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

Toll-like receptors in health and disease

Toll-like receptors (TLRs) are inflammatory triggers and belong to a family of pattern recognition receptors (PRRs) that are central to the regulation of host protective adaptive immune responses. Activation of TLRs in innate immune myeloid cells directs lymphocytes to produce the most appropriate effector responses to eliminate infection and maintain homeostasis of the body's internal environment. Inappropriate TLR stimulation can lead to the development of general autoimmune diseases as well as chronic and acute inflammation, and even cancer. Therefore, TLRs are expected to be targets for therapeutic treatment of inflammation-related diseases, autoimmune diseases, microbial infections, and human cancers. This review summarizes the recent discoveries in the molecular and structural biology of TLRs. The role of different TLR signaling pathways in inflammatory diseases, autoimmune diseases such as diabetes, cardiovascular diseases, respiratory diseases, digestive diseases, and even cancers (oral, gastric, breast, colorectal) is highlighted and summarizes new drugs and related clinical treatments in clinical trials, providing an overview of the potential and prospects of TLRs for the treatment of TLR-related diseases.

Porphyromonas gingivalis Lipopolysaccharide Damages Mucosal Barrier to Promote Gastritis-Associated Carcinogenesis

BACKGROUND

Recent epidemiological studies suggested correlation between gastric cancer (GC) and periodontal disease.

AIMS

We aim to clarify involvement of lipopolysaccharide of Porphyromonas gingivalis (Pg.), one of the red complex periodontal pathogens, in the GC development.

METHODS

To evaluate barrier function of background mucosa against the stimulations, we applied biopsy samples from 76 patients with GC using a Ussing chamber system (UCs). K19-Wnt1/C2mE transgenic (Gan) mice and human GC cell-lines ± THP1-derived macrophage was applied to investigate the role of Pg. lipopolysaccharide in inflammation-associated carcinogenesis.

RESULTS

In the UCs, Pg. lipopolysaccharide reduced the impedance of metaplastic and inflamed mucosa with increases in mRNA expression of toll-like receptor (TLR) 2, tumor necrosis factor (TNF) α, and apoptotic markers. In vitro, Pg. lipopolysaccharide promoted reactive oxidative stress (ROS)-related apoptosis as well as activated TLR2-β-catenin-signaling on MKN7, and it increased the TNFα production on macrophages, respectively. TNFα alone activated TLR2-β-catenin-signaling in MKN7, while it further increased ROS and TNFα in macrophages. Under coculture with macrophages isolated after stimulation with Pg. lipopolysaccharide, β-catenin-signaling in MKN7 was activated with an increase in supernatant TNFα concentration, both of which were decreased by adding a TNFα neutralization antibody into the supernatant. In Gan mice with 15-week oral administration of Pg. lipopolysaccharide, tumor enlargement with β-catenin-signaling activation were observed with an increase in TNFα with macrophage infiltration.

CONCLUSIONS

Local exposure of Pg. lipopolysaccharide may increase ROS on premalignant gastric mucosa to induce apoptosis-associated barrier dysfunction and to secrete TNFα from activated macrophages, and both stimulation of Pg. lipopolysaccharide and TNFα might activate TLR2-β-catenin-signaling in GC.

The Role of the Toll-like Receptor 2 and the cGAS-STING Pathways in Breast Cancer: Friends or Foes?

Breast cancer stands as a primary malignancy among women, ranking second in global cancer-related deaths. Despite treatment advancements, many patients progress to metastatic stages, posing a significant therapeutic challenge. Current therapies primarily target cancer cells, overlooking their intricate interactions with the tumor microenvironment (TME) that fuel progression and treatment resistance. Dysregulated innate immunity in breast cancer triggers chronic inflammation, fostering cancer development and therapy resistance. Innate immune pattern recognition receptors (PRRs) have emerged as crucial regulators of the immune response as well as of several immune-mediated or cancer cell-intrinsic mechanisms that either inhibit or promote tumor progression. In particular, several studies showed that the Toll-like receptor 2 (TLR2) and the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathways play a central role in breast cancer progression. In this review, we present a comprehensive overview of the role of TLR2 and STING in breast cancer, and we explore the potential to target these PRRs for drug development. This information will significantly impact the scientific discussion on the use of PRR agonists or inhibitors in cancer therapy, opening up new and promising avenues for breast cancer treatment.

ALKBH5 promotes hypopharyngeal squamous cell carcinoma apoptosis by targeting TLR2 in a YTHDF1/IGF2BP2-mediated manner

Hypopharyngeal squamous cell carcinoma (HPSCC) is one of the most aggressive cancers and is notorious for its extremely poor prognosis. However, very few molecular biological studies have been performed. As a novel method of epigenetic gene modulation, N6-methyladenosine (m6A) RNA modification occurs in HPSCC. The expression of the m6A demethylase AlkB homolog 5 (ALKBH5) is frequently downregulated in human HPSCC. Furthermore, we found that ALKBH5 impaired cell proliferation by regulating human Toll-like receptor 2 (TLR2) in an m6A-dependent manner in HPSCC cells. ALKBH5 decreased TLR2 m6A modification, which could be recognized by the m6A readers IGF2BP2 and YTHDF1. IGF2BP2 facilitates TLR2 mRNA stability, whereas YTHDF1 promotes TLR2 mRNA translation. The current work uncovered a critical function of ALKBH5 in TLR2 regulation and provides a novel role for m6A demethylation of mRNA in HPSCC. The inhibition of m6A modification of ALKBH5 in HPSCC deserves further clinical investigation.

Could Toll-like Receptor 2 Serve as Biomarker to Detect Advanced Gastric Cancer?

Gastric cancer is one of the five most common types of cancer worldwide. Due to the heterogeneous course and the involvement of many risk factors, its treatment and diagnosis is an important challenge for modern medicine. Recent studies have emphasized the i role of Toll-like receptors (TLRs) expressed on selected cells of the immune system in the pathogenesis of gastric cancer. The aim of this study was to determine the prevalence of TLR2 on T lymphocytes, B lymphocytes, monocytes, and dendritic cells in patients diagnosed with gastric cancer, with particular emphasis on the stage of the disease. Based on the obtained results, we have shown that patients with gastric cancer are characterized by a higher percentage of all tested populations of peripheral blood immune cells expressing TLR2 in relation to patients from the control group. Moreover, a detailed analysis of the collected results showed a significant link between TLR2 and the stage of the disease.

Helicobacter pylori outer membrane vesicles induce astrocyte reactivity through nuclear factor-κappa B activation and cause neuronal damage in vivo in a murine model

BACKGROUND

Helicobacter pylori (Hp) infects the stomach of 50% of the world's population. Importantly, chronic infection by this bacterium correlates with the appearance of several extra-gastric pathologies, including neurodegenerative diseases. In such conditions, brain astrocytes become reactive and neurotoxic. However, it is still unclear whether this highly prevalent bacterium or the nanosized outer membrane vesicles (OMVs) they produce, can reach the brain, thus affecting neurons/astrocytes. Here, we evaluated the effects of Hp OMVs on astrocytes and neurons in vivo and in vitro.

METHODS

Purified OMVs were characterized by mass spectrometry (MS/MS). Labeled OMVs were administered orally or injected into the mouse tail vein to study OMV-brain distribution. By immunofluorescence of tissue samples, we evaluated: GFAP (astrocytes), βIII tubulin (neurons), and urease (OMVs). The in vitro effect of OMVs in astrocytes was assessed by monitoring NF-κB activation, expression of reactivity markers, cytokines in astrocyte-conditioned medium (ACM), and neuronal cell viability.

RESULTS

Urease and GroEL were prominent proteins in OMVs. Urease (OMVs) was present in the mouse brain and its detection coincided with astrocyte reactivity and neuronal damage. In vitro, OMVs induced astrocyte reactivity by increasing the intermediate filament proteins GFAP and vimentin, the plasma membrane α_Vβ₃ integrin, and the hemichannel connexin 43. OMVs also produced neurotoxic factors and promoted the release of IFNγ in a manner dependent on the activation of the transcription factor NF-κB. Surface antigens on reactive astrocytes, as well as secreted factors in response to OMVs, were shown to inhibit neurite outgrowth and damage neurons.

CONCLUSIONS

OMVs administered orally or injected into the mouse bloodstream reach the brain, altering astrocyte function and promoting neuronal damage in vivo. The effects of OMVs on astrocytes were confirmed in vitro and shown to be NF-κB-dependent. These findings suggest that Hp could trigger systemic effects by releasing nanosized vesicles that cross epithelial barriers and access the CNS, thus altering brain cells.

Transcriptional signatures of the BCL2 family for individualized acute myeloid leukaemia treatment

BACKGROUND

Although anti-apoptotic proteins of the B-cell lymphoma-2 (BCL2) family have been utilized as therapeutic targets in acute myeloid leukaemia (AML), their complicated regulatory networks make individualized therapy difficult. This study aimed to discover the transcriptional signatures of BCL2 family genes that reflect regulatory dynamics, which can guide individualized therapeutic strategies.

METHODS

From three AML RNA-seq cohorts (BeatAML, LeuceGene, and TCGA; n = 451, 437, and 179, respectively), we constructed the BCL2 family signatures (BFSigs) by applying an innovative gene-set selection method reflecting biological knowledge followed by non-negative matrix factorization (NMF). To demonstrate the significance of the BFSigs, we conducted modelling to predict response to BCL2 family inhibitors, clustering, and functional enrichment analysis. Cross-platform validity of BFSigs was also confirmed using NanoString technology in a separate cohort of 47 patients.

RESULTS

We established BFSigs labeled as the BCL2, MCL1/BCL2, and BFL1/MCL1 signatures that identify key anti-apoptotic proteins. Unsupervised clustering based on BFSig information consistently classified AML patients into three robust subtypes across different AML cohorts, implying the existence of biological entities revealed by the BFSig approach. Interestingly, each subtype has distinct enrichment patterns of major cancer pathways, including MAPK and mTORC1, which propose subtype-specific combination treatment with apoptosis modulating drugs. The BFSig-based classifier also predicted response to venetoclax with remarkable performance (area under the ROC curve, AUROC = 0.874), which was well-validated in an independent cohort (AUROC = 0.950). Lastly, we successfully confirmed the validity of BFSigs using NanoString technology.

CONCLUSIONS

This study proposes BFSigs as a biomarker for the effective selection of apoptosis targeting treatments and cancer pathways to co-target in AML.

A20 Restricts NOS2 Expression and Intestinal Tumorigenesis in a Mouse Model of Colitis-Associated Cancer

BACKGROUND AND AIMS

Colon cancer can occur sporadically or in the setting of chronic inflammation, such as in patients with inflammatory bowel disease. We previously showed that A20, a critical negative regulator of tumor necrosis factor signal transduction, could regulate sporadic colon cancer development. In this report, we investigate whether A20 also acts as a tumor suppressor in a model of colitis-associated cancer.

METHODS

Colitis and colitis-associated tumors were induced in wild-type and A20 intestinal epithelial cell-specific knockout (A20dIEC) mice using dextran sodium sulfate and azoxymethane. Clinicopathologic markers of inflammation were assessed in conjunction with colonic tumor burden. Gene expression analyses and immunohistochemistry were performed on colonic tissue and intestinal enteroids. Nitric oxide (NO) production and activity were assessed in whole colonic lysates and mouse embryonic fibroblasts.

RESULTS

A20dIEC mice develop larger tumors after treatment with dextran sodium sulfate and azoxymethane than wild-type mice. In addition to elevated markers of inflammation, A20dIEC mice have significantly enhanced expression of inducible nitric oxide synthase (iNOS), a well-known driver of neoplasia. Enhanced iNOS expression is associated with the formation of reactive nitrogen species and DNA damage. Loss of A20 also enhances NO-dependent cell death directly.

CONCLUSION

Mechanistically, we propose that A20 normally restricts tumor necrosis factor-induced nuclear factor kappa B-dependent production of iNOS in intestinal epithelial cells, thereby protecting against colitis-associated tumorigenesis. We also propose that A20 plays a direct role in regulating NO-dependent cell death.

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.

Making sense of IL-6 signalling cues in pathophysiology

Unravelling the molecular mechanisms that account for functional pleiotropy is a major challenge for researchers in cytokine biology. Cytokine-receptor cross-reactivity and shared signalling pathways are considered primary drivers of cytokine pleiotropy. However, reports epitomized by studies of Jak-STAT cytokine signalling identify interesting biochemical and epigenetic determinants of transcription factor regulation that affect the delivery of signal-dependent cytokine responses. Here, a regulatory interplay between STAT transcription factors and their convergence to specific genomic enhancers support the fine-tuning of cytokine responses controlling host immunity, functional identity, and tissue homeostasis and repair. In this review, we provide an overview of the signalling networks that shape the way cells sense and interpret cytokine cues. With an emphasis on the biology of interleukin-6, we highlight the importance of these mechanisms to both physiological processes and pathophysiological outcomes.

IL-23 production in human macrophages is regulated negatively by tumor necrosis factor α-induced protein 3 and positively by specificity protein 1 after stimulation of the toll-like receptor 7/8 signaling pathway

The IL-23/IL-17 axis plays an important role in the development of autoimmune diseases, but the mechanism regulating IL-23 production is mainly unknown. We investigated how TNFAIP3 and Sp1 affect IL-23 production by human macrophages after exposure to resiquimod, a TLR7/8 agonist.

IL-23 production was significantly upregulated by resiquimod but only slightly by LPS (a TLR4 agonist). Interestingly, IL-23 levels were significantly attenuated after sequential stimulation with LPS and resiquimod, but IL-12p40 and IL-18 levels were not. TLR4-related factors induced by LPS may regulate IL-23 expression via TLR7/8 signaling. LPS significantly enhanced TNFAIP3 and IRAK-M levels but reduced Sp1 levels. After exposure to resiquimod, RNA interference of TNFAIP3 upregulated IL-23 significantly more than siRNA transfection of IRAK-M did. In contrast, knockdown of Sp1 by RNA interference significantly attenuated IL-23 production. Transfection with siRNA for TNFAIP3 enhanced IL-23 expression significantly. After stimulation with resiquimod, GW7647—an agonist for PPARα (an inducer of NADHP oxidase)—and siRNA for UCP2 (a negative regulator of mitochondrial ROS generation) enhanced TNFAIP3 and reduced IL-23. siRNA for p22phox and gp91phox slightly increased Sp1 levels. However, after exposure to resiquimod siRNA-mediated knockout of DUOX1/2 significantly enhanced Sp1 and IL-23 levels, and decreased TNFα-dependent COX-2 expression. Concomitantly, TNFAIP3 levels was attenuated by DUOX1/2 siRNA. TNFAIP3 and Sp1 levels are reciprocally regulated through ROS generation.

In conclusion, after stimulation of the TLR7/8 signaling pathway IL-23 production in human macrophages is regulated negatively by TNFAIP3.

Microbial Colonization and Inflammation as Potential Contributors to the Lack of Therapeutic Success in Oral Squamous Cell Carcinoma

This review discusses the microenvironment of evolving and established conventional oral squamous cell carcinoma, by far the most common oral cancer. The focus of this paper is mainly on the more recent data that describe the role of microorganisms, host-microbial interactions, and in particular, the contributions of cell-surface toll-like receptors on immune system cells and on normal and malignant epithelial cells to their functions that support carcinogenesis. Because carcinomas arising at various host surfaces share much in common, additional information available from studies of other carcinomas is included in the discussion. Accumulating evidence reveals the complex toll-like receptor-mediated tumor-supporting input into many aspects of carcinogenesis via malignant cells, stromal immune cells and non-immune cells, complicating the search for effective treatments.

TLR2 and TLR4 Signaling Pathways and Gastric Cancer: Insights from Transcriptomics and Sample Validation

Background

Pattern recognition receptors, especially toll-like receptors (TLRs), as the first line of defense for pathogen detection, were found to be associated with H.¬ pylori infection and gastric cancer (GC). However, the expression levels of TLRs, i.e. TLR2 and TLR4, as the main receptors sensed by H.¬ pylori, still remain largely ambiguous. We aimed to investigate the patterns of key transcripts of TLR2 and TLR4 in 100 GC transcriptome data. Additionally, we evaluated TLR2 and TLR4 gene expressions in gastric biopsies of Iranian GC patients, in order to validate RNA-seq outputs.

Methods

For this study, 100 runs of GC samples and controls were processed and analyzed using map read to reference. Differential gene expression method was used to distinguish between GC and normal samples in the expression of TLRs and other innate immune molecules. Also, using qRT-PCR assay, transcripts of TLRs molecules for 15 GC and 15 control samples were analyzed based on the analysis of variance and least significant differences.

Results

The results clearly showed that all signaling pathways molecules of TLR4, especially TLR4 (p = 0.019), NF-κB (p ¬= 0.047), IL-1β (p = 0.0096), and TNF-α (p = 0.048), were upregulated in a cancerous condition in different parts and at various stages of GC.

Conclusion

Our findings suggested that molecules involved in inflammation, including TLR4 and its related pro-inflammatory cytokines, may be responsible for the development and progression of GC. Accordingly, the control of H. pylori infection reduces inflammation in the gastric system and can play an important role in preventing gastrointestinal disorders.

Vertebrate Wnt5a - At the crossroads of cellular signalling

Wnt signalling is an essential pathway in embryogenesis, differentiation, cell motility, development, and adult tissue homeostasis in vertebrates. The Wnt signalling network can activate several downstream pathways such as the β-catenin-dependent TCF/LEF transcription, the Wnt/planar cell polarity (PCP) pathway, and the Wnt/Calcium pathway. Wnt5a is a vertebrate Wnt ligand that is most often associated with the Wnt/PCP signalling pathway. Wnt5a/PCP signalling has a well-described role in embryogenesis via binding to a receptor complex of Frizzled and its co-receptors to initiate downstream activation of the c-Jun N-terminal kinase (JNK) signalling cascade and the Rho and Rac GTPases, Rho-Kinase (ROCK). This activation results in the cytoskeletal remodelling required for cell polarity, migration, and subsequently, tissue re-arrangement and organ formation. This review will focus on more recent work that has revealed new roles for Wnt5a ligands and consequently, an emerging broader function. This is partly due to our growing understanding of the crosstalk between the Wnt/PCP pathway with both the Wnt/β-catenin pathway and other signalling pathways, and in part due to the identification of novel atypical receptors for Wnt5a that demonstrate a far broader role for this ligand.

Toll-like receptor 3 is a potential prognosis marker and associated with immune infiltration in stomach adenocarcinoma

BACKGROUND

Toll-like receptors participate in various biological mechanisms, mainly including the immune response and inflammatory response. Nevertheless, the role of TLRs in STAD remains unclear.

OBJECTIVE

We aimed to explore the expression, prognosis performance of TLRs in STAD and their relationship with immune infiltration.

METHODS

Student's t-test was used to evaluate the expression of TLRs between STAD tissues and normal tissues. Kaplan-Meier method was applied to explored the prognosis value of TLRs in STAD. And qRT-PCR validated their expression and prognosis value. Spearman's correlation analysis and Wilcoxon rank-sum test were used to assess the association between TLRs and immune infiltration in STAD.

RESULTS

The mRNA level of TLR3 was downregulated in STAD. We summarized genetic mutations and CNV alteration of TLRs in STAD cohort. Prognosis analysis revealed that STAD patients with high TLR3 expression showed better prognosis in OS, FP and PPS. The result of qRT-PCR suggested that TLR3 expression was decreased in STAD tissues and STAD patients with high TLR3 mRNA level had a better OS. Univariate and multivariate cox regression analysis suggested TLR3 expression and clinical stage as independent factors affecting STAD patients' prognosis. A positive association existed between TLR3 expression and the abundance of immune cells and the expression of various immune biomarkers. Furthermore, key targets related to TLR3 were identified in STAD, mainly including MIR-129 (GCAAAAA), PLK1, and V$IRF1_01.

CONCLUSIONS

Our result demonstrated TLR3 as a prognosis marker and associated with immune infiltration in STAD.

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.

Microbe-Mediated Activation of Toll-like Receptor 2 Drives PDL1 Expression in HNSCC

Simple Summary

Tumors use immunosuppressive signals to evade detection by the immune system. While recurrent and metastatic head and neck squamous cell carcinoma has historically carried a poor prognosis, therapies targeting the immunosuppressive PD1:PDL1 axis have improved survival in certain patients. Defining mechanisms regulating PDL1 in various contexts may inform refinement of immunotherapy protocols. We identified a role for Toll-like Receptor 2 (TLR2) signaling in driving PDL1 expression. In antigen-presenting cells, TLR2 functions to initiate response to pathogens, and it is overexpressed or genetically altered in some tumors. We found that the synthetic TLR2 ligand Pam3CSK4, as well as whole bacteria, induced PDL1 expression in specific HNSCC cell line models, suggesting that TLR2 may contribute to immune evasion in chronically inflamed tissues.

Abstract

As immunotherapies targeting the PDL1 checkpoint have become a mainstay of treatment for a subset of head and neck squamous cell carcinoma (HNSCC) patients, a detailed understanding of the mechanisms underlying PDL1-mediated immune evasion is needed. To elucidate factors regulating expression of PDL1 in HNSCC cells, a genome-wide CRISPR profiling approach was implemented to identify genes and pathways conferring altered PDL1 expression in an HNSCC cell line model. Our screen nominated several candidate PDL1 drivers, including Toll-like Receptor 2 (TLR2). Depletion of TLR2 blocks interferon-γ-induced PDL1 expression, and stimulation of TLR2 with either Staphylococcus aureus or a bacterial lipopeptide mimetic, Pam3CSK4, enhanced PDL1 expression in multiple models. The data herein demonstrate a role for TLR2 in modulating the expression of PDL1 in HNSCC models and suggest that microbiota may directly modulate immunosuppression in cancer cells. Our study represents a step toward disentangling the diverse pathways and stimuli regulating PDL1 expression in HNSCC and underscores a need for future work to characterize the complex microbiome in HNSCC patients treated with immunotherapy.

Exosomal SNHG16 secreted by CSCs promotes glioma development via TLR7

Background

Glioma is one of the most common central nervous system malignant tumors, accounting for 45~60% of adult intracranial tumors. However, the clinical treatment of glioma is limited. It is of great significance to seek new therapeutic methods for glioma via gene therapy.

Methods

Long non-coding RNA (lncRNA) SNHG16 expression level was measured by microarray and qRT-PCR assay; ISH was used to identify the location of SNHG16. Cancer stem cells (CSCs) were separated from glioma tissues and identified using immunofluorescence. Exosomes were isolated from CSCs and cancer cells and identified by TEM and western blot. MTT, wound healing, transwell, and colony formation assay were performed to explore the role of SNHG16 or si-SNHG16 from CSCs on progression of glioma cells. RIP was used to verify the interaction between SNHG16 and TLR7. The experiment of Xenograft used for exploring the function of SNHG16/ TLR7/MyD88/NFκB/c-Myc on growth on glioma in vivo.

Results

Microarray assay showed long non-coding RNA (lncRNA) SNHG16 was upregulated in glioma. Followed qRT-PCR also showed an increase of SNHG16 in glioma tissues; high expression of SNHG16 indicated a poor prognosis in glioma patients. Interestingly, SNHG16 was packaged into exosomes and derived from CSCs. Functional analysis showed exo-SNHG16 secreted by CSCs promoted the progression of glioma cell lines SHG44 and U251. Furthermore, SNHG16 interacted with TLR7 and activated NFκB/c-Myc signaling in glioma cells. And the silencing of TLR7 inhibited the progression of SHG44 and U251 cells by exo-SNHG16 from CSCs. In vivo tumorigenesis experiments showed that exo-SNHG16 induced glioma progression by activating TLR7/MyD88/NFκB/c-Myc signaling.

Conclusion

Our study suggested CSC-derived exo-SNHG16 promoted cancer progression by activating TLR7/MyD88/NFκB/c-Myc signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02393-8.

Toll-like receptor 2 (TLR2) is a candidate prognostic factor in testicular germ cell tumors as well as an indicator of immune function in the tumor microenvironment

Testicular cancer is the most common malignant tumor in young men, and its incidence has increased in recent years. The tumor microenvironment (TME) plays a crucial role in the development and progression of tumors; however, the TME of testicular germ cell tumor (TGCT) is poorly understood. In this study, we downloaded information for 156 TGCT cases from The Cancer Genome Atlas (TCGA) database, used the ESTIMATE method to determine immune and stromal scores, and used CIBERSORT to calculate the proportion of tumor-infiltrating immune cells (TICs). The differentially expressed genes were subjected to a COX regression analysis and used for the construction of a protein–protein interaction (PPI) network. Toll-like receptor 2 (TLR2) was identified as a predictive marker by combining the results of the Cox regression analysis and PPI network. A survival analysis showed that TLR2 was positively correlated with TGCT survival. A gene set enrichment analysis indicated that genes in the high TLR2 expression group were enriched for cell adhesion molecules (CAMs) and the chemokine signaling pathway, and genes in the low TLR2 expression group were mainly enriched in the spliceosome. Regarding proportions of TICs, naive B cells and follicular helper T cells were negatively correlated with the expression of TLR2. This suggests that as TLR2 expression increases, the immunocompetence of the TME decreases. The expression of TLR2 may affect the prognosis of TGCT, suggesting that this locus can be used as a prognostic factor for TGCT.

Identification of New Genes Involved in Germline Predisposition to Early-Onset Gastric Cancer

The genetic cause for several families with gastric cancer (GC) aggregation is unclear, with marked relevance in early-onset patients. We aimed to identify new candidate genes involved in GC germline predisposition. Whole-exome sequencing (WES) of germline samples was performed in 20 early-onset GC patients without previous germline mutation identified. WES was also performed in nine tumor samples to analyze the somatic profile using SigProfilerExtractor tool. Sequencing germline data were filtered to select those variants with plausible pathogenicity, rare frequency and previously involved in cancer. Then, a manual filtering was performed to prioritize genes according to current knowledge and function. These genetic variants were prevalidated with Integrative Genomics Viewer 2.8.2 (IGV). Subsequently, a further selection step was carried out according to function and information obtained from tumor samples. After IGV and selection step, 58 genetic variants in 52 different candidate genes were validated by Sanger sequencing. Among them, APC, FAT4, CTNND1 and TLR2 seem to be the most promising genes because of their role in hereditary cancer syndromes, tumor suppression, cell adhesion and Helicobacter pylori recognition, respectively. These encouraging results represent the open door to the identification of new genes involved in GC germline predisposition.

Toll-Like Receptor 2 at the Crossroad between Cancer Cells, the Immune System, and the Microbiota

Toll-like receptor 2 (TLR2) expressed on myeloid cells mediates the recognition of harmful molecules belonging to invading pathogens or host damaged tissues, leading to inflammation. For this ability to activate immune responses, TLR2 has been considered a player in anti-cancer immunity. Therefore, TLR2 agonists have been used as adjuvants for anti-cancer immunotherapies. However, TLR2 is also expressed on neoplastic cells from different malignancies and promotes their proliferation through activation of the myeloid differentiation primary response protein 88 (MyD88)/nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) pathway. Furthermore, its activation on regulatory immune cells may contribute to the generation of an immunosuppressive microenvironment and of the pre-metastatic niche, promoting cancer progression. Thus, TLR2 represents a double-edge sword, whose role in cancer needs to be carefully understood for the setup of effective therapies. In this review, we discuss the divergent effects induced by TLR2 activation in different immune cell populations, cancer cells, and cancer stem cells. Moreover, we analyze the stimuli that lead to its activation in the tumor microenvironment, addressing the role of danger, pathogen, and microbiota-associated molecular patterns and their modulation during cancer treatments. This information will contribute to the scientific debate on the use of TLR2 agonists or antagonists in cancer treatment and pave the way for new therapeutic avenues.

Comprehensive analysis of a 14 immune-related gene pair signature to predict the prognosis and immune features of gastric cancer

BACKGROUND

As a new method for predicting tumor prognosis, the predictive effect of immune-related gene pairs (IRGPs) has been confirmed in several cancers, but there is no comprehensive analysis of the clinical significance of IRGPs in gastric cancer (GC).

METHOD

Clinical and gene expression profile data of GC patients were obtained from the GEO database. Based on the ImmPort database, differentially expressed immune-related gene (DEIRG) events were determined by a comparison of GC samples and adjacent normal samples. Cox proportional regression was used to construct an IRGP signature, and its availability was validated using three external validation datasets. In addition, we explored the association between clinical data and immune features and established a nomogram to predict outcomes in GC patients.

RESULT

A total of 88 DEIRGs were identified in GC from the training set, which formed 3828 IRGPs. Fourteen overall survival (OS)-related IRGPs were used to construct the prognostic signature. As a result, patients in the high-risk group exhibited poorer OS compared to those in the low-risk group. In addition, the fraction of CD8+ T cells, plasma cells, CD4 memory activated T cells, and M1 macrophages was higher in the high-risk group. Expression of two immune checkpoints, CD276 and VTCN1, was significantly higher in the high-risk group as well. Based on the independent prognostic factors, a nomogram was established and showed excellent performance.

CONCLUSION

The 14 OS-related IRGP signature was associated with OS, immune cells, and immune checkpoints in GC patients, and it could provide the basis for related immunotherapy.

Zymosan promotes proliferation, Candida albicans adhesion and IL-1β production of oral squamous cell carcinoma in vitro

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck squamous cell carcinoma (HNSCC), and the effect of zymosan (ZYM), a component of the yeast cell wall, on oral cancer remains unclear. The CCK-8 proliferation assay was performed to evaluate the effect of ZYM on the proliferation of the OSCC cell lines WSU-HN4, WSU-HN6 and CAL27, and the potential mechanism was explored by quantitative real-time PCR, immunofluorescence assay and western blot. A cell adhesion assay was conducted to determine the adhesion of Candida albicans to OSCC cells, and the expression of related genes, including TLR2, MyD88, NLRP3, ASC, Caspase-1 and IL-1β, and proteins, including TLR2, MyD88, NF-κB p65, p-NF-κB p65 and E-cadherin was determined. Additionally, the pro-inflammatory cytokines including IL-6, IL-8, TNF-α and IL-1β produced by OSCC cells were detected using a chemiluminescence immunoassay (CLIA). In the current study, the CCK-8 assay showed that ZYM promoted the proliferation of WSU-HN4, WSU-HN6 and CAL27 cells via the TLR2/MyD88 pathway. The cell adhesion assay showed that the number of C. albicans cells per field significantly increased in ZYM-treated OSCC cells compared to controls. When treated with ZYM, OSCC cells secreted significantly more pro-inflammatory cytokine IL-1β, which could enhance inflammation in oral cancer microenvironment. In conclusion, ZYM from the fungal cell wall promotes the proliferation, C. albicans adhesion and IL-1β production in OSCC, as demonstrated by in vitro experiments.

Comparative proteomic analysis uncovers potential biomarkers involved in the anticancer effect of Scutellarein in human gastric cancer cells

Scutellarein (SCU), a flavone that belongs to the flavonoid family and abundantly present in Scutellaria baicalensis a flowering plant in the family Lamiaceae, has been reported to exhibit anticancer effects in several cancer cell lines including gastric cancer (GC). Although our previous study documented the mechanisms of Scutellarein‑induced cytotoxic effects, the literature shows that the proteomic changes that are associated with the cellular response to SCU have been poorly understood. To avoid adverse side‑effects and significant toxicity of chemotherapy in patients who react poorly, biomarkers anticipating therapeutic responses are imperative. In the present study, we utilized a comparative proteomic analysis to identify proteins associated with Scutellarein (SCU)‑induced cell death in GC cells (AGS and SNU484), by integrating two‑dimensional gel electrophoresis (2‑DE), mass spectrometry (MS), and bioinformatics to analyze the proteins. Proteomic analysis between SCU‑treated and DMSO (control) samples successfully identified 41 (AGS) and 31 (SNU484) proteins by MALDI‑TOF/MS analysis and protein database search. Comparative proteomics analysis between AGS and SNU484 cells treated with SCU revealed a total of 7 protein identities commonly expressed and western blot analysis validated a subset of identified critical proteins, which were consistent with those of the 2‑DE outcome. Molecular docking studies also confirmed the binding affinity of SCU towards these critical proteins. Phosphatidylinositol 4,5‑bisphosphate 3‑kinase catalytic subunit β isoform (PIK3CB) protein expression was accompanied by a distinct group of cellular functions, including cell growth, and proliferation. Cancerous inhibitor of protein phosphatase 2A (CIP2A), is one of the oncogenic molecules that have been shown to promote tumor growth and resistance to apoptosis and senescence‑inducing therapies. In the present study, both PIK3CB and CIP2A proteins were downregulated in SCU‑treated cells, which boosts our previous results of SCU to induce apoptosis and inhibits GC cell growth by regulating these critical proteins. The comparative proteomic analysis has yielded candidate biomarkers of response to SCU treatment in GC cell models and further validation of these biomarkers will help the future clinical development of SCU as a novel therapeutic drug.

Characterization and strong risk association of TLR2 del -196 to -174 polymorphism and Helicobacter pylori and their influence on mRNA expression in gastric cancer

BACKGROUND

Toll-like receptor-2 (TLR2) is responsible for recognizing Helicobacter pylori (H. pylori) and activating the immune response. Polymorphisms in TLR2 may modulate gastric carcinogenesis.

AIM

To evaluate whether the TLR2 19216T/C (rs3804099) and TLR2 -196 to -174 ins/del (rs111200466) polymorphisms contribute to gastric carcinogenesis in the Brazilian population, and to determine the influence of both polymorphisms and H. pylori infection on TLR2 mRNA expression.

METHODS

DNA was extracted from 854 peripheral blood leukocyte or gastric tissue samples [202 gastric cancer (GC), 269 chronic gastritis (CG), and 383 control/healthy (C)] and genotyped by allele-specific PCR or restriction fragment length polymorphism (RFLP)-PCR. Quantitative polymerase chain reaction by TaqMan® assay was used to quantify TLR2 mRNA levels in fresh gastric tissues (48 GC, 36 CG, and 14 C).

RESULTS

Regarding the TLR2 -196 to -174 polymorphism, the ins/del and del/del genotypes were associated with a higher risk of GC by comparison with the C in all of the analyzed inheritance models (codominant, dominant, recessive, overdominant and log-additive; P < 0.0001). Similarly, an increased risk was observed when comparing the GC and CG groups [codominant (P < 0.0001), dominant (P < 0.0001), recessive (P = 0.0260), overdominant (P < 0.0001) and log-additive (P < 0.0001)]. In contrast, TLR2 19216T/C was associated with a protective effect in the GC group compared to the C group [dominant (P = 0.0420) and log-additive (P = 0.0300)]. Regarding the association of polymorphisms with H. pylori infection, individuals infected with H. pylori and harboring the TLR2 -196 to -174 ins/del polymorphism had an increased risk of gastric carcinogenesis [codominant (P = 0.0120), dominant (P = 0.0051), overdominant (P = 0.0240) and log-additive (P = 0.0030)], while TLR2 19216T/C was associated with a protective effect [codominant (P = 0.0039), dominant (P < 0.0001), overdominant (P = 0.0097) and log-additive (P = 0.0021)]. TLR2 mRNA levels were significantly increased in the GC group (median RQ = 6.95) compared to the CG group (RQ = 0.84, P < 0.0001) and to the normal mucosa group (RQ = 1.0). In addition, both H. pylori infection (P < 0.0001) and the presence of the polymorphic TLR2 -196 to -174del (P = 0.0010) and TLR2 19216 C (P = 0.0004) alleles influenced TLR2 mRNA expression.

CONCLUSION

The TLR2 -196 to -174 ins/del and TLR2 19216 T/C polymorphisms are strongly associated with GC. TLR2 mRNA expression levels are upregulated in neoplastic tissues and influenced by both the presence of H. pylori and variant genotypes.

Dysregulation of TLR2 Serves as a Prognostic Biomarker in Breast Cancer and Predicts Resistance to Endocrine Therapy in the Luminal B Subtype

Background: Breast cancer (BCa) is a serious global health burden among females, and the development of resistance represents an important challenge to BCa treatment. Here, we examined the expression of toll-like receptor 2 (TLR2) in BCa patients and the prognostic value of TLR2 for predicting endocrine resistance.

Methods: The study included 150 BCa patients, of which 82 underwent endocrine therapy. TLR2 mRNA expression was measured by quantitative Real-Time PCR, and its prognostic value was determined by Kaplan-Meier survival analysis. Changes in the expression of TLR2 in BCa patients with endocrine resistance were assessed, and the value of TLR2 for predicting endocrine resistance was evaluated using the receiver operating characteristic curve analysis.

Results: TLR2 expression was higher in BCa tissue than in normal tissue and associated with tumor size, HER2 status, tumor subtype, and TNM stage. TLR2 upregulation was associated with poor prognosis in patients with BCa, as well as endocrine resistance, and TLR2 upregulation was more prevalent among HER2-positive BCa cases. The predictive performance of TLR2 for endocrine resistance was higher in HER2-positive BCa than in other hormone receptor-positive BCa cases.

Conclusion: TLR2 upregulation is a promising biomarker for prognosis and predicting resistance to endocrine therapy. The relationship between TLR2 and HER2 indicates that TLR2 may be involved in endocrine resistance through the HER2 signaling pathway in BCa.

The impact of DNA demethylation on the upregulation of the NRN1 and TNFAIP3 genes associated with advanced gastric cancer

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide. Very few therapeutic options are currently available in this neoplasia. The use of 5-Aza-2'-deoxycytidine (5-AZAdC) was approved for the treatment of myelodysplastic syndromes, and this drug can treat solid tumours at low doses. Epigenetic manipulation of GC cell lines is a useful tool to better understand gene expression regulatory mechanisms for clinical applications. Therefore, we compared the gene expression profile of 5-AZAdC-treated and untreated GC cell lines by a microarray assay. Among the genes identified in this analysis, we selected NRN1 and TNFAIP3 to be evaluated for gene expression by RT-qPCR and DNA methylation by bisulfite DNA next-generation sequencing in 43 and 52 pairs of GC and adjacent non-neoplastic tissue samples, respectively. We identified 83 candidate genes modulated by DNA methylation in GC cell lines. Increased expression of NRN1 and TNFAIP3 was associated with advanced tumours (P < 0.05). We showed that increased NRN1 and TNFAIP3 expression seems to be regulated by DNA demethylation in GC samples: inverse correlations between the mRNA and DNA methylation levels in the promoter of NRN1 (P < 0.05) and the intron of TNFAIP3 (P < 0.05) were detected. Reduced NRN1 promoter methylation was associated with III/IV TNM stage tumours (P = 0.03) and the presence of Helicobacter pylori infection (P = 0.02). The identification of demethylated activated genes in GC may be useful in clinical practice, stratifying patients who are less likely to benefit from 5-AZAdC-based therapies. KEY MESSAGES: Higher expression of NRN1 and TNFAIP3 is associated with advanced gastric cancer (GC). NRN1 promoter hypomethylation contributes to gene upregulation in advanced GC. TNFAIP3 intronic-specific CpG site demethylation contributes to gene upregulation in GC. These findings may be useful to stratify GC patients who are less likely to benefit from DNA demethylating-based therapies.

Effect of TLR2 on the proliferation of inflammation-related colorectal cancer and sporadic colorectal cancer

Background

Colitis-associated cancer (CAC) is a complication of inflammatory bowel disease (IBD) with a poor prognosis because it is often diagnosed in advanced stages with local progression or metastasis. Compared with the more common polyp-induced sporadic colorectal cancer (sCRC), CAC has different molecular mechanisms. Toll-like receptor 2 (TLR2) expression is not limited to cells related to inflammation and immune function. High levels of TLR2 expression in tumor tissues of colorectal cancer (CRC) patients have been reported. This report is to investigate the effects of knockout and knockdown of the TLR2 gene on the proliferation of CAC and sCRC.

Methods

Twelve C57BL/6 J wild-type mice (WT) and 12 TLR2 knockout mice (TLR2-/-) were used to rapidly establish a colitis-associated cancer (CAC) model via the 1,2-dimethylhydrazine-dextran sodium sulfate (DMH-DSS) method and were divided into the normal WT control group (NC), TLR2 knockout control group (KC), normal wild-type tumor modeling group (NT), and TLR2 knockout tumor modeling group (KT), with 6 mice in each group. The general performance of the mice during modeling, the gross changes of the colon and the rectum, and the pathological score of HE staining were used to observe tumor growth. The expression of TLR2 was detected by immunohistochemistry, and tumor proliferation was detected by Ki67 labeling. Lentivirus carrying TLR2-RNAi was used to stably infect colorectal cancer cells (HCT116 and HT29) to knock down TLR2 gene expression. The experimental groups included the uninfected control group, negative control group, and gene knockdown group. After infection, the expression of TLR2 protein was detected by Western blot, and cell proliferation and the cell cycle were detected by the CCK-8 method and fluorescence-activated cell sorting. Western blot was used to detect the expression levels of p- NF-κβ, cyclin D1 and cyclin D3 protein in each group of cells.

Results

TLR2 knockout in the CAC model resulted in greater changes in body weight and more severe diarrhea and colorectal hemorrhage. However, knocking out the TLR2 gene reduced the shortening of colorectal length, the number of tumors, and the total tumor volume and inhibited the growth of CAC. Knocking out the TLR2 gene also reduced the pathological score and tumor severity. TLR2 was localized in the cell membrane of the colorectal epithelium of the NC group and of the colorectal tumors of the NT group and was highly expressed in the NT group, while antigen Ki67 was localized in the nucleus of the colorectal tumor cells of the NT group and the KT group, and its expression was reduced in the KT group. In an in vitro sporadic colorectal cancer cell experiment, TLR2 protein in the TLR2 knockdown group was significantly downregulated, and TLR2 knockdown significantly inhibited the proliferation of HCT116 and HT29 colorectal cancer cells, resulting in G1 phase arrest. The expression levels of p-NF-κβ, cyclin D1 and cyclin D3 proteins in TLR2 gene knockdown group cells were significantly reduced.

Conclusion

Knockout and knockdown of TLR2 can inhibit the proliferation of inflammation-related colorectal cancer and sporadic colorectal cancer.

Toll-Like Receptors Signaling in the Tumor Microenvironment

The involvement of inflammation in cancer progression is well-established. The immune system can play both tumor-promoting and -suppressive roles, and efforts to harness the immune system to help fight tumor growth are at the forefront of research. Of particular importance is the inflammatory profile at the site of the tumor, with respect to both the leukocyte population numbers, the phenotype of these cells, as well as the contribution of the tumor cells themselves. In this regard, the pro-inflammatory effects of pattern recognition receptor expression and activation in the tumor microenvironment have emerged as a relevant issue both for therapy and to understand tumor development.Pattern recognition receptors (PRRs) were originally recognized as components of immune cells, particularly innate immune cells, as detectors of pathogens. PRR signaling in immune cells activates them, inducing robust antimicrobial responses. In particular, toll-like receptors (TLRs) constitute a family of membrane-bound PRRs which can recognize pathogen-associated molecular patterns (PAMPs) carried by bacteria, virus, and fungi. In addition, PRRs can recognize products generated by stressed cells or damaged tissues, namely damage-associated molecular patterns or DAMPS. Taking into account the role of the immune system in fighting tumors together with the presence of immune cells in the microenvironment of different types of tumors, strategies to activate immune cells via PRR ligands have been envisioned as an anticancer therapeutic approach.In the last decades, it has been determined that PRRs are present and functional on nonimmune cells and that their activation in these cells contributes to the inflammation in the tumor microenvironment. Both tumor-promoting and antitumor effects have been observed when tumor cell PRRs are activated. This argues against nonspecific activation of PRR ligands in the tumor microenvironment as a therapeutic approach. Therefore, the use of PRR ligands for anticancer therapy might benefit from strategies that specifically deliver these ligands to immune cells, thus avoiding tumor cells in some settings. This review focuses on these aspects of TLR signaling in the tumor microenvironment.

Cancer-associated V-ATPase induces delayed apoptosis of protumorigenic neutrophils

Tumors and neutrophils undergo an unexpected interaction, in which products released by tumor cells interact to support neutrophils that in turn support cancer growth, angiogenesis, and metastasis. A key protein that is highly expressed by cancer cells in tumors is the a2 isoform V‐ATPase (a2V). A peptide from a2V (a2NTD) is secreted specifically by cancer cells, but not normal cells, into the tumor microenvironment. This peptide reprograms neutrophils to promote angiogenesis, cancer cell invasiveness, and neutrophil recruitment. Here, we provide evidence that cancer‐associated a2V regulates the life span of protumorigenic neutrophils by influencing the intrinsic pathway of apoptosis. Immunohistochemical analysis of human cancer tissue sections collected from four different organs shows that levels of a2NTD and neutrophil counts are increased in cancer compared with normal tissues. Significant increases in neutrophil counts were present in both poorly and moderately differentiated tumors. In addition, there is a positive correlation between the number of neutrophils and a2NTD expression. Human neutrophils treated with recombinant a2NTD show significantly delayed apoptosis, and such prolonged survival was dependent on NF‐κB activation and ROS generation. Induction of antiapoptotic protein expression (Bcl‐xL and Bcl‐2A1) and decreased expression of proapoptotic proteins (Bax, Apaf‐1, caspase‐3, caspase‐6, and caspase‐7) were a hallmark of these treated neutrophils. Autocrine secretion of prosurvival cytokines of TNF‐α and IL‐8 by treated neutrophils prolongs their survival. Our findings highlight the important role of cancer‐associated a2V in regulating protumorigenic innate immunity, identifying a2V as a potential important target for cancer therapy.

Prediction of gastric cancer prognosis in the next-generation sequencing era

Gastric cancer (GC) is one of the most commonly diagnosed malignancies worldwide, and is caused by complex interactions of multiple risk factors such as environmental (Helicobacter pylori and Epstein–Barr Virus), hereditary (genetic alterations and epigenetic modifications), as well as dietary and lifestyle factors. GC is usually detected at an advanced stage, with a dismal prognosis. Even for patients with similar clinical or pathologic stage receiving similar treatment, the outcomes are still uneven and unpredictable. To better incorporate genetic and epigenetic profiles into GC prognostic predication, gene expression signatures have been developed to predict GC outcomes. More recently, the advancement of high-throughput sequencing technology, also known as next-generation sequencing (NGS) technology, and analysis has provided the basis for accurate molecular classification of GC tumors. Here, we summarized and updated the literature related to NGS studies of GC, including whole-genome sequencing, whole-exome sequencing, RNA sequencing, and targeted sequencing, and discussed current progresses. NGS has facilitated the identification of genetic/epigenetic targets for screening as well as development of targeted agent therapy, thus enabling individualized patient management and treatment.

18β-glycyrrhetinic acid inhibited mitochondrial energy metabolism and gastric carcinogenesis through methylation-regulated TLR2 signaling pathway

The natural phenolic substance, 18β-glycyrrhetinic acid (GRA), has shown enormous potential in the chemoprevention of cancers with rich resources and biological safety, but the GRA-regulated genetic and epigenetic profiles are unclear. Deregulated mitochondrial cellular energetics supporting higher adenosine triphosphate provisions relative to the uncontrolled proliferation of cancer cells is a cancer hallmark. The Toll-like receptor 2 (TLR2) signaling pathway has emerged as a key molecular component in gastric cancer (GC) cell proliferation and epithelial homeostasis. However, whether TLR2 influenced GC cell energy metabolism and whether the inhibition effects of GRA on GC relied on TLR2 signaling were not illustrated. In the present study, TLR2 mRNA and protein expression levels were elevated in gastric tumors in the K19-Wnt1/C2mE (Gan) mice model, GC cell lines and human GCs, and the overexpression of TLR2 was correlated with the high histological grade and was a poor prognostic factor in GC patients. Further gain and loss of function showed that TLR2 activation induced GC cell proliferation and promoted reactive oxygen species (ROS) generation, Ca2+ accumulation, oxidative phosphorylation and the electron transport chain, while blocking TLR2 inhibited mitochondrial function and energy metabolism. Furthermore, GRA pretreatment inhibited TLR2-activated GC cell proliferation, energy metabolism and carcinogenesis. In addition, expression of TLR2 was found to be downregulated by GRA through methylation regulation. Collectively, the results demonstrated that GRA inhibited gastric tumorigenesis through TLR2-accelerated energy metabolism, suggesting GRA as a promising therapeutic agency targeting TLR2 signaling in GC.

β-arrestin-2 up-regulates toll-like receptor 2 signaling and inhibits apoptosis in human endometrial cancer heterotransplants in nude mice

BACKGROUND

β-arrestin-2(Arr2) functions as an anti-apoptotic factor and affects cell proliferation, but its downstream molecular pathway in endometrial carcinoma (EC) is still unclear. This study aimed to investigate the effects of the stable overexpression of Arr2 on the proliferation and apoptosis of human EC heterotransplants and the expression of associated molecules, including Toll-like receptor 2(TLR2), serine-threonine kinase Akt (Akt), glycogen synthase kinase-3β(GSK3β) and some typical inflammatory cytokines such as NF-κB p56, TNF-α and IL-6 & IL-8.

METHODS

Human EC cell line Ishikawa, stably transfected with Arr2 full-length plasmid, was injected subcutaneously into nude mice. They were treated with 0, 10, 20 mg/kg paclitaxel and the volume and weight of the tumor tissue were measured and calculated. The necrotic index were assessed by H&E staining and microscopic observation. The levels of caspase-3, caspase-9, TLR2, NF-κB p56, Akt, GSK3β were measured by western blot, and the levels of TNF-α, IL-6, IL-8 were measured by real-time PCR.

RESULTS

We found that Arr2 overexpression promoted the growth of human EC heterotransplants. Arr2 attenuated the promotion of caspase-3 and caspase-9 by paclitaxel and mediated the increase of TLR2 and several inflammatory cytokines. The levels of Akt and GSK3β were not affected.

CONCLUSION

Arr2 overexpression was associated with the increase of TLR2 and several inflammatory factors, meanwhile inhibited paclitaxel-induced anti-tumor effect on human EC heterotransplants.

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.

Significance and Role of Pattern Recognition Receptors in Malignancy

Pattern recognition receptors (PRRs) are members of innate immunity, playing pivotal role in several immunological reactions. They are known to act as a bridge between innate and adaptive immunity. They are expressed on several normal cell types but have been shown with increasing frequency on/in tumor cells. Significance of this phenomenon is largely unknown, but it has been shown by several authors that they, predominantly Toll-like receptors (TLRs), act in the interest of tumor, by promotion of its growth and spreading. Preparation of artificial of TLRs ligands (agonists) paved the way to use them as a therapeutic agents for cancer, so far in a limited scale. Agonists may be combined with conventional anti-cancer modalities with apparently promising results. PRRs recognizing nucleic acids such as RIG-1 like receptors (sensing RNA) and STING (sensing DNA) constitute a novel promising approach for cancer immunotherapy.

The role of IRAK1 in breast cancer patients treated with neoadjuvant chemotherapy

Background

IRAK1 has been shown to be abnormally expressed in a set of tumors leading to tumorigenesis and progression. IRAK1 is a therapeutic target that drives breast cancer metastasis and resistance to paclitaxel. However, the exact role of IRAK1 in neoadjuvant chemotherapy (NCT) for breast cancer remains unclear. The aim of this study was to investigate the relationship between the expression of IRAK1 and the clinicopathological parameters and survival prognosis of breast cancer patients treated with NCT.

Patients and methods

Based on the clinical data and mRNA microarray data from 1,085 breast cancer patients in The Cancer Genome Atlas, the correlation between IRAK1 expression and clinicopathological parameters of breast cancer was analyzed. Immunohistochemistry was performed to evaluate the expression of IRAK1. The Human Protein Atlas and the String database were used to analyze the expression of IRAK1 protein and its interaction with altered neighboring proteins in breast cancer. IRAK1 alteration was analyzed in cBioPortal database. GEO enrichment of IRAK1 was performed using WEB-based Gene SeT AnaLysis Toolkit.

Results

The expression of IRAK1 was significantly downregulated following NCT. The decreased expression of IRAK1 following NCT was positively correlated with reduced tumor size. Finally, survival analysis confirmed that a shorter survival period was correlated to higher expression of IRAK1 both before and after NCT.

Conclusion

These findings advanced our understanding about the expression pattern of IRAK1 in breast cancer, especially in those patients who were treated with NCT, suggesting that IRAK1 could be used as a prognostic indicator, as well as a potential indicator for evaluating NCT efficacy for breast cancer patients.

Expanded Expression of Toll-Like Receptor 2 in Proliferative Verrucous Leukoplakia

Proliferative verrucous leukoplakia (PVL) is a premalignant condition of the oral mucosa with > 70% chance of progression to squamous cell carcinoma (SCC), while lacking the common risks and behavior seen in non-PVL oral squamous carcinogenesis. PVL follows a multi-stage slow, relentless and usually multifocal expansion of surface epithelial thickening that over time takes on a verrucous architecture, eventually leading to verrucous carcinoma and/or dysplasia followed by "conventional" SCC, a process that takes years and is notoriously difficult to manage. As mucosal surfaces and carcinomas arising at these sites, are colonized by microorganisms, host receptors for microbial products have received attention as potential contributors to carcinogenesis. Studies show that microbial pattern recognition toll-like receptor (TLR)2 in various epithelial cells is upregulated in premalignant lesions and in malignant cells and can activate oncogenic pathways. Because of the highly progressive nature of PVL, we examined TLR2 expression in well-characterized PVL samples by immunohistochemistry. We found that, similar to epithelial dysplasia and SCC, PVL keratinocytes throughout the epithelial thickness showed diffuse TLR2 expression even in early stage lesions prior to onset of dysplasia. In contrast, oral mucosal samples in the absence of hyperorothokeratosis or dysplasia, expressed TLR2 primarily in the basal and parabasal layers. Given the high rates of PVL transformation and the previously established pro-cancer role of high TLR2 expression in malignant oral squamous cells, it is important to determine how its' expression and functions are regulated in the oral squamous epithelium, and what is the specific TLR2 role in carcinogenesis.

25-HC decreases the sensitivity of human gastric cancer cells to 5-fluorouracil and promotes cells invasion via the TLR2/NF-κB signaling pathway

Hyperlipidemia is associated with metastasis in patients with gastric cancer (GC). 25-Hydroxycholesterol (25-HC) is a type of oxysterol which is synthesized from cholesterol and is involved in a number of processes, including inflammation, immune responses and cancer development. However, the role of 25-HC in gastric cancer remains unknown. In the present study, we demonstrated that 25-HC had no effects on GC cell proliferation and apoptosis, whereas it decreased the sensitivity of GC cells to 5-fluorouracil (5-FU), as demonstrated by the increased cell proliferation and the decreased cell apoptosis. On the other hand, exposure to 2.5-10 µM of 25-HC significantly promoted GC invasion, both in vitro (using AGS and MGC-803 GC cell lines) and in vivo (in an animal model), accompanied by the upregulation of the expression levels of matrix metalloproteinases (MMPs). Further investigations revealed that the promotion of GC invasion was, at least in part due to the activation of Toll-like receptor 2 (TLR2)/nuclear factor (NF)-κB signaling. Our results demonstrated that 25-HC promoted GC cells invasion by upregulating TLR2/NF-κB-mediated MMP expression. Thus, on the whole, the findings of this study suggest a novel mechanism of hyperlipidemia-induced GC progression.

Toll-like receptor 2 stimulation promotes colorectal cancer cell growth via PI3K/Akt and NF-κB signaling pathways

Toll-like receptor (TLR) 2 is a key regulator of innate immune responses and has been shown to play an important role in inflammation-associated cancers. In this study, we aimed to evaluate the role of TLR2 in colorectal cancer (CRC). We demonstrated that TLR2 mRNA and protein expression was significantly upregulated in tumors from CRC patients and indicated poor prognosis. Using the TLR2 agonist Pam3Cys (P3C) to activate TLR2 signaling in human CRC cell lines, we showed that TLR2 drives cellular proliferation, which was dependent upon PI3K/Akt and NF-κB signaling pathways and was associated with the upregulation of anti-apoptotic genes BCL2A1, WISP1 and BIRC3. Likewise, pharmacological blockade of PI3K/Akt and NF-κB pathways mitigated the CRC pro-survival effects of TLR2 stimulation. Furthermore, genetic ablation of TLR2 using CRISPR/Cas9 suppressed CRC cell proliferation, invasion and migration. Taken together, these findings demonstrate that TLR2 plays an important role in colorectal tumorigenesis and may represent a promising therapeutic target in CRC.

Toll-like receptor 2 induces adenosine receptor A2a and promotes human squamous carcinoma cell growth via extracellular signal regulated kinases ½

Patient treatment for oral squamous cell carcinoma (OSCC) not associated with Human papillomavirus remains problematic. OSCC microenvironment is typically inflamed and colonized by microorganisms, providing ligands for toll-like receptors (TLR). In immune cells TLR2 and TLR4 activate NF-kB and extracellular signal regulated kinase (ERK)1/2 pathways, leading to upregulation of inhibitory adenosine receptors A2a and A2b, and reduction in stimulatory A1 and A3. How TLR and adenosine receptors function in SCC cells is not understood. To address this gap, we evaluated TLR and adenosine receptor expression and function in human OSCC cells and keratinocytes. TLR2 and A2a were co-expressed in pre-cancer and SCC cells of 17 oral specimens. In vitro, 5/6 OSCC lines expressed more TLR2 than TLR1, 4 or 6 mRNA. TLR2 ligands stimulated A2a expression in TLR2-high cell lines, but no A1 or A3 was detected with or without stimuli. In TLR2-high OSCC, TLR2/1, 2/6 and adenosine receptor agonists activated ERK1/2. TLR2-mediated ERK1/2 phosphorylation resulted in accumulation of c-FOS, ERK-dependent cell proliferation and reduced caspase-3 activity. Similar ERK1/2-dependent proliferation and decreased caspase-3 activity were caused by combined TLR2 and adenosine receptor stimuli. We conclude that TLR2 and adenosine receptor agonists, known to be present in the tumor microenvironment, may contribute to OSCC progression in part via direct effects on the ERK1/2 pathway in squamous carcinoma cells.

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.