cGAS Mediates Inflammation by Polarizing Macrophages to M1 Phenotype via the mTORC1 Pathway.

Cyclic GMP-AMP synthase (cGAS), as a cytosolic DNA sensor, plays a crucial role in antiviral immunity, and its overactivation induces excess inflammation and tissue damage. Macrophage polarization is critically involved in inflammation; however, the role of cGAS in macrophage polarization during inflammation remains unclear. In this study, we demonstrated that cGAS was upregulated in the LPS-induced inflammatory response via the TLR4 pathway, and cGAS signaling was activated by mitochondria DNA in macrophages isolated from C57BL/6J mice. We further demonstrated that cGAS mediated inflammation by acting as a macrophage polarization switch, which promoted peritoneal macrophages and the bone marrow-derived macrophages to the inflammatory phenotype (M1) via the mitochondrial DNA-mTORC1 pathway. In vivo studies verified that deletion of Cgas alleviated sepsis-induced acute lung injury by promoting macrophages to shift from the M1 phenotype to the M2 phenotype. In conclusion, our study demonstrated that cGAS mediated inflammation by regulating macrophage polarization through the mTORC1 pathway, and it further provided a potential therapeutic strategy for inflammatory diseases, especially sepsis-induced acute lung injury.

TRIM50 promotes NLRP3 inflammasome activation by directly inducing NLRP3 oligomerization.

Tripartite motif protein (TRIM) 50 is a new member of the tripartite motif family, and its biological function and the molecular mechanism it is involved in remain largely unknown. The NOD-like receptor family protein (NLRP)3 inflammasome is actively involved in a wide array of biological processes while mechanisms of its regulation remain to be fully clarified. Here, we demonstrate the role of TRIM50 in NLRP3 inflammasome activation. In contrast to the conventional E3 ligase functions of TRIM proteins, TRIM50 mediates direct oligomerization of NLRP3, thereby suppressing its ubiquitination and promoting inflammasome activation. Mechanistically, TRIM50 directly interacts with NLRP3 through its RING domain and induces NLRP3 oligomerization via its coiled-coil domain. Finally, we show that TRIM50 promotes NLRP3 inflammasome-mediated diseases in mice. We thus reveal a novel regulatory mechanism of NLRP3 via TRIM50 and suggest that modulating TRIM50 might represent a therapeutic strategy for NLRP3-dependent pathologies.

Nuclear cGAS suppresses DNA repair and promotes tumorigenesis.

Accurate repair of DNA double-stranded breaks by homologous recombination preserves genome integrity and inhibits tumorigenesis. Cyclic GMP-AMP synthase (cGAS) is a cytosolic DNA sensor that activates innate immunity by initiating the STING-IRF3-type I IFN signalling cascade1,2. Recognition of ruptured micronuclei by cGAS links genome instability to the innate immune response3,4, but the potential involvement of cGAS in DNA repair remains unknown. Here we demonstrate that cGAS inhibits homologous recombination in mouse and human models. DNA damage induces nuclear translocation of cGAS in a manner that is dependent on importin-α, and the phosphorylation of cGAS at tyrosine 215-mediated by B-lymphoid tyrosine kinase-facilitates the cytosolic retention of cGAS. In the nucleus, cGAS is recruited to double-stranded breaks and interacts with PARP1 via poly(ADP-ribose). The cGAS-PARP1 interaction impedes the formation of the PARP1-Timeless complex, and thereby suppresses homologous recombination. We show that knockdown of cGAS suppresses DNA damage and inhibits tumour growth both in vitro and in vivo. We conclude that nuclear cGAS suppresses homologous-recombination-mediated repair and promotes tumour growth, and that cGAS therefore represents a potential target for cancer prevention and therapy.

Notch4 Negatively Regulates the Inflammatory Response to Mycobacterium tuberculosis Infection by Inhibiting TAK1 Activation.

Tuberculosis, caused by Mycobacterium tuberculosis infection, remains a global threat to human health, but knowledge of the molecular mechanisms underlying the pathogenesis of tuberculosis is still limited. Although Notch4, a member of the Notch receptor family, is involved in the initiation of mammary tumors, its function in M. tuberculosis infection remains unclear. In this study, we found that Notch4-deficient mice were more resistant to M. tuberculosis infection, with a much lower bacterial burden and fewer pathological changes in the lungs. Notch4 inhibited M. tuberculosis-induced production of proinflammatory cytokines by interaction with TAK1 and inhibition of its activation. Furthermore, we found that Notch intracellular domain 4 prevented TRAF6 autoubiquitination and suppressed TRAF6-mediated TAK1 polyubiquitination. Finally, Notch inhibitors made mice more resistant to M. tuberculosis infection. These results suggest that Notch4 is a negative regulator of M. tuberculosis-induced inflammatory response, and treatment with a Notch inhibitor could serve as a new therapeutic strategy for tuberculosis.

Combination of MicroRNAs and Cytokines: a Method for Better Evaluation of Acute-on-Chronic Liver Failure.

BACKGROUND: The aim was to establish expression profiles of microRNAs (miRNAs) in Peripheral Blood Mononuclear Cells (PBMC) and of plasma cytokines from the patients with hepatitis B virus related acute-on-chronic liver failure (HBV-ACLF) and high-risk of acute-on-chronic liver failure (ACLF) patients as well as healthy people and to examine the relationships between these profiles and clinical features. METHODS: Herein, we collected PBMCs and plasma from peripheral blood of HBV-ACLF and ACLF patients as well as healthy people. Microarray, real-time qPCR, and ELISA assays were used. RESULTS: In this study, we found 39 miRNAs including miR-146a, miR-150, and miR-29a downregulated and 5 miRNAs elevated in PBMCs from HBV-ACLF patients compared to healthy controls. However, elevated plasma levels of cytokines such as TNF-α, IFN-α, and TGF-ß were found in PBMCs from HBV-ACLF patients compared with the controls, but no significant difference was found between the high-risk and control groups. MiR-146a, miR-150, miR-29a, PTA, and anti-HBc were positively correlated with the survival of ACLF patients, while TNFα, IFN-α, INR, and TBiL were negatively correlated with the survival of these patients. CONCLUSIONS: Combined examination of miRNAs in PBMCs and cytokines in plasma together is a better method for monitoring and evaluating HBV-ACLF patients.

Simultaneous quantification of two steroidal glycosides after oral gavage of Marsdenia tenacissima extract in rats using a LC-MS/MS method.

A specific, sensitive and accurate analytical LC-MS/MS assay was developed for the simultaneous determination of two steroidal glycosides, tenacissoside H and tenacissoside I, in rat plasma. An Agilent ZORBAX SB-C18 column was used with an isocratic mobile phase system composed of methanol-water-formic acid (70:30:0.1, v/v/v) at a flow rate of 0.3 mL/min. The analysis was performed on a positive ionization electrospray mass spectrometer via selected reaction monitoring mode scan. One-step protein precipitation with acetonitrile was chosen to extract the analytes from plasma. The lower limits of quantification were 0.9 ng/mL for tenacissoside H and tenacissoside I. The intra- and inter-day precisions were 2.03-11.56 and 3.76-11.62%, respectively, and the accuracies were <110.28% at all quality control levels. The validated method was applied to a pharmacokinetic study in rats after oral gavage of Marsdenia tenacissima extract.

Identification of the shared molecular mechanisms between major depressive disorder and COVID-19 from postmortem brain transcriptome analysis.

OBJECTIVES: This study aims to investigate the molecular mechanisms underlying the interaction of major depressive disorder (MDD) and COVID-19, and on this basis, diagnostic biomarkers and potential therapeutic drugs are further explored. METHODS: Differential gene expression analysis and weighted gene co-expression network analysis (WGCNA) were employed to identify common key genes involved in the pathogenesis of COVID-19 and MDD. Correlations with clinical features were explored. Detailed mechanisms were further investigated through protein interaction networks, GSEA, and immune cell infiltration analysis. Finally, Enrichr's Drug Signature Database and Coremine Medical were used to predict the potential drugs associated with key genes. RESULTS: The study identified 18 genes involved in both COVID-19 and MDD. Four key genes (MBP, CYP4B1, ERMN, and SLC26A7) were selected based on clinical relevance. A multi-gene prediction model showed good diagnostic efficiency for the two diseases: AUC of 0.852 for COVID-19 and 0.915 for MDD. GO and GSEA analyses identified specific biological functions and pathways associated with key genes in COVID-19 (axon guidance, metabolism, stress response) and MDD (neuron ensheathment, biosynthesis, glutamatergic neuron differentiation). The key genes also affected immune infiltration. Potential therapeutic drugs, including small molecules and traditional Chinese medicines, targeting these genes were identified. CONCLUSION: This study provides insights into the complex biological mechanisms underlying COVID-19 and MDD, develops an effective diagnostic model, and predicts potential therapeutic drugs, which may contribute to the prevention and treatment of these two prevalent diseases.

cGAS suppresses hepatocellular carcinoma independent of its cGAMP synthase activity.

Cyclic GMP-AMP synthase (cGAS) is a key innate immune sensor that recognizes cytosolic DNA to induce immune responses against invading pathogens. The role of cGAS is conventionally recognized as a nucleotidyltransferase to catalyze the synthesis of cGAMP upon recognition of cytosolic DNA, which leads to the activation of STING and production of type I/III interferon to fight against the pathogen. However, given that hepatocytes are lack of functional STING expression, it is intriguing to define the role of cGAS in hepatocellular carcinoma (HCC), the liver parenchymal cells derived malignancy. In this study, we revealed that cGAS was significantly downregulated in clinical HCC tissues, and its dysregulation contributed to the progression of HCC. We further identified cGAS as an immune tyrosine inhibitory motif (ITIM) containing protein, and demonstrated that cGAS inhibited the progression of HCC and increased the response of HCC to sorafenib treatment by suppressing PI3K/AKT/mTORC1 pathway in cellular and animal models. Mechanistically, cGAS recruits SH2-containing tyrosine phosphatase 1 (SHP1) via ITIM, and dephosphorylates p85 in phosphatidylinositol 3-kinase (PI3K), which leads to the suppression of AKT-mTORC1 pathway. Thus, cGAS is identified as a novel tumor suppressor in HCC via its function independent of its conventional role as cGAMP synthase, which indicates a novel therapeutic strategy for advanced HCC by modulating cGAS signaling.

Impact of peptic ulcer bleeding on the in-hospital outcomes of cirrhotic patients with acute gastrointestinal bleeding: an international multicenter study.

OBJECTIVES: Peptic ulcer is the most common source of non-variceal bleeding. However, it remains controversial whether the outcomes of cirrhotic patients with peptic ulcer bleeding differ from those with variceal bleeding. METHODS: Cirrhotic patients with acute gastrointestinal bleeding (AGIB) who underwent endoscopy and had an identifiable source of bleeding were retrospectively screened from an international multicenter cohort. Logistic regression analyses were performed to explore the impact of peptic ulcer bleeding on in-hospital death and 5-day failure to control bleeding. Propensity score matching (PSM) analysis was performed by matching age, gender, Child-Pugh score, and model for end-stage liver disease score between the peptic ulcer bleeding and variceal bleeding groups. RESULTS: Overall, 1535 patients were included, of whom 73 (4.7%) had peptic ulcer bleeding. Multivariate logistic regression analyses showed that peptic ulcer bleeding was not independently associated with in-hospital death (OR = 2.169, p = 0.126) or 5-day failure to control bleeding (OR = 1.230, p = 0.680). PSM analyses demonstrated that both in-hospital mortality (9.7% vs. 6.3%, p = 0.376) and rate of 5-day failure to control bleeding (6.9% vs. 5.4%, p = 0.787) were not significantly different between the two groups. CONCLUSIONS: The impact of peptic ulcer bleeding on the in-hospital outcomes of cirrhotic patients is similar to that of variceal bleeding.

In this international multicenter study, we included 1535 patients with acute gastrointestinal bleeding (AGIB) and divided them into peptic ulcer bleeding and variceal bleeding groups. We found that only a minority of AGIB episodes in cirrhotic patients was attributed to peptic ulcer. Additionally, after adjusting for the severity of liver dysfunction, the in-hospital mortality and the rate of 5-day failure to control bleeding should be similar between cirrhotic patients with peptic ulcer bleeding and those with variceal bleeding.

Retrospective cohort study for thrombocytopenia during concurrent chemoradiotherapy for rectal cancer.

Background: The aim of this article was to establish the clinical prognostic models and identify the predictive radiation dosimetric parameters for thrombocytopenia during concurrent chemoradiotherapy for rectal cancer. Methods: In this retrospective cohort study, patients with rectal adenocarcinoma undergoing concurrent long-term chemoradiotherapy were included. The primary outcome of interest was grade 2 or higher (2+) thrombocytopenia (platelet(PLT) count <75,000/µL). Secondary outcomes included: grade 1 or higher thrombocytopenia (PLT count<100,000/µL) and the PLT count during chemoradiotherapy and its nadir. The risk prediction model was developed by logistic regression to identify clinical predictors of 2+ thrombocytopenia. Univariate linear regression models were used to test correlations between radiation dosimetric parameters and the absolute PLT count at nadirs. Results: This retrospective cohort comprised 238 patients. Fifty-four (22.6%) patients developed thrombocytopenia during concurrent chemoradiotherapy, while 15 (6.3%) patients developed 2+ thrombocytopenia. Four independently associated risk factors, including age, Alb level, PLT count, and chemotherapy regimen, were included in the final model and used to form a 2+ thrombocytopenia probability estimation nomogram. The C-index was 0.87 (95% CI: 0.78-0.96). The calibration plot showed a moderate agreement, and the Brier score was 0.047 (95% CI: 0.025-0.070). The total absolute volume of bone marrow irradiated by 5 Gy, 10 Gy and 15 Gy of radiation (BM-V5ab, BM-V10ab, BM-V15ab), calculated by the volume of bone marrow multiplied by the corresponding Vx, were identified as new predictors. The nadir of PLT was found to be negatively correlated with BM-V5ab (ß = -0.062, P =0.030), BM-V10ab (ß = -0.065, P =0.030) and BM-V15ab (ß = -0.064, P =0.042). Conclusion: The occurrence of 2+ thrombocytopenia during concurrent chemoradiotherapy for rectal cancer can be predicted by the patient's baseline status and chemoradiotherapy regimen, and low dose irradiation of bone marrow can affect the level of platelets during the treatment.

The E3 ubiquitin ligase MG53 inhibits hepatocellular carcinoma by targeting RAC1 signaling.

Ras-related C3 botulinum toxin substrate 1 (RAC1) overexpressiosn and hyperactivation are correlated with aggressive growth and other malignant characteristics in a wide variety of cancers including hepatocellular carcinoma (HCC). However, the regulatory mechanism of RAC1 expression and activation in HCC is not fully understood. Here, we demonstrated that E3 ubiquitin ligase MG53 (also known as tripartite motif 72, TRIM72) acted as a direct inhibitor of RAC1, and it catalyzed the ubiquitination of RAC1 and further inhibited RAC1 activity in HCC cells. Mechanistically, MG53 directly bound with RAC1 through its coiled-coil domain and suppressed RAC1 activity by catalyzing the Lys48 (K48)-linked polyubiquitination of RAC1 at Lys5 residue in HCC cells. We further demonstrated that MG53 significantly suppressed the malignant behaviors of HCC cells and enhanced the chemosensitivity of HCC cells to sorafenib treatment by inhibiting RAC1-MAPK signaling axis. In summary, we identified MG53 as a novel RAC1 inhibitor and tumor suppressor in HCC, and it suppressed HCC progression by inducing K48-linked polyubiquitination of RAC1 and further inhibiting the RAC1-MAPK signaling. Altogether, our investigation provided a new therapeutic strategy for RAC1 overactivated tumors by modulating MG53.

Inhibiting Src-mediated PARP1 tyrosine phosphorylation confers synthetic lethality to PARP1 inhibition in HCC.

Hepatocellular carcinoma (HCC), a heterogeneous cancer with high mortality, is resistant to single targeted therapy; thus, combination therapy based on synthetic lethality is a promising therapeutic strategy for HCC. Poly (adenosine diphosphate [ADP]-ribose) polymerase 1 (PARP1) is the most recognized target for synthetic lethality; however, the therapeutic effect of PARP1 inhibition on HCC is disappointing. Therefore, exploring new synthetic lethal partners for the efficient manipulation of HCC is urgently required. In this study, we identified Src and PARP1 as novel synthetic lethal partners, and the combination therapy produced significant anti-tumor effects without causing obvious side effects. Mechanistically, Src interacted with PARP1 and phosphorylated PARP1 at the Y992 residue, which further mediated resistance to PARP1 inhibition. Overall, this study revealed that Src-mediated PARP1 phosphorylation induced HCC resistance to PARP1 inhibitors and indicated a therapeutic window of the Y992 phosphorylation of PARP1 for HCC patients. Moreover, synthetic lethal therapy by co-targeting PARP1 and Src have the potential to broaden the strategies for HCC and might benefit HCC patients with high Src activation and resistance to PARP1 inhibitors alone.

Practice guidance for the use of terlipressin for liver cirrhosis-related complications.

Background: Liver cirrhosis is a major global health burden worldwide due to its high risk of morbidity and mortality. Role of terlipressin for the management of liver cirrhosis-related complications has been recognized during recent years. This article aims to develop evidence-based clinical practice guidance on the use of terlipressin for liver cirrhosis-related complications. Methods: Hepatobiliary Study Group of the Chinese Society of Gastroenterology of the Chinese Medical Association and Hepatology Committee of the Chinese Research Hospital Association have invited gastroenterologists, hepatologists, infectious disease specialists, surgeons, and clinical pharmacists to formulate the clinical practice guidance based on comprehensive literature review and experts' clinical experiences. Results: Overall, 10 major guidance statements regarding efficacy and safety of terlipressin in liver cirrhosis were proposed. Terlipressin can be beneficial for the management of cirrhotic patients with acute variceal bleeding and hepatorenal syndrome (HRS). However, the evidence regarding the use of terlipressin in cirrhotic patients with ascites, post-paracentesis circulatory dysfunction, and bacterial infections and in those undergoing hepatic resection and liver transplantation remains insufficient. Terlipressin-related adverse events, mainly including gastrointestinal symptoms, electrolyte disturbance, and cardiovascular and respiratory adverse events, should be closely monitored. Conclusion: The current clinical practice guidance supports the use of terlipressin for gastroesophageal variceal bleeding and HRS in liver cirrhosis. High-quality studies are needed to further clarify its potential effects in other liver cirrhosis-related complications.

Outcomes of early versus delayed endoscopy in cirrhotic patients with acute variceal bleeding: a systematic review with meta-analysis.

OBJECTIVES: Endoscopy is the mainstay treatment option for acute variceal bleeding (AVB) in liver cirrhosis. However, the optimal timing of endoscopy in such patients remains unclear. METHODS: PubMed, EMBASE and Cochrane Library databases were searched. We compared the mortality, incidence of rebleeding, length of stay, endoscopic hemostasis, need for salvage and units of transfusion between cirrhotic patients with AVB who underwent early and delayed endoscopy. Meta-analyses were performed by using a random-effect model. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Subgroup analysis was performed in studies where early endoscopy was defined as <12 h. RESULTS: Nine retrospective studies involving 2824 patients were included. The early endoscopy group had a significantly lower overall mortality than the delayed endoscopy group in overall analysis (OR = 0.56, 95% CI, 0.33-0.95, P = 0.03), but the difference between them was NS in subgroup analysis (OR = 0.72, 95% CI, 0.38-1.38, P = 0.33). In-hospital (OR = 0.77, 95% CI, 0.26-2.32, P = 0.65) and 6-week (OR = 0.78, 95% CI, 0.42-1.47, P = 0.45) mortality were not significantly different between them. Overall rebleeding was not significantly different between early and delayed endoscopy groups in both overall (OR = 0.88, 95% CI, 0.51-1.51, P = 0.63) and subgroup (OR = 1.04, 95% CI, 0.55-1.95, P = 0.90) analyses. In-hospital (OR = 1.41, 95% CI, 0.67-2.96, P = 0.37) and 6-week (OR = 0.93, 95% CI, 0.40-2.17, P = 0.86) rebleeding remained not significantly different between them. Additionally, the length of stay, endoscopic hemostasis, need for salvage and units of transfusion were not significantly different between them. CONCLUSIONS: Early endoscopy may improve the survival of cirrhotic patients with AVB, but has no remarkable benefit on the prevention of rebleeding. These findings should be further validated by high-quality studies.

Arginine methyltransferase PRMT5 negatively regulates cGAS-mediated antiviral immune response.

Cyclic GMP-AMP synthase (cGAS) functions as an essential DNA sensor, which senses the cytoplasmic double-stranded DNA and activates the antiviral response. However, the posttranslational modification of cGAS remains to be fully understood and whether it has arginine methylation modification remains unknown. Here, we identified protein arginine methyltransferase 5 (PRMT5) as a direct binding partner of cGAS, and it catalyzed the arginine symmetrical dimethylation of cGAS at the Arg124 residue. Further investigation demonstrated that methylation of cGAS by PRMT5 attenuated cGAS-mediated antiviral immune response by blocking the DNA binding ability of cGAS. Oral administration of PRMT5 inhibitors significantly protected mice from HSV-1 infection and prolonged the survival time of these infected mice. Therefore, our findings revealed an essential regulatory effect of PRMT5 on cGAS-mediated antiviral immune response and provided a promising potential antiviral strategy by modulating PRMT5.

Early Prediction of Severe COVID-19 in Patients by a Novel Immune-Related Predictive Model.

During the progression of coronavirus disease 2019 (COVID-19), immune response and inflammation reactions are dynamic events that develop rapidly and are associated with the severity of disease. Here, we aimed to develop a predictive model based on the immune and inflammatory response to discriminate patients with severe COVID-19. COVID-19 patients were enrolled, and their demographic and immune inflammatory reaction indicators were collected and analyzed. Logistic regression analysis was performed to identify the independent predictors, which were further used to construct a predictive model. The predictive performance of the model was evaluated by receiver operating characteristic curve, and optimal diagnostic threshold was calculated; these were further validated by 5-fold cross-validation and external validation. We screened three key indicators, including neutrophils, eosinophils, and IgA, for predicting severe COVID-19 and obtained a combined neutrophil, eosinophil, and IgA ratio (NEAR) model (NEU [109/liter] - 150×EOS [109/liter] + 3×IgA [g/liter]). NEAR achieved an area under the curve (AUC) of 0.961, and when a threshold of 9 was applied, the sensitivity and specificity of the predicting model were 100% and 88.89%, respectively. Thus, NEAR is an effective index for predicting the severity of COVID-19 and can be used as a powerful tool for clinicians to make better clinical decisions. IMPORTANCE The immune inflammatory response changes rapidly with the progression of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and is responsible for clearance of the virus and further recovery from the infection. However, the intensified immune and inflammatory response in the development of the disease may lead to more serious and fatal consequences, which indicates that immune indicators have the potential to predict serious cases. Here, we identified both eosinophils and serum IgA as prognostic markers of COVID-19, which sheds light on new research directions and is worthy of further research in the scientific research field as well as clinical application. In this study, the combination of NEU count, EOS count, and IgA level was included in a new predictive model of the severity of COVID-19, which can be used as a powerful tool for better clinical decision-making.

The E3 ubiquitin ligase TRIM7 suppressed hepatocellular carcinoma progression by directly targeting Src protein.

Aberrant Src kinase activity is known to be involved in a variety of human malignancies, whereas the regulatory mechanism of Src has not been completely clarified. Here, we demonstrated that tripartite motif containing 7 (TRIM7) directly interacted with Src, induced Lys48-linked polyubiquitination of Src and reduced the abundance of Src protein in hepatocellular carcinoma (HCC) cells. We further identified TRIM7 as a tumor suppressor in HCC cells through its negative modulation of the Src-mTORC1-S6K1 axis in vivo and in vitro in several HCC models. Moreover, we verified the dysregulated expression of TRIM7 in clinical liver cancer tissues and its negative correlation with Src protein in clinical HCC specimens. Overall, we demonstrated that TRIM7 suppressed HCC progression through its direct negative regulation of Src and modulation of the Src-mTORC1-S6K1 axis; thus, we provided a novel insight into the development of HCC and defined a promising therapeutic strategy for cancers with overactive Src by modulating TRIM7.

NOD2 inhibits tumorigenesis and increases chemosensitivity of hepatocellular carcinoma by targeting AMPK pathway.

Nucleotide binding oligomerization domain 2 (NOD2) is a recognized innate immune sensor which can initiate potent immune response against pathogens. Many innate immune sensors have been reported to be of great importance in carcinogenesis. However, the role of NOD2 in cancer is not well understood. Here we investigated the role of NOD2 in the development of hepatocellular carcinoma (HCC). We demonstrated that NOD2 deficiency promoted hepatocarcinogenesis in N-nitrosodiethylamine (DEN)/carbon tetrachloride (CCl4) induced HCC mice model and xenograft tumor model. In vitro investigation showed that NOD2 acted as a tumor suppressor and inhibited proliferation, colony formation and invasion of HCC cells. Clinical investigation showed that NOD2 expression was completely lost or significantly downregulated in clinical HCC tissues, and loss of NOD2 expression was significantly correlated with advanced disease stages. Further investigation showed that NOD2 exerted its anti-tumor effect through activating adenosine 5'-monophosphate (AMP) -activated protein kinase (AMPK) signaling pathway, and NOD2 significantly enhanced the sensitivity of HCC cells to sorafenib, lenvatinib and 5-FU treatment through activating AMPK pathway induced apoptosis. Moreover, we demonstrated that NOD2 activated AMPK pathway by directly binding with AMPKα-LKB1 complex, which led to autophagy-mediated apoptosis of HCC cells. Altogether, this study showed that NOD2 acted as a tumor suppressor as well as a chemotherapeutic regulator in HCC cells by directly activating AMPK pathway, which indicated a potential therapeutic strategy for HCC treatment by upregulating NOD2-AMPK signaling axis.

NOD1 inhibits proliferation and enhances response to chemotherapy via suppressing SRC-MAPK pathway in hepatocellular carcinoma.

NOD1 is an innate immune sensor playing an important role in fighting against infection. However, its role in cancer is far from being clarified, and whether NOD1 plays a role in the progression of hepatocellular carcinoma (HCC) has never been reported. Here, we found that NOD1 expression was significantly decreased in hepatocellular carcinoma tissues and overexpression of NOD1 significantly inhibited tumorigenesis in vivo. In vitro experiments demonstrated that NOD1 inhibited proliferation of HCC cells by directly targeting proto-oncogene SRC and inducing cell cycle arrest at G1 phase. Further investigation showed that NOD1 exerted its antitumor effect by inhibiting SRC activation and further suppressing SRC/MAPK axis in hepatocellular carcinoma cells. Moreover, NOD1 dramatically enhanced the response of HCC cells to chemotherapy via inhibition of SRC-MAPK axis both in vitro and in vivo. Collectively, these data indicated that NOD1 suppressed proliferation and enhanced response to sorafenib or 5-FU treatment through inhibiting SRC-MAPK axis in hepatocellular carcinoma. KEY MESSAGES: NOD1 significantly inhibited tumorigenesis of HCC in cellular and animal models. NOD1 inhibited proliferation of HCC cells by inducing cell cycle arrest. NOD1 exerted its antitumor effect on HCC by directly interacting with SRC and inhibiting SRC-MAPK axis. NOD1 significantly enhanced the chemosensitivity of HCC cells to chemotherapeutic drugs.

TRIM50 acts as a novel Src suppressor and inhibits ovarian cancer progression.

Src is a known proto-oncogene and its aberrant activity is involved in a variety of cancers, including ovarian cancer, whereas the regulatory mechanism of Src has not been fully clarified. In this study, we identified tripartite motif-containing (TRIM) 50 as a novel negative regulator of Src protein. Our data showed that TRIM50 directly interacted with SH3 domain of Src via its B-box domain; and TRIM50 reduced Src stability by inducing RING domain-dependent K48-linked poly-ubiquitous modification. We further demonstrated that TRIM50 acted as a tumor suppressor in ovarian cancer cells by its negative regulation of Src protein. In vivo animal model verified that TRIM50 inhibited the xenograft tumor growth of ovarian cancer by suppressing Src protein. Clinical investigation showed that expression of TRIM50 in clinical specimens was inversely correlated with the clinical stages, pathology grades and lymph node metastatic status of the patients, which indicated the involvement of aberrant TRIM50 expression in disease progression. Further analysis verified the negative correlation between TRIM50 and Src expression in clinical specimens. Altogether, we identified TRIM50 as a novel suppressor of Src protein, and demonstrated that TRIM50 inhibited ovarian cancer progression by targeting Src and reducing its activity, which provided a novel therapeutic strategy for Src over-activated cancers by positive regulation of TRIM50.