Demethylation of the Cosmc Promoter Alleviates the Progression of Breast Cancer Through Downregulation of the Tn and Sialyl-Tn Antigens

Emerging Roles of the Unique Molecular Chaperone Cosmc in the Regulation of Health and Disease

The core-1 β1-3galactosyltransferase-specific chaperone 1 (Cosmc) is a unique molecular chaperone of core-1 β1-3galactosyltransferase(C1GALT1), which typically functions inside the endoplasmic reticulum (ER). Cosmc helps C1GALT1 to fold correctly and maintain activity. It also participates in the synthesis of the T antigen, O-glycan, together with C1GALT1. Cosmc is a multifaceted molecule with a wide range of roles and functions. It involves platelet production and the regulation of immune cell function. Besides that, the loss of function of Cosmc also facilitates the development of several diseases, such as inflammation diseases, immune-mediated diseases, and cancer. It suggests that Cosmc is a critical control point in diseases and that it should be regarded as a potential target for oncotherapy. It is essential to fully comprehend Cosmc's roles, as they may provide critical information about its involvement in disease development and pathogenesis. In this review, we summarize the recent progress in understanding the role of Cosmc in normal development and diseases.

Golgi Apparatus Regulates Plasma Membrane Composition and Function

Golgi apparatus is the central component of the mammalian secretory pathway and it regulates the biosynthesis of the plasma membrane through three distinct but interacting processes: (a) processing of protein and lipid cargoes; (b) creation of a sharp transition in membrane lipid composition by non-vesicular transport of lipids; and (c) vesicular sorting of proteins and lipids at the trans-Golgi network to target them to appropriate compartments. We discuss the molecules involved in these processes and their importance in physiology and development. We also discuss how mutations in these molecules affect plasma membrane composition and signaling leading to genetic diseases and cancer.

Expression and Impact of C1GalT1 in Cancer Development and Progression

Simple Summary

C1GalT1 is one of the enzymes that catalyze the addition of sugar residues to proteins (protein glycosylation). It specifically controls the synthesis and formation of a special disaccharide structure Galβ1,3GalNAcα-, which occurs predominately in cancer but rarely in normal cells. Recent studies have shown that C1GalT1 is overexpressed in many common cancers including colon, breast, gastric, lung, head and neck, pancreatic, esophageal, prostate, and hepatocellular cancer. C1GalT1 overexpression is also often associated with poorer prognosis and poorer patient survival. This review summarizes our current understanding of the expression of C1GalT1 in various cancers and discusses the impact of C1GalT change on cancer cell activities in cancer development and progression.

Abstract

C1GalT1 (T-synthase) is one of the key glycosyltransferases in the biosynthesis of O-linked mucin-type glycans of glycoproteins. It controls the formation of Core-1 disaccharide Galβ1,3GalNAcα- (Thomsen–Friedenreich oncofetal antigen, T or TF antigen) and Core-1-associated carbohydrate structures. Recent studies have shown that C1GalT1 is overexpressed in many cancers of epithelial origin including colon, breast, gastric, head and neck, pancreatic, esophageal, prostate, and hepatocellular cancer. Overexpression of C1GalT1 is often seen to also be associated with poorer prognosis and poorer patient survival. Change of C1GalT1 expression causes glycosylation changes of many cell membrane glycoproteins including mucin proteins, growth factor receptors, adhesion molecules, and death receptors. This leads to alteration of the interactions of these cell surface molecules with their binding ligands, resulting in changes of cancer cell activity and behaviors. This review summarizes our current understanding of the expression of C1GalT1 in various cancers and discusses the impact of C1GalT change on cancer cell activities in cancer development and progression.

Cosmc transfection decreases malignant behavior of Tn+ cells and enhances sensitivity to apoptosis when induced by Apo2L/TRAIL via alteration of O-glycan structure

Cosmc mutations may cause abnormal O-glycosylation and result in Tn antigen expression. In the current study, it was discovered that proliferation and migration of Tn+ cells (Jurkat T and LS174T-Tn⁺ cells) with mutant Cosmc decreased after transfected Cosmc, and their sensitivity to apoptosis induced by Apo2L/TRAIL increased. Core 1-, 2-, and 3-derived O-glycans were absent in Tn⁺ cells. After Cosmc transfection, normal extended core 1-derived O-glycans appeared and were accompanied by increased T-synthase activity. Core 2-derived O-glycans appeared in transfected LS174T-Tn⁺ cells, and their structural types and levels were lower than those in LS174T-Tn⁻ cells. Core 3-derived O-glycans were present only in LS174T-Tn⁻ cells. The activity of C3GnT in LS174T-Tn⁺ cells was lower than that in LS174T-Tn⁻ cells, and it was absent in Jurkat T cells. Cosmc transfection did not alter C3GnT activity or core 3-derived O-glycans in Jurkat T and LS174T-Tn⁺ cells. The results demonstrated that the composition and structure of O-glycans were different among various Tn⁺ cells, which not only affected cell malignant behavior but also modulated sensitivity to apoptotic stimuli. Thus, Cosmc transfection may effectively decrease the malignant behavior of Tn⁺ tumor cells and enhance their sensitivity to apoptosis when induced by Apo2L/TRAIL through modification of O-glycans.

Mucin-type sialyl-Tn antigen is associated with PD-L1 expression and predicts poor clinical prognosis in breast cancer

Background

A recent study showed that mucin-type sialylated O-linked glycans could induce the increased expression of PD-L1 via binding to Siglec receptors. However, the relationship between the expression of the mucin-type sialyl-Tn antigen (sTn) and PD-L1 remains unclear in breast cancer (BC). Therefore, we investigate the clinicopathological and prognostic effects of sTn expression and its relationship with PD-L1 expression in BC tissues.

Methods

We retrospectively analyzed the clinical data of 380 invasive BC patients between January 2011 and January 2014. The last follow-up time was January 31, 2019 with a median follow-up of 62 months. The expression of the sTn antigen and PD-L1 in 380 tumor specimens was assessed by immunohistochemistry. Correlations between sTn/PD-L1 expression and clinicopathological features and prognoses were analyzed.

Results

In BC tissues, the positive expression rate of PD-L1 (20.5%) was much lower than that of sTn (41.8%). Pearson's contingency analysis showed that sTn and PD-L1 expression in tumor tissues demonstrated a high correlation (P<0.001). High sTn expression was associated with negative ER expression (P<0.001), positive HER-2 status (P<0.001), advanced tumor stage (P<0.001), high density of CD8+ tumor-infiltrating lymphocytes (TILs) (P=0.028), and positive lymph node metastasis (P=0.002). Moreover, patients with concomitant high expression of both markers had the highest risk of relapse (P<0.001) and mortality (P<0.001). The multivariate Cox regression model revealed that positive sTn expression (HRos: 1.941, 95% CI: 1.168, 3.223, Pos=0.028; HRpfs: 1.739, 95% CI: 1.063, 2.847, Ppfs=0.010) and positive PD-L1 expression (HRos: 1.912, 95% CI: 1.138, 3.212, Pos=0.017; HRpfs: 1.863, 95% CI: 1.116, 3.110, Ppfs=0.014) were independent indicators for poor overall survival (OS) and progression-free survival (PFS), respectively.

Conclusions

BC patients who expressed both sTn and PD-L1 had poorer survival. Therefore, combinational therapy with dual blockade might benefit BC patients with sTn(+)/PD-L1(+) expression, which requires further examination in future clinical trials.

Epigenetic Regulation of Glycosylation in Cancer and Other Diseases

In the last few decades, the newly emerging field of epigenetic regulation of glycosylation acquired more importance because it is unraveling physiological and pathological mechanisms related to glycan functions. Glycosylation is a complex process in which proteins and lipids are modified by the attachment of monosaccharides. The main actors in this kind of modification are the glycoenzymes, which are translated from glycosylation-related genes (or glycogenes). The expression of glycogenes is regulated by transcription factors and epigenetic mechanisms (mainly DNA methylation, histone acetylation and noncoding RNAs). This review focuses only on these last ones, in relation to cancer and other diseases, such as inflammatory bowel disease and IgA1 nephropathy. In fact, it is clear that a deeper knowledge in the fine-tuning of glycogenes is essential for acquiring new insights in the glycan field, especially if this could be useful for finding novel and personalized therapeutics.

Diagnostic value of sialyl-Tn immunocytochemistry in breast cancer presenting with pathological nipple discharge

Background

Mucin‐associated sialyl‐Tn (sTn) antigen is overexpressed and related with adverse outcome in breast cancer (BC). The role of sTn in BC has not been well defined in pathological nipple discharge (PND) cytology. The authors examined sTn immunocytochemistry (ICC) in PND to determine whether it could be a biomarker of malignancy or aggressive disease.

Methods

PND was subjected to immunocytochemical staining for sTn antigen expression and thinprep cytology test (TCT) for enhancing the sensitivity and specificity. The examination data was compared with histological findings of subsequent biopsy specimens. Logistic regression analysis was used to determine which factors were most associated with malignant breast lesions.

Results

PND specimens were collected including 120 cases of intraductal papilloma, 24 cases of hyperplasia, 45 cases of ductal carcinoma in situ (DCIS), and 48 cases of invasive ductal carcinoma (IDC). STn ICC differentiated BC from benign intraductal lesions with a low sensitivity of 41.9% and a high specificity of 95.8%, but increased in combination with TCT to 64.5% and 100%, respectively. A high degree of concordance was observed between the results of sTn expression in cell smears and histological specimens. Moreover, the sTn expression was strongly associated with HER2‐positive IDC (p = 0.039). Multivariate logistic analysis showed that positive sTn expression (OR: 14.241, 95%CI: 2.574, 78.794, p = 0.010) and accompanying mass (OR: 3.307, 95%CI: 1.073, 10.188, p = 0.037) were statistically significant independent risk factors for malignant PND.

Conclusions

Mucin‐associated sTn expression in PND cytology appears to be a reliable diagnostic marker for BC patients with the chief complaint of malignant nipple discharge and indicates a more aggressive behavior in IDC.