Tumor-neutrophil cross talk orchestrates the tumor microenvironment to determine the bladder cancer progression.

The immune landscape of bladder cancer progression is not fully understood, and effective therapies are lacking in advanced bladder cancer. Here, we visualized that bladder cancer cells recruited neutrophils by secreting interleukin-8 (IL-8); in turn, neutrophils played dual functions in bladder cancer, including hepatocyte growth factor (HGF) release and CCL3highPD-L1high super-immunosuppressive subset formation. Mechanistically, c-Fos was identified as the mediator of HGF up-regulating IL-8 transcription in bladder cancer cells, which was central to the positive feedback of neutrophil recruitment. Clinically, compared with serum IL-8, urine IL-8 was a better biomarker for bladder cancer prognosis and clinical benefit of immune checkpoint blockade (ICB). Additionally, targeting neutrophils or hepatocyte growth factor receptor (MET) signaling combined with ICB inhibited bladder cancer progression and boosted the antitumor effect of CD8+ T cells in mice. These findings reveal the mechanism by which tumor-neutrophil cross talk orchestrates the bladder cancer microenvironment and provide combination strategies, which may have broad impacts on patients suffering from malignancies enriched with neutrophils.

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.

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.

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.

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.

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.

Krill Oil Perturbs Proliferation and Migration of Mouse Colon Cancer Cells in vitro by Impeding Extracellular Signal-Regulated Protein Kinase Signaling Pathway.

The prevalence of colorectal cancer (CRC) continues to increase. Treatment of CRC remains a significant clinical challenge, and effective therapies for advanced CRC are desperately needed. Increasing attention and ongoing research efforts have focused on krill oil that may provide health benefits to the human body. Here we report that krill oil exerts in vitro anticancer activity through a direct inhibition on proliferation, colony formation, migration, and invasion of mouse colon cancer cells. Krill oil inhibited the proliferation and colony formation of CT-26 colon cancer cells by causing G0/G1 cell cycle arrest and apoptosis. Cell cycle arrest was attributable to reduction of cyclin D1 levels in krill oil-treated cells. Further studies revealed that krill oil induced mitochondrial-dependent apoptosis of CT-26 cells, including loss of mitochondrial membrane potential, increased cytosolic calcium levels, activation of caspase-3, and downregulation of anti-apoptotic proteins MCL-1 and BCL-XL. Krill oil suppressed migration of CT-26 cells by disrupting the microfilaments and microtubules. Extracellular signal-regulated protein kinase (ERK) plays crucial roles in regulating proliferation and migration of cancer cells. We found that krill oil attenuated the activation of ERK signaling pathway to exert the effects on cell cycle, apoptosis, and migration of colon cancer cells. We speculate that polyunsaturated fatty acids of krill oil may dampen ERK activation by decreasing the phospholipid saturation of cell membrane. Although findings from in vitro studies may not necessarily translate in vivo, our study provides insights into the possibility that krill oil or its components could have therapeutic potential in colon cancer.

G-CSF shifts erythropoiesis from bone marrow into spleen in the setting of systemic inflammation.

The anemia of inflammation is related in part to abnormal erythropoiesis in bone marrow. G-CSF regulates granulopoiesis and is increased during systemic inflammation. Here, we have showed that high levels of G-CSF are associated with repression of bone marrow erythropoiesis and expansion of splenic erythropoiesis in Escherichia coli-infected mice and lipopolysaccharide-treated mice. Under lipopolysaccharide-induced systemic inflammatory conditions in mice, G-CSF neutralization with antibody alleviated the blockage of bone marrow erythropoiesis, prevented the enhancement of splenic erythropoiesis, ameliorated splenomegaly, and reduced the brittleness of spleen. We further demonstrated that after lipopolysaccharide treatment, TLR4-knockout mice display low levels of G-CSF, healthy bone marrow erythropoiesis, almost no stress erythropoiesis in the spleen, and normal size and toughness of spleen. In addition, we found HIF-mediated erythropoietin production is essential for splenic erythropoiesis in the setting of G-CSF-induced suppression of bone marrow erythropoiesis. Our findings identify G-CSF as a critical mediator of inflammation-associated erythropoiesis dysfunction in bone marrow and offer insight into the mechanism of G-CSF-induced splenic erythropoiesis. We provide experimentally significant dimension to the biology of G-CSF.

Assembling custom side chains on proteoglycans to interrogate their function in living cells.

Proteoglycans (PGs) are composed of a core protein and one or more chains of glycosaminoglycans (GAGs). The highly heterogeneous GAG chains play an irreplaceable role in the functions of PGs. However, the lack of an approach to control the exact structure of GAG chains conjugated to PGs tremendously hinders functional studies of PGs. Herein, by using glypican-3 as a model, we establish an aldehyde tag-based approach to assemble PGs with specific GAG chains on the surface of living cells. We show that the engineered glypican-3 can regulate Wnt and Hedgehog signaling like the wild type. Furthermore, we also present a method for studying the interaction of PGs with their target glycoproteins by combining the assembly of PGs carrying specific GAG chains with metabolic glycan labeling, and most importantly, we obtain evidence of GPC3 directly interacting with Frizzled. In conclusion, this study provides a very useful platform for structural and functional studies of PGs with specific GAG chains.

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.

Breast cancer cells promote CD169+ macrophage-associated immunosuppression through JAK2-mediated PD-L1 upregulation on macrophages.

Macrophages are recognized as one of the major cell types in tumor microenvironment, and macrophage infiltration has been predominantly associated with poor prognosis among patients with breast cancer. Using the murine models of triple-negative breast cancer in CD169-DTR mice, we found that CD169+ macrophages support tumor growth and metastasis. CD169+ macrophage depletion resulted in increased accumulation of CD8+ T cells within tumor, and produced significant expansion of CD8+ T cells in circulation and spleen. In addition, we observed that CD169+ macrophage depletion alleviated tumor-induced splenomegaly in mice, but had no improvement in bone loss and repression of bone marrow erythropoiesis in tumor-bearing mice. Cancer cells and tumor associated macrophages exploit the upregulation of the immunosuppressive protein PD-L1 to subvert T cell-mediated immune surveillance. Within the tumor microenvironment, our understanding of the regulation of PD-L1 protein expression is limited. We showed that there was a 5-fold higher relative expression of PD-L1 on macrophages as compared with 4T1 tumor cells; coculture of macrophages with 4T1 cells augmented PD-L1 levels on macrophages, but did not upregulate the expression of PD-L1 on 4T1 cells. JAK2/STAT3 signaling pathway was activated in macrophages after coculture, and we further identified the JAK2 as a critical regulator of PD-L1 expression in macrophages during coculture with 4T1 cells. Collectively, our data reveal that breast cancer cells and CD169+ macrophages exhibit bidirectional interactions that play a critical role in tumor progression, and inhibition of JAK2 signaling pathway in CD169+ macrophages may be potential strategy to block tumor microenvironment-derived immune escape.

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.

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.

Undescribed C-geranylflavonoids isolated from the fruit peel of Paulownia catalpifolia T. Gong ex D.Y. Hong with their protection on human umbilical vein endothelial cells injury induced by hydrogen peroxide.

Six undescribed C-geranylated flavonoids, including five C-geranylflavanones named as paucatalinones F - J, one C-geranylflavonol named as paucatalinone K, along with seven known geranylated flavanones, were isolated from the fruit peel of Paulownia catalpifolia T. Gong ex D.Y. Hong. Their structures were elucidated distinctly according to their UV, IR, MS, NMR, and CD data. Among them, two compounds were substituted with unusual modified geranyl groups, namely paucatalinone F with an oxygenated cyclogeranyl substituent and paucatalinone H with a terminal pyranoid geranyl substituent. Furthermore, the protective effects on human umbilical vein endothelial cells (HUVECs) injury induced by H2O2 were evaluated, and paucatalinone F showed the most potential activity. The bioactive results suggested that the geranyl substituent may be an important factor for restraining oxidative HUVECs damage and Paulownia C-geranylated flavonoids might have the potential for preventing cardiovascular complications.

Targeting macrophages for cancer therapy disrupts bone homeostasis and impairs bone marrow erythropoiesis in mice bearing Lewis lung carcinoma tumors.

Macrophages are represented in all tissues by phenotypically distinct resident populations that show great functional diversity. Macrophages generally play a protumoral role, and they are attractive targets for cancer therapy. In this study, we found that CD169+ macrophages depletion inhibited the growth of established Lewis lung carcinoma tumors in mice. Benefits must be weighed against potential adverse effects in cancer therapy. Here, we investigated the adverse effects of CD169+ macrophages depletion on bone and bone marrow in mice bearing Lewis lung carcinoma tumors. Our studies showed that depletion of CD169+ macrophages in LLC tumor-bearing mice disrupted bone homeostasis, including bone weight loss and bone mineral density decrease. Further studies revealed that bone marrow erythropoiesis was severely impaired after depletion of CD169+ macrophages in LLC tumor-bearing mice. Our findings suggest that depletion of macrophages for cancer therapy may be associated with potential adverse effects that need to be recognized, prevented, and optimally managed.

G-CSF mediates lung injury in mice with adenine-induced acute kidney injury.

Acute lung injury (ALI) is a serious complication among patients with acute kidney injury (AKI) that is a systemic inflammatory disease with high morbidity and mortality. The pathophysiology of AKI-associated ALI is poorly understood. G-CSF regulates the production and function of neutrophils that mediate lung injury via elastase and other mediators. Here, we used a mouse model of adenine-induced AKI to determine the roles of G-CSF and neutrophil elastase in AKI-associated ALI. We confirmed that ALI was associated with high serum G-CSF levels, and elevated neutrophil elastase activity in the lungs and serum of mice with adenine-induced AKI. Systemic administration of G-CSF-specific neutralizing antibody normalized granulopoiesis, pulmonary neutrophil infiltration, and neutrophil elastase activity, conferring improved lung architecture in mice with adenine-induced AKI. Further studies revealed that macrophages secreted G-CSF upon urea stimulation. Consequently, G-CSF could be a target for new anti-lung injury strategy in patients with AKI.