Melanoma-associated glycosyltransferase GCNT2 as an emerging biomarker and therapeutic target

Integrated transcriptome analysis and combinatorial machine learning to construct a homeostatic model of acetylation for ccRCC and validate the key gene GCNT4

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is one of the most common malignant tumors of the urinary system. Protein acetylation plays a key role in regulating cellular processes and cancer signaling pathways. This study explores the potential biological mechanisms of ccRCC from the perspective of acetylation.

METHODS

This study obtained RNA-seq data and clinical information of ccRCC from TCGA and ICGC, and single-cell RNA sequencing datasets from the GEO database. Ten machine learning algorithms and their 101 combinations were used to analyze the prognostic significance of acetylation-related differentially expressed genes (DEGs) and to construct a prognostic risk model. GSEA was used to analyze the enrichment of different signaling pathways in high-risk and low-risk groups, and the correlation between immune infiltration and risk scores was assessed. Finally, the function of the key gene GCNT4 was verified through cell experiments.

RESULTS

This study identified 84 acetylation-regulated key genes with significant expression differences between tumor and normal tissues, closely linked to patient prognosis. The LASSO + RSF combination model performed best, and the model could accurately predict patient prognosis. The survival of patients in the high-risk group was significantly worse than that in the low-risk group. High expression of GCNT4 was associated with better survival prognosis and was expressed at higher levels in normal tissues than tumor tissues. Overexpression of GCNT4 significantly inhibited the proliferation, invasion, and migration of renal cancer cells and may affect acetylation by regulating the levels of O-GlcNAc modification in cells.

CONCLUSION

This study constructed a ccRCC acetylation homeostasis model via transcriptome analysis and machine learning, validating GCNT4 as a key gene. High expression of GCNT4 is associated with better survival prognosis and affects acetylation by regulating O-GlcNAc modification levels, inhibiting the proliferation and migration of renal cancer cells, providing a new potential target for the treatment of ccRCC.

Sialyltransferase-related genes as predictive factors for therapeutic response and prognosis in cervical cancer

Background

Cancer-associated hypersialylation is believed to be related to the metastatic cell phenotype and the suppression of sialyltransferases (SiaTs) has been suggested to be a potent preventive strategy against metastasis. The present research discovered SiaTs-related genes for cervical cancer (CC).

Methods

The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were applied to obtain the relevant samples. Mutation dataset were processed using mutect2 software. The gene modules were obtained via weighted gene co-expression network analysis (WGCNA), and the enrichment analysis on the genes within the modules was implemented. Cox regression analysis and "glmnet" R package were applied to establish the relevant risk model. "MCPcounter" R package, ESTIMATE algorithm and TIMER online tools were used to depict the tumor immune microenvironment in CC. The mutation landscape was additionally plotted, and the response to immunotherapy in different cohorts were compared. Further reverse-transcription quantitative PCR and Transwell assays were performed to verify the expression and potential function of the screened key genes.

Results

Mutation of 14 SiaTs was seen in CC. Subsequently, WGCNA-based identification of SiaTs-related gene modules was significantly enriched in metabolism-related pathways. The established RiskScore model manifested excellent prognostic classification efficiency. A poorer prognosis and occurrence of both immune evasion and reduced immunoreactivity may be seen in high-risk patients yet relatively higher immune cell scores were noticeable in low-risk patients. Angiogenesis and MYC target V2 may be the differentially activated pathways in high-risk patients, while those in low-risk patients were KRAS Signaling DN and Interferon alpha response. In addition, most immune checkpoint-correlated genes were identified to express higher in low-risk patients, while higher sensitivities to chemotherapy drugs was discovered in high-risk patients. Cellular assays have revealed that KCNK15, LIF, TCN2, SERPINF2, and CXCL3 were highly expressed yet PIH1D2, DTX1 and GCNT2 were low-expressed in Hela cells and that silencing CXCL3 diminished the number of migrated and invaded Hela cells.

Conclusion

In this study, we systematically constructed and validated a risk scoring model based on SiaTs-related genes, which can effectively predict the prognosis and potential response to immunotherapy and chemotherapy in CC patients. This provides a new molecular basis and clinical reference for achieving individualized treatment.

Melanoma Glycome Regulates the Pro-Oncogenic Properties of Extracellular Galectin-3

Metastatic melanoma is an aggressive skin cancer with a five-year survival rate of only 35%. Despite recent advances in immunotherapy, there is still an urgent need for the development of innovative therapeutic approaches to improve clinical outcomes of patients with metastatic melanoma. Prior research from our laboratory revealed that loss of the I-branching enzyme β1,6 N-acetylglucosaminyltransferase 2 (GCNT2), with consequent substitution of melanoma surface I-branched poly-N-acetyllactosamines (poly-LacNAcs) with i-linear poly-LacNAcs, is implicated in driving melanoma metastasis. In the current study, we explored the role of galectin-3 (Gal-3), a lectin that avidly binds surface poly-LacNAcs, in dictating melanoma aggressive behavior. Our results show that Gal-3 favors binding to i-linear poly-LacNAcs, while enforced GCNT2/I-branching disrupts this interaction, thereby suppressing Gal-3-dependent malignant characteristics, including extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway activation, BCL2 expression, cell proliferation, and migration. This report establishes the crucial role of extracellular Gal-3 interactions with i-linear glycans in promoting melanoma cell aggressiveness, placing GCNT2 as a tumor suppressor protein and suggesting both extracellular Gal-3 and i-linear glycans as potential therapeutic targets for metastatic melanoma.

Blood biochemical landscape and new insights into clinical decision-making for polycystic ovary syndrome in Chinese women: a prospective cohort study

Introduction

The Polycystic ovary syndrome (PCOS), a prevalent endocrine disorder affecting women's reproductive and metabolic health, faces diagnostic challenges due to heterogeneous clinical presentations and the absence of reliable biomarkers. This study investigates the role of Glucosaminyl (N-acetyl) transferase 2 (GCNT2) in modulating sex hormone-binding globulin (SHBG) and its potential as a therapeutic target in PCOS pathophysiology.

Methods

A prospective cohort of 103 PCOS patients treated with oral contraceptives (2021-2024) was established. Bidirectional Mendelian randomization (MR) was employed to assess genetic associations and causal relationships between PCOS and SHBG. Molecular docking studies evaluated cryptotanshinone's binding affinity to key proteins (COL1A1, COL4A2, COL6A2) in the PI3K/Akt pathway. GCNT2's regulatory effects on collagen synthesis and extracellular matrix pathways. Pharmacokinetic profiling validated therapeutic viability.

Results

Bidirectional MR revealed significant genetic associations (P < 0.001) and causal links between PCOS and SHBG, implicating GCNT2 as a key modulator. Cryptotanshinone exhibited strong binding affinity to PI3K/Akt signaling pathway proteins and favorable pharmacokinetic properties. Enrichment analyses highlighted GCNT2's role in collagen biosynthesis (FDR < 0.05) and extracellular matrix regulation.

Discussion

This study identifies GCNT2 as a critical mediator of PCOS pathophysiology through SHBG modulation and collagen remodeling. Cryptotanshinone emerges as a promising therapeutic candidate, targeting PI3K/Akt signaling pathway with high specificity. These findings advance the understanding of PCOS mechanisms and provide a foundation for biomarker-driven diagnostics and precision therapeutics. Further validation in clinical trials is warranted to translate these insights into practice.

Orthogonal-Group-Controlled Site-Selective I-Branching of Poly-N-acetyllactosamine Chains Reveals Unique Binding Specificities of Proteins towards I-Antigens

Poly-N-acetyllactosamine (poly-LacNAc) is ubiquitously expressed on cell surface glycoconjugates, serving as the backbone of complex glycans and an extended scaffold that presents diverse glycan epitopes. The branching of poly-LacNAc, where internal galactose (Gal) residues have β1-6 linked N-acetylglucosamine (GlcNAc) attached, forms the blood group I-antigen, which is closely associated with various physiological and pathological processes including cancer progression. However, the underlying mechanisms remain unclear as many of the I-antigen sequences are undefined and inaccessible. In this study, we developed a highly efficient orthogonal-group-controlled approach to access site-selectively I-branched poly-LacNAc chains. The approach relies on three orthogonal protecting groups, each of them "caps" one internal Gal residue of poly-LacNAc. These groups can be readily "decapped" by specific enzymes or chemical reduction to expose desired sites for GCNT2-catalyzed I-branching. This approach enabled the rapid preparation of a diverse library of 41 linear and branched poly-LacNAc glycans from a single precursor. Glycan microarray analysis using these complex glycans revealed unique recognitions of I-branches by lectins, anti-I mAbs, and galectins. Surprisingly, oxidized forms of linear poly-LacNAc strongly bound to several glycan-binding proteins (GBPs). These findings help to bridge the gap in recognition of I-branching and open new avenues for therapeutic development by targeting galectins.

Low GCNT2/I-Branching Glycan Expression Is Associated with Bladder Cancer Aggressiveness

Background/Objectives: Abnormal glycan formation on the cancer cell surface plays a crucial role in regulating tumor functions in bladder cancer. In this study, we investigated the roles of glucosaminyl (N-acetyl) transferase 2 (GCNT2) in bladder cancer progression and immune evasion. GCNT2 synthesizes I-branched polylactosamine chains on cell surface glycoproteins. Understanding its functions will provide insights into tumor-immune interactions, facilitating the development of effective immunotherapeutic strategies. Methods: GCNT2 expression levels in bladder cancer cell lines and patient tumor samples were analyzed via quantitative polymerase chain reaction and immunohistochemistry. GCNT2 functions were assessed via overexpression and knockdown experiments. Its effect on natural killer (NK) cell-mediated cytotoxicity was evaluated via in vitro assay. Cytotoxic granule release from NK cells was measured via enzyme-linked immunosorbent assay. Results: GCNT2 expression was inversely correlated with bladder cancer aggressiveness in both cell lines and patient samples. Low GCNT2 levels were associated with advanced tumor stage and grade, suggesting the tumor-suppressive roles of GCNT2. Notably, GCNT2 overexpression enhanced the susceptibility of bladder cancer cells to NK cell-mediated killing, whereas its knockdown promoted immune evasion. GCNT2-overexpressing cells strongly induced the release of cytotoxic granules from NK cells, indicating enhanced immune recognition. Conclusions: Our findings suggest that aggressive bladder tumors evade NK cell immunity by decreasing the GCNT2 levels and that I-antigen glycans synthesized by GCNT2 are crucial for NK cell recognition by tumor cells. Our findings provide insights into the tumor-immune interactions in bladder cancer and GCNT2 and its associated pathways as potential targets for novel immunotherapeutic strategies.

Altered glycosylation in cancer: molecular functions and therapeutic potential

Glycosylation, a key mode of protein modification in living organisms, is critical in regulating various biological functions by influencing protein folding, transportation, and localization. Changes in glycosylation patterns are a significant feature of cancer, are associated with a range of pathological activities in cancer-related processes, and serve as critical biomarkers providing new targets for cancer diagnosis and treatment. Glycoproteins like human epidermal growth factor receptor 2 (HER2) for breast cancer, alpha-fetoprotein (AFP) for liver cancer, carcinoembryonic antigen (CEA) for colon cancer, and prostate-specific antigen (PSA) for prostate cancer are all tumor biomarkers approved for clinical use. Here, we introduce the diversity of glycosylation structures and newly discovered glycosylation substrate-glycosylated RNA (glycoRNA). This article focuses primarily on tumor metastasis, immune evasion, metabolic reprogramming, aberrant ferroptosis responses, and cellular senescence to illustrate the role of glycosylation in cancer. Additionally, we summarize the clinical applications of protein glycosylation in cancer diagnostics, treatment, and multidrug resistance. We envision a promising future for the clinical applications of protein glycosylation.

Elevated α-1,2-mannosidase MAN1C1 in glioma stem cells and its implications for immunological changes and prognosis in glioma patients

Glioblastoma multiforme (GBM) is the most aggressive type of primary brain tumor, and the presence of glioma stem cells (GSCs) has been linked to its resistance to treatments and recurrence. Additionally, aberrant glycosylation has been implicated in the aggressiveness of cancers. However, the influence and underlying mechanism of N-glycosylation on the GSC phenotype and GBM malignancy remain elusive. Here, we performed an in-silico analysis approach on publicly available datasets to examine the function of N-glycosylation-related genes in GSCs and gliomas, accompanied by a qRT-PCR validation experiment. We found that high α-1,2-mannosidase MAN1C1 is associated with immunological functions and worse survival of glioma patients. Differential gene expression analysis and qRT-PCR validation revealed that MAN1C1 is highly expressed in GSCs. Furthermore, higher MAN1C1 expression predicts worse outcomes in glioma patients. Also, MAN1C1 expression is increased in the perinecrotic region of GBM and is associated with immunological and inflammatory functions, a hallmark of the GBM mesenchymal subtype. Further analysis confirmed that MAN1C1 expression is closely associated with infiltrating immune cells and disrupted immune response in the GBM microenvironment. These suggest that MAN1C1 is a potential biomarker for gliomas and may be important as an immunotherapeutic target for GBM.

Insights into the role of glycosyltransferase in the targeted treatment of gastric cancer

Gastric cancer is a remarkably heterogeneous tumor. Despite some advances in the diagnosis and treatment of gastric cancer in recent years, the precise treatment and curative outcomes remain unsatisfactory. Poor prognosis continues to pose a major challenge in gastric cancer. Therefore, it is imperative to identify effective targets to improve the treatment and prognosis of gastric cancer patients. It should be noted that glycosylation, a novel form of posttranslational modification, is a process capable of regulating protein function and influencing cellular activities. Currently, numerous studies have shown that glycosylation plays vital roles in the occurrence and progression of gastric cancer. As crucial enzymes that regulate glycan synthesis in glycosylation processes, glycosyltransferases are potential targets for treating GC. Hence, investigating the regulation of glycosyltransferases and the expression of associated proteins in gastric cancer cells is highly important. In this review, the related glycosyltransferases and their related signaling pathways in gastric cancer, as well as the existing inhibitors of glycosyltransferases, provide more possibilities for targeted therapies for gastric cancer.

Glycosylation in cancer as a source of biomarkers

INTRODUCTION

Glycosylation, the process of glycan synthesis and attachment to target molecules, is a crucial and common post-translational modification (PTM) in mammalian cells. It affects the protein's hydrophilicity, charge, solubility, structure, localization, function, and protection from proteolysis. Aberrant glycosylation in proteins can reveal new detection and therapeutic Glyco-biomarkers, which help to improve accurate early diagnosis and personalized treatment. This review underscores the pivotal role of glycans and glycoproteins as a source of biomarkers in human diseases, particularly cancer.

AREAS COVERED

This review delves into the implications of glycosylation, shedding light on its intricate roles in cancer-related cellular processes influencing biomarkers. It is underpinned by a thorough examination of literature up to June 2024 in PubMed, Scopus, and Google Scholar; concentrating on the terms: (Glycosylation[Title/Abstract]) OR (Glycan[Title/Abstract]) OR (glycoproteomics[Title/Abstract]) OR (Proteoglycans[Title/Abstract]) OR (Glycomarkers[Title/Abstract]) AND (Cancer[Title/Abstract]) AND ((Diagno*[Title/Abstract]) OR (Progno*[Title/Abstract])).

EXPERT OPINION

Glyco-biomarkers enhance early cancer detection, allow early intervention, and improve patient prognoses. However, the abundance and complex dynamic glycan structure may make their scientific and clinical application difficult. This exploration of glycosylation signatures in cancer biomarkers can provide a detailed view of cancer etiology and instill hope in the potential of glycosylation to revolutionize cancer research.

Advances in adoptive T-cell therapy for metastatic melanoma

Adoptive T cell therapy (ACT) is a fast developing, niche area of immunotherapy (IO), which is revolutionising the therapeutic landscape of solid tumour oncology, especially metastatic melanoma (MM). Identifying tumour antigens (TAs) as potential targets, the ACT response is mediated by either Tumour Infiltrating Lymphocytes (TILs) or genetically modified T cells with specific receptors - T cell receptors (TCRs) or chimeric antigen receptors (CARs) or more prospectively, natural killer (NK) cells. Clinical trials involving ACT in MM from 2006 to present have shown promising results. Yet it is not without its drawbacks which include significant auto-immune toxicity and need for pre-conditioning lymphodepletion. Although immune-modulation is underway using various combination therapies in the hope of enhancing efficacy and reducing toxicity. Our review article explores the role of ACT in MM, including the various modalities - their safety, efficacy, risks and their development in the trial and the real world setting.

Hypoxia Controls the Glycome Signature and Galectin-8-Ligand Axis to Promote Protumorigenic Properties of Metastatic Melanoma

The prognosis for patients with metastatic melanoma (MM) involving distant organs is grim, and treatment resistance is potentiated by tumor-initiating cells (TICs) that thrive under hypoxia. MM cells, including TICs, express a unique glycome featuring i-linear poly-N-acetyllactosamines through the loss of I-branching enzyme, β1,6 N-acetylglucosaminyltransferase 2. Whether hypoxia instructs MM TIC development by modulating the glycome signature remains unknown. In this study, we explored hypoxia-dependent alterations in MM glycome‒associated genes and found that β1,6 N-acetylglucosaminyltransferase 2 was downregulated and a galectin (Gal)-8-ligand axis, involving both extracellular and cell-intrinsic Gal-8, was induced. Low β1,6 N-acetylglucosaminyltransferase 2 levels correlated with poor patient outcomes, and patient serum samples were elevated for Gal-8. Depressed β1,6 N-acetylglucosaminyltransferase 2 in MM cells upregulated TIC marker, NGFR/CD271, whereas loss of MM cell‒intrinsic Gal-8 markedly lowered NGFR and reduced TIC activity in vivo. Extracellular Gal-8 bound preferentially to i-linear poly-N-acetyllactosamines on N-glycans of the TIC marker and prometastatic molecule CD44, among other receptors, and activated prosurvival factor protein kinase B. This study reveals the importance of hypoxia governing the MM glycome by enforcing i-linear poly-N-acetyllactosamine and Gal-8 expression. This mechanistic investigation also uncovers glycome-dependent regulation of pro-MM factor, NGFR, implicating i-linear poly-N-acetyllactosamine and Gal-8 as biomarkers and therapeutic targets of MM.

Total serum N-glycans associate with response to immune checkpoint inhibition therapy and survival in patients with advanced melanoma

BACKGROUND

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of melanoma and other cancers. However, no reliable biomarker of survival or response has entered the clinic to identify those patients with melanoma who are most likely to benefit from ICIs. Glycosylation affects proteins and lipids' structure and functions. Tumours are characterized by aberrant glycosylation which may contribute to their progression and hinder an effective antitumour immune response.

METHODS

We aim at identifying novel glyco-markers of response and survival by leveraging the N-glycome of total serum proteins collected in 88 ICI-naive patients with advanced melanoma from two European countries. Samples were collected before and during ICI treatment.

RESULTS

We observe that responders to ICIs present with a pre-treatment N-glycome profile significantly shifted towards higher abundancy of low-branched structures containing lower abundances of antennary fucose, and that this profile is positively associated with survival and a better predictor of response than clinical variables alone.

CONCLUSION

While changes in serum protein glycosylation have been previously implicated in a pro-metastatic melanoma behaviour, we show here that they are also associated with response to ICI, opening new avenues for the stratification of patients and the design of adjunct therapies aiming at improving immune response.

Apprising Diagnostic and Prognostic Biomarkers in Cutaneous Melanoma—Persistent Updating

The incidence of melanoma, a very aggressive skin cancer, has increased over the past few decades. Although there are well-established clinical, dermoscopic and histopathological criteria, the diagnosis is often performed late, which has important implications on the patient’s clinical outcome. Unfortunately, melanoma is one of the most challenging tumors to diagnose because it is a heterogeneous neoplasm at the clinical, histopathological, and molecular level. The use of reliable biomarkers for the diagnosis and monitoring of disease progression is becoming a standard of care in modern medicine. In this review, we discuss the latest studies, which highlight findings from the genomics, epitranscriptomics, proteomics and metabolomics areas, pointing out different genes, molecules and cells as potential diagnostic and prognostic biomarkers in cutaneous melanoma.

The Role of Glycosylation in Melanoma Progression

Malignant melanoma is the most aggressive form of skin cancer, which originates from the malignant transformation of melanocytes, the melanin-producing cells of the skin. Melanoma progression is typically described as a stepwise process in which metastasis formation ensues late during disease. A large body of evidence has shown that the accumulation of genetic and epigenetic alterations drives melanoma progression through the different steps. Mortality in melanoma is associated with metastatic disease. Accordingly, early-stage melanoma can be cured in the majority of cases by surgical excision, while late-stage melanoma is a highly lethal disease. Glycosylation is a post-translational modification that involves the transfer of glycosyl moieties to specific amino acid residues of proteins to form glycosidic bonds through the activity of glycosyltransferases. Aberrant glycosylation is considered a hallmark of cancer as it occurs in the majority of tumor types, including melanoma. The most widely occurring glycosylation changes in melanoma are represented by sialylation, fucosylation, and N- and I-glycan branching. In this review, we discuss the role of glycosylation in melanoma and provide insights on the mechanisms by which aberrant glycosylation promotes melanoma progression through activation of invasion and metastasis, immune evasion and cell proliferation.