High Glucose Stimulates Tumorigenesis in Hepatocellular Carcinoma Cells Through AGER-Dependent O-GlcNAcylation of c-Jun

Tumor suppressive role of the antimicrobial lectin REG3A targeting the O -GlcNAc glycosylation pathway

BACKGROUND AND AIMS

Antimicrobial proteins of the regenerating family member 3 alpha (REG3A) family provide a first line of protection against infections and transformed cells. Their expression is inducible by inflammation, which makes their role in cancer biology less clear since an immune-inflammatory context may preexist or coexist with cancer, as occurs in HCC. The aim of this study is to clarify the role of REG3A in liver carcinogenesis and to determine whether its carbohydrate-binding functions are involved.

APPROACH AND RESULTS

This study provides evidence for a suppressive role of REG3A in HCC by reducing O -GlcNAcylation in 2 mouse models of HCC, in vitro cell studies, and clinical samples. REG3A expression in hepatocytes significantly reduced global O -GlcNAcylation and O -GlcNAcylation of c-MYC in preneoplastic and tumor livers and markedly inhibited HCC development in REG3A-c-MYC double transgenic mice and mice exposed to diethylnitrosamine. REG3A modified O -GlcNAcylation without altering the expression or activity of O-linked N-acetylglucosaminyltransferase, O-linked N-acetylglucosaminyl hydrolase, or glutamine fructose-6-phosphate amidotransferase. Reduced O -GlcNAcylation was consistent with decreased levels of UDP-GlcNAc in precancerous and cancerous livers. This effect was linked to the ability of REG3A to bind glucose and glucose-6 phosphate, suggested by a REG3A mutant unable to bind glucose and glucose-6 phosphate and alter O -GlcNAcylation. Importantly, patients with cirrhosis with high hepatic REG3A expression had lower levels of O -GlcNAcylation and longer cancer-free survival than REG3A-negative cirrhotic livers.

CONCLUSIONS

REG3A helps fight liver cancer by reducing O -GlcNAcylation. This study suggests a new paradigm for the regulation of O -GlcNAc signaling in cancer-related pathways through interactions with the carbohydrate-binding function of REG3A.

Biological Functions and Potential Therapeutic Significance of O-GlcNAcylation in Hepatic Cellular Stress and Liver Diseases

O-linked-β-D-N-acetylglucosamine (O-GlcNAc) glycosylation (O-GlcNAcylation), which is dynamically regulated by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), is a post-translational modification involved in multiple cellular processes. O-GlcNAcylation of proteins can regulate their biological functions via crosstalk with other post-translational modifications, such as phosphorylation, ubiquitination, acetylation, and methylation. Liver diseases are a major cause of death worldwide; yet, key pathological features of the disease, such as inflammation, fibrosis, steatosis, and tumorigenesis, are not fully understood. The dysregulation of O-GlcNAcylation has been shown to be involved in some severe hepatic cellular stress, viral hepatitis, liver fibrosis, nonalcoholic fatty acid liver disease (NAFLD), malignant progression, and drug resistance of hepatocellular carcinoma (HCC) through multiple molecular signaling pathways. Here, we summarize the emerging link between O-GlcNAcylation and hepatic pathological processes and provide information about the development of therapeutic strategies for liver diseases.

Protein O-GlcNAcylation: The sweet hub in liver metabolic flexibility from a (patho)physiological perspective

O-GlcNAcylation is a dynamic, reversible and atypical O-glycosylation that regulates various cellular physiological processes via conformation, stabilisation, localisation, chaperone interaction or activity of target proteins. The O-GlcNAcylation cycle is precisely controlled by collaboration between O-GlcNAc transferase and O-GlcNAcase. Uridine-diphosphate-N-acetylglucosamine, the sole donor of O-GlcNAcylation produced by the hexosamine biosynthesis pathway, is controlled by the input of glucose, glutamine, acetyl coenzyme A and uridine triphosphate, making it a sensor of the fluctuation of molecules, making O-GlcNAcylation a pivotal nutrient sensor for the metabolism of carbohydrates, amino acids, lipids and nucleotides. O-GlcNAcylation, particularly prevalent in liver, is the core hub for controlling systemic glucose homeostasis due to its nutritional sensitivity and precise spatiotemporal regulation of insulin signal transduction. The pathology of various liver diseases has highlighted hepatic metabolic disorder and dysfunction, and abnormal O-GlcNAcylation also plays a specific pathological role in these processes. Therefore, this review describes the unique features of O-GlcNAcylation and its dynamic homeostasis maintenance. Additionally, it explains the underlying nutritional sensitivity of O-GlcNAcylation and discusses its mechanism of spatiotemporal modulation of insulin signal transduction and liver metabolic homeostasis during the fasting and feeding cycle. This review emphasises the pathophysiological implications of O-GlcNAcylation in nonalcoholic fatty liver disease, nonalcoholic steatohepatitis and hepatic fibrosis, and focuses on the adverse effects of hyper O-GlcNAcylation on liver cancer progression and metabolic reprogramming.

Synovium is a sensitive tissue for mapping the negative effects of systemic iron overload in osteoarthritis: identification and validation of two potential targets

BACKGROUND

The prevention and treatment of osteoarthritis (OA) pose a major challenge in its research. The synovium is a critical tissue in the systematic treatment of OA. The present study aimed to investigate potential target genes and their correlation with iron overload in OA patients.

METHODS

The internal datasets for analysis included the microarray datasets GSE46750, GSE55457, and GSE56409, while the external datasets for validation included GSE12021 and GSE55235. The GSE176308 dataset was used to generate single-cell RNA sequencing profiles. To investigate the expression of the target genes in synovial samples, quantitative reverse transcription-PCR, western blotting, and immunohistochemical assay were conducted. ELISA was used to detect the levels of ferritin and Fe2+ in both serum and synovium.

RESULTS

JUN and ZFP36 were screened from the differentially expressed genes, and their mRNA were significantly reduced in the OA synovium compared to that in normal synovium. Subsequently, complex and dynamically evolving cellular components were observed in the OA synovium. The mRNA level of JUN and ZFP36 differed across various cell clusters of OA synovium and correlated with immune cell infiltration. Moreover, ferritin and Fe2+ were significantly increased in the serum and synovium of OA patients. Further, we found that JUN elevated and ZFP36 decreased at protein level.

CONCLUSIONS

The synovium is a sensitive tissue for mapping the adverse effects of systemic iron overload in OA. JUN and ZFP36 represent potential target genes for attenuating iron overload during OA treatment. Some discrepancies between the transcription and protein levels of JUN suggest that post-transcriptional modifications may be implicated. Future studies should also focus on the roles of JUN and ZFP36 in inducing changes in cellular components in the synovium during OA pathogenesis.

A robust activatable two-photon fluorescent probe for endogenous formaldehyde biomarker visualization diagnosis and evaluation of diabetes mellitus

Diabetes mellitus and its complications are one of the largest healthcare burdens in the world and are increasing every year. However, the lack of effective biomarkers and non-invasive real-time monitoring tools remains a great challenge for the early diagnosis of diabetes mellitus. Endogenous formaldehyde (FA) represents a key reactive carbonyl species in biological systems, and altered metabolism and functions of FA have been closely related to the pathogenesis and maintenance of diabetes. Among various noninvasive biomedical imaging techniques, the identification-responsive fluorescence (FL) imaging could greatly benefit the comprehensive multi-scale assessment of some diseases such as diabetes. Herein, we have designed a robust activatable two-photon probe DM-FA for the first highly selective monitoring of fluctuations in FA levels during diabetes mellitus. Through the density functional theory (DFT) theoretical calculations, we elucidated the rationality of the activatable fluorescent probe DM-FA turning on the FL before and after the reaction with FA. In addition, DM-FA has excellent high selectivity, high growth factor and good photostability in the process of recognizing FA. Due to the brilliant two-photon and one-photon FL imaging capabilities of DM-FA, it has been successfully used to visualize of exogenous and endogenous FA in cells and mice. Remarkably, as a powerful FL imaging visualization tool, DM-FA was introduced for the first time to visually diagnose and explore diabetes through the fluctuation of FA content. The successful application of DM-FA in two-photon and one-photon FL imaging experiments found elevated FA levels in high glucose-stimulated diabetic cell models. We successfully visualized upregulation of FA levels in diabetic mice and decreased of FA levels in diabetic mice scavenged by NaHSO₃ from multiple perspectives using multiple imaging modalities. This work may provide a novel strategy for the initial diagnosis of diabetes mellitus and the evaluation of the efficacy of drug therapy for treating diabetes mellitus, which will likely have a positive impact on clinical medicine.

The association between alcohol consumption and the risk of hepatocellular carcinoma according to glycemic status in Korea: A nationwide population-based study

BACKGROUND

Alcohol and diabetes are known risk factors for hepatocellular carcinoma (HCC); however, it is unclear whether the association between alcohol consumption and HCC risk differs by fasting serum glucose level and diabetes. We investigated the dose-response relationship between alcohol consumption and the risk of HCC according to glycemic status.

METHODS AND FINDINGS

This population-based observational cohort study included patients who underwent general health checkups in 2009 using the Korean National Health Insurance Service Database. The primary outcome was HCC incidence, and Cox proportional hazard regression analysis was performed to estimate the relationship between alcohol consumption and HCC risk according to glycemic status. A total of 34,321 patients newly diagnosed with HCC were observed in the median follow-up period of 8.3 years. In the multivariable model, we adjusted for age, sex, smoking, regular exercise, income, hypertension, dyslipidemia, and body mass index. Mild-to-moderate alcohol consumption increased the risk of HCC in all glycemic statuses (normoglycemia: hazard ratio [HR], 1.06; 95% confidence interval [CI], 1.02 to 1.10; prediabetes: HR, 1.19; 95% CI, 1.14 to 1.24; and diabetes: HR, 2.02; 95% CI, 1.93 to 2.11) compared to normoglycemic nondrinking. Heavy alcohol consumption also increased the risk of HCC in all glycemic statuses (normoglycemia: HR, 1.39; 95% CI, 1.32 to 1.46; prediabetes: HR, 1.67; 95% CI, 1.58 to 1.77; and diabetes: HR, 3.29; 95% CI, 3.11 to 3.49) compared to normoglycemic nondrinking. Since alcohol consumption information in this study was based on a self-administered questionnaire, there may be a possibility of underestimation. Although we excluded patients with a history of viral hepatitis using diagnosis codes, we could not obtain information on hepatitis B or hepatitis C serum markers.

CONCLUSIONS

Both mild-to-moderate and heavy alcohol consumption was associated with an increased risk of HCC in all glycemic statuses. The increased risk of HCC according to alcohol consumption was the highest in the diabetes group, suggesting that more intensive alcohol abstinence is required for patients with diabetes.

Ameliorative Effect of Posidonia oceanica on High Glucose-Related Stress in Human Hepatoma HepG2 Cells

Metabolic disorders characterized by elevated blood glucose levels are a recognized risk factor for hepatocellular carcinoma (HCC). Lipid dysregulation is critically involved in the HCC progression, regulating energy storage, metabolism, and cell signaling. There is a clear link between de novo lipogenesis in the liver and activation of the NF-κB pathway, which is involved in cancer metastasis via regulation of metalloproteinases MMP-2/9. As conventional therapies for HCC reach their limits, new effective and safe drugs need to be found for the prevention and/or adjuvant therapy of HCC. The marine plant Posidonia oceanica (L.) Delile is endemic to the Mediterranean and has traditionally been used to treat diabetes and other health disorders. The phenol-rich leaf extract of Posidonia oceanica (POE) is known to have cell-safe bioactivities. Here, high glucose (HG) conditions were used to study lipid accumulation and fatty acid synthase (FASN) expression in human HepG2 hepatoma cells using Oil Red O and Western blot assays. Under HG conditions, the activation status of MAPKs/NF-κB axis and MMP-2/9 activity were determined by Western blot and gelatin zymography assays. The potential ameliorative role of POE against HG-related stress in HepG2 cells was then investigated. POE reduced lipid accumulation and FASN expression with an impact on de novo lipogenesis. Moreover, POE inhibited the MAPKs/NF-κB axis and, consequently, MMP-2/9 activity. Overall, these results suggest that P. oceanica may be a potential weapon in the HCC additional treatment.

Dysregulation of hexosamine biosynthetic pathway wiring metabolic signaling circuits in cancer

Metabolite sensing, a fundamental biological process, plays a key role in metabolic signaling circuit rewiring. Hexosamine biosynthetic pathway (HBP) is a glucose metabolic pathway essential for the synthesis of uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), which senses key nutrients and integrally maintains cellular homeostasis. UDP-GlcNAc dynamically regulates protein N-glycosylation and O-linked-N-acetylglucosamine modification (O-GlcNAcylation). Dysregulated HBP flux leads to abnormal protein glycosylation, and contributes to cancer development and progression by affecting protein function and cellular signaling. Furthermore, O-GlcNAcylation regulates cellular signaling pathways, and its alteration is linked to various cancer characteristics. Additionally, recent findings have suggested a close association between HBP stimulation and cancer stemness; an elevated HBP flux promotes cancer cell conversion to cancer stem cells and enhances chemotherapy resistance via downstream signal activation. In this review, we highlight the prominent roles of HBP in metabolic signaling and summarize the recent advances in HBP and its downstream signaling, relevant to cancer.

O-GlcNAcylation: an important post-translational modification and a potential therapeutic target for cancer therapy

O-linked β-d-N-acetylglucosamine (O-GlcNAc) is an important post-translational modification of serine or threonine residues on thousands of proteins in the nucleus and cytoplasm of all animals and plants. In eukaryotes, only two conserved enzymes are involved in this process. O-GlcNAc transferase is responsible for adding O-GlcNAc to proteins, while O-GlcNAcase is responsible for removing it. Aberrant O-GlcNAcylation is associated with a variety of human diseases, such as diabetes, cancer, neurodegenerative diseases, and cardiovascular diseases. Numerous studies have confirmed that O-GlcNAcylation is involved in the occurrence and progression of cancers in multiple systems throughout the body. It is also involved in regulating multiple cancer hallmarks, such as metabolic reprogramming, proliferation, invasion, metastasis, and angiogenesis. In this review, we first describe the process of O-GlcNAcylation and the structure and function of O-GlcNAc cycling enzymes. In addition, we detail the occurrence of O-GlcNAc in various cancers and the role it plays. Finally, we discuss the potential of O-GlcNAc as a promising biomarker and novel therapeutic target for cancer diagnosis, treatment, and prognosis.

The O-GlcNAcylation and its promotion to hepatocellular carcinoma

O-GlcNAcylation is a posttranslational modification that attaches O-linked β-N-acetylglucosamine (O-GlcNAc) to the serine and threonine residues of proteins. Such a glycosylation would alter the activities, stabilities, and interactions of target proteins that are functional in a wide range of biological processes and diseases. Accumulating evidence indicates that O-GlcNAcylation is tightly associated with hepatocellular carcinoma (HCC) in its onset, growth, invasion and metastasis, drug resistance, and stemness. Here we summarize the discoveries of the role of O-GlcNAcylation in HCC and its function mechanism, aiming to deepen our understanding of HCC pathology, generate more biomarkers for its diagnosis and prognosis, and offer novel molecular targets for its treatment.

Context dependent isoform specific PI3K inhibition confers drug resistance in hepatocellular carcinoma cells

BACKGROUND

Targeted therapies for Primary liver cancer (HCC) is limited to the multi-kinase inhibitors, and not fully effective due to the resistance to these agents because of the heterogeneous molecular nature of HCC developed during chronic liver disease stages and cirrhosis. Although combinatorial therapy can increase the efficiency of targeted therapies through synergistic activities, isoform specific effects of the inhibitors are usually ignored. This study concentrated on PI3K/Akt/mTOR pathway and the differential combinatory bioactivities of isoform specific PI3K-α inhibitor (PIK-75) or PI3K-β inhibitor (TGX-221) with Sorafenib dependent on PTEN context.

METHODS

The bioactivities of inhibitors on PTEN adequate Huh7 and deficient Mahlavu cells were investigated with real time cell growth, cell cycle and cell migration assays. Differentially expressed genes from RNA-Seq were identified by edgeR tool. Systems level network analysis of treatment specific pathways were performed with Prize Collecting Steiner Tree (PCST) on human interactome and enriched networks were visualized with Cytoscape platform.

RESULTS

Our data from combinatory treatment of Sorafenib and PIK-75 and TGX-221 showed opposite effects; while PIK-75 displays synergistic effects on Huh7 cells leading to apoptotic cell death, Sorafenib with TGX-221 display antagonistic effects and significantly promotes cell growth in PTEN deficient Mahlavu cells. Signaling pathways were reconstructed and analyzed in-depth from RNA-Seq data to understand mechanism of differential synergistic or antagonistic effects of PI3K-α (PIK-75) and PI3K-β (TGX-221) inhibitors with Sorafenib. PCST allowed as to identify AOX1 and AGER as targets in PI3K/Akt/mTOR pathway for this combinatory effect. The siRNA knockdown of AOX1 and AGER significantly reduced cell proliferation in HCC cells.

CONCLUSIONS

Simultaneously constructed and analyzed differentially expressed cellular networks presented in this study, revealed distinct consequences of isoform specific PI3K inhibition in PTEN adequate and deficient liver cancer cells. We demonstrated the importance of context dependent and isoform specific PI3K/Akt/mTOR signaling inhibition in drug resistance during combination therapies. ( https://github.com/cansyl/Isoform-spesific-PI3K-inhibitor-analysis ).

Highly Efficient Enrichment of O-GlcNAc Glycopeptides Based on Chemical Oxidation and Reversible Hydrazide Chemistry

Protein O-GlcNAcylation has been implicated in a broad range of cellular processes, while the functional research is still lagging behind other post-translational modification (PTMs), as a result of the low stoichiometry and limited enrichment efficiency. Herein, a strategy, named CHO-GlcNAc, was developed for O-GlcNAc glycopeptide enrichment. In this strategy, the O-GlcNAc glycopeptides were first enzymatically labeled with a Gal moiety, followed by chemical oxidation to efficiently introduce the aldehyde groups. The labeled O-GlcNAc glycopeptides could be efficiently enriched based on the equilibrium between the hydrazine and oxime bonds. Good specificity of the glycopeptide enrichment was observed from the mixtures of glycopeptide and non-glycopeptides using the CHO-GlcNAc method. Then, it was applied to analyze O-GlcNAcylation in the nucleus of HeLa cells, and 829 potential O-GlcNAcylation sites on 274 glycoproteins were identified, including the two readers of m6A (YTHDF1 and YTHDF3), which could provide clues for the mechanism of crosstalk between O-GlcNAcylation and other PTMs of proteins and RNA. Thus, this method could be a versatile tool for the proteomic analysis of O-GlcNAcylation.

Transcriptional Repression of Ferritin Light Chain Increases Ferroptosis Sensitivity in Lung Adenocarcinoma

Ferroptosis is an iron- and lipid peroxidation-dependent form of regulated cell death. The release of labile iron is one of the important factors affecting sensitivity to ferroptosis. Yes-associated protein (YAP) controls intracellular iron levels by affecting the transcription of ferritin heavy chain (FTH) and transferrin receptor (TFRC). However, whether YAP regulates iron metabolism through other target genes remains unknown. Here, we observed that the system Xc^– inhibitor erastin inhibited the binding of the WW domain and PSY motif between YAP and transcription factor CP2 (TFCP2), and then suppressed the transcription of ferritin light chain (FTL) simultaneously mediated by YAP, TFCP2 and forkhead box A1 (FOXA1). Furthermore, inhibition of FTL expression abrogated ferroptosis-resistance in cells with sustained YAP expression. Unlike FTH, which exhibited first an increase and then a decrease in transcription, FTL transcription continued to decline after the addition of erastin, and a decrease in lysine acetyltransferase 5 (KAT5)-dependent acetylation of FTL was also observed. In lung adenocarcinoma (LUAD) tissues, lipid peroxidation and labile iron decreased, while YAP, TFCP2 and FTL increased compared to their adjacent normal tissues, and the lipid peroxidation marker 4-hydroxynonenal (4-HNE) was negatively correlated with the level of FTL or the degree of LUAD malignancy, but LUAD tissues with lower levels of 4-HNE showed a higher sensitivity to ferroptosis. In conclusion, the findings from this study indicated that the suppression of FTL transcription through the inhibition of the YAP-TFCP2-KAT5 complex could be another mechanism for elevating ferroptosis sensitivity and inducing cell death, and ferroptotic therapy is more likely to achieve better results in LUAD patients with a lower degree of lipid peroxidation.

Genetics, Immunity and Nutrition Boost the Switching from NASH to HCC

Nonalcoholic fatty liver disease (NAFLD) is the leading contributor to the global burden of chronic liver diseases. The phenotypic umbrella of NAFLD spans from simple and reversible steatosis to nonalcoholic steatohepatitis (NASH), which may worsen into cirrhosis and hepatocellular carcinoma (HCC). Notwithstanding, HCC may develop also in the absence of advanced fibrosis, causing a delayed time in diagnosis as a consequence of the lack of HCC screening in these patients. The precise event cascade that may precipitate NASH into HCC is intricate and it entails diverse triggers, encompassing exaggerated immune response, endoplasmic reticulum (ER) and oxidative stress, organelle derangement and DNA aberrancies. All these events may be accelerated by both genetic and environmental factors. On one side, common and rare inherited variations that affect hepatic lipid remodeling, immune microenvironment and cell survival may boost the switching from steatohepatitis to liver cancer, on the other, diet-induced dysbiosis as well as nutritional and behavioral habits may furtherly precipitate tumor onset. Therefore, dietary and lifestyle interventions aimed to restore patients' health contribute to counteract NASH progression towards HCC. Even more, the combination of therapeutic strategies with dietary advice may maximize benefits, with the pursuit to improve liver function and prolong survival.

Ferroptosis as a new therapeutic opportunity for nonviral liver disease

Nonviral liver disease is a global public health problem due to its high mortality and morbidity. However, its underlying mechanism is unclear. Ferroptosis is a novel form of cell death that is involved in a variety of disease processes. Both abnormal iron metabolism (e.g., iron overload) and lipid peroxidation, which is induced by deletion of glutathione (GSH) or glutathione peroxidase 4 (GPX4), and the accumulation of polyunsaturated fatty acid-containing phospholipids (PUFA-PLs) trigger ferroptosis. Recently, ferroptosis has been involved in the pathological process of nonviral liver diseases [including alcohol-related liver disease (ALD); nonalcoholic fatty liver disease (NAFLD); hereditary hemochromatosis (HH); drug-, ischemia/reperfusion- or immune-induced liver injury; liver fibrosis; and liver cancer]. Hepatocyte ferroptosis is activated in ALD; NAFLD; HH; drug-, ischemia/reperfusion- or immune-induced liver injury; and liver fibrosis, whereas hepatic stellate cell and liver cancer cell ferroptosis are inhibited in liver fibrosis and liver cancer, respectively. Thus, ferroptosis is an ideal target for nonviral liver diseases. In the present review, we discuss the latest findings on ferroptosis and potential drugs targeting ferroptosis for nonviral liver diseases. This review will highlight further directions for the treatment and prevention of nonviral liver diseases.

Corosolic acid inhibits cancer progression by decreasing the level of CDK19-mediated O-GlcNAcylation in liver cancer cells

Diabetes is an important risk factor for liver cancer, but its mechanism is unknown. Corosolic acid (CA) has been proven to have both hypoglycemic and antitumor effects, so revealing the function of CA can help us understand the relationship between diabetes and liver cancer. In previous studies, we confirmed that CA can effectively inhibit the expression of YAP, an important oncoprotein in HCC cells, and the proliferation of HCC cells. In addition, we also found that O-GlcNAcylation plays an indispensable role in HCC tumorigenesis. However, it is not clear whether CA can inhibit the effect of O-GlcNAcylation on HCC cells. In this study, the antitumor ability of CA was investigated by inhibiting the O-GlcNAcylation level and its corresponding mechanism. The results showed that HG (high glucose) could promote the proliferation of liver cancer cells, while CA could inhibit cell growth under HG conditions and tumor growth in a xenotransplantation model. CA can inhibit the activation of the HBP pathway and reduce the expression of YAP and OGT under HG conditions. Importantly, we found that CA can reduce YAP expression and O-GlcNAcylation by inhibiting the activity of CDK19. Overexpression of CDK19 partially reversed the CA-induced decrease in YAP and O-GlcNAcylation. This is the first evidence that CA can reduce the proliferative capacity of cells with high glucose levels and further inhibit tumor growth by inactivating the CDK19/YAP/O-GlcNAcylation pathway, suggesting that CA is a candidate drug for the development of treatments against diabetes-associated liver cancer.

Loss of TARBP2 Drives the Progression of Hepatocellular Carcinoma via miR-145-SERPINE1 Axis

The clinical outcomes of hepatocellular carcinoma (HCC) remain dismal. Elucidating the molecular mechanisms for the progression of aggressive HCC holds the promise for developing novel intervention strategies. The transactivation response element RNA-binding protein (TRBP/TARBP2), a key component of microRNA (miRNA) processing and maturation machinery has been shown to play conflicting roles in tumor development and progression. We sought to investigate the expression of TARBP2 in HCC using well-characterized HCC cell lines, patient-derived tissues and blood samples. Additionally, the potential prognostic and diagnostic value of TARBP2 in HCC were analyzed using Kaplan-Meier plots and ROC curve. Cell counting kit-8 (CCK-8), wound healing and transwell assays examined the ability of TARBP2 to induce cell proliferation, migration, and invasion in HCC cell lines. RNA sequencing was applied to identify the downstream elements of TARBP2. The interaction of potential targets of TARBP2, miR-145 and serpin family E member 1 (SERPINE1), was assessed using luciferase reporter assay. TARBP2 expression was down-regulated in HCC cell lines relative to normal hepatocyte cells, with a similar pattern further confirmed in tissue and blood samples. Notably, the loss of TARBP2 was demonstrated to promote proliferation, migration, and invasion in HCC cell lines. Interestingly, the reduction of TARBP2 was shown to result in the upregulation of SERPINE1, also known as plasminogen activator inhibitor (PAI-1), which is a vital gene of the HIF-1 signaling pathway. Knockdown of SERPINE1 rescued the TARBP2-lost phenotype. Moreover, TARBP2 depletion induced the upregulation of SERPINE1 through reducing the processing of miR-145, which directly targets SERPINE1. Finally, overexpression of miR-145 repressed SERPINE1 and rescued the functions in sh-TARBP2 HCC cells. Our findings underscore a linear TARBP2-miR-145-SERPINE1 pathway that drives HCC progression, with the potential as a novel intervention target for aggressive HCC.

Target protein deglycosylation in living cells by a nanobody-fused split O-GlcNAcase

O-linked N-acetylglucosamine (O-GlcNAc) is an essential and dynamic post-translational modification that is presented on thousands of nucleocytoplasmic proteins. Interrogating the role of O-GlcNAc on a single target protein is crucial, yet challenging to perform in cells. Herein, we developed a nanobody-fused split O-GlcNAcase (OGA) as an O-GlcNAc eraser for selective deglycosylation of a target protein in cells. After systematic cellular optimization, we identified a split OGA with reduced inherent deglycosidase activity that selectively removed O-GlcNAc from the desired target protein when directed by a nanobody. We demonstrate the generality of the nanobody-fused split OGA using four nanobodies against five target proteins and use the system to study the impact of O-GlcNAc on the transcription factors c-Jun and c-Fos. The nanobody-directed O-GlcNAc eraser provides a new strategy for the functional evaluation and engineering of O-GlcNAc via the selective removal of O-GlcNAc from individual proteins directly in cells.

Glucose Variability and Risk of Hepatocellular Carcinoma in Patients with Diabetes: A Nationwide Population-Based Study

BACKGROUND

Although diabetes is a well-known risk factor for hepatocellular carcinoma, exactly which metabolic parameters of diabetes are associated with hepatocellular carcinoma remain unexplored. In this study, we investigated the relationship between glucose variability (GV) and hepatocellular carcinoma in patients with diabetes through a nationwide population-based study.

METHODS

A population-based cohort study including 674,178 diabetic subjects participating in more than three health examinations within 5 years from the index year (2009 and 2010) were followed until the end of 2017. The coefficient of variation, SD, variability independent of the mean, and average real variability were calculated as GV indices.

RESULTS

During a median follow-up of 6.7 years, there were 5,494 cases of hepatocellular carcinoma. When groups were classified according to glucose level, the highest risk for hepatocellular carcinoma was observed when the basal blood glucose level was 180 mg/dL or greater [adjusted HR (aHR), 1.19; 95% confidence interval (CI), 1.08-1.31]. We observed increasing trends for the relationship between GV and hepatocellular carcinoma in multivariable Cox proportional analyses. The risk of hepatocellular carcinoma increased by 27% (aHR, 1.27; 95% CI, 1.17-1.38) for the highest quartile of GV relative to the lowest quartile. These findings were consistent regardless of the presence of chronic viral hepatitis or cirrhosis, alcohol consumption, or body mass index.

CONCLUSIONS

GV was an independent predictor of hepatocellular carcinoma, even after adjusting for confounding factors. There was a linear relationship between increase in GV and prevalence of hepatocellular carcinoma.

IMPACT

Visit-to-visit GV might be helpful for identifying patients with diabetes at high risk of hepatocellular carcinoma.

Natural Progression of Non-Alcoholic Steatohepatitis to Hepatocellular Carcinoma

Non-alcoholic steatohepatitis (NASH) is a chronic and progressive form of non-alcoholic fatty liver disease (NAFLD). Its global incidence is increasing which makes NASH an epidemic and a public health threat. Due to repeated insults to the liver, patients are at risk for developing hepatocellular carcinoma (HCC). The progression of NASH to HCC was initially defined according to a two-hit model which involved the development of steatosis, followed by lipid peroxidation and inflammation. However, current research defines a “multi-hit” or “multi-parallel hit” model which synthesizes several contributing pathways involved in progressive fibrosis and oncogenesis. This perspective considers the effects of cellular, genetic, immunologic, metabolic, and endocrine pathways leading up to HCC which underscores the complexity of this condition. This article will provide an updated review of the pathogenic mechanisms leading from NASH to HCC as well as an exploration of the role of biomarkers and screening.

Metabolic alterations and vulnerabilities in hepatocellular carcinoma

Liver cancer is a serious disease. It is ranked as the cancer with the second highest number of cancer-related deaths worldwide. Hepatocellular carcinoma (HCC), which arises from transformed hepatocytes, is the major subtype of liver cancer. It accounts for 85% of total liver-cancer cases. An important aspect of HCC that has been actively studied is its metabolism. With the liver as the primary site of numerous metabolic processes in the body, it has been shown that the metabolism of HCC cells is highly dysregulated compared to that of normal hepatocytes. It is therefore crucial to understand the metabolic alterations caused by HCC and the underlying mechanisms for these alterations. This deeper understanding will allow diagnostic and therapeutic advancements in the treatment of HCC. In this review, we will summarize the current literature in HCC metabolic alterations, induced vulnerabilities, and potential therapeutic interventions.

The role of RAGE in host pathology and crosstalk between RAGE and TLR4 in innate immune signal transduction pathways

Although the innate immune receptor protein, Receptor for Advanced Glycation End products (RAGE), has been extensively studied, there has been renewed interest in RAGE for its potential role in sepsis, along with a host of other inflammatory diseases of chronic, noninfectious origin. In contrast to other innate immune receptors, for example, Toll-like receptors (TLRs), that recognize ligands derived from pathogenic organisms that are collectively known as "pathogen-associated molecular patterns" (PAMPs) or host-derived "damage-associated molecular patterns" (DAMPs), RAGE has been shown to recognize a broad collection of DAMPs exclusively. Historically, these DAMPs have been shown to be pro-inflammatory in nature. Early studies indicated that the adaptor molecule, MyD88, might be important for this change. More recent studies have explored further the mechanisms underlying this inflammatory change. Overall, the newer results have shown that there is extensive crosstalk between RAGE and TLRs. The three canonical RAGE ligands, Advanced Glycation End products (AGEs), HMGB1, and S100 proteins, have all been shown to activate both TLRs and RAGE to varying degrees in order to induce inflammation in in vitro models. As with any field that delves deeply into innate signaling, obstacles of reagent purity may be a cause of some of the discrepancies in the literature, and we have found that commercial antibodies that have been widely used exhibit a high degree of nonspecificity. Nonetheless, the weight of published evidence has led us to speculate that RAGE may be physically interacting with TLRs on the cell surface to elicit inflammation via MyD88-dependent signaling.

The Liver Microbiome Is Implicated in Cancer Prognosis and Modulated by Alcohol and Hepatitis B

Hepatocellular carcinoma (HCC) is one of the deadliest cancers in the world. Previous studies have identified the importance of alcohol and hepatitis B (HBV) infection on HCC carcinogenesis, indicating synergy in the methods by which these etiologies advance cancer. However, the specific molecular mechanism behind alcohol and HBV-mediated carcinogenesis remains unknown. Because the microbiome is emerging as a potentially important regulator of cancer development, this study aims to classify the effects of HBV and alcohol on the intratumoral liver microbiome. RNA-sequencing data from The Cancer Genome Atlas (TCGA) were used to infer microbial abundance. This abundance was then correlated to clinical variables and to cancer and immune-associated gene expression, in order to determine how microbial abundance may contribute to differing cancer progression between etiologies. We discovered that the liver microbiome is likely oncogenic after exposure to alcohol or HBV, although these etiological factors could decrease the abundance of a few oncogenic microbes, which would lead to a tumor suppressive effect. In HBV-induced tumors, this tumor suppressive effect was inferred based on the downregulation of microbes that induce cancer and stem cell pathways. Alcohol-induced tumors were observed to have distinct microbial profiles from HBV-induced tumors, and different microbes are clinically relevant in each cohort, suggesting that the effects of the liver microbiome may be different in response to different etiological factors. Collectively, our data suggest that HBV and alcohol operate within a normally oncogenic microbiome to promote tumor development, but are also able to downregulate certain oncogenic microbes. Insight into why these microbes are downregulated following exposure to HBV or alcohol, and why the majority of oncogenic microbes are not downregulated, may be critical for understanding whether a pro-tumor liver microbiome could be suppressed or reversed to limit cancer progression.

The positive feedback between ACSL4 expression and O-GlcNAcylation contributes to the growth and survival of hepatocellular carcinoma

Acyl-CoA ligase 4 (ACSL4) has been reported to be overexpressed in hepatocellular carcinoma (HCC) and to enhance cell proliferation. However, the molecular mechanisms underlying the role of ACSL4 in HCC progression remain largely unclear. Here, we aimed to investigate whether and how O-GlcNAcylation and ACSL4 regulate each other and HCC progression. The clinical significance of ACSL4, O-GlcNAc and GLUT1 in HCC was determined by Pearson chi-squared test and Kaplan-Meier analysis. CCK-8, flow cytometry and in vivo tumour formation assays were performed to detect cell proliferation, apoptosis and tumorigenesis. IP technology was used to evaluate the relationship between ACSL4 and O-GlcNAc. ACSL4, GLUT1 and O-GlcNAc levels were elevated in HCC tissues and predicted poor prognosis in HCC patients. ACSL4 overexpression significantly promoted cell proliferation and tumorigenesis and inhibited cell apoptosis, whereas these effects were all obviously impaired when mTOR signalling was repressed or GLUT1 was downregulated. ACSL4 could be O-GlcNAcylated, and silencing of ACSL4 abolished the effects of O-GlcNAcylation on cell growth promotion and apoptosis inhibition. Collectively, this study demonstrates that ACSL4 contributes to the growth and survival of HCC by enhancing GLUT1-mediated O-GlcNAcylation. In turn, O-GlcNAcylation promotes HCC growth partially by increasing ACSL4 expression.

Corosolic Acid Inhibits Cancer Progress Through Inactivating YAP in Hepatocellular Carcinoma

Chemotherapy is critical for the treatment of hepatocellular carcinoma (HCC). Despite the proapoptotic effects of corosolic acid (CA) treatment, its underlying mechanism is not completely clear. The aim of this study was to determine the molecular mechanism of CA in HCC treatment. MTT assay was used to determine the IC₅₀ of CA. Immunoprecipitation and immunofluorescence were used to detect the interaction and subcellular localization of Yes-associated protein (YAP) and mouse double minute 2 (MDM2). In addition, in vivo xenotransplantation was performed to assess the effects of CA, YAP, and MDM2 on tumorigenesis. The IC₅₀ of CA was about 40 μM in different HCC cell lines, and CA decreased YAP expression by reducing its stability and increasing its ubiquitination. CA treatment and MDM2 overexpression significantly decreased the crosstalk between YAP and cAMP-responsive element-binding protein (CREB), TEA domain transcription factor (TEAD), and Runt-related transcription factor 2 (Runx2). CA stimulation promoted the translocation of YAP and MDM2 from the nucleus to the cytoplasm and increased their binding. In addition, CA treatment obviously reduced tumorigenesis, whereas this effect was abolished when cells were transfected with sh-MDM2 or Vector-YAP. The present study uncovered that CA induced cancer progress repression through translocating YAP from the nucleus in HCC, which might provide a new therapeutic target for HCC.

Integrating Chinese and Western medicines reduced the incidence of hepatocellular carcinoma in patients with diabetes mellitus: A Taiwanese population-based cohort study

OBJECTIVES

Much epidemiological evidence links diabetes mellitus (DM) to the development of multiple cancers and, in particular, the development of hepatocellular carcinoma (HCC). The aim of this study was to investigate whether Chinese herbal medicine (CHM) reduces the incidence of HCC in patients receiving Western antidiabetic drugs.

INTERVENTIONS AND MAIN OUTCOME MEASURES

This retrospective cohort study used data from the National Health Insurance Research Database involving 81,105 diabetic patients, including 5122 CHM users and 25,966 non-CHM users. Analyses of treatment effects were adjusted for covariates including gender, age, comorbidities, antidiabetic drugs and liver medications. NodeXL software performed a network analysis to identify the 50 most commonly used CHM herbs and formulas.

RESULTS

In Cox proportional hazards models adjusted for demographic and clinical characteristics, DM patients exposed to adjuvant CHM therapy were significantly less likely to develop HCC compared with non-CHM users (adjusted hazard ratio [aHR] 0.59; 95 % confidence interval [CI], 0.41-0.87; p = 0.01). Kaplan-Meier analysis revealed a lower 10-year cumulative risk of HCC among CHM users compared with non-CHM users. Amongst the 10 individual CHM herbs and herbal formulas most commonly prescribed for DM, the most frequent were Salvia miltiorrhiza (Dan Shen) and Liu Wei Di Huang Wan, respectively.

CONCLUSION

This nationwide retrospective cohort study from Taiwan provides some valuable insights into the prescribing characteristics of CHM treatment in patients with DM. Compared with use of Western antidiabetic medications alone, use of adjuvant CHM effectively reduces the incidence of HCC in patients with DM.

Identification of biomarkers, pathways and potential therapeutic agents for white adipocyte insulin resistance using bioinformatics analysis

For the better understanding of insulin resistance (IR), the molecular biomarkers in IR white adipocytes and its potential mechanism, we downloaded two mRNA expression profiles from Gene Expression Omnibus (GEO). The white adipocyte samples in two databases were collected from the human omental adipose tissue of IR obese (IRO) subjects and insulin-sensitive obese (ISO) subjects, respectively. We identified 86 differentially expressed genes (DEGs) between the IRO and ISO subjects using limma package in R software. Gene Set Enrichment Analysis (GSEA) provided evidence that the most gene sets enriched in kidney mesenchyme development in the ISO subjects, as compared with the IRO subjects. The Gene Ontology (GO) analysis indicated that the most significantly enriched in cellular response to interferon-gamma. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the DEGs were most significantly enriched in cytokine-cytokine receptor interaction. Protein–Protein Interaction (PPI) network was performed with the STRING, and the top 10 hub genes were identified with the Cytohubba. CMap analysis found several small molecular compounds to reverse the altered DEGs, including dropropizine, aceclofenac, melatonin, and so on. Our outputs could empower the novel potential targets to treat omental white adipocyte insulin resistance, diabetes, and diabetes-related diseases.

Metabolic rearrangements in primary liver cancers: cause and consequences

Primary liver cancer (PLC) is the fourth most frequent cause of cancer-related death. The high mortality rates arise from late diagnosis and the limited accuracy of diagnostic and prognostic biomarkers. The liver is a major regulator, orchestrating the clearance of toxins, balancing glucose, lipid and amino acid uptake, managing whole-body metabolism and maintaining metabolic homeostasis. Tumour onset and progression is frequently accompanied by rearrangements of metabolic pathways, leading to dysregulation of metabolism. The limitation of current therapies targeting PLCs, such as hepatocellular carcinoma and cholangiocarcinoma, points towards the importance of deciphering this metabolic complexity. In this Review, we discuss the role of metabolic liver disruptions and the implications of these processes in PLCs, emphasizing their clinical relevance and value in early diagnosis and prognosis and as putative therapeutic targets. We also describe system biology approaches able to reconstruct the metabolic complexity of liver diseases. We also discuss whether metabolic rearrangements are a cause or consequence of PLCs, emphasizing the opportunity to clinically exploit the rewired metabolism. In line with this idea, we discuss circulating metabolites as promising biomarkers for PLCs.

Global profiling of O-GlcNAcylated and/or phosphorylated proteins in hepatoblastoma

O-linked-β-N-acetylglucosamine (O-GlcNAc) glycosylation (O-GlcNAcylation) and phosphorylation are critical posttranslational modifications that are involved in regulating the functions of proteins involved in tumorigenesis and the development of various solid tumors. However, a detailed characterization of the patterns of these modifications at the peptide or protein level in hepatoblastoma (HB), a highly malignant primary hepatic tumor with an extremely low incidence in children, has not been performed. Here, we examined O-GlcNAc-modified or phospho-modified peptides and proteins in HB through quantitative proteomic analysis of HB tissues and paired normal liver tissues. Our results identified 114 O-GlcNAcylated peptides belonging to 78 proteins and 3494 phosphorylated peptides in 2088 proteins. Interestingly, 41 proteins were modified by both O-GlcNAcylation and phosphorylation. These proteins are involved in multiple molecular and cellular processes, including chromatin remodeling, transcription, translation, transportation, and organelle organization. In addition, we verified the accuracy of the proteomics results and found a competitive inhibitory effect between O-GlcNAcylation and phosphorylation of HSPB1. Further, O-GlcNAcylation modification of HSPB1 promoted proliferation and enhanced the chemotherapeutic resistance of HB cell lines in vitro. Collectively, our research suggests that O-GlcNAc-modified and/or phospho-modified proteins may play a crucial role in the pathogenesis of HB.

O-GlcNAcylated c-Jun antagonizes ferroptosis via inhibiting GSH synthesis in liver cancer

Ferroptosis is a metabolism-related cell death. Stimulating ferroptosis in liver cancer cells is a strategy to treat liver cancer. However, how to eradicate liver cancer cells through ferroptosis and the obstacles to inducing ferroptosis in liver cancer remain unclear. Here, we observed that erastin suppressed the malignant phenotypes of liver cancer cells by inhibiting O-GlcNAcylation of c-Jun and further inhibited protein expression, transcription activity and nuclear accumulation of c-Jun. Overexpression of c-Jun-WT with simultaneous PuGNAc treatment conversely inhibited erastin-induced ferroptosis, whereas overexpression of c-Jun-WT alone or overexpression of c-Jun-S73A (a non-O-GlcNAcylated form of c-Jun) with PuGNAc treatment did not exert a similar effect. GSH downregulation induced by erastin was restored by overexpression of c-Jun-WT with simultaneous PuGNAc treatment. In addition, overexpression of c-Jun-WT, but not its S73A mutant, induced PSAT1 and CBS transcription via directly binding to their promoter regions, suggesting that GSH synthesis is regulated by O-GlcNAcylated c-Jun. A positive correlation between c-Jun O-GlcNAcylation and GSH was observed in clinical samples. Collectively, O-GlcNAcylated c-Jun represents an obstructive factor to ferroptosis, and targeting O-GlcNAcylated c-Jun might be helpful for treating liver cancer.

O-GlcNAc Transferase Inhibition Differentially Affects Breast Cancer Subtypes

Post-translational modification of intracellular proteins with a single N-acetylglucosamine sugar (O-GlcNAcylation) regulates signaling, proliferation, metabolism and protein stability. In breast cancer, expression of the enzyme that catalyzes O-GlcNAcylation – O-GlcNAc-transferase (OGT), and the extent of protein O-GlcNAcylation, are upregulated in tumor tissue, and correlate with cancer progression. Here we compare the significance of O-GlcNAcylation in a panel of breast cancer cells of different phenotypes. We find a greater dependency on OGT among triple-negative breast cancer (TNBC) cell lines, which respond to OGT inhibition by undergoing cell cycle arrest and apoptosis. Searching for the cause of this response, we evaluate the changes in the proteome that occur after OGT inhibition or knock-down, employing a reverse-phase protein array (RPPA). We identify transcriptional repressor - hairy and enhancer of split-1 (HES1) - as a mediator of the OGT inhibition response in the TNBC cells. Inhibition of OGT as well as the loss of HES1 results in potent cytotoxicity and apoptosis. The study raises a possibility of using OGT inhibition to potentiate DNA damage in the TNBC cells.

ILF2 Directly Binds and Stabilizes CREB to Stimulate Malignant Phenotypes of Liver Cancer Cells

Cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) is overexpressed and has an oncogenic role in hepatocellular carcinoma (HCC). Interleukin enhancer binding factor 2 (ILF2) has become research hotspot in liver cancer recently. However, it is still unclear whether and how CREB and ILF2 interact with each other. And how this interaction exerts its role in occurrence and development of liver cancer is still unclear. Here, we found that ILF2 directly bound with CREB, and this binding was essential for the malignant phenotypes of liver cancer cells. Moreover, we found that ILF2 acted as one of the upstream proteins of CREB and promoted CREB only in the protein level, whereas ILF2 expression was not regulated by CREB. Mechanistically, ILF2 bound to the pKID domain of CREB and stimulated its phosphorylation at Ser133. Taken together, our study finds a novel interaction between CREB and ILF2 in liver cancer, and this interaction might play a role in the diagnosis and remedy of liver cancer.

High Glucose-Induced ROS Production Stimulates Proliferation of Pancreatic Cancer via Inactivating the JNK Pathway

Aberrant glucose metabolism of diabetes mellitus or hyperglycemia stimulates pancreatic tumorigenesis and progression. Hyperglycemic environment can increase the ROS level of tumors, but the role of upregulation of ROS levels in pancreatic cancer (PC) still remains controversial. Here, the same as other reports, we demonstrate that high glucose promoted pancreatic cancer cell growth and resulted in an increase in the level of ROS. However, it is interesting that the phosphorylation of JNK was reduced. When treating PC cells with N-acetyl-L-cysteine (NAC), the intracellular ROS generation is repressed, but the expression of phosphorylation of JNK and c-Jun increased. Moreover, the JNK inhibitor SP600125 significantly promoted cell proliferation and suppressed cell apoptosis of pancreatic cancer cells under high glucose conditions. Collectively, high levels of ROS induced by high glucose conditions stimulated the proliferation of pancreatic cancer cells, and it may be achieved by inactivating the JNK pathway.

Aberrant Metabolism in Hepatocellular Carcinoma Provides Diagnostic and Therapeutic Opportunities

Hepatocellular carcinoma (HCC) accounts for over 80% of liver cancer cases and is highly malignant, recurrent, drug-resistant, and often diagnosed in the advanced stage. It is clear that early diagnosis and a better understanding of molecular mechanisms contributing to HCC progression is clinically urgent. Metabolic alterations clearly characterize HCC tumors. Numerous clinical parameters currently used to assess liver functions reflect changes in both enzyme activity and metabolites. Indeed, differences in glucose and acetate utilization are used as a valid clinical tool for stratifying patients with HCC. Moreover, increased serum lactate can distinguish HCC from normal subjects, and serum lactate dehydrogenase is used as a prognostic indicator for HCC patients under therapy. Currently, the emerging field of metabolomics that allows metabolite analysis in biological fluids is a powerful method for discovering new biomarkers. Several metabolic targets have been identified by metabolomics approaches, and these could be used as biomarkers in HCC. Moreover, the integration of different omics approaches could provide useful information on the metabolic pathways at the systems level. In this review, we provided an overview of the metabolic characteristics of HCC considering also the reciprocal influences between the metabolism of cancer cells and their microenvironment. Moreover, we also highlighted the interaction between hepatic metabolite production and their serum revelations through metabolomics researches.

circRNA_104075 stimulates YAP-dependent tumorigenesis through the regulation of HNF4a and may serve as a diagnostic marker in hepatocellular carcinoma

Some types of circular RNA (circRNA) are aberrantly expressed in human diseases including hepatocellular carcinoma (HCC). However, its regulation mechanism and diagnostic roles are largely unknown. Here, we identified that circRNA_104075 (circ_104075) was highly expressed in HCC tissues, cell lines and serum. Mechanistically, HNF4a bound to the -1409 to -1401 region of the circ_104075 promoter to stimulate the expression of circ_104075. Moreover, circ_104075 acted as a ceRNA to upregulate YAP expression by absorbing miR-582-3p. Interestingly, an N6-methyladenosine (m6A) motif was identified in the 353-357 region of YAP 3'UTR, and this m6A modification was essential for the interaction between miR-582-3p and YAP 3'UTR. Further, the diagnostic performance of circ_104075 was evaluated. The area under the receiver operating characteristic (AUC-ROC) for circ_104075 was 0.973 with a sensitivity of 96.0% and a specificity of 98.3%. Collectively, we determined that circ_104075 was highly expressed in HCC and elucidated its upstream and downstream regulatory mechanisms. circ_104075 additionally has the potential to serve as a new diagnostic biomarker in HCC. Targeting circ_104075 may provide new strategies in HCC diagnosis and therapy.

High glucose stimulates proliferative capacity of liver cancer cells possibly via O-GlcNAcylation-dependent transcriptional regulation of GJC1

Although it is generally accepted that diabetes is one of the most important risk factors for liver cancer, the underlying mechanism is still not well understood. The purpose of the current study is to further investigate how high concentrations of glucose (HG), a major symptom of diabetes, stimulate the development of liver malignancy. Using data mining, gap junction protein gamma 1 (GJC1) was identified as a critical proto-oncoprotein that is essential for the HG stimulation of proliferative capacity in liver cancer cells. Furthermore, enhanced transcriptional expression of GJC1 might occur after stimulation by HG. A transcription factor zinc finger protein 410 (APA1)-binding motif was found to be located at the -82 to -77 nt region within the GJC1 promoter. Without APA1, HG was unable to increase GJC1 expression. Interestingly, APA1, but not GJC1, can be O-GlcNAcylated in liver cancer cells. Moreover, O-GlcNAcylation is essential for HG-induced APA1 binding to the GJC1 promoter. Notably, global O-GlcNAcylation and expression of APA1 and GJC1 were highly elevated in liver cancer patients with diabetes compared to those in patients without diabetes. The HG-stimulated proliferative capacity was abolished upon decreasing O-GlcNAcylation, which could be reversed gradually by the simultaneous overexpression of APA1 and GJC1. Therefore, GJC1 could be a potential target for preventing liver cancer in patients with diabetes.

Neuropilin 1 (NRP1) is a novel tumor marker in hepatocellular carcinoma

BACKGROUND

TEA domain transcription factor (TEAD) has an oncogenic role in hepatocellular carcinoma (HCC). However, whether a membrane protein can serve not only as a tumor marker that reflects TEAD function but also as a therapeutic target that stimulates tumorigenesis in HCC remains unknown.

METHODS

Tissue NRP1 was measured using immunohistochemistry. Cell viability, colony formation and caspase3/7 activity were assessed using MTT, soft agar and caspase 3/7 Glo assays, respectively. Serum NRP1 was examined using ELISA and Western blotting.

RESULTS

NRP1 expression was up-regulated by TEAD. We also identified a conserved TEAD-binding motif in the NRP1 promoters, which was essential for the TEAD-NRP1 interaction. NRP1 was upregulated in HCC tissues and cell lines, and knockdown of NRP1 inhibited the transformative phenotypes of HCC cells. Notably, the concentrations of serum NRP1 in the HCC patients were much higher than those of hepatitis B, hepatitis C, cirrhosis, breast cancer, colon cancer, gastric cancer and lung cancer patients. Moreover, serum NRP1 was significantly associated with AFP, γ-GT, Alb, bile acid, ALT, AST, ALP and pre-Alb. The area under the receiver operating characteristic curve (AUC-ROC) for serum NRP1 was 0.971, presenting better diagnostic performance compared to AFP.

CONCLUSIONS

NRP1 is a novel tumor marker in HCC.

Mapping and Quantification of Over 2000 O-linked Glycopeptides in Activated Human T Cells with Isotope-Targeted Glycoproteomics (Isotag)

Post-translational modifications (PTMs) on proteins often function to regulate signaling cascades, with the activation of T cells during an adaptive immune response being a classic example. Mounting evidence indicates that the modification of proteins by O-linked N-acetylglucosamine (O-GlcNAc), the only mammalian glycan found on nuclear and cytoplasmic proteins, helps regulate T cell activation. Yet, a mechanistic understanding of how O-GlcNAc functions in T cell activation remains elusive, partly because of the difficulties in mapping and quantifying O-GlcNAc sites. Thus, to advance insight into the role of O-GlcNAc in T cell activation, we performed glycosite mapping studies via direct glycopeptide measurement on resting and activated primary human T cells with a technique termed Isotope Targeted Glycoproteomics. This approach led to the identification of 2219 intact O-linked glycopeptides across 1045 glycoproteins. A significant proportion (>45%) of the identified O-GlcNAc sites lie near or coincide with a known phosphorylation site, supporting the potential for PTM crosstalk. Consistent with other studies, we find that O-GlcNAc sites in T cells lack a strict consensus sequence. To validate our results, we employed gel shift assays based on conjugating mass tags to O-GlcNAc groups. Notably, we observed that the transcription factors c-JUN and JUNB show higher levels of O-GlcNAc glycosylation and higher levels of expression in activated T cells. Overall, our findings provide a quantitative characterization of O-GlcNAc glycoproteins and their corresponding modification sites in primary human T cells, which will facilitate mechanistic studies into the function of O-GlcNAc in T cell activation.

The association between fasting blood glucose and the risk of primary liver cancer in Chinese males: a population-based prospective study

BACKGROUND

To investigate the association between fasting blood glucose (FBG) levels and the risk of incident primary liver cancer (PLC) in Chinese males, a large prospective cohort was performed in the current study.

METHODS

A total of 109 169 males participating in the routine checkups every two years were recruited in the Kailuan male cohort study since May 2006. Cox proportional hazards regression models and restricted cubic spline (RCS) were used to evaluate the association between levels of baseline FBG and the risk of incident PLC.

RESULTS

Compared to the males with normal FBG (3.9⩽FBG<6.1 mmol l^-1), the males with impaired fasting glucose (IFG: 6.1⩽FBG<7.0 mmol l^-1) and diabetes mellitus (DM: FBG ⩾7.0 mmol l^-1) had a 60% (95% CI: 1.09-2.35) and a 58% (95% CI: 1.07-2.34) higher risk of incident PLC, respectively. Subgroup analysis found that IFG increased the risk of PLC among the non-smoker (HR=1.73, 95% CI: 1.01-2.98) and current alcohol drinker (HR=1.80, 95% CI: 1.03-3.16). While DM increased the risk of PLC especially among the males with normal BMI (<25 kg m^-2) (HR=1.76, 95% CI: 1.05-2.94) and the HBV negativity (HR=1.89, 95% CI: 1.16-3.09), RCS analysis showed a positive non-linearly association between the FBG levels and the risk of PLC (p-overall=0.041, p-non-linear=0.049).

CONCLUSIONS

Increased FBG may be an important and potentially modifiable exposure that could have key scientific and clinical importance for preventing PLC development.

Augmented TME O-GlcNAcylation Promotes Tumor Proliferation through the Inhibition of p38 MAPK

O-GlcNAcylation is a dynamic O-linked glycosylation event that plays a crucial role in regulating cellular signaling. Recent studies indicate that increased O-GlcNAcylation is a general feature in cancer and contributes to various cancer phenotypes, including cell proliferation, survival, invasion, metastasis, and energy metabolism. However, the role of O-GlcNAcylation in the tumor microenvironment (TME) is not fully elucidated. Here, B16 melanoma cells were subcutaneously transplanted into O-GlcNAc transferase transgenic (Ogt-Tg) mice exhibiting elevated O-GlcNAcylation to examine the effect of O-GlcNAcylation in the TME on tumor progression. In this model system, B16 tumor growth was significantly higher in Ogt-Tg/+ mice compared with wild-type (WT) mice. The tumors grown in Ogt-Tg/+ mice showed significant downregulation of p38 MAPK activity and upregulation of the ERK1/2 signaling pathway. In addition, proinflammatory cytokine production was significantly lower in the tumor tissues from Ogt-Tg/+ mice than in those from WT mice. Activation of NF-κB, a key regulator in the cytokine production, was downregulated in the macrophages of the tumor tissues grown in Ogt-Tg/+ mice. These data reveal that elevated O-GlcNAcylation in the TME reduces the production of inflammatory cytokines and promotes cancer progression through downregulation of p38 MAPK activity and subsequent upregulation of the ERK1/2 signaling pathway.Implications: The reduced production of inflammatory cytokines by augmented O-GlcNAcylation in the TME, mainly macrophages, promotes tumor proliferation through the inhibition of p38 MAPK and suggests a possible cause of increased morbidity and mortality rates for various cancers in diabetic patients. Mol Cancer Res; 15(9); 1287-98. ©2017 AACR.

The essential role of YAP O-GlcNAcylation in high-glucose-stimulated liver tumorigenesis

O-GlcNAcylation has been implicated in the tumorigenesis of various tissue origins, but its function in liver tumorigenesis is not clear. Here, we demonstrate that O-GlcNAcylation can enhance the expression, stability and function of Yes-associated protein (YAP), the downstream transcriptional regulator of the Hippo pathway and a potent oncogenic factor in liver cancer. O-GlcNAcylation induces transformative phenotypes of liver cancer cells in a YAP-dependent manner. An O-GlcNAc site of YAP was identified at Thr241, and mutating this site decreased the O-GlcNAcylation, stability, and pro-tumorigenic capacities of YAP, while increasing YAP phosphorylation. Importantly, we found via in vitro cell-based and in vivo mouse model experiments that O-GlcNAcylation of YAP was required for high-glucose-induced liver tumorigenesis. Interestingly, a positive feedback between YAP and global cellular O-GlcNAcylation is also uncovered. We conclude that YAP O-GlcNAcylation is a potential therapeutic intervention point for treating liver cancer associated with high blood glucose levels and possibly diabetes.

Yap is a transcriptional factor involved in tumorigenesis. Here the authors show that a previously unknown post-translational modification of Yap, O-GlcNAcylation, increases its transcriptional activity and is required for high glucose-induced liver cancer development.