Cytosolic DNA sensor AIM2 promotes KRAS-driven lung cancer independent of inflammasomes

Constitutively active KRAS mutations are among the major drivers of lung cancer, yet the identity of molecular co-operators of oncogenic KRAS in the lung remains ill-defined. The innate immune cytosolic DNA sensor and pattern recognition receptor (PRR) Absent-in-melanoma 2 (AIM2) is best known for its assembly of multiprotein inflammasome complexes and promoting an inflammatory response. Here, we define a role for AIM2, independent of inflammasomes, in KRAS-addicted lung adenocarcinoma (LAC). In genetically defined and experimentally induced (nicotine-derived nitrosamine ketone; NNK) LAC mouse models harboring the KrasG12D driver mutation, AIM2 was highly upregulated compared with other cytosolic DNA sensors and inflammasome-associated PRRs. Genetic ablation of AIM2 in KrasG12D and NNK-induced LAC mouse models significantly reduced tumor growth, coincident with reduced cellular proliferation in the lung. Bone marrow chimeras suggest a requirement for AIM2 in KrasG12D-driven LAC in both hematopoietic (immune) and non-hematopoietic (epithelial) cellular compartments, which is supported by upregulated AIM2 expression in immune and epithelial cells of mutant KRAS lung tissues. Notably, protection against LAC in AIM2-deficient mice is associated with unaltered protein levels of mature Caspase-1 and IL-1β inflammasome effectors. Moreover, genetic ablation of the key inflammasome adapter, ASC, did not suppress KrasG12D-driven LAC. In support of these in vivo findings, AIM2, but not mature Caspase-1, was upregulated in human LAC patient tumor biopsies. Collectively, our findings reveal that endogenous AIM2 plays a tumor-promoting role, independent of inflammasomes, in mutant KRAS-addicted LAC, and suggest innate immune DNA sensing may provide an avenue to explore new therapeutic strategies in lung cancer.

Patient-Derived Xenografts: A Valuable Preclinical Model for Drug Development and Biomarker Discovery

Patient-derived xenografts (PDXs), established by implanting patient tumor cells into immunodeficient mice, offer a platform for faithfully replicating human tumors. They closely mimic the histopathology, genomics, and drug sensitivity of patient tumors. This chapter highlights the versatile applications of PDXs, including studying tumor biology, metastasis, and chemoresistance, as well as their use in biomarker identification, drug screening, and personalized medicine. It also addresses challenges in using PDXs in cancer research, including variations in metastatic potential, lengthy establishment timelines, stromal changes, and limitations in immunocompromised models. Despite these challenges, PDXs remain invaluable tools guiding patient treatment and advancing preclinical drug development.

The protease ADAM17 at the crossroads of disease: revisiting its significance in inflammation, cancer, and beyond

The protease A Disintegrin And Metalloproteinase 17 (ADAM17) plays a central role in the pathophysiology of several diseases. ADAM17 is involved in the cleavage and shedding of at least 80 known membrane-tethered proteins, which subsequently modulate several intracellular signaling pathways, and therefore alter cell behavior. Dysregulated expression and/or activation of ADAM17 has been linked to a wide range of autoimmune and inflammatory diseases, cancer, and cardiovascular disease. In this review, we provide an overview of the current state of knowledge from preclinical models and clinical data on the diverse pathophysiological roles of ADAM17, and discuss the mechanisms underlying ADAM17-mediated protein shedding and the potential therapeutic implications of targeting ADAM17 in these diseases.

Targeting IL-6 trans-signalling: past, present and future prospects

Interleukin-6 (IL-6) is a key immunomodulatory cytokine that affects the pathogenesis of diverse diseases, including autoimmune diseases, chronic inflammatory conditions and cancer. Classical IL-6 signalling involves the binding of IL-6 to the membrane-bound IL-6 receptor α-subunit (hereafter termed 'mIL-6R') and glycoprotein 130 (gp130) signal-transducing subunit. By contrast, in IL-6 trans-signalling, complexes of IL-6 and the soluble form of IL-6 receptor (sIL-6R) signal via membrane-bound gp130. A third mode of IL-6 signalling - known as cluster signalling - involves preformed complexes of membrane-bound IL-6-mIL-6R on one cell activating gp130 subunits on target cells. Antibodies and small molecules have been developed that block all three forms of IL-6 signalling, but in the past decade, IL-6 trans-signalling has emerged as the predominant pathway by which IL-6 promotes disease pathogenesis. The first selective inhibitor of IL-6 trans-signalling, sgp130, has shown therapeutic potential in various preclinical models of disease and olamkicept, a sgp130Fc variant, had promising results in phase II clinical studies for inflammatory bowel disease. Technological developments have already led to next-generation sgp130 variants with increased affinity and selectivity towards IL-6 trans-signalling, along with indirect strategies to block IL-6 trans-signalling. Here, we summarize our current understanding of the biological outcomes of IL-6-mediated signalling and the potential for targeting this pathway in the clinic.

Th1 Cells Alter the Inflammatory Signature of IL-6 by Channeling STAT Transcription Factors to Alu-like Retroelements

Cytokines that signal via STAT1 and STAT3 transcription factors instruct decisions affecting tissue homeostasis, antimicrobial host defense, and inflammation-induced tissue injury. To understand the coordination of these activities, we applied RNA sequencing, chromatin immunoprecipitation sequencing, and assay for transposase-accessible chromatin with high-throughput sequencing to identify the transcriptional output of STAT1 and STAT3 in peritoneal tissues from mice during acute resolving inflammation and inflammation primed to drive fibrosis. Bioinformatics focused on the transcriptional signature of the immunomodulatory cytokine IL-6 in both settings and examined how profibrotic IFN-γ-secreting CD4+ T cells altered the interpretation of STAT1 and STAT3 cytokine cues. In resolving inflammation, STAT1 and STAT3 cooperated to drive stromal gene expression affecting antimicrobial immunity and tissue homeostasis. The introduction of IFN-γ-secreting CD4+ T cells altered this transcriptional program and channeled STAT1 and STAT3 to a previously latent IFN-γ activation site motif in Alu-like elements. STAT1 and STAT3 binding to this conserved sequence revealed evidence of reciprocal cross-regulation and gene signatures relevant to pathophysiology. Thus, we propose that effector T cells retune the transcriptional output of IL-6 by shaping a regulatory interplay between STAT1 and STAT3 in inflammation.

The cytosolic DNA sensor AIM2 promotes Helicobacter-induced gastric pathology via the inflammasome

Helicobacter pylori (H. pylori) infection can trigger chronic gastric inflammation perpetuated by overactivation of the innate immune system, leading to a cascade of precancerous lesions culminating in gastric cancer. However, key regulators of innate immunity that promote H. pylori-induced gastric pathology remain ill-defined. The innate immune cytosolic DNA sensor absent in melanoma 2 (AIM2) contributes to the pathogenesis of numerous autoimmune and chronic inflammatory diseases, as well as cancers including gastric cancer. We therefore investigated whether AIM2 contributed to the pathogenesis of Helicobacter-induced gastric disease. Here, we reveal that AIM2 messenger RNA and protein expression levels are elevated in H. pylori-positive versus H. pylori-negative human gastric biopsies. Similarly, chronic Helicobacter felis infection in wild-type mice augmented Aim2 gene expression levels compared with uninfected controls. Notably, gastric inflammation and hyperplasia were less severe in H. felis-infected Aim2-/- versus wild-type mice, evidenced by reductions in gastric immune cell infiltrates, mucosal thickness and proinflammatory cytokine and chemokine release. In addition, H. felis-driven proliferation and apoptosis in both gastric epithelial and immune cells were largely attenuated in Aim2-/- stomachs. These observations in Aim2-/- mouse stomachs correlated with decreased levels of inflammasome activity (caspase-1 cleavage) and the mature inflammasome effector cytokine, interleukin-1β. Taken together, this work uncovers a pathogenic role for the AIM2 inflammasome in Helicobacter-induced gastric disease, and furthers our understanding of the host immune response to a common pathogen and the complex and varying roles of AIM2 at different stages of cancerous and precancerous gastric disease.

Circulating Tumor DNA Is an Accurate Diagnostic Tool and Strong Prognostic Marker in Pancreatic Cancer

OBJECTIVE

The objectives of the study are to investigate the sensitivity and specificity of circulating tumor DNA (ctDNA) for the diagnosis of pancreatic cancer and to assess the utility of ctDNA as a prognostic marker in this disease.

METHODS

Cell-free DNA was extracted from plasma of patients who underwent endoscopic ultrasound fine-needle aspiration or surgical resections for pancreatic cancer. The cell-free DNA was then analyzed using droplet digital polymerase chain reaction for KRAS G12/13 mutations. Eighty-one patients with pancreatic cancer and 30 patients with benign pancreatic disease were analyzed.

RESULTS

ctDNA KRAS G12/13 mutations were detected in 63% of all patients with pancreatic cancer and in 76% of those patients who also had KRAS G12/13 mutations detected in the pancreatic primary. Specificity and tissue concordance were both 100%. Circulating tumor DNA corresponded with tumor size and stage, and high ctDNA was associated with significantly worse prognosis on both univariate and multivariate testing.

CONCLUSION

Our study shows that ctDNA is an accurate diagnostic tool and strong prognostic marker in patients with pancreatic cancer. The continued investigation of ctDNA will enable its implementation in clinical practice to optimize the care and survival outcomes of patients with pancreatic cancer.

An In Vitro Model for Assessing Acute Lung Injury During Pancreatitis Development Using Primary Mouse Cell Co-cultures

Acute pancreatitis is a serious inflammatory disease of the pancreas that can lead to lung injury. Despite extensive research, the mechanisms underlying this complication are ill-defined. In recent years, in vitro co-culture systems have emerged as powerful tools for studying complex interactions between different cell types in disease. In the context of pancreatitis, pancreatic acinar epithelial cells produce and secrete digestive enzymes, and their cellular damage, death, and/or dysfunction is a major contributing factor to the onset of pancreatitis. Here, in this chapter we describe a co-culture system of acinar cells and lung epithelial progenitor/stem cells to model for lung injury associated with pancreatitis.

KRAS G12D Mutation Subtype in Pancreatic Ductal Adenocarcinoma: Does It Influence Prognosis or Stage of Disease at Presentation?

Background: KRAS G12D mutation subtype is present in over 40% of pancreatic ductal adenocarcinoma (PDAC), one of the leading global causes of cancer death. This retrospective cohort study aims to investigate whether detection of the KRAS G12D mutation subtype in PDAC patients is a determinant of prognosis across all stages of disease. Methods: We reviewed the medical records of 231 patients presenting with PDAC at a large tertiary hospital, and compared survival using the Kaplan Meier, log-rank test and Cox proportional hazards regression model. Results: KRAS G12D mutation subtype was not significantly associated with poorer survival compared across the whole population of PDAC patients (p = 0.107; HR 1.293 95% CI (0.946-1.767)). However, KRAS G12D patients who were resectable had a shorter median survival time of 356 days compared to all other genotypes (median survival 810 days) (p = 0.019; HR 1.991 95% CI (1.121-3.537)). Conclusions: KRAS G12D patients who were resectable at diagnosis had shorter survival compared to all other PDAC patients. These data suggest that KRAS G12D may be a clinically useful prognostic biomarker of PDAC.

STAT3-mediated upregulation of the AIM2 DNA sensor links innate immunity with cell migration to promote epithelial tumourigenesis

OBJECTIVE

The absent in melanoma 2 (AIM2) cytosolic pattern recognition receptor and DNA sensor promotes the pathogenesis of autoimmune and chronic inflammatory diseases via caspase-1-containing inflammasome complexes. However, the role of AIM2 in cancer is ill-defined.

DESIGN

The expression of AIM2 and its clinical significance was assessed in human gastric cancer (GC) patient cohorts. Genetic or therapeutic manipulation of AIM2 expression and activity was performed in the genetically engineered gp130 ^F/F spontaneous GC mouse model, as well as human GC cell line xenografts. The biological role and mechanism of action of AIM2 in gastric tumourigenesis, including its involvement in inflammasome activity and functional interaction with microtubule-associated end-binding protein 1 (EB1), was determined in vitro and in vivo.

RESULTS

AIM2 expression is upregulated by interleukin-11 cytokine-mediated activation of the oncogenic latent transcription factor STAT3 in the tumour epithelium of GC mouse models and patients with GC. Genetic and therapeutic targeting of AIM2 in gp130 ^F/F mice suppressed tumourigenesis. Conversely, AIM2 overexpression augmented the tumour load of human GC cell line xenografts. The protumourigenic function of AIM2 was independent of inflammasome activity and inflammation. Rather, in vivo and in vitro AIM2 physically interacted with EB1 to promote epithelial cell migration and tumourigenesis. Furthermore, upregulated expression of AIM2 and EB1 in the tumour epithelium of patients with GC was independently associated with poor patient survival.

CONCLUSION

AIM2 can play a driver role in epithelial carcinogenesis by linking cytokine-STAT3 signalling, innate immunity and epithelial cell migration, independent of inflammasome activation.

Context-dependent functions of pattern recognition receptors in cancer

The immune system plays a critical role in shaping all facets of cancer, from the early initiation stage through to metastatic disease and resistance to therapy. Our understanding of the importance of the adaptive arm of the immune system in antitumour immunity has led to the implementation of immunotherapy with immune checkpoint inhibitors in numerous cancers, albeit with differing efficacy. By contrast, the clinical utility of innate immunity in cancer has not been exploited, despite dysregulated innate immunity being a feature of at least one-third of all cancers associated with tumour-promoting chronic inflammation. The past two decades have seen innate immune pattern recognition receptors (PRRs) emerge as critical regulators of the immune response to microbial infection and host tissue damage. More recently, it has become apparent that in many cancer types, PRRs play a central role in modulating a vast array of tumour-inhibiting and tumour-promoting cellular responses both in immune cells within the tumour microenvironment and directly in cancer cells. Herein, we provide a comprehensive overview of the fast-evolving field of PRRs in cancer, and discuss the potential to target PRRs for drug development and biomarker discovery in a wide range of oncology settings.

Toll-like Receptor 9 Promotes Initiation of Gastric Tumorigenesis by Augmenting Inflammation and Cellular Proliferation

BACKGROUND & AIMS

Gastric cancer (GC) is strongly linked with chronic gastritis after Helicobacter pylori infection. Toll-like receptors (TLRs) are key innate immune pathogenic sensors that mediate chronic inflammatory and oncogenic responses. Here, we investigated the role of TLR9 in the pathogenesis of GC, including Helicobacter infection.

METHODS

TLR9 gene expression was profiled in gastric tissues from GC and gastritis patients and from the spontaneous gp130^F/F GC mouse model and chronic H felis-infected wild-type (WT) mice. Gastric pathology was compared in gp130^F/F and H felis infection models with or without genetic ablation of Tlr9. The impact of Tlr9 targeting on signaling cascades implicated in inflammation and tumorigenesis (eg, nuclear factor kappa B, extracellular signal-related kinase, and mitogen-activated protein kinase) was assessed in vivo. A direct growth-potentiating effect of TLR9 ligand stimulation on human GC cell lines and gp130^F/F primary gastric epithelial cells was also evaluated.

RESULTS

TLR9 expression was up-regulated in Helicobacter-infected gastric tissues from GC and gastritis patients and gp130^F/F and H felis-infected WT mice. Tlr9 ablation suppressed initiation of tumorigenesis in gp130^F/F:Tlr9^-/- mice by abrogating gastric inflammation and cellular proliferation. Tlr9^-/- mice were also protected against H felis-induced gastric inflammation and hyperplasia. The suppressed gastric pathology upon Tlr9 ablation in both mouse models associated with attenuated nuclear factor kappa B and, to a lesser extent, extracellular signal-related kinase, mitogen-activated protein kinase signaling. TLR9 ligand stimulation of human GC cells and gp130^F/F GECs augmented their proliferation and viability.

CONCLUSIONS

Our data reveal that TLR9 promotes the initiating stages of GC and facilitates Helicobacter-induced gastric inflammation and hyperplasia, thus providing in vivo evidence for TLR9 as a candidate therapeutic target in GC.

Inflammasome-Associated Gastric Tumorigenesis Is Independent of the NLRP3 Pattern Recognition Receptor

Inflammasomes are important multiprotein regulatory complexes of innate immunity and have recently emerged as playing divergent roles in numerous inflammation-associated cancers. Among these include gastric cancer (GC), the third leading cause of cancer-associated death worldwide, and we have previously discovered a pro-tumorigenic role for the key inflammasome adaptor apoptosis-associated speck-like protein containing a CARD (ASC) in the spontaneous genetic gp130^F/F mouse model for GC. However, the identity of the specific pattern recognition receptors (PRRs) that activate tumor-promoting inflammasomes during GC is unknown. Here, we investigated the role of the best-characterized inflammasome-associated PRR, nucleotide-binding domain, and leucine-rich repeat containing receptor, pyrin domain-containing (NLRP) 3, in GC. In gastric tumors of gp130^F/F mice, although NLRP3 expression was elevated at the mRNA (qPCR) and protein (immunohistochemistry) levels, genetic ablation of NLRP3 in gp130^F/F:Nlrp3^-/- mice did not alleviate the development of gastric tumors. Similarly, cellular processes associated with tumorigenesis in the gastric mucosa, namely, proliferation, apoptosis, and inflammation, were comparable between gp130^F/F and gp130^F/F:Nlrp3^-/- mice. Furthermore, inflammasome activation levels, determined by immunoblotting and immunohistochemistry for cleaved Caspase-1, which along with ASC is another integral component of inflammasome complexes, were unchanged in gp130^F/F and gp130^F/F:Nlrp3^-/- gastric tumors. We also observed variable NLRP3 expression levels (mRNA and protein) among independent GC patient cohorts, and NLRP3 was not prognostic for survival outcomes. Taken together, these data suggest that NLRP3 does not play a major role in promoting inflammasome-driven gastric tumorigenesis, and thus pave the way for further investigations to uncover the key inflammasome-associated PRR implicated in GC.

Oncostatin M expression induced by bacterial triggers drives airway inflammatory and mucus secretion in severe asthma

[Figure: see text].

EUS-FNA Biopsies to Guide Precision Medicine in Pancreatic Cancer: Results of a Pilot Study to Identify KRAS Wild-Type Tumours for Targeted Therapy

Background

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer death and lacks effective treatment options. Diagnostic endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsies represent an appealing source of material for molecular analysis to inform targeted therapy, as they are often the only available tissue for patients presenting with PDAC irrespective of disease stage. However, EUS-FNA biopsies are typically not used to screen for precision medicine studies due to concerns about low tissue yield and quality. Epidermal growth factor receptor (EGFR) inhibition has shown promise in clinical trials of unselected patients with advanced pancreatic cancer, but has not been prospectively tested in KRAS wild-type patients. Here, we examine the clinical utility of EUS-FNA biopsies for molecular screening of KRAS wild-type PDAC patients for targeted anti-EGFR therapy to assess the feasibility of this approach.

Patients and Methods

Fresh frozen EUS-FNA or surgical biopsies from PDAC patient tumours were used to screen for KRAS mutations. Eligible patients with recurrent, locally advanced, or metastatic KRAS wild-type status who had received at least one prior line of chemotherapy were enrolled in a pilot study (ACTRN12617000540314) and treated with panitumumab at 6mg/kg intravenously every 2 weeks until progression or unacceptable toxicity. The primary endpoint was 4-month progression-free survival (PFS).

Results

275 patient biopsies were screened for KRAS mutations, which were detected in 88.3% of patient samples. 8 eligible KRAS wild-type patients were enrolled onto the interventional study between November 2017 and December 2020 and treated with panitumumab. 4-month PFS was 14.3% with no objective tumour responses observed. The only grade 3/4 treatment related toxicity observed was hypomagnesaemia.

Conclusions

This study demonstrates proof-of-principle feasibility to molecularly screen patients with pancreatic cancer for targeted therapies, and confirms diagnostic EUS-FNA biopsies as a reliable source of tumour material for molecular analysis. Single agent panitumumab was safe and tolerable but led to no objective tumour responses in this population.

TLR2 activation promotes tumour growth and associates with patient survival and chemotherapy response in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis, and is plagued by a paucity of targeted treatment options and tumour resistance to chemotherapeutics. The causal link between chronic inflammation and PDAC suggests that molecular regulators of the immune system promote disease pathogenesis and/or therapeutic resistance, yet their identity is unclear. Here, we couple endoscopic ultrasound-guided fine-needle aspiration, which captures tumour biopsies from all stages, with whole transcriptome profiling of PDAC patient primary tumours to reveal enrichment of the innate immune Toll-like receptor 2 (TLR2) molecular pathway. Augmented TLR2 expression associated with a 4-gene "TLR2 activation" signature, and was prognostic for survival and predictive for gemcitabine-based chemoresistance. Furthermore, antibody-mediated anti-TLR2 therapy suppressed the growth of human PDAC tumour xenografts, independent of a functional immune system. Our results support TLR2-based therapeutic targeting for precision medicine in PDAC, with further clinical utility that TLR2 activation is prognostic and predictive for chemoresponsiveness.

Targeted transcriptome and KRAS mutation analysis improve the diagnostic performance of EUS-FNA biopsies in pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) carries a poor prognosis, and current diagnostic tests have suboptimal sensitivity. Incorporating standard cytology with targeted transcriptomic and mutation analysis may improve the accuracy of diagnostic biopsies, thus reducing the burden of repeat procedures and delays to treatment initiation.

METHODS

We reviewed the accuracy of 308 EUS-FNA PDAC biopsies using a large multicenter clinical and biospecimen database, then performed RNA sequencing on 134 EUS-FNA biopsies spanning all stages of disease. We identified a transcriptomic diagnostic gene signature which was validated using external datasets and 60 further diagnostic EUS-FNAs. KRAS ddPCR analysis was performed and correlated with signature gene expression.

RESULTS

The sensitivity of EUS-FNA cytology in diagnosing solid pancreatic masses in our retrospective cohort (n=308) was 78.6% (95% CI 73.2 to 83.2%). KRAS mutation analysis and our custom transcriptomic signature significantly improved upon the diagnostic accuracy of standard cytology to 91.3% in external validation sets and 91.6% in our validation cohort (n=60). Exploratory ddPCR analysis of KRAS mutant allele fraction (MAF%) correlated with signature performance and may represent a novel surrogate marker of tumour cellularity in EUS-FNA biopsies.

CONCLUSIONS

Our findings support EUS-FNA biopsies as a feasible tissue source for integrated genomic and transcriptomic analysis of PDAC across all tumour stages, including cases with non-diagnostic cytology. Our transcriptome-derived genetic signature in combination with tissue KRAS mutation analysis significantly improves upon the diagnostic accuracy of current standard procedures, and has potential clinical utility in improving the speed and accuracy of diagnosis for patients presenting with PDAC.

Aspirin-Triggered Resolvin D1 Reduces Proliferation and the Neutrophil to Lymphocyte Ratio in a Mutant KRAS-Driven Lung Adenocarcinoma Model

Simple Summary

Aspirin-triggered resolvin D1 (AT-RvD1) is biosynthesised by leukocytes as a mechanism to resolve inflammation during infection and/or injury. Emerging studies reveal that AT-RvD1 also has anti-cancer properties associated with stimulating macrophage-mediated clearance of tumour debris. No study to date has investigated how AT-RvD1 influences the neutrophil to lymphocyte ratio (NLR) in lung cancer, an established marker of poor prognosis. The biosynthesis of AT-RvD1 is dependent on the ALOX5 gene, and we reveal that ALOX5 mRNA expression was markedly reduced in lung adenocarcinoma tumours. We next utilised an oncogenic Kras^G12D lung adenocarcinoma mouse model to investigate the efficacy of AT-RvD1 in vivo. We show for the first time that AT-RvD1 reduces tumour growth in the lungs of Kras^G12D mice and alters the immune landscape in tumours by reducing the NLR.

Abstract

Tumour-associated neutrophils (TANs) can support tumour growth by suppressing cytotoxic lymphocytes. AT-RvD1 is an eicosanoid that can antagonise neutrophil trafficking instigated by ALX/FPR2 ligands such as serum amyloid A (SAA). We aimed to establish whether SAA and ALOX5 expression associates with TANs and investigate the immunomodulatory actions of AT-RvD1 in vivo. MPO-positive neutrophils were quantified in tumour blocks from lung adenocarcinoma (n = 48) and control tissue (n = 20) by IHC. Tumour expression of SAA and ALOX5 were analysed by RTqPCR and an oncogenic Kras^G12D lung adenocarcinoma mouse model was used to investigate the in vivo efficacy of AT-RvD1 treatment. ALOX5 expression was markedly reduced in lung adenocarcinoma tumours. The SAA/ALOX5 ratio strongly correlated with TANs and was significantly increased in tumours harbouring an oncogenic KRAS mutation. AT-RvD1 treatment reduced tumour growth in Kras^G12D mice, which was accompanied by suppressed cellular proliferation within parenchymal lesions. In addition, AT-RvD1 significantly reduced the neutrophil to lymphocyte ratio (NLR), an established prognostic marker of poor survival in adenocarcinoma. This study identifies a novel molecular signature whereby elevated levels of SAA relative to ALOX5 favour accumulation of TANs. Furthermore, the ALOX5/5-LO enzymatic product, AT-RvD1, markedly reduced the NLR and suppressed tumour growth in Kras^G12D mice.

IL-6 family cytokines in respiratory health and disease

Chronic lung diseases including asthma, chronic obstructive pulmonary disease (COPD) and lung fibrosis represent a major burden on healthcare systems with limited effective therapeutic options. Developing effective treatments for these debilitating diseases requires an understanding of how alterations at the molecular level affect lung macroscopic architecture. A common theme among these lung disorders is the presence of an underlying dysregulated immune system which can lead to sustained chronic inflammation. In this respect, several inflammatory cytokines have been implicated in the pathogenesis of lung diseases, thus leading to the notion that cytokines are attractive therapeutic targets for these disorders. In this review, we discuss and highlight the recent breakthroughs that have enhanced our understanding of the role of the interleukin (IL)-6 family of cytokines in lung homeostasis and chronic diseases including asthma, COPD, lung fibrosis and lung cancer.

ADAM17 Deficiency Protects against Pulmonary Emphysema

Pulmonary emphysema is the major debilitating component of chronic obstructive pulmonary disease (COPD), which is a leading cause of morbidity and mortality worldwide. The ADAM17 (A disintegrin and metalloproteinase 17) protease mediates inflammation via ectodomain shedding of numerous proinflammatory cytokines, cytokine receptors, and adhesion molecules; however, its role in the pathogenesis of emphysema and COPD is poorly understood. This study aims to define the role of the protease ADAM17 in the pathogenesis of pulmonary emphysema. ADAM17 protein expression and activation was investigated in lung biopsies from patients with emphysema, as well as lungs of the emphysematous gp130F/F mouse model and an acute (4 d) cigarette smoke (CS)-induced lung pathology model. The Adam17ex/ex mice, which display significantly reduced global ADAM17 expression, were coupled with emphysema-prone gp130F/F mice to produce gp130F/F:Adam17ex/ex. Both Adam17ex/ex and wild-type mice were subjected to acute CS exposure. Histological, immunohistochemical, immunofluorescence, and molecular analyses as well as lung function tests were performed to assess pulmonary emphysema, inflammation, and alveolar cell apoptosis. ADAM17 was hyperphosphorylated in the lungs of patients with emphysema and also in emphysematous gp130F/F and CS-exposed mice. ADAM17 deficiency ameliorated the development of pulmonary emphysema in gp130F/F mice by suppressing elevated alveolar cell apoptosis. In addition, genetic blockade of ADAM17 protected mice from CS-induced pulmonary inflammation and alveolar cell apoptosis. Our study places the protease ADAM17 as a central molecular switch implicated in the development of pulmonary emphysema, which paves the way for using ADAM17 inhibitors as potential therapeutic agents to treat COPD and emphysema.

The ADAM17 protease promotes tobacco smoke carcinogen-induced lung tumorigenesis

Lung cancer is the leading cause of cancer-related mortality, with most cases attributed to tobacco smoking, in which nicotine-derived nitrosamine ketone (NNK) is the most potent lung carcinogen. The ADAM17 protease is responsible for the ectodomain shedding of many pro-tumorigenic cytokines, growth factors and receptors, and therefore is an attractive target in cancer. However, the role of ADAM17 in promoting tobacco smoke carcinogen-induced lung carcinogenesis is unknown. The hypomorphic Adam17ex/ex mice-characterized by reduced global ADAM17 expression-were backcrossed onto the NNK-sensitive pseudo-A/J background. CRISPR-driven and inhibitor-based (GW280264X, and ADAM17 prodomain) ADAM17 targeting was employed in the human lung adenocarcinoma cell lines A549 and NCI-H23. Human lung cancer biopsies were also used for analyses. The Adam17ex/ex mice displayed marked protection against NNK-induced lung adenocarcinoma. Specifically, the number and size of lung lesions in NNK-treated pseudo-A/J Adam17ex/ex mice were significantly reduced compared with wild-type littermate controls. This was associated with lower proliferative index throughout the lung epithelium. ADAM17 targeting in A549 and NCI-H23 cells led to reduced proliferative and colony-forming capacities. Notably, among select ADAM17 substrates, ADAM17 deficiency abrogated shedding of the soluble IL-6 receptor (sIL-6R), which coincided with the blockade of sIL-6R-mediated trans-signaling via ERK MAPK cascade. Furthermore, NNK upregulated phosphorylation of p38 MAPK, whose pharmacological inhibition suppressed ADAM17 threonine phosphorylation. Importantly, ADAM17 threonine phosphorylation was significantly upregulated in human lung adenocarcinoma with smoking history compared with their cancer-free controls. Our study identifies the ADAM17/sIL-6R/ERK MAPK axis as a candidate therapeutic strategy against tobacco smoke-associated lung carcinogenesis.

Innate Immune Molecule NLRC5 Protects Mice From Helicobacter-induced Formation of Gastric Lymphoid Tissue

BACKGROUND & AIMS

Helicobacter pylori induces strong inflammatory responses that are directed at clearing the infection, but if not controlled, these responses can be harmful to the host. We investigated the immune-regulatory effects of the innate immune molecule, nucleotide-binding oligomerization domain-like receptors (NLR) family CARD domain-containing 5 (NLRC5), in patients and mice with Helicobacter infection.

METHODS

We obtained gastric biopsies from 30 patients in Australia. We performed studies with mice that lack NLRC5 in the myeloid linage (Nlrc5^møKO) and mice without Nlrc5 gene disruption (controls). Some mice were gavaged with H pylori SS1 or Helicobacter felis; 3 months later, stomachs, spleens, and sera were collected, along with macrophages derived from bone marrow. Human and mouse gastric tissues and mouse macrophages were analyzed by histology, immunohistochemistry, immunoblots, and quantitative polymerase chain reaction. THP-1 cells (human macrophages, controls) and NLRC5^-/- THP-1 cells (generated by CRISPR-Cas9 gene editing) were incubated with Helicobacter and gene expression and production of cytokines were analyzed.

RESULTS

Levels of NLRC5 messenger RNA were significantly increased in gastric tissues from patients with H pylori infection, compared with patients without infection (P < .01), and correlated with gastritis severity (P < .05). H pylori bacteria induced significantly higher levels of chemokine and cytokine production by NLRC5^-/- THP-1 macrophages than by control THP-1 cells (P < .05). After 3 months of infection with H felis, Nlrc5^mø-KO mice developed gastric hyperplasia (P < .0001), splenomegaly (P < .0001), and increased serum antibody titers (P < .01), whereas control mice did not. Nlrc5^mø-KO mice with chronic H felis infection had increased numbers of gastric B-cell follicles expressing CD19 (P < .0001); these follicles had features of mucosa-associated lymphoid tissue lymphoma. We identified B-cell-activating factor as a protein that promoted B-cell hyperproliferation in Nlrc5^mø-KO mice.

CONCLUSIONS

NLRC5 is a negative regulator of gastric inflammation and mucosal lymphoid formation in response to Helicobacter infection. Aberrant NLRC5 signaling in macrophages can promote B-cell lymphomagenesis during chronic Helicobacter infection.

ADAM17 selectively activates the IL-6 trans-signaling/ERK MAPK axis in KRAS-addicted lung cancer

Oncogenic KRAS mutations are major drivers of lung adenocarcinoma (LAC), yet the direct therapeutic targeting of KRAS has been problematic. Here, we reveal an obligate requirement by oncogenic KRAS for the ADAM17 protease in LAC In genetically engineered and xenograft (human cell line and patient-derived) Kras ^G12D-driven LAC models, the specific blockade of ADAM17, including with a non-toxic prodomain inhibitor, suppressed tumor burden by reducing cellular proliferation. The pro-tumorigenic activity of ADAM17 was dependent upon its threonine phosphorylation by p38 MAPK, along with the preferential shedding of the ADAM17 substrate, IL-6R, to release soluble IL-6R that drives IL-6 trans-signaling via the ERK1/2 MAPK pathway. The requirement for ADAM17 in Kras ^G12D-driven LAC was independent of bone marrow-derived immune cells. Furthermore, in KRAS mutant human LAC, there was a significant positive correlation between augmented phospho-ADAM17 levels, observed primarily in epithelial rather than immune cells, and activation of ERK and p38 MAPK pathways. Collectively, these findings identify ADAM17 as a druggable target for oncogenic KRAS-driven LAC and provide the rationale to employ ADAM17-based therapeutic strategies for targeting KRAS mutant cancers.

Constitutive STAT3 Serine Phosphorylation Promotes Helicobacter-Mediated Gastric Disease

Gastric cancer is associated with chronic inflammation (gastritis) triggered by persistent Helicobacter pylori (H. pylori) infection. Elevated tyrosine phosphorylation of the latent transcription factor STAT3 is a feature of gastric cancer, including H. pylori-infected tissues, and aligns with nuclear transcriptional activity. However, the transcriptional role of STAT3 serine phosphorylation, which promotes STAT3-driven mitochondrial activities, is unclear. Here, by coupling serine-phosphorylated (pS)-STAT3-deficient Stat3^SA/SA mice with chronic H. felis infection, which mimics human H. pylori infection in mice, we reveal a key role for pS-STAT3 in promoting Helicobacter-induced gastric pathology. Immunohistochemical staining for infiltrating immune cells and expression analyses of inflammatory genes revealed that gastritis was markedly suppressed in infected Stat3^SA/SA mice compared with wild-type mice. Stomach weight and gastric mucosal thickness were also reduced in infected Stat3^SA/SA mice, which was associated with reduced proliferative potential of infected Stat3^SA/SA gastric mucosa. The suppressed H. felis-induced gastric phenotype of Stat3^SA/SA mice was phenocopied upon genetic ablation of signaling by the cytokine IL-11, which promotes gastric tumorigenesis via STAT3. pS-STAT3 dependency by Helicobacter coincided with transcriptional activity on STAT3-regulated genes, rather than mitochondrial and metabolic genes. In the gastric mucosa of mice and patients with gastritis, pS-STAT3 was constitutively expressed irrespective of Helicobacter infection. Collectively, these findings suggest an obligate requirement for IL-11 signaling via constitutive pS-STAT3 in Helicobacter-induced gastric carcinogenesis.

STAT3-driven hematopoiesis and lymphopoiesis abnormalities are dependent on serine phosphorylation

Deregulated activation of the latent transcription factor STAT3 has been implicated in the pathogenesis of myeloproliferative and lymphoproliferative hematologic disorders. The uncontrolled activation of STAT3 has traditionally been assigned to its elevated phosphorylation at tyrosine 705 (pY705) and associated nuclear transcriptional activity. By contrast, a transcriptional role for serine 727 phosphorylation (pS727) of STAT3 has recently emerged, suggesting that pS727 may account for the pathological activity of STAT3 in certain disease settings. Here, by coupling pS727-STAT3-deficient Stat3SA/SA mice with a STAT3-driven mouse model (gp130F/F) for myeloproliferative and lymphoproliferative pathologies, we reveal a key role for pS727-STAT3 in promoting multiple hematologic pathologies. The genetic blockade of pS727-STAT3 in gp130F/F:Stat3SA/SA mice ameliorated the neutrophilia, thrombocytosis, splenomegaly and lymphadenopathy that are features of gp130F/F mice. The protection against thrombocytosis in gp130F/F:Stat3SA/SA mice coincided with normalized megakaryopoiesis in both bone marrow and spleen compartments. Interestingly, pS727-STAT3-mediated abnormal lymphopoiesis in gp130F/F mice was more pronounced in lymph nodes compared to thymus, and was characterized by elevated numbers of B cells at the expense of T cells. Furthermore, pS727-STAT3 dependency for these hematologic pathologies coincided with transcriptional activity on STAT3-regulated genes, rather than its effect on mitochondrial and metabolic genes. Collectively, these findings suggest that pS727 plays a critical pathological role in modulating the transcriptional activity of STAT3 in hematologic disorders.

Serine-Phosphorylated STAT3 Promotes Tumorigenesis via Modulation of RNA Polymerase Transcriptional Activity

Deregulated activation of the latent oncogenic transcription factor STAT3 in many human epithelial malignancies, including gastric cancer, has invariably been associated with its canonical tyrosine phosphorylation and enhanced transcriptional activity. By contrast, serine phosphorylation (pS) of STAT3 can augment its nuclear transcriptional activity and promote essential mitochondrial functions, yet the role of pS-STAT3 among epithelial cancers is ill-defined. Here, we reveal that genetic ablation of pS-STAT3 in the gp130 ^F/F spontaneous gastric cancer mouse model and human gastric cancer cell line xenografts abrogated tumor growth that coincided with reduced proliferative potential of the tumor epithelium. Microarray gene expression profiling demonstrated that the suppressed gastric tumorigenesis in pS-STAT3-deficient gp130 ^F/F mice associated with reduced transcriptional activity of STAT3-regulated gene networks implicated in cell proliferation and migration, inflammation, and angiogenesis, but not mitochondrial function or metabolism. Notably, the protumorigenic activity of pS-STAT3 aligned with its capacity to primarily augment RNA polymerase II-mediated transcriptional elongation, but not initiation, of STAT3 target genes. Furthermore, by using a combinatorial in vitro and in vivo proteomics approach based on the rapid immunoprecipitation mass spectrometry of endogenous protein (RIME) assay, we identified RuvB-like AAA ATPase 1 (RUVBL1/Pontin) and enhancer of rudimentary homolog (ERH) as interacting partners of pS-STAT3 that are pivotal for its transcriptional activity on STAT3 target genes. Collectively, these findings uncover a hitherto unknown transcriptional role and obligate requirement for pS-STAT3 in gastric cancer that could be extrapolated to other STAT3-driven cancers. SIGNIFICANCE: These findings reveal a new transcriptional role and mandatory requirement for constitutive STAT3 serine phosphorylation in gastric cancer.

ADAM17: An Emerging Therapeutic Target for Lung Cancer

Lung cancer is the leading cause of cancer-related mortality, which histologically is classified into small-cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLC accounts for approximately 85% of all lung cancer diagnoses, with the majority of patients presenting with lung adenocarcinoma (LAC). KRAS mutations are a major driver of LAC, and are closely related to cigarette smoking, unlike mutations in the epidermal growth factor receptor (EGFR) which arise in never-smokers. Although the past two decades have seen fundamental progress in the treatment and diagnosis of NSCLC, NSCLC still is predominantly diagnosed at an advanced stage when therapeutic interventions are mostly palliative. A disintegrin and metalloproteinase 17 (ADAM17), also known as tumour necrosis factor-α (TNFα)-converting enzyme (TACE), is responsible for the protease-driven shedding of more than 70 membrane-tethered cytokines, growth factors and cell surface receptors. Among these, the soluble interleukin-6 receptor (sIL-6R), which drives pro-inflammatory and pro-tumourigenic IL-6 trans-signaling, along with several EGFR family ligands, are the best characterised. This large repertoire of substrates processed by ADAM17 places it as a pivotal orchestrator of a myriad of physiological and pathological processes associated with the initiation and/or progression of cancer, such as cell proliferation, survival, regeneration, differentiation and inflammation. In this review, we discuss recent research implicating ADAM17 as a key player in the development of LAC, and highlight the potential of ADAM17 inhibition as a promising therapeutic strategy to tackle this deadly malignancy.

Toll-like receptor 2 regulates metabolic reprogramming in gastric cancer via superoxide dismutase 2

Toll-like receptors (TLRs) play critical roles in host defense after recognition of conserved microbial- and host-derived components, and their dysregulation is a common feature of various inflammation-associated cancers, including gastric cancer (GC). Despite the recent recognition that metabolic reprogramming is a hallmark of cancer, the molecular effectors of altered metabolism during tumorigenesis remain unclear. Here, using bioenergetics function assays on human GC cells, we reveal that ligand-induced activation of TLR2, predominantly through TLR1/2 heterodimer, augments both oxidative phosphorylation (OXPHOS) and glycolysis, with a bias toward glycolytic activity. Notably, DNA microarray-based expression profiling of human cancer cells stimulated with TLR2 ligands demonstrated significant enrichment of gene-sets for oncogenic pathways previously implicated in metabolic regulation, including reactive oxygen species (ROS), p53 and Myc. Moreover, the redox gene encoding the manganese-dependent mitochondrial enzyme, superoxide dismutase (SOD)2, was strongly induced at the mRNA and protein levels by multiple signaling pathways downstream of TLR2, namely JAK-STAT3, JNK MAPK and NF-κB. Furthermore, siRNA-mediated suppression of SOD2 ameliorated the TLR2-induced metabolic shift in human GC cancer cells. Importantly, patient-derived tissue microarrays and bioinformatics interrogation of clinical datasets indicated that upregulated expression of TLR2 and SOD2 were significantly correlated in human GC, and the TLR2-SOD2 axis was associated with multiple clinical parameters of advanced stage disease, including distant metastasis, microvascular invasion and stage, as well as poor survival. Collectively, our findings reveal a novel TLR2-SOD2 axis as a potential biomarker for therapy and prognosis in cancer.

Interleukin 1 Up-regulates MicroRNA 135b to Promote Inflammation-Associated Gastric Carcinogenesis in Mice

BACKGROUND & AIMS

Gastritis is associated with development of stomach cancer, but little is known about changes in microRNA expression patterns during gastric inflammation. Specific changes in gene expression in epithelial cells are difficult to monitor because of the heterogeneity of the tissue. We investigated epithelial cell-specific changes in microRNA expression during gastric inflammation and gastritis-associated carcinogenesis in mice.

METHODS

We used laser microdissection to enrich epithelial cells from K19-C2mE transgenic mice, which spontaneously develop gastritis-associated hyperplasia, and Gan mice, which express activated prostaglandin E2 and Wnt in the gastric mucosa and develop gastric tumors. We measured expression of epithelial cell-enriched microRNAs and used bioinformatics analyses to integrate data from different systems to identify inflammation-associated microRNAs. We validated our findings in gastric tissues from mice and evaluated protein functions in gastric cell lines (SNU-719, SNU-601, SNU-638, AGS, and GIF-14) and knockout mice. Organoids were cultured from gastric corpus tissues of wild-type and miR-135b-knockout C57BL/6 mice. We measured levels of microRNAs in pairs of gastric tumors and nontumor mucosa from 28 patients in Japan.

RESULTS

We found microRNA 135b (miR-135B) to be the most overexpressed microRNA in gastric tissues from K19-C2mE and Gan mice: levels increased during the early stages of gastritis-associated carcinogenesis. Levels of miR-135B were also increased in gastric tumor tissues from gp130^F/F mice and patients compared with nontumor tissues. In gastric organoids and immortalized cell lines, expression of miR-135B was induced by interleukin 1 signaling. K19-C2mE mice with disruption of Mir-135b developed hyperplastic lesions that were 50% smaller than mice without Mir-135b disruption and had significant reductions in cell proliferation. Expression of miR-135B in gastric cancer cell lines increased their colony formation, migration, and sphere formation. We identified FOXN3 and RECK messenger RNAs (mRNAs) as targets of miR-135B; their knockdown reduced migration of gastric cancer cell lines. Levels of FOXN3 and RECK mRNAs correlated inversely with levels of miR-135B in human gastric tumors and in inflamed mucosa from K19-C2mE mice.

CONCLUSIONS

We found expression of miR-135B to be up-regulated by interleukin L1 signaling in gastric cancer cells and organoids. miR-135B promotes invasiveness and stem-cell features of gastric cancer cells in culture by reducing FOXN3 and RECK messenger RNAs. Levels of these messenger RNA targets, which encode tumor suppressor, are reduced in human gastric tumors.

Hyperactive gp130/STAT3-driven gastric tumourigenesis promotes submucosal tertiary lymphoid structure development

Tertiary lymphoid structures (TLSs) display phenotypic and functional characteristics of secondary lymphoid organs, and often develop in tissues affected by chronic inflammation, as well as in certain inflammation-associated cancers where they are prognostic of improved patient survival. However, the mechanisms that govern the development of tumour-associated TLSs remain ill-defined. Here, we observed tumour-associated TLSs in a preclinical mouse model (gp130F/F ) of gastric cancer, where tumourigenesis is dependent on hyperactive STAT3 signalling through the common IL-6 family signalling receptor, gp130. Gastric tumourigenesis was associated with the development of B and T cell-rich submucosal lymphoid aggregates, containing CD21+ cellular networks and high endothelial venules. Temporally, TLS formation coincided with the development of gastric adenomas and induction of homeostatic chemokines including Cxcl13, Ccl19 and Ccl21. Reflecting the requirement of gp130-driven STAT3 signalling for gastric tumourigenesis, submucosal TLS development was also STAT3-dependent, but independent of the cytokine IL-17 which has been linked with lymphoid neogenesis in chronic inflammation and autoimmunity. Interestingly, upregulated lymphoid chemokine expression and TLS formation were also observed in a chronic gastritis model induced by Helicobacter felis infection. Tumour-associated TLSs were also observed in patients with intestinal-type gastric cancer, and a gene signature linked with TLS development in gp130F/F mice was associated with advanced clinical disease, but was not prognostic of patient survival. Collectively, our in vivo data reveal that hyperactive gp130-STAT3 signalling closely links gastric tumourigenesis with lymphoid neogenesis, and while a TLS gene signature was associated with advanced gastric cancer in patients, it did not indicate a favourable prognosis.

Impact of Conventional and Three-Dimensional Thallium-Technetium Scans on Surgery for Primary Hyperparathyroidism

Twenty-nine patients with primary hyperparathyroidism underwent double-tracer subtraction scanning after injection of 201Tl as thallous chloride for thyroid and parathyroid images followed by 99mtechnetium as sodium pertechnetate for thyroid images prior to surgical exploration of the neck. The operative findings were correlated with the scans. All 23 adenomas (100%) and 13 of 18 (72%) hyperplastic glands were correctly localized. The ability of the scan to identify abnormal parathyroids was determined by the gland mass rather than whether the tissue was adenomatous or hyperplastic as all 32 (100%) abnormal glands weighing more than 180 mg were successfully localized in contrast to four of nine (44%) glands weighing less than 180 mg. An additional technique, in which emission tomography was carried out after subtraction scintigraphy, was used on 11 patients in the series. In all 11, the site of a single abnormal gland was predicted by the conventional subtraction scan: in nine of these patients, emission tomography provided additional localization of the gland in the anteroposterior plane.

Helicobacter pylori Type IV Secretion System and Its Adhesin Subunit, CagL, Mediate Potent Inflammatory Responses in Primary Human Endothelial Cells

The Gram-negative bacterium, Helicobacter pylori, causes chronic gastritis, peptic ulcers, and gastric cancer in humans. Although the gastric epithelium is the primary site of H. pylori colonization, H. pylori can gain access to deeper tissues. Concurring with this notion, H. pylori has been found in the vicinity of endothelial cells in gastric submucosa. Endothelial cells play crucial roles in innate immune response, wound healing and tumorigenesis. This study examines the molecular mechanisms by which H. pylori interacts with and triggers inflammatory responses in endothelial cells. We observed that H. pylori infection of primary human endothelial cells stimulated secretion of the key inflammatory cytokines, interleukin-6 (IL-6) and interleukin-8 (IL-8). In particular, IL-8, a potent chemokine and angiogenic factor, was secreted by H. pylori-infected endothelial cells to levels ~10- to 20-fold higher than that typically observed in H. pylori-infected gastric epithelial cells. These inflammatory responses were triggered by the H. pylori type IV secretion system (T4SS) and the T4SS-associated adhesin CagL, but not the translocation substrate CagA. Moreover, in contrast to integrin α5β1 playing an essential role in IL-8 induction by H. pylori upon infection of gastric epithelial cells, both integrin α5β1 and integrin αvβ3 were dispensable for IL-8 induction in H. pylori-infected endothelial cells. However, epidermal growth factor receptor (EGFR) is crucial for mediating the potent H. pylori-induced IL-8 response in endothelial cells. This study reveals a novel mechanism by which the H. pylori T4SS and its adhesin subunit, CagL, may contribute to H. pylori pathogenesis by stimulating the endothelial innate immune responses, while highlighting EGFR as a potential therapeutic target for controlling H. pylori-induced inflammation.

Clinical Utility of a STAT3-Regulated miRNA-200 Family Signature with Prognostic Potential in Early Gastric Cancer

Purpose: The majority of gastric cancer patients are diagnosed with late-stage disease, for which distinct molecular subtypes have been identified that are potentially amenable to targeted therapies. However, there exists no molecular classification system with prognostic power for early-stage gastric cancer (EGC) because the molecular events promoting gastric cancer initiation remain ill-defined.Experimental Design: miRNA microarrays were performed on gastric tissue from the gp130^F/F preclinical EGC mouse model, prior to tumor initiation. Computation prediction algorithms were performed on multiple data sets and independent gastric cancer patient cohorts. Quantitative real-time PCR expression profiling was undertaken in gp130^F/F-based mouse strains and human gastric cancer cells genetically engineered for suppressed activation of the oncogenic latent transcription factor STAT3. Human gastric cancer cells with modulated expression of the miR-200 family member miR-429 were also assessed for their proliferative response.Results: Increased expression of miR-200 family members is associated with both tumor initiation in a STAT3-dependent manner in gp130^F/F mice and EGC (i.e., stage IA) in patient cohorts. Overexpression of miR-429 also elicited contrasting pro- and antiproliferative responses in human gastric cancer cells depending on their cellular histologic subtype. We also identified a miR-200 family-regulated 15-gene signature that integrates multiple key current indicators of EGC, namely tumor invasion depth, differentiation, histology, and stage, and provides superior predictive power for overall survival compared with each EGC indicator alone.Conclusions: Collectively, our discovery of a STAT3-regulated, miR-200 family-associated gene signature specific for EGC, with predictive power, provides a molecular rationale to classify and stratify EGC patients for endoscopic treatment. Clin Cancer Res; 24(6); 1459-72. ©2018 AACR.

Inflammasome Adaptor ASC Suppresses Apoptosis of Gastric Cancer Cells by an IL18-Mediated Inflammation-Independent Mechanism

Inflammasomes are key regulators of innate immunity in chronic inflammatory disorders and autoimmune diseases, but their role in inflammation-associated tumorigenesis remains ill-defined. Here we reveal a protumorigenic role in gastric cancer for the key inflammasome adaptor apoptosis-related speck-like protein containing a CARD (ASC) and its effector cytokine IL18. Genetic ablation of ASC in the gp130^F/F spontaneous mouse model of intestinal-type gastric cancer suppressed tumorigenesis by augmenting caspase-8-like apoptosis in the gastric epithelium, independently from effects on myeloid cells and mucosal inflammation. This phenotype was characterized by reduced activation of caspase-1 and NF-κB activation and reduced expression of mature IL18, but not IL1β, in gastric tumors. Genetic ablation of IL18 in the same model also suppressed gastric tumorigenesis, whereas blockade of IL1β and IL1α activity upon genetic ablation of the IL1 receptor had no effect. The specific protumorigenic role for IL18 was associated with high IL18 gene expression in the gastric tumor epithelium compared with IL1β, which was preferentially expressed in immune cells. Supporting an epithelial-specific role for IL18, we found it to be highly secreted from human gastric cancer cell lines. Moreover, IL18 blockade either by a neutralizing anti-IL18 antibody or by CRISPR/Cas9-driven deletion of ASC augmented apoptosis in human gastric cancer cells. In clinical specimens of human gastric cancer tumors, we observed a significant positive correlation between elevated mature IL18 protein and ASC mRNA levels. Collectively, our findings reveal the ASC/IL18 signaling axis as a candidate therapeutic target in gastric cancer.Significance: Inflammasome activation that elevates IL18 helps drive gastric cancer by protecting cancer cells against apoptosis, with potential implications for new therapeutic strategies in this setting. Cancer Res; 78(5); 1293-307. ©2017 AACR.

In vivo evidence that RBM5 is a tumour suppressor in the lung

Cigarette smoking is undoubtedly a risk factor for lung cancer. Moreover, smokers with genetic mutations on chromosome 3p21.3, a region frequently deleted in cancer and notably in lung cancer, have a dramatically higher risk of aggressive lung cancer. The RNA binding motif 5 (RBM5) is one of the component genes in the 3p21.3 tumour suppressor region. Studies using human cancer specimens and cell lines suggest a role for RBM5 as a tumour suppressor. Here we demonstrate, for the first time, an in vivo role for RBM5 as a tumour suppressor in the mouse lung. We generated Rbm5 loss-of-function mice and exposed them to a tobacco carcinogen NNK. Upon exposure to NNK, Rbm5 loss-of-function mice developed lung cancer at similar rates to wild type mice. As tumourigenesis progressed, however, reduced Rbm5 expression lead to significantly more aggressive lung cancer i.e. increased adenocarcinoma nodule numbers and tumour size. Our data provide in vivo evidence that reduced RBM5 function, as occurs in a large number of patients, coupled with exposure to tobacco carcinogens is a risk factor for an aggressive lung cancer phenotype. These data suggest that RBM5 loss-of-function likely underpins at least part of the pro-tumourigenic consequences of 3p21.3 deletion in humans.

Therapeutic Targeting of the IL-6 Trans-Signaling/Mechanistic Target of Rapamycin Complex 1 Axis in Pulmonary Emphysema

RATIONALE

The potent immunomodulatory cytokine IL-6 is consistently up-regulated in human lungs with emphysema and in mouse emphysema models; however, the mechanisms by which IL-6 promotes emphysema remain obscure. IL-6 signals using two distinct modes: classical signaling via its membrane-bound IL-6 receptor (IL-6R), and trans-signaling via a naturally occurring soluble IL-6R.

OBJECTIVES

To identify whether IL-6 trans-signaling and/or classical signaling contribute to the pathogenesis of emphysema.

METHODS

We used the gp130^F/F genetic mouse model for spontaneous emphysema and cigarette smoke-induced emphysema models. Emphysema in mice was quantified by various methods including in vivo lung function and stereology, and terminal deoxynucleotidyl transferase dUTP nick end labeling assay was used to assess alveolar cell apoptosis. In mouse and human lung tissues, the expression level and location of IL-6 signaling-related genes and proteins were measured, and the levels of IL-6 and related proteins in sera from emphysematous mice and patients were also assessed.

MEASUREMENTS AND MAIN RESULTS

Lung tissues from patients with emphysema, and from spontaneous and cigarette smoke-induced emphysema mouse models, were characterized by excessive production of soluble IL-6R. Genetic blockade of IL-6 trans-signaling in emphysema mouse models and therapy with the IL-6 trans-signaling antagonist sgp130Fc ameliorated emphysema by suppressing augmented alveolar type II cell apoptosis. Furthermore, IL-6 trans-signaling-driven emphysematous changes in the lung correlated with mechanistic target of rapamycin complex 1 hyperactivation, and treatment of emphysema mouse models with the mechanistic target of rapamycin complex 1 inhibitor rapamycin attenuated emphysematous changes.

CONCLUSIONS

Collectively, our data reveal that specific targeting of IL-6 trans-signaling may represent a novel treatment strategy for emphysema.

Identification of a TLR2-regulated gene signature associated with tumor cell growth in gastric cancer

Toll-like receptors (TLRs) are key regulators of innate immune responses, and their dysregulation is observed in numerous inflammation-associated malignancies, including gastric cancer (GC). However, the identity of specific TLRs and their molecular targets which promote the pathogenesis of human GC is ill-defined. Here, we sought to determine the clinical utility of TLR2 in human GC. TLR2 mRNA and protein expression levels were elevated in >50% of GC patient tumors across multiple ethnicities. TLR2 was also widely expressed among human GC cell lines, and DNA microarray-based expression profiling demonstrated that the TLR2-induced growth responsiveness of human GC cells corresponded with the up-regulation of six anti-apoptotic (BCL2A1, BCL2, BIRC3, CFLAR, IER3, TNFAIP3) and down-regulation of two tumor suppressor (PDCD4, TP53INP1) genes. The TLR2-mediated regulation of these anti-apoptotic and tumor suppressor genes was also supported by their increased and reduced expression, respectively, in two independent genetic GC mouse models (gp130^F/F and Gan) characterized by high tumor TLR2 expression. Notably, enrichment of this TLR2-regulated gene signature also positively correlated with augmented TLR2 expression in human GC tumors, and served as an indicator of poor patient survival. Furthermore, treatment of gp130^F/F and cell line-derived xenograft (MKN1) GC mouse models with a humanized anti-TLR2 antibody suppressed gastric tumor growth, which was coincident with alterations to the TLR2-driven gene signature. Collectively, our study demonstrates that in the majority of GC patients, elevated TLR2 expression is associated with a growth-potentiating gene signature which predicts poor patient outcomes, thus supporting TLR2 as a promising therapeutic target in GC.

Endoscopic ultrasound-guided fine-needle aspirate-derived preclinical pancreatic cancer models reveal panitumumab sensitivity in KRAS wild-type tumors

Pancreatic cancer (PC) is largely refractory to existing therapies used in unselected patient trials, thus emphasizing the pressing need for new approaches for patient selection in personalized medicine. KRAS mutations occur in 90% of PC patients and confer resistance to epidermal growth factor receptor (EGFR) inhibitors (e.g., panitumumab), suggesting that KRAS wild-type PC patients may benefit from targeted panitumumab therapy. Here, we use tumor tissue procured by endoscopic ultrasound-guided fine-needle aspirate (EUS-FNA) to compare the in vivo sensitivity in patient-derived xenografts (PDXs) of KRAS wild-type and mutant PC tumors to panitumumab, and to profile the molecular signature of these tumors in patients with metastatic or localized disease. Specifically, RNASeq of EUS-FNA-derived tumor RNA from localized (n = 20) and metastatic (n = 20) PC cases revealed a comparable transcriptome profile. Screening the KRAS mutation status of tumor genomic DNA obtained from EUS-FNAs stratified PC patients into either KRAS wild-type or mutant cohorts, and the engraftment of representative KRAS wild-type and mutant EUS-FNA tumor samples into NOD/SCID mice revealed that the growth of KRAS wild-type, but not mutant, PDXs was selectively suppressed with panitumumab. Furthermore, in silico transcriptome interrogation of The Cancer Genome Atlas (TCGA)-derived KRAS wild-type (n = 38) and mutant (n = 132) PC tumors revealed 391 differentially expressed genes. Taken together, our study validates EUS-FNA for the application of a novel translational pipeline comprising KRAS mutation screening and PDXs, applicable to all PC patients, to evaluate personalized anti-EGFR therapy in patients with KRAS wild-type tumors.

Interleukin-11-driven gastric tumourigenesis is independent of trans-signalling

Deregulated gp130-dependent STAT3 signalling by the pleiotropic cytokine interleukin (IL)-11 has been implicated in the pathogenesis of gastric cancer (GC), the third most common cancer worldwide. While the IL-11-gp130-STAT3 signalling axis has traditionally been thought to exclusively use the membrane-bound IL-11 receptor (mIL-11R), recent evidence suggests that mIL-11R can be proteolytically cleaved to generate a soluble form (sIL-11R) which can elicit trans-signalling. Since the role of IL-11 trans-signalling in disease pathogenesis is unknown, here we have employed the IL-11-driven gp130^F/F spontaneous model of GC to determine whether IL-11 trans-signalling promotes gastric tumourigenesis. sIL-11R protein was detectable in gastric tissue from GC patients, and sIL-11R levels were elevated in tumours of gp130^F/F mice compared to matched non-tumours. Among candidate proteases associated with the generation of sIL-11R, ADAM10 and the related metalloprotease ADAM17 were significantly upregulated in tumours of both gp130^F/F mice and GC patients compared to matched non-tumour tissues. The genetic blockade of IL-11 trans-signalling in gp130^F/F mice upon the transgenic over-expression of the trans-signalling antagonist, sgp130Fc, failed to suppress gastric inflammation and associated tumour growth, and also had no effect on reducing hyper-activated STAT3 levels. Furthermore, a non-essential role for ADAM17 in IL-11-driven gastric tumourigenesis was supported by the observation that the tumour burden was unaffected in gp130^F/F:Adam17^ex/ex mice in which ADAM17 expression levels have been substantially reduced. Collectively, these findings suggest that classic signalling rather than trans-signalling is the mode by which IL-11 promotes gastric tumourigenesis.

Laboratory evaluation of a novel anaesthesia delivery device

Here, we describe proof of concept of a novel method for delivering volatile anaesthetics, where the liquid anaesthetic (sevoflurane or isoflurane) is formulated into an emulsion that is contained in a compact, lightweight device through which carrier gas flows. Release of anaesthetic is achieved by stirring of the formulation, allowing controlled and responsive release of anaesthetic at a variety of fixed flow rates between 0.5 l.min^-1 and 5 l.min^-1 , with ventilated, non-ventilated and draw-over breathing systems. Anaesthetic release was evaluated using target anaesthetic concentrations ranging from 0.5% v/v to 8% v/v to mimic those typically required for induction and maintenance of anaesthesia, and lower concentrations suitable for sedation. Under all conditions, output could be maintained within 0.1% v/v of the intended setting, and the device could deliver a controlled level of anaesthetic for at least 60 min, with compensation for different ambient temperatures (10-30 °C) and carrier gas flow rates. This device offers a simple, inexpensive method of delivering safe concentrations of volatile anaesthetics for a wide range of applications.

Transcriptional regulation of inflammasome-associated pattern recognition receptors, and the relevance to disease pathogenesis

Over the last decade it has emerged that inflammasome complexes provide a pivotal platform for the host innate immune system to respond to exogenous infectious microbes (viruses, bacteria, fungi) and non-infectious environmental agents (cigarette smoke, pollution), as well as endogenous "danger" signals. Upon the canonical activation of inflammasomes, a key effector function is to catalyze, via caspase-1, the maturation of the potent pro-inflammatory cytokines interleukin (IL)-1β and IL-18, which, in addition to chronic inflammatory responses have also been intimately linked to the inflammatory form of lytic cell death, pyroptosis. However, recent evidence suggests that inflammasomes exhibit marked pleiotropism beyond their canonical functions, whereby their activation can also influence a large number of cellular responses including proliferation, apoptosis, autophagy and metabolism. It is therefore not surprising that the dysregulated expression and/or activation of inflammasomes is increasingly implicated in numerous disease states, such as chronic auto-inflammatory and autoimmune disorders, metabolic syndrome, neurodegenerative and cardiovascular diseases, as well as cancer. In this review we will highlight recent advancements in our understanding of the transcriptional regulation of genes encoding inflammasome-associated innate immune receptors, and the impact on a variety of cellular responses during disease pathogenesis.

Murine Oncostatin M Acts via Leukemia Inhibitory Factor Receptor to Phosphorylate Signal Transducer and Activator of Transcription 3 (STAT3) but Not STAT1, an Effect That Protects Bone Mass

Oncostatin M (OSM) and leukemia inhibitory factor (LIF) are IL-6 family members with a wide range of biological functions. Human OSM (hOSM) and murine LIF (mLIF) act in mouse cells via a LIF receptor (LIFR)-glycoprotein 130 (gp130) heterodimer. In contrast, murine OSM (mOSM) signals mainly via an OSM receptor (OSMR)-gp130 heterodimer and binds with only very low affinity to mLIFR. hOSM and mLIF stimulate bone remodeling by both reducing osteocytic sclerostin and up-regulating the pro-osteoclastic factor receptor activator of NF-κB ligand (RANKL) in osteoblasts. In the absence of OSMR, mOSM still strongly suppressed sclerostin and stimulated bone formation but did not induce RANKL, suggesting that intracellular signaling activated by the low affinity interaction of mOSM with mLIFR is different from the downstream effects when mLIF or hOSM interacts with the same receptor. Both STAT1 and STAT3 were activated by mOSM in wild type cells or by mLIF/hOSM in wild type and Osmr^-/- cells. In contrast, in Osmr^-/- primary osteocyte-like cells stimulated with mOSM (therefore acting through mLIFR), microarray expression profiling and Western blotting analysis identified preferential phosphorylation of STAT3 and induction of its target genes but not of STAT1 and its target genes; this correlated with reduced phosphorylation of both gp130 and LIFR. In a mouse model of spontaneous osteopenia caused by hyperactivation of STAT1/3 signaling downstream of gp130 (gp130^Y757F/Y757F), STAT1 deletion rescued the osteopenic phenotype, indicating a beneficial effect of promoting STAT3 signaling over STAT1 downstream of gp130 in this low bone mass condition, and this may have therapeutic value.

Multifaceted Role of IRAK-M in the Promotion of Colon Carcinogenesis via Barrier Dysfunction and STAT3 Oncoprotein Stabilization in Tumors

Dysregulated interactions between the host immune system and gut microbiota can underpin inflammation, leading to colorectal cancer (CRC). In this issue of Cancer Cell, Kesselring et al. reveal a bimodal role of the TLR/IL-1R-signaling negative regulator, IRAK-M, in promoting tumoral microbial colonization and STAT3 oncoprotein stabilization during CRC.

Inflammatory and non-inflammatory roles for Toll-like receptors in gastrointestinal cancer

Collectively, cancers of the gastrointestinal (GI) tract (including the esophagus, stomach, duodenum, colon, rectum, liver, gall bladder and bile ducts) are the most prevalent and deadly worldwide. A common denominator in the pathogenesis of these GI tract cancers is chronic inflammation, as evidenced by the fact that sufferers of inflammatory bowel disease (IBD) are significantly more susceptible to colon cancer than healthy individuals. However, since only a relatively small proportion of individuals with chronic inflammatory conditions such as IBD go on to develop cancer, research has focused on identifying discrepancies in the host immune system that may be responsible for promoting carcinogenesis in inflamed tissue. To this end, molecular pathways linking inflammation and cancer are emerging, with one series of candidates being members of the Toll-like receptor family.

IL6 Trans-signaling Promotes KRAS-Driven Lung Carcinogenesis

Oncogenic KRAS mutations occur frequently in lung adenocarcinoma. The signaling pathways activated by IL6 promote Kras-driven lung tumorigenesis, but the basis for this cooperation is uncertain. In this study, we used the gp130(F/F) (Il6st) knock-in mouse model to examine the pathogenic contribution of hyperactivation of the STAT3 arm of IL6 signaling on KRAS-driven lung tumorigenesis. Malignant growths in the gp130(F/F):Kras(G12D) model displayed features of atypical adenomatous hyperplasia, adenocarcinoma in situ, and invasive adenocarcinoma throughout the lung, as compared with parental Kras(G12D) mice, where STAT3 was not hyperactivated. Among IL6 family cytokines, only IL6 was upregulated in the lung. Accordingly, normalization of pulmonary STAT3 activity, by genetic ablation of either Il6 or Stat3, suppressed the extent of lung cancer in the model. Mechanistic investigations revealed elevation in the lung of soluble IL6 receptor (sIL6R), the key driver of IL6 trans-signaling, and blocking this mechanism via interventions with an anti-IL6R antibody or the inhibitor sgp130Fc ameliorated lung cancer pathogenesis. Clinically, expression of IL6 and sIL6R was increased significantly in human specimens of lung adenocarcinoma or patient serum. Our results offer a preclinical rationale to clinically evaluate IL6 trans-signaling as a therapeutic target for the treatment of KRAS-driven lung adenocarcinoma.

Investigating the Role of Toll-Like Receptors in Mouse Models of Gastric Cancer

Gastric cancer (GC) is the second most lethal cancer world-wide, and the poor overall 5-year survival rate of <25 % for GC is largely due to both the late detection of this aggressive disease and limited effectiveness of current treatment options. Collectively, these observations underscore the need to identify new molecular targets (i.e., genes) to serve as biomarkers for early detection and/or treatment strategies to improve patient outcomes. While GC represents a growing number of cancers whereby deregulation of the immune system is linked to tumor initiation and progression, the identity of innate immune regulators with oncogenic potential in the host gastric mucosal epithelium remains obscure. Over the last couple of decades experimental mouse models for many cancer types have been widely used with great success to identify genes whose expression and/or mutation status influences tumorigenesis. Considering the recent mounting evidence for the role of innate immunity in the pathogenesis of inflammation-associated cancers such as GC, much attention has focused on members of the Toll-like receptor (TLR) family, which are key components of the innate immune system primarily known to trigger inflammatory responses upon pathogen detection. Here, we describe techniques used on genetic mouse models for GC to examine the role of specific TLR family members in the pathogenesis of GC.