

Ferreira

Orlandani

et al. 2020

Cells

“…Both transcripts contain a translational start site from which two different transmembrane polypeptides originate: the one referred to as “long form” contains an exceptionally long cytoplasmic tail, while the one referred to as “short form” contains a cytoplasmic domain of conventional length [ 15 , 16 ]. Both forms localize mainly in the Golgi, although the long form exhibits also post-Golgi localizations [ 20 ]. B4GALNT2 is expressed at a very high level in normal colon but undergoes a dramatic down-regulation in CRC [ 21 , 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

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

Ferreira

Malagolini

et al. 2020

IJMS

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.

“…Both isoforms display Golgi localization, although the long form is present also in post-Golgi vesicles and the plasma membrane [ 25 ]. The short form appears to be enzymatically more active than the long form [ 26 ] and is by far the dominant form in both normal and cancer colon [ 27 ].…”

Section: The Sd a Antigen: Structure And Biosynthesismentioning

confidence: 99%

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

Dall’Olio

Malagolini

2021

Cancers

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.