Loss of N-Acetylgalactosaminyltransferase-4 Orchestrates Oncogenic MicroRNA-9 in Hepatocellular Carcinoma

Myriad mechanisms: factors regulating the synthesis of aberrant mucin-type O-glycosylation found on cancer cells

Mucin-type O-linked glycosylation is initiated by the transfer of a single N-acetyl-D-galactosamine (GalNAc) to the hydroxyl group of either a serine (Ser) or threonine (Thr) residue. This process is catalysed by a portfolio of twenty isoenzymes, the UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts, GalNAc-Ts or GALNTs) to create the Thomsen nouvelle (Tn) antigen (GalNAcα1-O-Ser/Thr ). In healthy adult cells, Tn antigen is further elaborated by the action of specific glycosyltransferases to either form one of eight core structures, which themselves can be extended to form more complex glycans, or into sialyl Tn or sialyl core 1 (sialyl T), where sialylation terminates chain extension. These O-glycans, produced through mucin-type O-linked glycosylation, are a feature of many secreted and membrane-bound proteins, and are fundamental in a wide range of biological functions. Dysregulation of this process, often resulting in the exposure of usually cryptic truncated O-glycans including Tn antigen, is important in a wide range of pathologies and has been implicated in cancer metastasis. The regulation of mucin-type O-linked glycosylation, in health and disease, is highly complex and not fully understood. It is determined by a myriad of mechanisms, from transcriptional control, mutation, posttranslational control, stability of transferases, their relocation within the secretory pathway, and changes in the fundamental structure and environment of the Golgi apparatus. This review presents an overview of the evidence for these potential regulatory steps in the synthesis of truncated mucin-type O-linked glycans in cancer.

TRIM23 promotes 5-Fluorouracil resistance in colorectal cancer by upregulating GALNT4 expression

5-Fluorouracil (5-FU) is one of the most common chemotherapeutic agents for colorectal cancer (CRC), but its application is often limited by resistance. Tripartite motif containing 23 (TRIM23) has been reported to be dysregulated in various tumors and involved in tumor progression and chemotherapy resistance. However, its relationship with CRC 5-FU resistance and the underlying mechanism are still unclear. In this study, we found that TRIM23 was upregulated in CRC. Patients treated with 5-FU and with high TRIM23 expression had a lower disease control rate (DCR) and a poorer median progression-free survival (mPFS). In vitro, the expression of TRIM23 in CRC cells was elevated after 5-FU treatment. Compared to parental cells, TRIM23 was significantly overexpressed in 5-FU-resistant CRC cells. Mechanistically, TRIM23 mediated 5-FU resistance of CRC by upregulating the expression of N-acetylgalactosaminyltransferase-4 (GALNT4). Knocking down TRIM23 in 5-FU-resistant colon cancer cells restored the sensitivity to 5-FU, while overexpression of GALNT4 in TRIM23 knockdown cells counteracted the chemosensitization caused by TRIM23 downregulation. The TRIM23/GALNT4 axis may play a crucial role in 5-FU resistance in CRC, and targeted inhibition of this axis is expected to reverse resistance. As a potential biomarker for screening 5-FU-sensitive patients and predicting prognosis in clinical practice, TRIM23 deserves further investigation.

GALNT6 drives lenvatinib resistance in hepatocellular carcinoma through autophagy and cancer-associated fibroblast activation

BACKGROUND

Hepatocellular carcinoma (HCC) remains a significant global health challenge with limited treatment options. Lenvatinib, a tyrosine kinase inhibitor, has shown promise but is often undermined by the development of drug resistance.

METHODS

Utilizing high-throughput sequencing, we investigated the molecular mechanisms underlying lenvatinib resistance in HCC cells, with a focus on metabolic pathways. Key genes, including GALNT6, were validated through quantitative real-time PCR. The effects of GALNT6 knockdown on lenvatinib sensitivity were examined in vitro and in vivo. O-GalNAc glycosylation was assessed using Vicia Villosa Lectin. Immune cell infiltration and interactions were analyzed in the TCGA-LIHC cohort, with further validation by Western blotting and immunohistochemistry.

RESULTS

Our findings indicate that lenvatinib resistance in HCC is driven by the mucin-type O-glycosylation pathway, with GALNT6 playing a critical role. Knockdown of GALNT6 led to reduced O-GalNAc glycosylation, including the modification of LAPTM5, resulting in decreased LAPTM5 activity and autophagy inhibition. Additionally, GALNT6 silencing disrupted the PDGFA-PDGFRB axis, impairing the activation of cancer-associated fibroblasts (CAFs) and reducing their secretion of SPP1, which collectively diminished lenvatinib resistance.

CONCLUSIONS

GALNT6 is integral to the resistance mechanisms against lenvatinib in HCC by modulating autophagy and CAF activation. Targeting GALNT6 offers a promising strategy to enhance lenvatinib efficacy and improve therapeutic outcomes in HCC.

BarH-Like Homeobox 2 Suppresses Cell Proliferation, Invasion, and Angiogenesis in Hepatocellular Carcinoma by Activating N-Acetylgalactosaminyltransferase 4

BarH-like homeobox 2 (BARX2) has been identified to play a key role in the development of multiple cancers. Meanwhile, BARX2 may be an independent prognostic biomarker for patients suffering from hepatocellular carcinoma (HCC). Nevertheless, the regulatory role of BARX2 in HCC is still unclear and needs to be unveiled. In this study, the expressions of BARX2 and N-acetylgalactosaminyltransferase 4 (GALNT4) were evaluated by quantitative real-time PCR (qRT-PCR) as well as western blot. Besides, the abilities of cells to proliferate, migrate, invade, and angiogenesis were assessed with CCK-8, colony formation, wound-healing, Transwell, and tube formation assays, separately. Cell apoptosis was determined by flow cytometry analysis. The binding relationship between BARX2 and GALNT4 was predicted by JASPAR website and verified using Chromatin immunoprecipitation (ChIP) and luciferase report assay. It was discovered that BARX2 was reduced in HCC cell lines, while its overexpression greatly repressed cell proliferation, migration, invasion, and angiogenesis and promoted cell apoptosis in HuH7 and MHCC97-H cells. BARX2 could bind to GALNT4 promoter and positively regulate GALNT4 expression. In addition, GALNT4 deficiency partly abolished the inhibitory effects of BARX2 on the progression of HCC. In summary, this study highlights that BARX2 may hold promise for serving as a potential therapeutic target, facilitating the development of a novel therapeutic strategy against HCC.

Cosmc regulates O-glycan extension in murine hepatocytes

Hepatocytes synthesize a vast number of glycoproteins found in their membranes and secretions, many of which contain O-glycans linked to Ser/Thr residues. As the functions and distribution of O-glycans on hepatocyte-derived membrane glycoproteins and blood glycoproteins are not well understood, we generated mice with a targeted deletion of Cosmc (C1Galt1c1) in hepatocytes. Liver glycoproteins in WT mice express typical sialylated core 1 O-glycans (T antigen/CD176) (Galβ1-3GalNAcα1-O-Ser/Thr), whereas the Cosmc knockout hepatocytes (HEP-Cosmc-KO) lack extended O-glycans and express the Tn antigen (CD175) (GalNAcα1-O-Ser/Thr). Tn-containing glycoproteins occur in the sera of HEP-Cosmc-KO mice but not in WT mice. The LDL-receptor (LDLR), a well-studied O-glycosylated glycoprotein in hepatocytes, behaves as a ∼145kD glycoprotein in WT liver lysates, whereas it is reduced to ∼120 kDa in lysates from HEP-Cosmc-KO mice. Interestingly, the expression of the LDLR, as well as HMG-CoA reductase, which is typically altered in response to dysregulated cholesterol metabolism, are similar between WT and HEP-Cosmc-KO mice, indicating no significant effect by Cosmc deletion on either LDLR stability or cholesterol metabolism. Consistent with this, we observed no detectable phenotype in the HEP-Cosmc-KO mice regarding development, appearance or aging compared to WT. These results provide surprising, novel information about the pathway of O-glycosylation in the liver.

miRGediNET: A comprehensive examination of common genes in miRNA-Target interactions and disease associations: Insights from a grouping-scoring-modeling approach

In the broad and complex field of biological data analysis, researchers frequently gather information from a single source or database. Despite being a widespread practice, this has disadvantages. Relying exclusively on a single source can limit our comprehension as it may omit various perspectives that could be obtained by combining multiple knowledge bases. Acknowledging this shortcoming, we report on miRGediNET, a novel approach combining information from three biological databases. Our investigation focuses on microRNAs (miRNAs), small non-coding RNA molecules that regulate gene expression post-transcriptionally. We delve deeply into the knowledge of these miRNA's interactions with genes and the possible effects these interactions may have on different diseases. The scientific community has long recognized a direct correlation between the progression of specific diseases and miRNAs, as well as the genes they target. By using miRGediNET, we go beyond simply acknowledging this relationship. Rather, we actively look for the critical genes that could act as links between the actions of miRNAs and the mechanisms underlying disease. Our methodology, which carefully identifies and investigates these important genes, is supported by a strategic framework that may open up new possibilities for comprehending diseases and creating treatments. We have developed a tool on the Knime platform as a concrete application of our research. This tool serves as both a validation of our study and an invitation to the larger community to interact with, investigate, and build upon our findings. miRGediNET is publicly accessible on GitHub at https://github.com/malikyousef/miRGediNET, providing a collaborative environment for additional research and innovation for enthusiasts and fellow researchers.

Protein glycosylation alterations in hepatocellular carcinoma: function and clinical implications

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death worldwide. Understanding the cancer mechanisms provides novel diagnostic, prognostic, and therapeutic markers for the management of HCC disease. In addition to genomic and epigenomic regulation, post-translational modification exerts a profound influence on protein functions and plays a critical role in regulating various biological processes. Protein glycosylation is one of the most common and complex post-translational modifications of newly synthesized proteins and acts as an important regulatory mechanism that is implicated in fundamental molecular and cell biology processes. Recent studies in glycobiology suggest that aberrant protein glycosylation in hepatocytes contributes to the malignant transformation to HCC by modulating a wide range of pro-tumorigenic signaling pathways. The dysregulated protein glycosylation regulates cancer growth, metastasis, stemness, immune evasion, and therapy resistance, and is regarded as a hallmark of HCC. Changes in protein glycosylation could serve as potential diagnostic, prognostic, and therapeutic factors in HCC. In this review, we summarize the functional importance, molecular mechanism, and clinical application of protein glycosylation alterations in HCC.

The Mutual Relationship between Glycosylation and Non-Coding RNAs in Cancer and Other Physio-Pathological Conditions

Glycosylation, which consists of the enzymatic addition of sugars to proteins and lipids, is one of the most important post-co-synthetic modifications of these molecules, profoundly affecting their activity. Although the presence of carbohydrate chains is crucial for fine-tuning the interactions between cells and molecules, glycosylation is an intrinsically stochastic process regulated by the relative abundance of biosynthetic (glycosyltransferases) and catabolic (glycosidases) enzymes, as well as sugar carriers and other molecules. Non-coding RNAs, which include microRNAs, long non-coding RNAs and circRNAs, establish a complex network of reciprocally interacting molecules whose final goal is the regulation of mRNA expression. Likewise, these interactions are stochastically regulated by ncRNA abundance. Thus, while protein sequence is deterministically dictated by the DNA/RNA/protein axis, protein abundance and activity are regulated by two stochastic processes acting, respectively, before and after the biosynthesis of the protein axis. Consequently, the worlds of glycosylation and ncRNA are closely interconnected and mutually interacting. In this paper, we will extensively review the many faces of the ncRNA-glycosylation interplay in cancer and other physio-pathological conditions.

Emerging roles of GALNT5 on promoting EGFR activation in cholangiocarcinoma: a mechanistic insight

Cholangiocarcinoma (CCA) is a lethal cancer in that the incidence is now increasing worldwide. N-acetylgalactosaminyltransferase 5 (GALNT5), an enzyme that initiates the first step of mucin type-O glycosylation, has been reported to promote aggressiveness of CCA cells via the epithelial to the mesenchymal transition (EMT) process, and Akt/Erk activation. In this study, the clinical and biological relevance of GALNT5 and the molecular mechanisms by which GALNT5 modulated EGFR in promoting CCA progression were examined. Using publicly available datasets, upregulation of GALNT5 in patient CCA tissues and its correlation with EGFR expression was noted. High levels of GALNT5 were significantly associated with the short survival of patients, suggesting a prognostic marker of GALNT5 for CCA. GALNT5 modulated EGFR expression as shown in CCA cell lines. Upregulation of GALNT5 significantly increased EGFR mRNA and protein in GALNT5 overexpressing cells, whereas suppression of GALNT5 expression gave the opposite results. The molecular dynamics simulations and MM/PB(GB)SA-based free energy calculations showed that O-glycosylation on the EGFR extracellular domain enhanced the structural stability, compactness, and H-bond formation of the EGF/GalNAc-EGFR complex compared with those of EGF/EGFR. This stabilized the growth factor binding site and fostered stronger interactions between EGF and EGFR. Using the EGF-induced EGFR activation model, GALNT5 was shown to mediate EGFR stability via a decreased rate of EGFR degradation and enhanced EGFR activity by increasing the binding affinity of EGF/EGFR that consequently increasing the activation of EGFR and its downstream effectors Akt and Erk. In summary, GALNT5 was upregulated in CCA tissues and associated with a worse prognosis. The study identified for the first time the impacts of GALNT5 on EGFR activity by increasing: 1) EGFR expression via a transcriptional-dependent mechanism, 2) EGFR stability by reducing EGFR degradation, and 3) EGFR activation through an increased binding affinity of EGF/EGFR which all together fostered the activation of EGFR. These results expanded the understanding of the molecular mechanism of how GALNT5 impacted CCA progression and suggested GALNT5 as a new target for therapeutic intervention against metastatic CCA.

N-acetylgalactosaminyltransferase-4 protects against hepatic ischemia/reperfusion injury by blocking apoptosis signal-regulating kinase 1 N-terminal dimerization

BACKGROUND AND AIMS

Ischemia-reperfusion (I/R) injury is an inevitable complication of liver transplantation (LT) and compromises its prognosis. Glycosyltransferases have been recognized as promising targets for disease therapy, but their roles remain open for study in hepatic I/R (HIR) injury. Here, we aim to demonstrate the exact function and molecular mechanism of a glycosyltransferase, N-acetylgalactosaminyltransferase-4 (GALNT4), in HIR injury.

APPROACH AND RESULTS

By an RNA-sequencing data-based correlation analysis, we found a close correlation between GALNT4 expression and HIR-related molecular events in a murine model. mRNA and protein expression of GALNT4 were markedly up-regulated upon reperfusion surgery in both clinical samples from subjects who underwent LT and in a mouse model. We found that GALNT4 deficiency significantly exacerbated I/R-induced liver damage, inflammation, and cell death, whereas GALNT4 overexpression led to the opposite phenotypes. Our in-depth mechanistic exploration clarified that GALNT4 directly binds to apoptosis signal-regulating kinase 1 (ASK1) to inhibit its N-terminal dimerization and subsequent phosphorylation, leading to a robust inactivation of downstream c-Jun N-terminal kinase (JNK)/p38 and NF-κB signaling. Intriguingly, the inhibitory capacity of GALNT4 on ASK1 activation is independent of its glycosyltransferase activity.

CONCLUSIONS

GALNT4 represents a promising therapeutic target for liver I/R injury and improves liver surgery prognosis by inactivating the ASK1-JNK/p38 signaling pathway.

GALNT8 suppresses breast cancer cell metastasis potential by regulating EGFR O-GalNAcylation

Breast cancer represents the most lethal malignancy that threatens the health of females. Metastasis is the fatal hallmark of breast cancer, and current effective therapeutic targets of metastasis are still lacking. Aberrant O-GalNAcylation, which is attributed to alteration of polypeptide N-acetylgalactosaminyl transferases (GALNTs), has been implicated in cancer metastasis. However, GALNTs that drive metastasis in breast cancer and their underlying mechanisms are largely unclear. In the present study, a negative correlation between GALNT8 and the prognosis of breast cancer patients was observed in multiple groups of Gene Expression Omnibus (GEO) datasets. We then constructed a stable GALNT8 knockdown MCF7 cell line and performed transcriptome analysis using RNA sequencing, which revealed that the expression of multiple migration-related genes was changed. GALNT8 was identified as a regulator of epithelial-mesenchymal transition (EMT) markers, including E-cadherin, N-cadherin, ZO-1 and vimentin. Moreover, loss- and gain-of-function GALNT8 assays demonstrated that this glycosyltransferase inhibited the metastatic potential of breast cancer cells. Interestingly, the O-GalNAcylation of EGFR, which is the key factor related to the metastasis cascade, was impacted by GALNT8. Furthermore, our results suggested that the GALNT8-mediated O-GalNAcylation led to the suppression of the EGFR signaling pathway and metastatic potential in breast cancer cells. These results suggested that GALNT8 acts as a tumor suppressor, represses tumor metastasis and inhibits the EMT process through the EGFR signaling pathway. This finding may provide insight into the mechanism by which aberrant O-glycosylation modulates breast cancer metastasis.

Identification of a Novel Glycosyltransferase Prognostic Signature in Hepatocellular Carcinoma Based on LASSO Algorithm

Although many prognostic models have been developed to help determine personalized prognoses and treatments, the predictive efficiency of these prognostic models in hepatocellular carcinoma (HCC), which is a highly heterogeneous malignancy, is less than ideal. Recently, aberrant glycosylation has been demonstrated to universally participate in tumour initiation and progression, suggesting that dysregulation of glycosyltransferases can serve as novel cancer biomarkers. In this study, a total of 568 RNA-sequencing datasets of HCC from the TCGA database and ICGC database were analysed and integrated via bioinformatic methods. LASSO regression analysis was applied to construct a prognostic signature. Kaplan-Meier survival, ROC curve, nomogram, and univariate and multivariate Cox regression analyses were performed to assess the predictive efficiency of the prognostic signature. GSEA and the "CIBERSORT" R package were utilized to further discover the potential biological mechanism of the prognostic signature. Meanwhile, the differential expression of the prognostic signature was verified by western blot, qRT-PCR and immunohistochemical staining derived from the HPA. Ultimately, we constructed a prognostic signature in HCC based on a combination of six glycosyltransferases, whose prognostic value was evaluated and validated successfully in the testing cohort and the validation cohort. The prognostic signature was identified as an independent unfavourable prognostic factor for OS, and a nomogram including the risk score was established and showed the good performance in predicting OS. Further analysis of the underlying mechanism revealed that the prognostic signature may be potentially associated with metabolic disorders and tumour-infiltrating immune cells.

The fungal Clitocybe nebularis lectin binds distinct cell surface glycoprotein receptors to induce cell death selectively in Jurkat cells

Clitocybe nebularis lectin (CNL) is a GalNAcβ1-4GlcNAc-binding lectin that exhibits an antiproliferative effect exclusively on the Jurkat leukemic T cell line by provoking homotypic aggregation and dose-dependent cell death. Cell death of Jurkat cells exhibited typical features of early apoptosis, but lacked the activation of initiating and executing caspases. None of the features of CNL-induced cell death were effectively blocked with the pan-caspase inhibitor or different cysteine peptidase inhibitors. Furthermore, CNL binding induced Jurkat cells to release the endogenous damage-associated molecular pattern molecule high-mobility group box 1 (HMGB1). A plant lectin with similar glycan-binding specificity, Wisteria floribunda agglutinin (WFA) showed less selective toxicity and induced cell death in Jurkat, Tall-104, and Hut-87 cell lines. HMGB1 release was also detected when Jurkat cells were treated with WFA. We identified the CD45 and CD43 cell surface glycoproteins on Jurkat cells as the main targets for CNL binding. However, the blockade of CD45 phosphatase activity failed to block either CNL-induced homotypic agglutination or cell death. Overall, our results indicate that CNL triggers atypical cell death selectively on Jurkat cells, suggesting the potential applicability of CNL in novel strategies for treating and/or detecting acute T cell leukemia.

Biology, Significance and Immune Signaling of Mucin 1 in Hepatocellular Carcinoma

Mucin 1 (MUC 1) is a highly glycosylated tumor-associated antigen (TAA) overexpressed in hepatocellular carcinoma (HCC). This protein plays a critical role in various immune-mediated signaling pathways at its transcriptional and post-transcriptional levels, leading to immune evasion and metastasis in HCC. HCC cells maintain an immune-suppressive environment with the help of immunesuppressive tumor-associated antigens, resulting in a metastatic spread of the disease. The development of intense immunotherapeutic strategies to target tumor-associated antigen is critical to overcoming the progression of HCC. MUC 1 remains the most recognized tumor-associated antigen since its discovery over 30 years ago. A few promising immunotherapies targeting MUC 1 are currently under clinical trials, including CAR-T and CAR-pNK-mediated therapies. This review highlights the biosynthesis, significance, and clinical implication of MUC 1 as an immune target in HCC.

Prognostic model of AU-rich genes predicting the prognosis of lung adenocarcinoma

Background

AU-rich elements (ARE) are vital cis-acting short sequences in the 3’UTR affecting mRNA stability and translation. The deregulation of ARE-mediated pathways can contribute to tumorigenesis and development. Consequently, ARE-genes are promising to predict prognosis of lung adenocarcinoma (LUAD) patients.

Methods

Differentially expressed ARE-genes between LUAD and adjacent tissues in TCGA were investigated by Wilcoxon test. LASSO and Cox regression analyses were performed to identify a prognostic genetic signature. The genetic signature was combined with clinicopathological features to establish a prognostic model. LUAD patients were divided into high- and low-risk groups by the model. Kaplan–Meier curve, Harrell’s concordance index (C-index), calibration curves and decision curve analyses (DCA) were used to assess the model. Function enrichment analysis, immunity and tumor mutation analyses were performed to further explore the underlying molecular mechanisms. GEO data were used for external validation.

Results

Twelve prognostic genes were identified. The gene riskScore, age and stage were independent prognostic factors. The high-risk group had worse overall survival and was less sensitive to chemotherapy and radiotherapy (P < 0.01). C-index and calibration curves showed good performance on survival prediction in both TCGA (1, 3, 5-year ROC: 0.788, 0.776, 0.766) and the GSE13213 validation cohort (1, 3, 5-year ROC: 0.781, 0.811, 0.734). DCA showed the model had notable clinical net benefit. Furthermore, the high-risk group were enriched in cell cycle, DNA damage response, multiple oncological pathways and associated with higher PD-L1 expression, M1 macrophage infiltration. There was no significant difference in tumor mutation burden (TMB) between high- and low-risk groups.

Conclusion

ARE-genes can reliably predict prognosis of LUAD and may become new therapeutic targets for LUAD.

Role of GALNT4 in protecting against cardiac hypertrophy through ASK1 signaling pathway

Pathological myocardial hypertrophy is regulated by multiple pathways. However, its underlying pathogenesis has not been fully explored. The goal of this work was to elucidate the function of polypeptide N-acetylgalactosaminyltransferase 4 (GALNT4) in myocardial hypertrophy and its underlying mechanism of action. We illustrated that GALNT4 was upregulated in the models of hypertrophy. Two cardiac hypertrophy models were established through partial transection of the aorta in GALNT4-knockout (GALNT4-KO) mice and adeno-associated virus 9-GALNT4 (AAV9-GALNT4) mice. The GALNT4-KO mice demonstrated accelerated cardiac hypertrophy, dysfunction, and fibrosis, whereas the opposite phenotype was observed in AAV9-GALNT4 mice. Similarly, GALNT4 overexpression mitigated the degree of phenylephrine-induced cardiomyocyte hypertrophy in vitro whereas GALNT4 knockdown aggravated the hypertrophy. In terms of mechanism, GALNT4 deficiency increased the phosphorylation and activation of ASK1 and its downstream targets (JNK and p38), whereas GALNT4 overexpression inhibited activation of the ASK1 pathway. Furthermore, we demonstrated that GALNT4 can directly bind to ASK1 inhibiting its N-terminally mediated dimerization and the subsequent phosphorylation of ASK1. Finally, an ASK1 inhibitor (iASK1) was able to reverse the effects of GALNT4 in vitro. In summary, GALNT4 may serve as a new regulatory factor and therapeutic target by blocking the activation of the ASK1 signaling cascade.

GALNT14 regulates ferroptosis and apoptosis of ovarian cancer through the EGFR/mTOR pathway

Background: Chemoresistance usually occurs in ovarian cancer. We aimed to explore the mechanisms of chemoresistance. Methods: Western blotting assay was used to detect the expression of GALNT14. Further cell function experiments were performed to investigate the effect of GALNT14 in ovarian cancer. Results: GALNT14 is significantly upregulated in ovarian cancer. Downregulation of GALNT14 significantly inhibits both apoptosis and ferroptosis of ovarian cancer cells. A further mechanism assay illustrated that downregulation of GALNT14 suppresses the activity of the mTOR pathway through modifying O-glycosylation of EGFR. Finally, an additive effect promoting cell death occurs with a combination of an mTOR inhibitor and cisplatin. Conclusion: Our study might provide a promising method to overcome cisplatin resistance for patients with ovarian cancer.

GALNT3 suppresses lung cancer by inhibiting myeloid-derived suppressor cell infiltration and angiogenesis in a TNFR and c-MET pathway-dependent manner

The deregulation of polypeptide N-acetyl-galactosaminyltransferases (GALNTs) contributes to several cancers, but their roles in lung cancer remain unclear. In this study, we have identified a tumor-suppressing role of GALNT3 in lung cancer. We found that GALNT3 suppressed lung cancer development and progression in both xenograft and syngeneic mouse models. Specifically, GALNT3 suppressed lung cancer initiation by inhibiting the self-renewal of lung cancer cells. More importantly, GALNT3 attenuated lung cancer growth by preventing the creation of a favorable tumor microenvironment (TME), which was attributed to GALNT3's ability to inhibit myeloid-derived suppressor cell (MDSC) infiltration into tumor sites and subsequent angiogenesis. We also identified a GALNT3-regulated gene (GRG) signature and found that lung cancer patients whose tumors exhibit the GRG signature showed more favorable prognoses. Further investigation revealed that GALNT3 suppressed lung cancer cell self-renewal by reducing β-catenin levels, which led to reduced expression of the downstream targets of the WNT pathway. In addition, GALNT3 inhibited MDSC infiltration into tumor sites by suppressing both the TNFR1-NFκB and cMET-pAKT pathways. Specifically, GALNT3 inhibited the nuclear localization of NFκB and the c-MET-induced phosphorylation of AKT. This then led to reduced production of CXCL1, a chemokine required for MDSC recruitment. Finally, we confirmed that the GALNT3-induced inhibition of the TNFR1-NFκB and cMET-pAKT pathways involved the O-GalNAcylation of the TNFR1 and cMET receptors. In summary, we have identified GALNT3 as the first GALNT member capable of suppressing lung cancer and uncovered a novel mechanism by which GALNT3 regulates the TME.

Systems glycobiology for discovering drug targets, biomarkers, and rational designs for glyco-immunotherapy

Cancer immunotherapy has revolutionized treatment and led to an unprecedented wave of immuno-oncology research during the past two decades. In 2018, two pioneer immunotherapy innovators, Tasuku Honjo and James P. Allison, were awarded the Nobel Prize for their landmark cancer immunotherapy work regarding “cancer therapy by inhibition of negative immune regulation” –CTLA4 and PD-1 immune checkpoints. However, the challenge in the coming decade is to develop cancer immunotherapies that can more consistently treat various patients and cancer types. Overcoming this challenge requires a systemic understanding of the underlying interactions between immune cells, tumor cells, and immunotherapeutics. The role of aberrant glycosylation in this process, and how it influences tumor immunity and immunotherapy is beginning to emerge. Herein, we review current knowledge of miRNA-mediated regulatory mechanisms of glycosylation machinery, and how these carbohydrate moieties impact immune cell and tumor cell interactions. We discuss these insights in the context of clinical findings and provide an outlook on modulating the regulation of glycosylation to offer new therapeutic opportunities. Finally, in the coming age of systems glycobiology, we highlight how emerging technologies in systems glycobiology are enabling deeper insights into cancer immuno-oncology, helping identify novel drug targets and key biomarkers of cancer, and facilitating the rational design of glyco-immunotherapies. These hold great promise clinically in the immuno-oncology field.

Prognostic significance of miR-203 and ZEB1 expression in early-stage hepatocellular carcinoma

Background: Approximately one-quarter of patients with early-stage hepatocellular carcinoma (HCC) suffer from tumor recurrence within the first year after hepatectomy. Identification of patients at high risk of recurrence and new therapeutic approaches are crucial to improve clinical outcome. This study aimed to assess the prognostic significance of miR-203 and Zinc finger E-box binding homeobox 1 (ZEB1) in early-stage HCC and explore the association between the expression of ZEB1 and miR-203 in HCC.

Methods: Tissue microarray-based immunohistochemistry (IHC) and in situ hybridization (ISH) were performed to investigate ZEB1 and miR-203 expression in 73 patients with early-stage HCC and their correlation with clinicopathological features and prognosis of patients were analyzed. The prognostic value of the two factors was also measured by public KM plotter database. Quantitative reverse transcription PCR (qRT-PCR) assays were conducted to study the relationship between miR-203 and ZEB1. Transwell assays, Cell Counting Kit-8 (CCK-8) assays were performed to detect the roles of miR-203 in migration, invasion and proliferation of HCC cells.

Results: We found low expression of miR-203 was associated significantly with tumor recurrence (P<0.001) and poor survival (P=0.020) of patients with early-stage HCC. Multivariate analysis revealed that low miR-203 expression was a poor prognostic factor for both overall survival (OS) (P=0.036) and recurrence free survival (RFS) (P=0.017). ZEB1 did not show any prognostic significance in our cohort. Correlation analysis indicated that there was no significant correlation between miR-203 and ZEB1 on both mRNA and protein levels. Furthermore, functional studies indicated that miR-203 repressed migration, invasion and proliferation of HCC cells in vitro.

Conclusion: Our study suggested that miR-203 could be a novel predictor in early-stage HCC and might also be a potential molecular target for HCC therapy.

The Role of Noncoding RNAs in the Regulation of Anoikis and Anchorage-Independent Growth in Cancer

Cancer is a global health concern, and the prognosis of patients with cancer is associated with metastasis. Multistep processes are involved in cancer metastasis. Accumulating evidence has shown that cancer cells acquire the capacity of anoikis resistance and anchorage-independent cell growth, which are critical prerequisite features of metastatic cancer cells. Multiple cellular factors and events, such as apoptosis, survival factors, cell cycle, EMT, stemness, autophagy, and integrins influence the anoikis resistance and anchorage-independent cell growth in cancer. Noncoding RNAs (ncRNAs), such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), are dysregulated in cancer. They regulate cellular signaling pathways and events, eventually contributing to cancer aggressiveness. This review presents the role of miRNAs and lncRNAs in modulating anoikis resistance and anchorage-independent cell growth. We also discuss the feasibility of ncRNA-based therapy and the natural features of ncRNAs that need to be contemplated for more beneficial therapeutic strategies against cancer.

ppGalNAc-T4-catalyzed O-Glycosylation of TGF-β type Ⅱ receptor regulates breast cancer cells metastasis potential

GalNAc-type O-glycosylation, initially catalyzed by polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts), is one of the most abundant and complex posttranslational modifications of proteins. Emerging evidence has proven that aberrant ppGalNAc-Ts are involved in malignant tumor transformation. However, the exact molecular functions of ppGalNAc-Ts are still unclear. Here, the role of one isoform, ppGalNAc-T4, in breast cancer cell lines was investigated. The expression of ppGalNAc-T4 was found to be negatively associated with migration of breast cancer cells. Loss-of-function studies revealed that ppGalNAc-T4 attenuated the migration and invasion of breast cancer cells by inhibiting the epithelial-mesenchymal transition (EMT) process. Correspondingly, transforming growth factor beta (TGF-β) signaling, which is the upstream pathway of EMT, was impaired by ppGalNAc-T4 expression. ppGalNAc-T4 knockout decreased O-GalNAc modification of TGF-β type Ⅰ and Ⅱ receptor (TβR Ⅰ and Ⅱ) and led to the elevation of TGF-β receptor dimerization and activity. Importantly, a peptide from TβR Ⅱ was identified as a naked peptide substrate of ppGalNAc-T4 with a higher affinity than ppGalNAc-T2. Further, Ser31, corresponding to the extracellular domain of TβR Ⅱ, was identified as the O-GalNAcylation site upon in vitro glycosylation by ppGalNAc-T4. The O-GalNAc-deficient S31 A mutation enhanced TGF-β signaling activity and EMT in breast cancer cells. Together, these results identified a novel mechanism of ppGalNAc-T4-catalyzed TGF-β receptors O-GalNAcylation that suppresses breast cancer cell migration and invasion via the EMT process. Targeting ppGalNAc-T4 may be a potential therapeutic strategy for breast cancer treatment.

Reduced expression of ppGalNAc-T4 promotes proliferation of human breast cancer cells

Breast cancer, one of the most frequently diagnosed and aggressive malignancies, is the major cause of cancer-related death greatly threatening women health. Polypeptide N-acetylgalactosaminyltransferase 4 (ppGalNAc-T4), responsible for the initial step of mucin-type O-glycosylation, has been reported to be implicated in diverse types of human tumors. However, the biological role of ppGalNAc-T4 in breast cancer is still undetermined. In this study, we investigate the effects and mechanism of ppGalNAc-T4 to breast cancer cell proliferation. From analysis of high throughput RNA sequencing datasets of Gene Expression Omnibus and ArrayExpress, a positive correlation between ppGalNAc-T4 and the recurrence-free survival was observed in multigroup of human breast cancer datasets. Moreover, transcriptomes analysis using RNA-sequencing in MCF7 cells revealed that cell cycle-related genes induced the effects of ppGalNAc-T4 on breast cancer cell proliferation. Additionally, investigations showed that ppGalNAc-T4 impaired cell proliferation in MCF-7 and MDA-MB-231 breast cells. Furthermore, our results suggested that the ppGalNAc-T4 knockout activated Notch signaling pathway and enhanced cell proliferation. Collectively, our data indicated that ppGalNAc-T4 affected the proliferation of human breast cancer cells, which appears to be a novel target for understanding the underlying molecular mechanism of breast cancer.

Sweet Control: MicroRNA Regulation of the Glycome

Glycosylation is a sophisticated informational system that controls specific biological functions at the cellular and organismal level. Dysregulation of glycosylation may underlie some of the most complex and common diseases of the modern era. In the past 5 years, microRNAs have come to the forefront as a critical regulator of the glycome. Herein, we review the current literature on miRNA regulation of glycosylation and how this work may point to a new way to identify the biological importance of glycosylation enzymes.

Hepatitis C Virus-Induced FUT8 Causes 5-FU Drug Resistance in Human Hepatoma Huh7.5.1 Cells

Hepatitis C virus (HCV) is a major cause of human chronic liver disease and hepatocellular carcinoma. Our recent studies showed that α1,6-fucosyltransferase (FUT8), a key glycosyltransferase, was the most up-regulated glycosyltransferase after the HCV infection of human hepatocellular carcinoma Huh7.5.1 cells. Here, we further studied the effects and possible mechanism of FUT8 on the proliferation of HCV and chemotherapy-resistance of HCV-infected Huh7.5.1 cells. The effects of FUT8 on the proliferation and drug resistance of HCV-infected Huh7.5.1 cells were analyzed by flow cytometry analysis (FCM), quantitative real-time polymerase chain reaction (qRT-PCR), Western blot analysis and lactate dehydrogenase (LDH) release assay. Results: We found that FUT8 not only promoted Huh7.5.1 proliferation by activating PI3K-AKT-NF-κB signaling, but also stimulated the expression of the drug-resistant proteins P-glycoprotein (P-gp) and multidrug resistance related protein 1 (MRP1) and enhanced the 5-fluorouracil (5-FU) chemo-resistance of Huh7.5.1 cells. Silencing of FUT8 reduced the cell proliferation and increased the 5-FU sensitivity of HCV-infected Huh7.5.1 cells. Inhibition of P-gp and MRP1 increased the 5-FU drug sensitivity in HCV infected Huh7.5.1 cells. HCV-induced FUT8 promotes proliferation and 5-FU resistance of Huh7.5.1 cells. FUT8 may serve as a therapeutic target to reverse chemotherapy resistance in HCV-infected Huh7.5.1 cells.

The polypeptide N-acetylgalactosaminyltransferase 4 exhibits stage-dependent expression in colorectal cancer and affects tumorigenesis, invasion and differentiation

The aberrant expression of mucin-type O-glycosylation plays important roles in cancer malignancy. The polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts) are a family of conserved enzymes that initiate the mucin-type O-glycosylation in cells. In human, consistent up- or down-regulation of ppGalNAc-Ts expression during cancer development has been frequently reported. Here, we provide evidence that ppGalNAc-T4 shows a stage-dependent expression at the different stages of colorectal cancer (CRC) in the 62 pair-matched tumor/normal tissues. In detail, ppGalNAc-T4 expression is significantly induced at stage I and II but not at stage III and IV. Overexpression of ppGalNAc-T4 in CRC cells enhances colony formation and sphere formation suggesting an important role of ppGalNAc-T4 in tumorigenesis. Conversely, knockdown of ppGalNAc-T4 in CRC cells increases the cell migration and invasion, and leads to an epithelial-mesenchymal transition-like transition. Further analysis suggests that loss of ppGalNAc-T4 contributes to the dedifferentiation of CRC and high expression of ppGalNAc-T4 correlates to a good prognosis of patients. Taken together, our results not only demonstrate a stage-dependent expression of ppGalNAc-T4 in CRC progression, but also suggest that such stage-dependent expression may contribute to the tumorigenesis at the early stage and promote cell migration and invasion at the advanced stage.

Organelle Specific O-Glycosylation Drives MMP14 Activation, Tumor Growth, and Metastasis

Cancers grow within tissues through molecular mechanisms still unclear. Invasiveness correlates with perturbed O-glycosylation, a covalent modification of cell-surface proteins. Here, we show that, in human and mouse liver cancers, initiation of O-glycosylation by the GALNT glycosyl-transferases increases and shifts from the Golgi to the endoplasmic reticulum (ER). In a mouse liver cancer model, expressing an ER-targeted GALNT1 (ER-G1) massively increased tumor expansion, with median survival reduced from 23 to 10 weeks. In vitro cell growth was unaffected, but ER-G1 strongly enabled matrix degradation and tissue invasion. Unlike its Golgi-localized counterpart, ER-G1 glycosylates the matrix metalloproteinase MMP14, a process required for tumor expansion. Together, our results indicate that GALNTs strongly promote liver tumor growth after relocating to the ER.

Prognostic value of microRNAs in hepatocellular carcinoma: a meta-analysis

Background

Numerous articles reported that dysregulated expression levels of miRNAs correlated with survival time of HCC patients. However, there has not been a comprehensive meta-analysis to evaluate the accurate prognostic value of miRNAs in HCC.

Design

Meta-analysis.

Materials and Methods

Studies, published in English, estimating expression levels of miRNAs with any survival curves in HCC were identified up until 15 April, 2017 by performing online searches in PubMed, EMBASE, Web of Science and Cochrane Database of Systematic Reviews by two independent authors. The pooled hazard ratios (HR) with 95% confidence intervals (CI) were used to estimate the correlation between miRNA expression and overall survival (OS).

Results

54 relevant articles about 16 miRNAs, with 6464 patients, were ultimately included. HCC patients with high expression of tissue miR-9 (HR = 2.35, 95% CI = 1.46–3.76), miR-21 (HR = 1.76, 95% CI = 1.29–2.41), miR-34c (HR = 1.64, 95% CI = 1.05–2.57), miR-155 (HR = 2.84, 95% CI = 1.46–5.51), miR-221 (HR = 1.76, 95% CI = 1.02–3.04) or low expression of tissue miR-22 (HR = 2.29, 95% CI = 1.63–3.21), miR-29c (HR = 1.35, 95% CI = 1.10–1.65), miR-34a (HR = 1.84, 95% CI = 1.30–2.59), miR-199a (HR = 2.78, 95% CI = 1.89–4.08), miR-200a (HR = 2.64, 95% CI = 1.86–3.77), miR-203 (HR = 2.20, 95% CI = 1.61–3.00) have significantly poor OS (P < 0.05). Likewise, HCC patients with high expression of blood miR-21 (HR = 1.73, 95% CI = 1.07–2.80), miR-192 (HR = 2.42, 95% CI = 1.15–5.10), miR-224 (HR = 1.56, 95% CI = 1.14–2.12) or low expression of blood miR-148a (HR = 2.26, 95% CI = 1.11–4.59) have significantly short OS (P < 0.05).

Conclusions

In conclusion, tissue miR-9, miR-21, miR-22, miR-29c, miR-34a, miR-34c, miR-155, miR-199a, miR-200a, miR-203, miR-221 and blood miR-21, miR-148a, miR-192, miR-224 demonstrate significantly prognostic value. Among them, tissue miR-9, miR-22, miR-155, miR-199a, miR-200a, miR-203 and blood miR-148a, miR-192 are potential prognostic candidates for predicting OS in HCC.

Epigenetic Bases of Aberrant Glycosylation in Cancer

In this review, the sugar portions of glycoproteins, glycolipids, and glycosaminoglycans constitute the glycome, and the genes involved in their biosynthesis, degradation, transport and recognition are referred to as “glycogenes“. The extreme complexity of the glycome requires the regulatory layer to be provided by the epigenetic mechanisms. Almost all types of cancers present glycosylation aberrations, giving rise to phenotypic changes and to the expression of tumor markers. In this review, we discuss how cancer-associated alterations of promoter methylation, histone methylation/acetylation, and miRNAs determine glycomic changes associated with the malignant phenotype. Usually, increased promoter methylation and miRNA expression induce glycogene silencing. However, treatment with demethylating agents sometimes results in silencing, rather than in a reactivation of glycogenes, suggesting the involvement of distant methylation-dependent regulatory elements. From a therapeutic perspective aimed at the normalization of the malignant glycome, it appears that miRNA targeting of cancer-deranged glycogenes can be a more specific and promising approach than the use of drugs, which broad target methylation/acetylation. A very specific type of glycosylation, the addition of GlcNAc to serine or threonine (O-GlcNAc), is not only regulated by epigenetic mechanisms, but is an epigenetic modifier of histones and transcription factors. Thus, glycosylation is both under the control of epigenetic mechanisms and is an integral part of the epigenetic code.