Small Molecule Targets TMED9 and Promotes Lysosomal Degradation to Reverse Proteinopathy.

Intracellular accumulation of misfolded proteins causes toxic proteinopathies, diseases without targeted therapies. Mucin 1 kidney disease (MKD) results from a frameshift mutation in the MUC1 gene (MUC1-fs). Here, we show that MKD is a toxic proteinopathy. Intracellular MUC1-fs accumulation activated the ATF6 unfolded protein response (UPR) branch. We identified BRD4780, a small molecule that clears MUC1-fs from patient cells, from kidneys of knockin mice and from patient kidney organoids. MUC1-fs is trapped in TMED9 cargo receptor-containing vesicles of the early secretory pathway. BRD4780 binds TMED9, releases MUC1-fs, and re-routes it for lysosomal degradation, an effect phenocopied by TMED9 deletion. Our findings reveal BRD4780 as a promising lead for the treatment of MKD and other toxic proteinopathies. Generally, we elucidate a novel mechanism for the entrapment of misfolded proteins by cargo receptors and a strategy for their release and anterograde trafficking to the lysosome.

Mucins and Their Role in Shaping the Functions of Mucus Barriers.

We review what is currently understood about how the structure of the primary solid component of mucus, the glycoprotein mucin, gives rise to the mechanical and biochemical properties of mucus that are required for it to perform its diverse physiological roles. Macroscale processes such as lubrication require mucus of a certain stiffness and spinnability, which are set by structural features of the mucin network, including the identity and density of cross-links and the degree of glycosylation. At the microscale, these same features affect the mechanical environment experienced by small particles and play a crucial role in establishing an interaction-based filter. Finally, mucin glycans are critical for regulating microbial interactions, serving as receptor binding sites for adhesion, as nutrient sources, and as environmental signals. We conclude by discussing how these structural principles can be used in the design of synthetic mucin-mimetic materials and provide suggestions for directions of future work in this field.

The mucin MUC1 modulates the tumor immunological microenvironment through engagement of the lectin Siglec-9.

Siglec-9 is a sialic-acid-binding lectin expressed predominantly on myeloid cells. Aberrant glycosylation occurs in essentially all types of cancers and results in increased sialylation. Thus, when the mucin MUC1 is expressed on cancer cells, it is decorated by multiple short, sialylated O-linked glycans (MUC1-ST). Here we found that this cancer-specific MUC1 glycoform, through engagement of Siglec-9, 'educated' myeloid cells to release factors associated with determination of the tumor microenvironment and disease progression. Moreover, MUC1-ST induced macrophages to display a tumor-associated macrophage (TAM)-like phenotype, with increased expression of the checkpoint ligand PD-L1. Binding of MUC1-ST to Siglec-9 did not activate the phosphatases SHP-1 or SHP-2 but, unexpectedly, induced calcium flux that led to activation of the kinases MEK-ERK. This work defines a critical role for aberrantly glycosylated MUC1 and identifies an activating pathway that follows engagement of Siglec-9.

Whole-genome sequencing reveals host factors underlying critical COVID-19.

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2-4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes-including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)-in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease.

The MUC1-HIF-1α signaling axis regulates pancreatic cancer pathogenesis through polyamine metabolism remodeling.

Dysregulation of polyamine metabolism has been implicated in cancer initiation and progression; however, the mechanism of polyamine dysregulation in cancer is not fully understood. In this study, we investigated the role of MUC1, a mucin protein overexpressed in pancreatic cancer, in regulating polyamine metabolism. Utilizing pancreatic cancer patient data, we noted a positive correlation between MUC1 expression and the expression of key polyamine metabolism pathway genes. Functional studies revealed that knockdown of spermidine/spermine N1-acetyltransferase 1 (SAT1), a key enzyme involved in polyamine catabolism, attenuated the oncogenic functions of MUC1, including cell survival and proliferation. We further identified a regulatory axis whereby MUC1 stabilized hypoxia-inducible factor (HIF-1α), leading to increased SAT1 expression, which in turn induced carbon flux into the tricarboxylic acid cycle. MUC1-mediated stabilization of HIF-1α enhanced the promoter occupancy of the latter on SAT1 promoter and corresponding transcriptional activation of SAT1, which could be abrogated by pharmacological inhibition of HIF-1α or CRISPR/Cas9-mediated knockout of HIF1A. MUC1 knockdown caused a significant reduction in the levels of SAT1-generated metabolites, N1-acetylspermidine and N8-acetylspermidine. Given the known role of MUC1 in therapy resistance, we also investigated whether inhibiting SAT1 would enhance the efficacy of FOLFIRINOX chemotherapy. By utilizing organoid and orthotopic pancreatic cancer mouse models, we observed that targeting SAT1 with pentamidine improved the efficacy of FOLFIRINOX, suggesting that the combination may represent a promising therapeutic strategy against pancreatic cancer. This study provides insights into the interplay between MUC1 and polyamine metabolism, offering potential avenues for the development of treatments against pancreatic cancer.

Cancer-stromal cell interactions in breast cancer brain metastases induce glycocalyx-mediated resistance to HER2-targeting therapies.

Brain metastatic breast cancer is particularly lethal largely due to therapeutic resistance. Almost half of the patients with metastatic HER2-positive breast cancer develop brain metastases, representing a major clinical challenge. We previously described that cancer-associated fibroblasts are an important source of resistance in primary tumors. Here, we report that breast cancer brain metastasis stromal cell interactions in 3D cocultures induce therapeutic resistance to HER2-targeting agents, particularly to the small molecule inhibitor of HER2/EGFR neratinib. We investigated the underlying mechanisms using a synthetic Notch reporter system enabling the sorting of cancer cells that directly interact with stromal cells. We identified mucins and bulky glycoprotein synthesis as top-up-regulated genes and pathways by comparing the gene expression and chromatin profiles of stroma-contact and no-contact cancer cells before and after neratinib treatment. Glycoprotein gene signatures were also enriched in human brain metastases compared to primary tumors. We confirmed increased glycocalyx surrounding cocultures by immunofluorescence and showed that mucinase treatment increased sensitivity to neratinib by enabling a more efficient inhibition of EGFR/HER2 signaling in cancer cells. Overexpression of truncated MUC1 lacking the intracellular domain as a model of increased glycocalyx-induced resistance to neratinib both in cell culture and in experimental brain metastases in immunodeficient mice. Our results highlight the importance of glycoproteins as a resistance mechanism to HER2-targeting therapies in breast cancer brain metastases.

Characterization of human tibrovirus envelope glycoproteins.

Tibroviruses are novel rhabdoviruses detected in humans, cattle, and arthropods. Four tibroviruses are known to infect humans: Bas-Congo virus (BASV), Ekpoma virus 1 (EKV-1), Ekpoma virus 2, and Mundri virus. However, since none of them has been isolated, their biological properties are largely unknown. We aimed to characterize the human tibrovirus glycoprotein (G), which likely plays a pivotal role in viral tropism and pathogenicity. Human tibrovirus Gs were found to share some primary structures and display 14 conserved cysteine residues, although their overall amino acid homology was low (29%-48%). Multiple potential glycosylation sites were found on the G molecules, and endoglycosidase H- and peptide-N-glycosidase F-sensitive glycosylation was confirmed. AlphaFold-predicted three-dimensional (3D) structures of human tibrovirus Gs were overall similar. Membrane fusion mediated by these tibrovirus Gs was induced by acidic pH. The low pH-induced conformational change that triggers fusion was reversible. Virus-like particles (VLPs) were produced by transient expression of Gs in cultured cells and used to produce mouse antisera. Using vesicular stomatitis Indiana virus pseudotyped with Gs, we found that the antisera to the respective tibrovirus VLPs showed limited cross-neutralizing activity. It was also found that human C-type lectins and T-cell immunoglobulin mucin 1 acted as attachment factors for G-mediated entry into cells. Interestingly, BASV-G showed the highest ability to utilize these molecules. The viruses infected a wide range of cell lines with preferential tropism for human-derived cells whereas the preference of EKV-1 was unique compared with the other human tibroviruses. These findings provide fundamental information to understand the biological properties of the human tibroviruses. IMPORTANCE: Human tibroviruses are poorly characterized emerging rhabdoviruses associated with either asymptomatic infection or severe disease with a case fatality rate as high as 60% in humans. However, the extent and burden of human infection as well as factors behind differences in infection outcomes are largely unknown. In this study, we characterized human tibrovirus glycoproteins, which play a key role in virus-host interactions, mainly focusing on their structural and antigenic differences and cellular tropism. Our results provide critical information for understanding the biological properties of these novel viruses and for developing appropriate preparedness interventions such as diagnostic tools, vaccines, and effective therapies.

Targeting of Tumor-Associated Glycoforms of MUC1 with CAR T Cells.

We read with interest the manuscript by June and colleagues published recently in Immunity in which they describe targeting of aberrantly glycosylated tumor-associated cell membrane mucin MUC1 using chimeric antigen receptor-engineered human T cells (Posey et al., 2016). In that study, the authors used a second generation 4-1BB costimulatory-molecule-based chimeric antigen receptor (CAR) (Imai et al., 2004) in which targeting was achieved using a single-chain variable fragment (scFv) derived from the 5E5 antibody. This CAR selectively binds MUC1 that carries the Tn or sialyl (S)Tn glycan. Both of these truncated glycans are aberrantly expressed on the MUC1 glycoprotein in a spectrum of malignancies and consequently represent attractive targets for immunotherapeutic exploitation.

Engineered CAR T Cells Targeting the Cancer-Associated Tn-Glycoform of the Membrane Mucin MUC1 Control Adenocarcinoma.

Genetically modified T cells expressing chimeric antigen receptors (CARs) demonstrate robust responses against lineage restricted, non-essential targets in hematologic cancers. However, in solid tumors, the full potential of CAR T cell therapy is limited by the availability of cell surface antigens with sufficient cancer-specific expression. The majority of CAR targets have been normal self-antigens on dispensable hematopoietic tissues or overexpressed shared antigens. Here, we established that abnormal self-antigens can serve as targets for tumor rejection. We developed a CAR that recognized cancer-associated Tn glycoform of MUC1, a neoantigen expressed in a variety of cancers. Anti-Tn-MUC1 CAR T cells demonstrated target-specific cytotoxicity and successfully controlled tumor growth in xenograft models of T cell leukemia and pancreatic cancer. These findings demonstrate the therapeutic efficacy of CAR T cells directed against Tn-MUC1 and present aberrantly glycosylated antigens as a novel class of targets for tumor therapy with engineered T cells.

Overcoming effector T cell exhaustion in ovarian cancer ascites with a novel adenovirus encoding for a MUC1 bispecific antibody engager and IL-2 cytokine.

T cell-focused cancer immunotherapy including checkpoint inhibitors and cell therapies has been rapidly evolving over the past decade. Nevertheless, there remains a major unmet medical need in oncology generally and immuno-oncology specifically. We have constructed an oncolytic adenovirus, Ad5/3-E2F-d24-aMUC1aCD3-IL-2 (TILT-322), which is armed with a human aMUC1aCD3 T cell engager and IL-2. TILT-322 treatment stimulated T cell cytotoxicity through the increased presence of granzyme B, perforin, and interferon-gamma. Additional immune profiling indicated TILT-322 increased gamma delta T cell activation and impacted other cell types such as natural killer cells and natural killer-like T cells that are traditionally involved in cancer immunotherapy. TILT-322 treatment also decreased the proportion of exhausted CD8+ T cells as demarked by immune checkpoint expression in ovarian ascites samples. Overall, our data showed that TILT-322 treatment led to an enhanced T cell activation and reversed T cell exhaustion translating into high antitumor efficacy when given locally or intravenously. The analysis of blood and tumors isolated from an in vivo patient-derived ovarian cancer xenograft model suggested TILT-322 mediated tumor control through improved T cell functions. Therefore, TILT-322 is a promising novel anti-tumor agent for clinical translation.

Helical self-assembly of a mucin segment suggests an evolutionary origin for von Willebrand factor tubules.

The glycoprotein von Willebrand factor (VWF) contributes to hemostasis by stanching injuries in blood vessel walls. A distinctive feature of VWF is its assembly into long, helical tubules in endothelial cells prior to secretion. When VWF is released into the bloodstream, these tubules unfurl to release linear polymers that bind subendothelial collagen at wound sites, recruit platelets, and initiate the clotting cascade. VWF evolved from gel-forming mucins, the polymeric glycoproteins that coat and protect exposed epithelia. Despite the divergent function of VWF in blood vessel repair, sequence conservation and shared domain organization imply that VWF retained key aspects of the mucin bioassembly mechanism. Here, we show using cryo-electron microscopy that the ability to form tubules, a property hitherto thought to have arisen as a VWF adaptation to the vasculature, is a feature of the amino-terminal region of mucin. This segment of the human intestinal gel-forming mucin (MUC2) was found to self-assemble into tubules with a striking resemblance to those of VWF itself. To facilitate a comparison, we determined the residue-resolution structure of tubules formed by the homologous segment of VWF. The structures of the MUC2 and VWF tubules revealed the flexible joints and the intermolecular interactions required for tubule formation. Steric constraints in full-length MUC2 suggest that linear filaments, a previously observed supramolecular assembly form, are more likely than tubules to be the physiological mucin storage intermediate. Nevertheless, MUC2 tubules indicate a possible evolutionary origin for VWF tubules and elucidate design principles present in mucins and VWF.

Influence of glycoprotein MUC1 on trafficking of the Ca2+-selective ion channels, TRPV5 and TRPV6, and on in vivo calcium homeostasis.

Polymorphism of the gene encoding mucin 1 (MUC1) is associated with skeletal and dental phenotypes in human genomic studies. Animals lacking MUC1 exhibit mild reduction in bone density. These phenotypes could be a consequence of modulation of bodily Ca homeostasis by MUC1, as suggested by the previous observation that MUC1 enhances cell surface expression of the Ca2+-selective channel, TRPV5, in cultured unpolarized cells. Using biotinylation of cell surface proteins, we asked whether MUC1 influences endocytosis of TRPV5 and another Ca2+-selective TRP channel, TRPV6, in cultured polarized epithelial cells. Our results indicate that MUC1 reduces endocytosis of both channels, enhancing cell surface expression. Further, we found that mice lacking MUC1 lose apical localization of TRPV5 and TRPV6 in the renal tubular and duodenal epithelium. Females, but not males, lacking MUC1 exhibit reduced blood Ca2+. However, mice lacking MUC1 exhibited no differences in basal urinary Ca excretion or Ca retention in response to PTH receptor signaling, suggesting compensation by transport mechanisms independent of TRPV5 and TRPV6. Finally, humans with autosomal dominant tubulointerstitial kidney disease due to frame-shift mutation of MUC1 (ADTKD-MUC1) exhibit reduced plasma Ca concentrations compared to control individuals with mutations in the gene encoding uromodulin (ADTKD-UMOD), consistent with MUC1 haploinsufficiency causing reduced bodily Ca2+. In summary, our results provide further insight into the role of MUC1 in Ca2+-selective TRP channel endocytosis and the overall effects on Ca concentrations.

Research progress of KL-6 in respiratory system diseases.

This article comprehensively elucidates the discovery of Krebs von den Lungen-6 (KL-6), its structural features, functional mechanisms, and the current research status in various respiratory system diseases. Discovered in 1985, KL-6 was initially considered a tumor marker, but its elevated levels in interstitial lung disease (ILD) led to its recognition as a relevant serum marker for ILD. KL-6 is primarily produced by type 2 alveolar epithelial cell regeneration. Over the past 30 years since the discovery of KL-6, the number of related research papers has steadily increased annually. Following the coronavirus disease 2019 (COVID-19) pandemic, there has been a sudden surge in relevant literature. Despite KL-6's potential as a biomarker, its value in the diagnosis, treatment, and prognosis varies across different respiratory diseases, including ILD, idiopathic pulmonary fibrosis (IPF), COVID-19, and lung cancer. Therefore, as an important serum biomarker in respiratory system diseases, the value of KL-6 still requires further investigation.

A Portable Device for in Situ Noninvasive Monitoring of Cell Secretions and Communications with Fluorescence and Nanochannel Electrochemistry.

In situ monitoring of cell secretions and communications plays a fundamental role in screening of disease diagnostic biomarkers and drugs. Quantitative detection of cell secretions and monitoring of intercellular communication have been separately reported, which often rely on target labeling or complex pretreatment steps, inevitably causing damage to the target. Simultaneous in situ noninvasive detection of cell secretions and monitoring of intercellular communication are challenging and have never been reported. Herein, we smartly developed a portable device for in situ label-free monitoring of cell secretions and communications with fluorescence and ion-transport-based nanochannel electrochemistry. Based on the dual signal mode, a series of nonelectroactive secretions were sensitively and accurately quantified. The detection limits for VEGF, MUC1, and ATP were 3.84 pg/mL, 32.7 pg/mL, and 47.4 fM (3σ/S), which were 1/3.9, 1/1.1, and 1/41 of those of commercial ELISA kits, respectively. More interestingly, under the released secretions, the gradual opening of the nanochannel connected the two cells in the left and right chambers of the device; thus, the secretion mediated intercellular communication can be monitored. The proposed platform may provide a promising tool for understanding the mechanism of intercellular communication and discovering new therapeutic targets.

DNA Walker-Driven Mass Nanotag Assembly System for Simultaneously Profiling Dual Markers of Oxidative Stress at Different Cellular Locations.

Simultaneous profiling of redox-regulated markers at different cellular sublocations is of great significance for unraveling the upstream and downstream molecular mechanisms of oxidative stress in living cells. Herein, by synchronizing dual target-triggered DNA machineries in one nanoentity, we engineered a DNA walker-driven mass nanotag (MNT) assembly system (w-MNT-AS) that can be sequentially activated by oxidative stress-associated mucin 1 (MUC1) and apurinic/apyrimidinic endonuclease 1 (APE1) from plasma membrane to cytoplasm and induce recycled assembly of MNTs for multiplex detection of the two markers by matrix-assisted laser desorption ionization mass spectrometry (MALDI MS). In the working cascade, the sensing process governs the separate activation of w-MNT-AS by MUC1 and APE1 in diverse locations, while the assembly process contributes to the parallel amplification of the ion signal of the characteristic mass tags. In this manner, the differences between MCF-7, HeLa, HepG2, and L02 cells in membrane MUC1 expression and cytoplasmic APE1 activation were fully characterized. Furthermore, the oxidative stress level and dynamics caused by exogenous H2O2, doxorubicin, and simvastatin were comprehensively demonstrated by tracking the fate of the two markers across different cellular locations. The proposed w-MNT-AS coupled MS method provides an effective route to probe multiple functional molecules that lie at different locations while participating in the same cellular event, facilitating the mechanistic studies on cellular response to oxidative stress and other disease-related cellular processes.

Target-Triggered Aggregation of Modified E. coli for Diagnosis of Ovarian Cancer.

Bacteria inherently possess the capability of quorum sensing in response to the environment. In this work, we have proposed a strategy to confer bacteria with the ability to recognize targets with quorum-sensing behavior. Meanwhile, we have successfully achieved artificial control over the target-triggered aggregation of Escherichia coli (E. coli) by modifying the bacteria surface in a new way. Furthermore, by making use of green fluorescent protein (GFP) expressed by E. coli as the output signal, the aggregation of modified E. coli can be observed with the naked eye. Therefore, via the detection of the target, MUC1, an ovarian cancer biomarker, a simple and conveniently operated method to diagnose ovarian cancer is developed in this work. Experimental results show that the developed low-background and enzyme-free amplification method enables the highly sensitive detection of MUC1, achieving a remarkable limit of detection (LOD) of 5.47 fM and a linear detection range spanning from 1 pM to 50 nM and 50 nM to 100 nM, respectively. Clinical samples from healthy donors and patients can give distant assay results, showing great potential for clinical applications of this method.

Versatile Metal-Organic Framework Incorporating Ag2S for Constructing a Photoelectrochemical Immunosensor for Two Breast Cancer Markers.

Breast cancer poses the significance of early diagnosis and treatment. Here, we developed an innovative photoelectrochemical (PEC) immunosensor characterized by high-level dual photocurrent signals and exceptional sensitivity. The PEC sensor, denoted as MIL&Ag2S, was constructed by incorporating Ag2S into a metal-organic framework of MIL-101(Cr). This composite not only enhanced electron-hole separation and conductivity but also yielded robust and stable dual photocurrent signals. Through the implementation of signal switching, we achieved the combined detection of cancer antigen 15-3 (CA15-3) and carcinoembryonic antigen (CEA) with outstanding stability, reproducibility, and specificity. The results revealed a linear range for CEA detection spanning 0.01-32 ng/mL, with a remarkably low detection limit of 0.0023 ng/mL. Similarly, for CA15-3 detection, the linear range extended from 0.1 to 320 U/mL, with a low detection limit of 0.014 U/mL. The proposed strategy introduces new avenues for the development of highly efficient, cost-effective, and user-friendly PEC sensors. Furthermore, it holds promising prospects for early clinical diagnosis, contributing to potential breakthroughs in medical detection and ultimately improving patient outcomes.

Intelligent Cell Profiling and Precision Release: Multimolecular Marker-Activated Transmembrane DNA Computing Nanosystem.

Accurate classification of tumor cells is of importance for cancer diagnosis and further therapy. In this study, we develop multimolecular marker-activated transmembrane DNA computing systems (MTD). Employing the cell membrane as a native gate, the MTD system enables direct signal output following simple spatial events of "transmembrane" and "in-cell target encounter", bypassing the need of multistep signal conversion. The MTD system comprises two intelligent nanorobots capable of independently sensing three molecular markers (MUC1, EpCAM, and miR-21), resulting in comprehensive analysis. Our AND-AND logic-gated system (MTDAND-AND) demonstrates exceptional specificity, allowing targeted release of drug-DNA specifically in MCF-7 cells. Furthermore, the transformed OR-AND logic-gated system (MTDOR-AND) exhibits broader adaptability, facilitating the release of drug-DNA in three positive cancer cell lines (MCF-7, HeLa, and HepG2). Importantly, MTDAND-AND and MTDOR-AND, while possessing distinct personalized therapeutic potential, share the ability of outputting three imaging signals without any intermediate conversion steps. This feature ensures precise classification cross diverse cells (MCF-7, HeLa, HepG2, and MCF-10A), even in mixed populations. This study provides a straightforward yet effective solution to augment the versatility and precision of DNA computing systems, advancing their potential applications in biomedical diagnostic and therapeutic research.

TRPV4 activation in human corneal epithelial cells promotes membrane mucin production.

Given that the corneal epithelium is situated on the outermost part of the eye, its functions can be influenced by external temperatures and chemical substances. This study aimed to elucidate the expression profile of chemosensory receptors in corneal epithelial cells and analyze their role in eye function regulation. A comprehensive analysis of 425 chemosensory receptors in human corneal epithelial cells-transformed (HCE-T) revealed the functional expression of TRPV4. The activation of TRPV4 in HCE-T cells significantly increased the expression of membrane-associated mucins MUC1, MUC4, and MUC16, which are crucial for stabilizing tear films, with efficacy comparable to the active components of dry eye medications. The present study suggests that TRPV4, which is activated by body temperature, regulates mucin expression and proposes it as a novel target for dry eye treatment.

C1GALT1-mediated O-glycan T antigen increase enhances the migration and invasion ability of gastric cancer cells.

Gastric cancer (GC) is one of the most aggressive and lethal diseases in the world. Cancer metastasis is the mainly leading cause of death in GC patients. Aberrant Protein O-glycosylation is closely associated with tumor occurrence and metastasis. However, the effect of aberrant O-glycosylation on the progress of GC is not completely clear. This study aimed to investigate the biological function and its underlying effects mechanism of core 1 ß 1, 3-galactosyltransferase 1 (C1GALT1) C1GALT1-mediated O-glycan T antigen on GC progress. We conducted data mining analysis that C1GALT1 was obviously up-regulated in GC tissues than in para-carcinoma tissues. Elevated expression of C1GALT1 was closely associated with advanced TNM stage, lymph node metastasis, histological grade, and poor overall survival. In addition, C1GALT1 overexpression could promote GC cell proliferation, migration, and invasion, which was due to C1GALT1 overexpression-mediated O-glycan T antigen increase. Moreover, MUC1 was predicted to be a new downstream target of C1GALT1, which may be abnormally O-glycosylated by C1GALT1 thereby activating the cell adhesion signaling pathway. In conclusion, our studies proved that C1GALT1-mediated O-glycosylation increase could promote the metastasis of gastric cancer cells. These discoveries hint that C1GALT1 may serve as a novel therapeutic target for GC treatment.