Cancer Cells Expressing Toll-like Receptors and the Tumor Microenvironment

Sodium Butyrate as a Histone Deacetylase Inhibitor Affects Toll-Like Receptor 4 Expression in Colorectal Cancer Cell Lines

We assessed the effect of sodium butyrate (SB) as a histone deacetylase inhibitor (HDACi) on Toll-like receptor 4 (TLR4) gene expression levels, in low TLR4 expressing (HCT116) and high TLR4 expressing (SW480) colorectal cancer cells. The cytotoxic effect of SB was assessed by culturing SW480 and HCT116 cell lines using a broad spectrum of times and concentrations of SB. The MTT assay was done to check the cytotoxic properties of different SB concentrations. Gene expression levels of TLR4 was then evaluated for non-cytotoxic SB concentrations. Morphological analysis and MTT assay confirmed that SB concentrations equal to or less than 5mM were not cytotoxic for both cell lines. At 5mM concentration of SB in SW480 cell line and 1mM concentration of SB in HCT116 cell line, TLR4 gene expression level significantly increased from 24 to 48 hrs and decreased significantly from 48 to 72 hrs with an "early increased and late decreased pattern". At 1mM concentration of SB in SW480 cell line and 5mM concentration of SB in HCT116 cell line, TLR4 expression had a "gradually increased pattern". This study focuses on the dose-time-effect of SB in the pathogenesis of colorectal cancer. SB alters the expression level of TLR4 in colorectal cancer cells. This effect may depend on the cell type, treatment duration and SB concentration. The alterations in TLR4 expression may be due to the direct effect of SB on TLR4 and/or the expression changes of in other genes which may indirectly affect the TLR4 expression. Abbreviations: TLR4: Toll-like receptor 4; HDACi: histone deacetylase inhibitor; SB: sodium Butyrate; CRC: colorectal cancer; SCFA: short-chain fatty acid; hrs: hours.

Ingestion of Non-digestible Carbohydrates From Plant-Source Foods and Decreased Risk of Colorectal Cancer: A Review on the Biological Effects and the Mechanisms of Action

The hypothesis that links the increase in the intake of plant-source foods to a decrease in colorectal cancer (CRC) risk has almost 50 years. Nowadays, systematic reviews and meta-analysis of case-control and cohort studies confirmed the association between dietary patterns and CRC risk, in which the non-digestible carbohydrates (NDC) from plant-source foods are known to play beneficial effects. However, the mechanisms behind the physicochemical properties and biological effects induced by NDC on the decrease of CRC development and progression remain not fully understood. NDC from plant-source foods consist mainly of complex carbohydrates from plant cell wall including pectin and hemicellulose, which vary among foods in structure and in composition, therefore in both physicochemical properties and biological effects. In the present review, we highlighted the mechanisms and described the recent findings showing how these complex NDC from plant-source foods are related to a decrease in CRC risk through induction of both physicochemical effects in the gastrointestinal tract, fermentation-related effects, and direct effects resulting from the interaction between NDC and cellular components including toll-like receptors and galectin-3. Studies support that the definition of the structure-function relationship-especially regarding the fermentation-related effects of NDC, as well as the direct effects of these complex carbohydrates in cells-is crucial for understanding the possible NDC anticancer effects. The dietary recommendations for the intake of NDC are usually quantitative, describing a defined amount of intake per day. However, as NDC from plant-source foods can exert effects that vary widely according to the NDC structure, the dietary recommendations for the intake of NDC plant-source foods are expected to change from a quantitative to a qualitative perspective in the next few years, as occurred for lipid recommendations. Thus, further studies are necessary to define whether specific and well-characterized NDC from plant-source foods induce beneficial effects related to a decrease in CRC risk, thereby improving nutritional recommendations of healthy individuals and CRC patients.

The Interaction Between Two Worlds: MicroRNAs and Toll-Like Receptors

MicroRNAs (miRNAs) are critical mediators of posttranscriptional regulation via their targeting of the imperfect antisense complementary regions of coding and non-coding transcripts. Recently, researchers have shown that miRNAs play roles in many aspects of regulation of immune cell function by targeting of inflammation-associated genes, including Toll-like receptors (TLRs). Besides this indirect regulatory role of miRNAs, they can also act as physiological ligands of specific TLRs and initiate the signaling cascade of immune response. In this review, we summarize the potential roles of miRNAs in regulation of TLR gene expression and TLR signaling, with a focus on the ability of miRNAs bind to TLRs.

Breast Cancer Tumor Stroma: Cellular Components, Phenotypic Heterogeneity, Intercellular Communication, Prognostic Implications and Therapeutic Opportunities

Although the mechanisms underlying the genesis and progression of breast cancer are better understood than ever, it is still the most frequent malignant tumor in women and one of the leading causes of cancer death. Therefore, we need to establish new approaches that lead us to better understand the prognosis of this heterogeneous systemic disease and to propose new therapeutic strategies. Cancer is not only a malignant transformation of the epithelial cells merely based on their autonomous or acquired proliferative capacity. Today, data support the concept of cancer as an ecosystem based on a cellular sociology, with diverse components and complex interactions between them. Among the different cell types that make up the stroma, which have a relevant role in the dynamics of tumor/stromal cell interactions, the main ones are cancer associated fibroblasts, endothelial cells, immune cells and mesenchymal stromal cells. Several factors expressed by the stroma of breast carcinomas are associated with the development of metastasis, such as matrix metalloproteases, their tissular inhibitors or some of their regulators like integrins, cytokines or toll-like receptors. Based on the expression of these factors, two types of breast cancer stroma can be proposed with significantly different influence on the prognosis of patients. In addition, there is evidence about the existence of bi-directional signals between cancer cells and tumor stroma cells with prognostic implications, suggesting new therapeutic strategies in breast cancer.

A novel polysaccharide from Dendrobium devonianum serves as a TLR4 agonist for activating macrophages

Dendrobium devonianum has been used as herbal medicines and nutraceutical products since ancient time in China. However, its chemical composition and pharmacological mechanisms are not fully known. In present studies, by chemical purification and characteristic identification, we discovered a novel polysaccharide from D. devonianum, which was designated as DvP-1 with molecular weights of 9.52 × 10⁴ Da. DvP-1 is a homogeneous heteropolysaccharide consisting of D-mannose and d-glucose in the molar ration of 10.11: 1. The main glycosidic linkages were β-1, 4-Manp, which were substituted with acetyl groups at the O-2, O-3 and/or O-6 positions. DvP-1 was found to directly stimulate the activation of macrophages in vitro, as evidenced by inducing morphologic change, thereby promoting the production of cytokines TNF-α, IL-6 and NO, and enhancing the pinocytic activity of macrophages. By establishing a zebrafish model, we also found that DvP-1 could alleviate vinorelbine-induced decrease of macrophages in vivo. Further findings indicated that DvP-1 activated macrophages through several toll-like receptors (TLRs), but mainly through TLR4. DvP-1 served as a TLR4 agonist and induced ERK, JNK, p38, and IκB-α phosphorylation, suggesting the activation of MAPK and NFκB signaling pathways downstream of TLR4. These findings could help us further understand the immunomodulating effects of D. devonianum in Chinese medicines or health foods for immunocompromised persons. They also show the medicinal value of DvP-1 for the treatment of cancer and infectious diseases caused by TLR4 dysfunction.

A metabolite of endophytic fungus Cadophora orchidicola from Kalimeris indica serves as a potential fungicide and TLR4 agonist

AIM

To investigate the bioactive metabolite of endophytic fungus from Kalimeris indica.

METHODS AND RESULTS

A strain ZJLQ336 was separated from the leaves of K. indica. It was identified as Cadophora orchidicola based on the phylogenetic analysis of ITS-rDNA sequences. From the fermentation broth a metabolite cercosporamide (compound 1) was isolated, and its structure was determined by spectroscopic analysis. Additionally, this compound was subjected to bioactivity assays, including antifungal activity against seven plant pathogenic fungi, as well as its potential immunoregulatory effects on HEK-BLUE™-hTLR4 cells, splenocytes and macrophages. The results showed that cercosporamide had strong growth inhibition against five common plant pathogenic fungi, including Pestalotia diospyri, Botrytis cinerea, Fusarium oxysporum, Sclerotium rolfsii and Penicillum digitatum with EC₅₀ values of 5·29 × 10^-3 , 0·61, 0·93, 2·89 and 6·7 μg ml^-1 respectively. Among which S. rolfsii was one of the main pathogens in K. indica. Moreover, cercosporamide not only significantly stimulated TLR4 activation, splenocyte proliferation and production of cytokines, IFN-γ and TNF-α, but also up-regulated the production of TNF-α and NO in RAW264.7 macrophages clearly.

CONCLUSIONS

This is the first report of endophytic C. orchidicola from K. indica and its metabolite cercosporamide. The results of pharmacological tests highlight the potential fungicide and TLR4 agonist of cercosporamide.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study indicates endophytic fungi are good resources for natural bioactive metabolites. It also suggests that cercosporamide is a potential fungicide and TLR4 agonist.

Crosstalk between Peroxisome Proliferator-Activated Receptors and Toll-Like Receptors: A Systematic Review

As one of the four major families of pattern recognition receptors (PRRs), toll like receptors (TLRs) are crucial and important components of the innate immune system. Peroxisome proliferatoractivated receptors (PPARs) with three isoforms are transcription factors classified as a subfamily of nuclear receptor proteins, and are of significant regulatory activity in cellular differentiation, development, metabolism, and tumorigenesis. It is well established that PPARs agonists display anti-inflammatory effects through inhibition of the nuclear factor-kappa B (NF-κB) pathway, a key regulator of immune and inflammatory responses, in a sense that TLRs signaling pathways are mainly toward activation of NF-κB. Through a systematic review of previous studies, we aimed to address and clarify the reciprocal interaction between TLRs and PPARs in hope to find alternative therapeutic approaches for inflammatory diseases. Among the available scientific database, 31 articles were selected for this review. A comprehensive review of this database confirms the presence of a cross-talk between PPARs and TLRs, indicating that not only PPARs stimulation may affect the expression level of TLRs via several mechanisms leading to modulating TLRs activities, but also TLRs have the potential to moderate the expression of PPARs. We, therefore, conclude that, as a key regulator of the innate immune system, the interaction between PPARs and TLRs is a potential therapeutic target in disease treatment.

Myeloid-Derived Suppressor Cells in Hematologic Diseases: Promising Biomarkers and Treatment Targets

Myeloid-derived suppressor cells (MDSC) are a heterogeneous group of immature myeloid cells that exist at very low numbers in healthy subjects but can expand significantly in malignant, infectious, and chronic inflammatory diseases. These cells are characterized as early-MDSCs, monocytic-MDSCs, and polymorphonuclear-MDSCs and can be studied on the basis of their immunophenotypic characteristics and their functional properties to suppress T-cell activation and proliferation. MDSCs have emerged as important contributors to tumor expansion and chronic inflammation progression by inducing immunosuppressive mechanisms, angiogenesis and drug resistance. Most experimental and clinical studies concerning MDSCs have been mainly focused on solid tumors. In recent years, however, the implication of MDSCs in the immune dysregulation associated with hematologic malignancies, immune-mediated cytopenias and allogeneic hemopoietic stem cell transplantation has been documented and the potential role of these cells as biomarkers and therapeutic targets has started to attract a particular interest in hematology. The elucidation of the molecular and signaling pathways associated with the generation, expansion and function of MDSCs in malignant and immune-mediated hematologic diseases and the clarification of mechanisms related to the circulation and the crosstalk of MDSCs with malignant cells and other components of the immune system are anticipated to lead to novel therapeutic strategies. This review summarizes all available evidence on the implication of MDSCs in hematologic diseases highlighting the challenges and perspectives arising from this novel field of research.

Myeloid-Derived Suppressor Cells in Hematologic Diseases: Promising Biomarkers and Treatment Targets

Myeloid-derived suppressor cells (MDSC) are a heterogeneous group of immature myeloid cells that exist at very low numbers in healthy subjects but can expand significantly in malignant, infectious, and chronic inflammatory diseases. These cells are characterized as early-MDSCs, monocytic-MDSCs, and polymorphonuclear-MDSCs and can be studied on the basis of their immunophenotypic characteristics and their functional properties to suppress T-cell activation and proliferation. MDSCs have emerged as important contributors to tumor expansion and chronic inflammation progression by inducing immunosuppressive mechanisms, angiogenesis and drug resistance. Most experimental and clinical studies concerning MDSCs have been mainly focused on solid tumors. In recent years, however, the implication of MDSCs in the immune dysregulation associated with hematologic malignancies, immune-mediated cytopenias and allogeneic hemopoietic stem cell transplantation has been documented and the potential role of these cells as biomarkers and therapeutic targets has started to attract a particular interest in hematology. The elucidation of the molecular and signaling pathways associated with the generation, expansion and function of MDSCs in malignant and immune-mediated hematologic diseases and the clarification of mechanisms related to the circulation and the crosstalk of MDSCs with malignant cells and other components of the immune system are anticipated to lead to novel therapeutic strategies. This review summarizes all available evidence on the implication of MDSCs in hematologic diseases highlighting the challenges and perspectives arising from this novel field of research.

Ultraviolet radiation, both UVA and UVB, influences the composition of the skin microbiome

BACKGROUND

Studies have begun to investigate the complex relationship between host and microorganisms in non-infectious pathologies such as acne, atopic dermatitis and psoriasis. Though the skin is exposed to environmental stressors such as ultraviolet radiation (UVR), no studies exist examining the effects of both UVA and UVB on the skin microbiome.

OBJECTIVE

To test the effect of UVA and UVB on human skin microbiome.

METHODS

To test whether UV will alter the cutaneous microbiome, participants were exposed to doses of UVA (22-47 J/cm² ) or UVB (100-350 mJ/cm² ) and samples were collected. DNA was isolated and sequenced to identify the microbial composition of each sample.

RESULTS

There was vast intra- and inter-subject variation at all time points, and phylum and species-level differences were identified. These included an increase in the phylum Cyanobacteria and a decrease in the family Lactobacillaceae and Pseudomonadaceae. The sensitivity of microbes to UVR and their re-colonization potential following exposure differed in UVA vs UVB samples.

LIMITATIONS

The sample size was small, and the study was limited to males.

CONCLUSION

The results demonstrate that UVR has profound qualitative and quantitative influences on the composition of the skin microbiome, possibly effecting skin pathology in which UVR is a factor.

Nanoparticle Delivery of RIG-I Agonist Enables Effective and Safe Adjuvant Therapy in Pancreatic Cancer

Local immunomodulation can be a promising strategy to augment the efficacy and decrease off-target toxicities associated with cancer treatment. Pancreatic cancer is resistant to immunotherapies due to the immunosuppressive tumor microenvironment. Herein, we investigated a therapeutic approach involving delivery of a short interfering double-stranded RNA (dsRNA), specific to Bcl2, with 5' triphosphate ends, by lipid calcium phosphate nanoparticles, in an orthotopic allograft KPC model of pancreatic cancer. Retinoic acid-inducible gene I (RIG-I)-like receptors can bind to 5' triphosphate dsRNA (ppp dsRNA), a pathogen-associated molecular pattern, producing type I interferon, while Bcl2 silencing can drive apoptosis of cancer cells. Our approach demonstrated a robust enrichment of tumor tissue with therapeutic nanoparticles and enabled a significant tumor growth inhibition, prolonging median overall survival. Nanoparticles encapsulating dual-therapeutic ppp dsRNA allowed strong induction in levels of pro-inflammatory Th1 cytokines, further increasing proportions of CD8⁺ T cells over regulatory T cells, M1 over M2 macrophages, and decreased levels of immunosuppressive B regulatory and plasma cells in the tumor microenvironment. Thus, these results provide a new immunotherapy approach for pancreatic cancer.

Triggering TLR3 pathway promotes tumor growth and cisplatin resistance in head and neck cancer cells

Over the last decades, significant advances in targeted therapies have helped provide more effective treatment for head and neck cancer patients. However, chemo-resistance to cisplatin significantly contributes to treatment failure in the clinical management of patients. In response to chemotherapeutic agents, certain molecules inside the cell are released or secreted from damaged or dead/dying cells, named damage-associated molecular patterns (DAMPs), thereby initiating an immune response through interaction with pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs). In present study, we investigated the link between cisplatin-induced DAMPs and TLR3 signaling. We found that cisplatin could be a potential activator of TLR3 and cisplatin treatment results in activation of PRRs' signaling and down-stream associated cytokine/chemokine, IFNβ, and CCL5 in TLR3^High OC2 cells, but not in TLR3^Low FaDu cells. Furthermore, knockdown of the TLR3 gene attenuates the expression of IFNβ and CCL5 mRNA and enhances the cytotoxicity of cisplatin in TLR3^High OC2 cells. To determine whether TLR3 status affects the stress response of OC2 cells to cisplatin, we generated TLR3 knockdown OC2 cells (psi-TLR3 cells) with a psiRNA-hTLR3 plasmid containing shRNA to TLR3 and control OC2 cells (psi-NT cells) expressing non-silencing shRNA. OC2 cells were more sensitive to cisplatin treatment after TLR3 knockdown. In our animal model, OC2 psi-NT cells were more tumorigenic than were OC2 psi-TLR3 cells. Together, our in vitro and in vivo data imply TLR3 may contribute to tumor development and protect cisplatin-induced DNA damage response leading to cisplatin resistance in head and neck cancer cells.

The Role of Toll-Like Receptor in Inflammation and Tumor Immunity

Toll-like receptors (TLRs) activation enables host to recognize a large number of pathogen-associated molecule patterns (PAMPs), ignite immune cells to discriminate between self and non-self, and then promote the following innate and adaptive immune responses. Accumulated clinical/preclinical evidences have proven TLRs to be critical role in the autoimmune diseases, including inflammatory and tumor-associated diseases. Activation of TLRs is becoming or has been a target for cancer treatment. It is shown that TLRs can induce preferable anti-tumor effect by eliciting inflammatory cytokines expression and cytotoxic T lymphocytes (CTLs) response. As adjuvant, TLRs agonists can launch a strong immune response to assist cancer radiotherapy and bio-chemotherapy. On the other hand, tumor-associated antigens acting as PAMPs, can also activate TLRs and induce tumor gene-related programmed cell death, including apoptosis, autophagy and programmed necrosis. While there are also arguments that the excessive TLRs expression will promote tumor deterioration in various organisms, as the TLR-induced inflammation will accelerate the cancer cells boost in the tumor microenvironment (TME). However, the effect of TLRs acting on cancers is still not quite clear today. In this review, we will summarize the recent researches of TLRs in cancer treatment and their role in TME, giving a brief overview on future expectation.

A history of exploring cancer in context

The concept that progression of cancer is regulated by interactions of cancer cells with their microenvironment was postulated by Stephen Paget over a century ago. Contemporary tumour microenvironment (TME) research focuses on the identification of tumour-interacting microenvironmental constituents, such as resident or infiltrating non-tumour cells, soluble factors and extracellular matrix components, and the large variety of mechanisms by which these constituents regulate and shape the malignant phenotype of tumour cells. In this Timeline article, we review the developmental phases of the TME paradigm since its initial description. While illuminating controversies, we discuss the importance of interactions between various microenvironmental components and tumour cells and provide an overview and assessment of therapeutic opportunities and modalities by which the TME can be targeted.

Targeting Toll-like Receptors in Cancer Prevention

There is a pressing need for the development of new prevention strategies for the most common worldwide malignancy, nonmelanoma skin cancer (NMSC), as sun protection efforts have not proven to be completely effective. Interestingly, despite the known circumstance that individuals undergoing chronic immunosuppression are at a substantially increased risk for developing NMSC, in this issue of Cancer Prevention Research, Blohm-Mangone and colleagues provide new evidence that topical application of the Toll-like receptor 4 (TLR4) antagonist resatorvid may be efficacious as a chemopreventive agent in NMSC specifically via blocking UV-induced inflammatory signaling. These new findings highlight a potentially delicate dichotomy between the role of innate immune receptors in the normal, protective immunosurveillance of damaged cells in the skin and the pathogenic UV-induced overstimulation of cutaneous inflammation that promotes photocarcinogenesis. Given the tremendous cancer burden incurred by NMSC, further exploration of the use of TLR4 antagonists in NMSC chemoprevention strategies is certainly warranted. Cancer Prev Res; 11(5); 251-4. ©2018 AACRSee related article by Blohm-Mangone et al., p. 265.

Small Molecules Drive Big Improvements in Immuno-Oncology Therapies

Immuno-oncology therapies have the potential to revolutionize the armamentarium of available cancer treatments. To further improve clinical response rates, researchers are looking for novel combination regimens, with checkpoint blockade being used as a backbone of the treatment. This Review highlights the significance of small molecules in this approach, which holds promise to provide increased benefit to cancer patients.

Role of Pattern Recognition Receptors in KSHV Infection

Kaposi’s sarcoma-associated herpesvirus or Human herpesvirus-8 (KSHV/HHV-8), an oncogenic human herpesvirus and the leading cause of cancer in HIV-infected individuals, is a major public health concern with recurring reports of epidemics on a global level. The early detection of KSHV virus and subsequent activation of the antiviral immune response by the host’s immune system are crucial to prevent KSHV infection. The host’s immune system is an evolutionary conserved system that provides the most important line of defense against invading microbial pathogens, including viruses. Viruses are initially detected by the cells of the host innate immune system, which evoke concerted antiviral responses via the secretion of interferons (IFNs) and inflammatory cytokines/chemokines for elimination of the invaders. Type I IFN and cytokine gene expression are regulated by multiple intracellular signaling pathways that are activated by germline-encoded host sensors, i.e., pattern recognition receptors (PRRs) that recognize a conserved set of ligands, known as ‘pathogen-associated molecular patterns (PAMPs)’. On the contrary, persistent and dysregulated signaling of PRRs promotes numerous tumor-causing inflammatory events in various human cancers. Being an integral component of the mammalian innate immune response and due to their constitutive activation in tumor cells, targeting PRRs appears to be an effective strategy for tumor prevention and/or treatment. Cellular PRRs are known to respond to KSHV infection, and KSHV has been shown to be armed with an array of strategies to selectively inhibit cellular PRR-based immune sensing to its benefit. In particular, KSHV has acquired specific immunomodulatory genes to effectively subvert PRR responses during the early stages of primary infection, lytic reactivation and latency, for a successful establishment of a life-long persistent infection. The current review aims to comprehensively summarize the latest advances in our knowledge of role of PRRs in KSHV infections.

Toll like receptor signaling pathway as a potential therapeutic target in colorectal cancer

Toll like receptor (TLR) signaling is involved in activating innate and adaptive immune responses and plays a critical role in inflammation-induced diseases such as colorectal cancer (CRC). Dysregulation of this signaling pathway can result in disturbance of epithelial layer hemostasis, chronic inflammatory, excessive repair responses, and development of CRC. There is now substantial evidence for the benefit of targeting of this pathway in cancer treatment, and several agents have been approved, such as BCG (Bacillus Calmette Guérin), MPL (monophosphoryl lipid A) and imiquimod. This review summarizes the current knowledge about the different functions of TLRs on tumor cells and their application in cancer therapy with particular emphasis on recent preclinical and clinical research in treatment of CRC.

Interleukin-30/IL27p28 Shapes Prostate Cancer Stem-like Cell Behavior and Is Critical for Tumor Onset and Metastasization

Prostate cancer stem-like cells (PCSLC) are believed to be responsible for prostate cancer onset and metastasis. Autocrine and microenvironmental signals dictate PCSLC behavior and patient outcome. In prostate cancer patients, IL30/IL27p28 has been linked with tumor progression, but the mechanisms underlying this link remain mostly elusive. Here, we asked whether IL30 may favor prostate cancer progression by conditioning PCSLCs and assessed the value of blocking IL30 to suppress tumor growth. IL30 was produced by PCSLCs in human and murine prostatic intraepithelial neoplasia and displayed significant autocrine and paracrine effects. PCSLC-derived IL30 supported PCSLC viability, self-renewal and tumorigenicity, expression of inflammatory mediators and growth factors, tumor immune evasion, and regulated chemokine and chemokine receptor genes, primarily via STAT1/STAT3 signaling. IL30 overproduction by PCSLCs promoted tumor onset and development associated with increased proliferation, vascularization, and myeloid cell recruitment. Furthermore, it promoted PCSLC dissemination to lymph nodes and bone marrow by upregulating the CXCR5/CXCL13 axis, and drove metastasis to lungs through the CXCR4/CXCL12 axis. These mechanisms were drastically hindered by IL30 knockdown or knockout in PCSLCs. Collectively, these results mark IL30 as a key driver of PCSLC behavior. Targeting IL30 signaling may be a potential therapeutic strategy against prostate cancer progression and recurrence.Significance: IL30 plays an important role in regulating prostate cancer stem-like cell behavior and metastatic potential, therefore targeting this cytokine could hamper prostate cancer progression or recurrence. Cancer Res; 78(10); 2654-68. ©2018 AACR.

Compound A attenuates toll-like receptor 4-mediated paclitaxel resistance in breast cancer and melanoma through suppression of IL-8

Background

Paclitaxel (PTX) is a potent anti-cancer drug commonly used for the treatment of advanced breast cancer (BCA) and melanoma. Toll-like receptor 4 (TLR4) promotes the production of pro-inflammatory cytokines associated with cancer chemoresistance. This study aims to explore the effect of TLR4 in PTX resistance in triple-negative BCA and advanced melanoma and the effect of compound A (CpdA) to attenuate this resistance.

Methods

BCA and melanoma cell lines were checked for the response to PTX by cytotoxic assay. The response to PTX of TLR4-transient knockdown cells by siRNA transfection was evaluated compared to the control cells. Levels of pro-inflammatory cytokines, IL-6 and IL-8, and anti-apoptotic protein, XIAP were measured by real-time PCR whereas the secreted IL-8 was quantitated by ELISA in TLR4-transient knockdown cancer cells with or without CpdA treatment. The apoptotic cells after adding PTX alone or in combination with CpdA were detected by caspase-3/7 assay.

Results

PTX could markedly induce TLR4 expression in both MDA-MB-231 BCA and MDA-MB-435 melanoma cell lines having a basal level of TLR4 whereas no significant induction in TLR4-transient knockdown cells occurred. The siTLR4-treated BCA cells revealed more dead cells after PTX treatment than that of mock control cells. IL-6, IL-8 and XIAP showed increased expressions in PTX-treated cells and this over-production effect was inhibited in TLR4-transient knockdown cells. Apoptotic cells were detected higher when PTX and CpdA were combined than PTX treatment alone. Isobologram exhibited the synergistic effect of CpdA and PTX. CpdA could significantly decrease expressions of IL-6, XIAP and IL-8, as well as excreted IL-8 levels together with reduced cancer viability after PTX treatment.

Conclusions

The acquired TLR4-mediated PTX resistance in BCA and melanoma is explained partly by the paracrine effect of IL-6 and IL-8 released into the tumor microenvironment and over-production of anti-apoptotic protein, XIAP, in BCA cells and importantly CpdA could reduce this effect and sensitize PTX-induced apoptosis in a synergistic manner. In conclusion, the possible impact of TLR4-dependent signaling pathway in PTX resistance in BCA and melanoma is proposed and using PTX in combination with CpdA may attenuate TLR4-mediated PTX resistance in the treatment of the patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4155-6) contains supplementary material, which is available to authorized users.

Role of TLR4 as a prognostic factor for survival in various cancers: a meta-analysis

BACKGROUND

Accumulating evidence showed that high expression of toll like receptor 4 (TLR4) was significantly associated with the outcome of patients with solid cancers. However, other studies failed to draw a similar conclusion. Thus, a systematic meta-analysis was performed to assess the prognostic value of TLR4 in solid tumors.

RESULTS

Data from 15 studies and 1294 patients were enrolled. Among the 15 studies, 14 studies demonstrated the association between overall survival(OS) and TLR4 expression, and 7 studies described the relationship between disease-free survival(DFS) and TLR4 expression. High expression of TLR4 was significantly associated with poor OS (pooled hazard ratio (HR) = 2.05; 95% confidence interval (CI) (1.49, 2,49), P < 0.001). The results of meta regression analysis indicated that the subgroups of ethnic (PD = 0.924), tumor type (PD = 0.669), HR obtained method (PD = 0.945), analysis type (PD = 0.898), and cut-off value(PD = 0.835) were not the resource of heterogeneity. Moreover, patients with elevated TLR4 had a significantly worse DFS (pooled HR = 1.79; 95% CI (1.11, 2.88), P < 0.05).

MATERIALS AND METHODS

We searched PubMed, Embase and the Cochrane Library (last update by April 18, 2017) to identify literatures evaluating the value of TLR4 in cancer patients. Combined hazard ratios (HRs) for OS and DFS were assessed using fixed-effects models and random effects models respectively.

CONCLUSIONS

The meta-analysis suggests that elevated expression of TLR4 is associated with poor OS and shorter DFS of patients with solid tumors. The results indicate that TLR4, as a novel prognostic biomarker in solid tumors, could potentially help to improve treatment decision-making of solid tumors in clinical.

TLR3 expression status predicts prognosis in patients with advanced thoracic esophageal squamous cell carcinoma after esophagectomy

BACKGROUND

The relationship between Toll-like receptors (TLRs) and esophageal squamous cell carcinoma (ESCC) is not completely understood.

METHODS

RT-qPCR was used to evaluate the mRNA expression of TLR1-10 in 13 ESCC lines. We then used ESCC tissue microarray (TMA) to confirm expression of TLR3 protein in patients with ESCC.

RESULTS

All ESCC lines showed 10-60 times higher TLR3 mRNA expression than PBLs. High expression of TLR3 correlated with favorable 5-year overall survival (OS) and disease specific survival (DSS) among patients with ESCC after esophagectomy (p < 0.01). Additionally, In the adjuvant chemotherapy group, TLR3 high patients had significantly better 5-year OS compared to TLR3 low patients (60.2%, 34.4%, respectively) but not in the surgery alone group.

CONCLUSION

High TLR3 expression is an independent prognostic factor and has the potential to serve as a clinically useful marker of the need for adjuvant chemotherapy after esophagectomy in patients with advanced thoracic ESCC.

Current state and future prospects of immunotherapy for glioma

There is a large unmet need for effective therapeutic approaches for glioma, the most malignant brain tumor. Clinical and preclinical studies have enormously expanded our knowledge about the molecular aspects of this deadly disease and its interaction with the host immune system. In this review we highlight the wide array of immunotherapeutic interventions that are currently being tested in glioma patients. Given the molecular heterogeneity, tumor immunoediting and the profound immunosuppression that characterize glioma, it has become clear that combinatorial approaches targeting multiple pathways tailored to the genetic signature of the tumor will be required in order to achieve optimal therapeutic efficacy.

Soluble Toll-like receptor 4 is a potential serum biomarker in non-small cell lung cancer

This study investigated the clinical significance of serum soluble Toll-like receptor 4 (sTLR4) in non-small cell lung cancer (NSCLC). A total of 54 NSCLC patients and 13 healthy volunteers were enrolled from January 2012 to December 2013. The patients with NSCLC were characterized by significantly higher serum levels of sTLR4 compared with those in healthy controls (P < 0.01). A positive correlation between serum sTLR4 and tumor stage was found in patients with stages I–III NSCLC. However, serum sTLR4 in patients with metastatic NSCLC was significantly decreased compared with those with stage III NSCLC (P < 0.05). Furthermore, low serum sTLR4 was identified as a prognostic marker for poor survival of early-stage NSCLC patients who received surgical resection. In conclusion, our present study identified sTLR4 as a potential serum biomarker of NSCLC.

Basic understanding and therapeutic approaches to target toll-like receptors in cancerous microenvironment and metastasis

Toll-like receptors (TLRs) are transmembrane components that sense danger signals, like damage- and pathogen-associated molecular pattern molecules, as receptors, and maintain homeostasis in tissues. They are mainly involved in immune system activation through a variety of mediators, which either carry out (1) elimination of pathogenic threats and redressing homeostatic imbalances or (2) contribution to the initiation and worsening of pathological conditions, including cancers. Under physiological conditions, TLRs coordinate the innate and adaptive immunity, and inhibit autoimmune disorders. In pathological conditions, such as cancer, they can present both tumor and receptor-specific roles. Although the roles of individual TLRs in various cancers have been described, the effects of targeting TLRs to treat cancer and prevent metastasis are still controversial. A growing body of literature has suggested contribution of both activators and inhibitors of TLR signaling pathway for cancer treatment, dependent on several context-specific factors. In short, TLRs can play dual roles with contradictory outcomes in neoplastic conditions. This hampers the development of TLR-based therapeutic interventions. A better understanding of the interwoven TLR pathways in cancerous microenvironment is necessary to design TLR-based therapies. In this review, we consider the molecular mechanisms of TLRs signaling and their involvement in tumor progression. Therapeutic modalities targeting TLRs for cancer treatment are discussed as well.

Toll-like receptor 2 activation implicated in oral squamous cell carcinoma development

Recent studies have revealed that Toll-like receptors (TLRs) are highly expressed and activated in many types of cancer. Physiologically, TLR2 recognizes bacteria and other microorganisms in the oral cavity; however, the role of TLR2 in oral squamous cell carcinoma (OSCC) is unclear. In this study, we demonstrated that TLR2 is highly expressed in OSCC in comparison with adjacent non-malignant tissue. TLR2 was also expressed in OSCC-derived cell lines, and its expression was activated by ligands derived from bacteria and mycoplasma. Furthermore, to elucidate the mechanism of OSCC progression via TLR2 signal transduction, we focused on microRNAs (miRNAs) that are induced by TLR2 activation. Interestingly, ligand activation of TLR2 induced the expression of miR-146a and we found that downregulation of caspase recruitment domain-containing protein 10 (CARD10) mRNA in OSCC-derived cell lines. Moreover, knockdown of CARD10 induced resistance to cisplatin-induced apoptosis in OSCC cells. These findings suggest that the activation of TLR2 by bacterial components can enhance the progression of OSCC and may be implicated in acquired resistance to cisplatin-induced apoptosis through regulation of the miR-146a pathway.

DAMP-TLR-cytokine axis dictates the fate of tumor

Random mutations leading to loss of cell cycle control is not a rare occurrence in an organism but the mutated cells are recognized and eliminated preventing the development of a tumor. These potentially tumorigenic cells release damage-associated molecular patterns (DAMPs), which are recognized by toll-like receptors (TLRs) on macrophages and dendritic cells. The initial TLR-DAMP interactions lead to different responses such as altered antigen presentation and cytokine release that directly affect T cell activation and removal of the tumorigenic cells. The indirect effects of TLR-DAMP interaction include chemokine-directed altered T cell trafficking, angiogenesis for both T cell infiltration and tumor cell metastasis, and alteration of intra-tumoral milieu contributing to the development of tumor cells heterogeneity. Thus, the initial TLR-DAMP interaction has a set of local effects that modulate tumor cell growth and heterogeneity and a disseminating set of central effects that dynamically affect T cell trafficking and functions. Herein, we argue that the DAMP-TLR-cytokine axis in the tumor microenvironment serves as the mainstay that orchestrates and regulates the pro- and anti-tumor elements which dynamically interact between themselves eventuating in tumor regression or growth. The knowledge of this TLR-based immuno-surveillance framework is a key to developing a novel immunotherapy against cancer.

Expression of inflammatory lipopolysaccharide binding protein (LBP) predicts the progression of conventional renal cell carcinoma - a short report

BACKGROUND

The mortality of conventional renal cell carcinoma (RCC) correlates directly with the presence or postoperative development of metastases. The aim of this study was to identify new markers associated with the postoperative progression of conventional RCC.

METHODS

Tissue microarrays (TMA) of conventional RCC from a cohort of 414 patients were analysed by immunohistochemistry for expression of the lipopolysaccharide binding protein (LBP), which was identified as a candidate biomarker through Affymetrix U133 Plus 2.0 array analysis. Univariate and multivariate Cox regression models were addressed to cancer-specific survival in association with age, sex, clinicopathological parameters and LBP expression. The survival time of the patients was estimated by Kaplan-Meier analyses, and comparisons of survival curves were made using the Log rank test.

RESULTS

Univariate analysis revealed an association of patient survival with all clinicopathological parameters tested and LBP expression. In multivariate analysis only T classification, grade and LBP staining showed a significant association with postoperative cancer-specific survival (p < 0.001). LBP expression was found to be associated with a poor patient survival in Kaplan-Meier analyses. The estimated median survival time for patients with tumours showing LBP expression was 74 months, whereas the overall survival time was 142 months.

CONCLUSION

LBP expression in conventional RCC defines a group of patients at a high risk of postoperative progression and may help to direct optimized active surveillance and timely adjuvant therapy.

Immunomodulatory and antitumor effects of type I interferons and their application in cancer therapy

During the last decades, the pleiotropic antitumor functions exerted by type I interferons (IFNs) have become universally acknowledged, especially their role in mediating interactions between the tumor and the immune system. Indeed, type I IFNs are now appreciated as a critical component of dendritic cell (DC) driven T cell responses to cancer. Here we focus on IFN-α and IFN-β, and their antitumor effects, impact on immune responses and their use as therapeutic agents. IFN-α/β share many properties, including activation of the JAK-STAT signaling pathway and induction of a variety of cellular phenotypes. For example, type I IFNs drive not only the high maturation status of DCs, but also have a direct impact in cytotoxic T lymphocytes, NK cell activation, induction of tumor cell death and inhibition of angiogenesis. A variety of stimuli, including some standard cancer treatments, promote the expression of endogenous IFN-α/β, which then participates as a fundamental component of immunogenic cell death. Systemic treatment with recombinant protein has been used for the treatment of melanoma. The induction of endogenous IFN-α/β has been tested, including stimulation through pattern recognition receptors. Gene therapies involving IFN-α/β have also been described. Thus, harnessing type I IFNs as an effective tool for cancer therapy continues to be studied.

Aeroallergen Der p 2 promotes motility of human non-small cell lung cancer cells via toll-like receptor-mediated up-regulation of urokinase-type plasminogen activator and integrin/focal adhesion kinase signaling

House dust mite (HDM) allergens are one of the major causes leading to respiratory hypersensitiveness and airway remodeling. Here we hypothesized that a major HDM allergen Der p 2 could increase cell motility and invasiveness of non-small cell lung cancer (NSCLC) cells. Our results showed that low dose (1 and 3 μg/mL) recombinant Der p 2 protein (DP2) enhanced the migration and invasiveness of human NSCLC cell A549, H1299 and CL1-5, but nonsignificantly altered their growth. Further investigation revealed that integrin αV level was increased and its downstream signaling including focal adhesion kinase (FAK) and paxillin were activated in A549 cells exposed to DP2. In parallel, DP2 also activated the FAK-associated signaling effectors such as Src, phosphatidyl inositol 3-kinase (PI3K), AKT, p38 mitogen-activated protein kinase (P38), extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK). Our findings also revealed that DP2 increased expression level of urokinase type plasminogen-activated kinase (uPA) and uPA receptor (uPAR), and subsequently enhanced the binding of uPAR to integrin αV. Moreover, the involvement of toll-like receptor 2/4 (TLR2/4)-triggered ERK1/2 activation in the increased expression of uPA and uPAR was also demonstrated. Collectively, these findings indicate that DP2 can enhance cell motility and invasiveness of NSCLC cells, attributing to TLR2/4-ERK1/2 activation, increased uPA and uPAR expression, enhanced binding of uPAR to integrin αV, and the consequent FAK signaling cascades. Thus, we suggest that DP2 may exacerbate NSCLC via promoting metastatic ability of carcinoma cell.

Human TLR gene family members are differentially expressed in patients with urothelial carcinoma of the bladder

PURPOSE

Toll-like receptors (TLRs) have an important role in the activation of both innate and adaptive immunity in response to pathogens and endogenous danger signals from damaged or dying cells. The aim of this study was to determine the relationship between urothelial carcinoma (UC) and TLR expression.

BASIC PROCEDURES

Real-time polymerase chain reaction evaluation was made of the messenger RNA expression of TLRs 1-10 in 24 UC samples and 46 nontumoral bladder tissue samples. The levels of proinflammatory cytokines (IL-1β, IL-6, and IL-8) in the urine samples were also determined with enzyme-linked immunosorbent assay.

MAIN FINDINGS

TLR2-7 and TLR10 expressions were significantly higher in UC than in the control group (P<0.05 for all comparisons). No concordance was found between matched tumor tissue and urine samples in terms of TLR expression. IL-1β, IL-6, and IL-8 levels were significantly higher in urine specimens of patients with UC (P = 0.033, P = 0.001, and P = 0.008, respectively).

PRINCIPAL CONCLUSIONS

The results of this study demonstrated that the TLR gene expression profiles reflect the heterogeneity within UC. These results might also prompt further investigation to better understand the role of the TLR gene family expression in the tumor progression of UC.

Inhibition of Toll-Like Receptor Signaling as a Promising Therapy for Inflammatory Diseases: A Journey from Molecular to Nano Therapeutics

The recognition of invading pathogens and endogenous molecules from damaged tissues by toll-like receptors (TLRs) triggers protective self-defense mechanisms. However, excessive TLR activation disrupts the immune homeostasis by sustained pro-inflammatory cytokines and chemokines production and consequently contributes to the development of many inflammatory and autoimmune diseases, such as systemic lupus erythematosus (SLE), infection-associated sepsis, atherosclerosis, and asthma. Therefore, inhibitors/antagonists targeting TLR signals may be beneficial to treat these disorders. In this article, we first briefly summarize the pathophysiological role of TLRs in the inflammatory diseases. We then focus on reviewing the current knowledge in both preclinical and clinical studies of various TLR antagonists/inhibitors for the prevention and treatment of inflammatory diseases. These compounds range from conventional small molecules to therapeutic biologics and nanodevices. In particular, nanodevices are emerging as a new class of potent TLR inhibitors for their unique properties in desired bio-distribution, sustained circulation, and preferred pharmacodynamic and pharmacokinetic profiles. More interestingly, the inhibitory activity of these nanodevices can be regulated through precise nano-functionalization, making them the next generation therapeutics or “nano-drugs.” Although, significant efforts have been made in developing different kinds of new TLR inhibitors/antagonists, only limited numbers of them have undergone clinical trials, and none have been approved for clinical uses to date. Nevertheless, these findings and continuous studies of TLR inhibition highlight the pharmacological regulation of TLR signaling, especially on multiple TLR pathways, as future promising therapeutic strategy for various inflammatory and autoimmune diseases.

Naltrexone Inhibits IL-6 and TNFα Production in Human Immune Cell Subsets following Stimulation with Ligands for Intracellular Toll-Like Receptors

The opioid antagonist naltrexone hydrochloride has been suggested to be a potential therapy at low dosage for multiple inflammatory conditions and cancers. Little is known about the immune-modulating effects of naltrexone, but an effect on the activity of toll-like receptor 4 (TLR4) has been reported. We analyzed the effects of naltrexone hydrochloride on IL-6 secretion by peripheral blood mononuclear cells (PBMC) in vitro following stimulation with ligands for TLR4 and for the intracellular receptors TLR7, TLR8, and TLR9. Naltrexone did not affect cell viability or induce apoptosis of PBMC. Intracellular staining demonstrated that naltrexone inhibited production of IL-6 and TNFα by monocyte and plasmacytoid dendritic cell subsets within the PBMC population following treatment with ligands for TLR7/8 and TLR9, respectively. No effect of cytokine production by PBMC following stimulation of TLR4 was observed. Additionally, naltrexone inhibited IL-6 production in isolated monocytes and B cells after TLR7/8 and TLR9 stimulation, respectively, but no effect on IL-6 production in isolated monocytes after TLR4 stimulation was observed. These findings indicate that naltrexone has the potential to modulate the secretion of inflammatory cytokines in response to intracellular TLR activity, supporting the hypothesis that it may have potential for use as an immunomodulator.

The influence of the commensal microbiota on distal tumor-promoting inflammation

Commensal microbes inhabit barrier surfaces, providing a first line of defense against invading pathogens, aiding in metabolic function of the host, and playing a vital role in immune development and function. Several recent studies have demonstrated that commensal microbes influence systemic immune function and homeostasis. For patients with extramucosal cancers, or cancers occurring distal to barrier surfaces, the role of commensal microbes in influencing tumor progression is beginning to be appreciated. Extrinsic factors such as chronic inflammation, antibiotics, and chemotherapy dysregulate commensal homeostasis and drive tumor-promoting systemic inflammation through a variety of mechanisms, including disruption of barrier function and bacterial translocation, release of soluble inflammatory mediators, and systemic changes in metabolic output. Conversely, it has also been demonstrated that certain immune therapies, immunogenic chemotherapies, and checkpoint inhibitors rely on the commensal microbiota to facilitate anti-tumor immune responses. Thus, it is evident that the mechanisms associated with commensal microbe facilitation of both pro- and anti-tumor immune responses are context dependent and rely upon a variety of factors present within the tumor microenvironment and systemic periphery. The goal of this review is to highlight the various contexts during which commensal microbes orchestrate systemic immune function with a focus on describing possible scenarios where the loss of microbial homeostasis enhances tumor progression.

Gene polymorphisms of TLR2 and TLR3 in HBV clearance and HBV-related hepatocellular carcinoma in a Chinese male population

BACKGROUND

The Toll-like receptor plays an essential role in controlling immunity and inflammation. This study was to investigate the relationships of genetic variants in TLR2 and TLR3 with hepatitis B virus (HBV) natural clearance and HBV-related hepatocellular carcinoma (HCC) risk in a Chinese male population.

METHODS

We analyzed 5 polymorphisms of TLR2 (rs3804099 and rs3804100) and TLR3 (rs5743305, rs3775296 and rs3775291) in a population consisting of 686 participants with HBV natural clearance, 293 chronic HBV carriers and 395 HBV-positive HCC patients, using the improved multiplex ligase detection reaction method.

RESULTS

After adjustment for age and smoking and drinking status, no associations were observed either between the 5 single-nucleotide polymorphisms (SNPs) and the HBV natural clearance participants, or between the 5 SNPs and HCC patients. Whereas the stratified analysis showed that under the dominant models, nondrinkers with TLR2 rs3804100 and participants younger than 40 years old with TLR3 rs3775291 were significantly associated with HCC risk when compared with persistent HBV carriers (adjusted odd ratio [OR] = 0.49, 95% confidence interval [95% CI], 0.31-0.78, p = 0.003; and adjusted OR = 0.50, 95% CI, 0.29-0.86, p = 0.013, respectively). Furthermore, the TTTCT haplotype was found to promote the progress of HBV clearance and inhibit development of HBV-related HCC (OR = 0.77, 95% CI, 0.61-0.97, p = 0.029; and OR = 0.72, 95% CI, 0.55-0.94, p = 0.016, respectively). And the CCACC and CCTCT haplotypes were observed to decrease susceptibility to HCC (OR = 0.64, 95% CI, 0.40-1.00, p = 0.048; and OR = 0.43, 95% CI, 0.28-0.68, p<0.001, respectively).

CONCLUSIONS

This study revealed that TLR2 rs3804100 and TLR3 rs3775291 polymorphisms may be protective factors for HBV-related HCC.

Papilloma-pseudovirus eradicates intestinal tumours and triples the lifespan of ApcMin/+ mice

Inducing tumour-specific adaptive immunity, such as cytotoxic T lymphocyte (CTL) response, can result in promising antitumour effect against several human malignancies, especially in combination with immune checkpoint blockade strategies. However, little is known whether activation of innate immunity can lead to direct tumoricidal effect. Here, we develop a papilloma pseudovirus-based oral immunotherapeutic approach that shows strong tumoricidal effects in the gut, resulting in an almost tripled lifespan of Apc^Min/+ mice (an animal model of human intestinal tumorigenesis). Mechanistically, these pseudoviruses activate the NLRP3 and AIM2 inflammasomes, leading to caspase-1-mediated tumour regression that is dependent on neither cytotoxic T lymphocytes nor humoral immune response. Blocking caspase-1 activation abrogated the therapeutic effects of the pseudoviruses. Thus, targeting innate immune sensors in tumours by the pseudoviruses might represent a strategy to treat intestinal tumours.

Combination antiretroviral therapy (cART) restores HIV-1 infection-mediated impairment of JAK-STAT signaling pathway

JAK-STAT signaling pathway has a crucial role in host innate immunity against viral infections, including HIV-1. We therefore examined the impact of HIV-1 infection and combination antiretroviral therapy (cART) on JAK-STAT signaling pathway. Compared to age-matched healthy donors (n = 18), HIV-1-infected subjects (n = 18) prior to cART had significantly lower expression of toll-like receptors (TLR-1/4/6/7/8/9), the IFN regulatory factors (IRF-3/7/9), and the antiviral factors (OAS-1, MxA, A3G, PKR, and Tetherin). Three months’ cART partially restores the impaired functions of JAK-STAT-mediated antiviral immunity. We also found most factors had significantly positive correlations (p < 0.05) between each two factors in JAK-STAT pathway in healthy donors (98.25%, 168/171), but such significant positive associations were only found in small part of HIV-1-infected subjects (43.86%, 75/171), and stably increased during the cART (57.31%, 98/171 after 6 months’ cART). With regard to the restoration of some HIV-1 restriction factors, HIV-1-infected subjects who had CD4+ T cell counts > 350//μl responded better to cART than those with the counts < 350/μl. These findings indicate that the impairment of JAK-STAT pathway may play a role in the immunopathogenesis of HIV-1 disease.

Forkhead box-P3+ regulatory T cells and toll-like receptor 2 co-expression in oral squamous cell carcinoma

BACKGROUND

The function of forkhead box-P3 (FoxP3) regulatory T cells (Treg) and toll-like receptor (TLR)2 protein in the oral cancer microenvironment is not fully understood, but evidence from other malignancies suggests it is likely they are involved with tumour development and progression. The aim of this study was to investigate the distribution of FoxP3⁺cells, TLR2⁺ cells and double-labelled FoxP3⁺TLR2⁺ immune cells in oral squamous cell carcinoma (OSCC), using immunohistochemistry (IHC) and immunofluorescence (IF).

METHODS

25 archival cases of OSCC were immunostained with anti-FoxP3 and anti-TLR2 antibodies. Inflamed hyperplastic oral mucosal tissues were used as controls. The proportion of single-labelled, double-labelled and negative cells was determined.

RESULTS

A higher frequency of double-labelled FoxP3⁺TLR2⁺ Tregs was observed within the immune cells of OSCC compared to inflamed controls using IHC (p<0.05). Cell-to-cell contact between single-stained TLR2⁺ cells and FoxP3⁺ cells was noted. Double IF studies validated demonstration of co-expression of FoxP3⁺/TLR2⁺ immune cells in OSCC.

CONCLUSION

The presence of FoxP3⁺TLR2⁺ cells within the OSCC microenvironment may represent a dendritic cell-dependent pathway capable of inhibiting Treg suppressive activity, potentially enhancing the anti-tumour response. Modulation of TLR2-Treg interactions should be further explored to determine if they have a role in the therapeutic management of OSCC.

High mobility group box 1/toll-like receptor 4/myeloid differentiation factor 88 signaling promotes progression of gastric cancer

High mobility group box 1 and toll-like receptor 4/myeloid differentiation factor 88 signaling pathway have been indicated to have oncogenic effects in many cancers. However, the role of high mobility group box 1/toll-like receptor 4/myeloid differentiation factor 88 signaling pathway in the development of gastric cancer remains unclear. In this study, we demonstrated that high mobility group box 1, toll-like receptor 4, and myeloid differentiation factor 88 were overexpressed in gastric cancer tumors compared with the adjacent non-tumor tissues. The overexpression of high mobility group box 1, toll-like receptor 4, and myeloid differentiation factor 88 were correlated with tumor-node-metastasis stage (p = 0.0068, p = 0.0063, p = 0.0173) and lymph node metastasis (p = 0.0272, p = 0.0382, and p = 0.0495). Furthermore, we observed that knockdown of high mobility group box 1 by high mobility group box 1-small interfering RNA suppressed the expression of toll-like receptor 4 and myeloid differentiation factor 88. Blockage of high mobility group box 1/toll-like receptor 4/myeloid differentiation factor 88 signaling by high mobility group box 1-small interfering RNA resulted in elevation of apoptotic ratio and inhibition of cell growth, migration, and invasion by upregulating Bax expression and downregulating Bcl-2, matrix metalloproteinase-2, nuclear factor kappa B/p65 expression, and the nuclear translocation of nuclear factor kappa B/p65 in gastric cancer cells. Our findings suggest that high mobility group box 1/toll-like receptor 4/myeloid differentiation factor 88 signaling pathway may contribute to the development and progression of gastric cancer via the nuclear factor kappa B pathway and it also represents a novel potential therapeutic target for gastric cancer.

Induction of galectin-1 by TLR-dependent PI3K activation enhances epithelial-mesenchymal transition of metastatic ovarian cancer cells

The expression of different toll-like receptors (TLRs) on tumor cells has been associated with disease aggressiveness, treatment resistance, and poor prognosis. The phosphatidylinositol 3-kinase (PI3K)/AKT pathway is considered critical for cancer cell survival and proliferation. Thus, we investigated the effect of TLR-stimulated PI3K activation on the epithelial-to-mesenchymal transition (EMT) of primary (Caov-3) and metastatic (SK‑OV‑3) epithelial ovarian cancer cell lines in this study. TLR engagement with various ligands promoted the expression of class IA PI3K (p110α, p110β, and p110δ) and increased the expression of mesenchymal markers (N-cadherin, Slug, Vimentin, Snail, α-SMA, and TCF) in SK‑OV‑3 cells. The migratory activity and secretion of EMT-related cytokines of SK‑OV‑3 were significantly higher compared to those of Caov-3 after activation with TLR agonist. Although the invasive capacity and production of EMT-related cytokines of LPS-stimulated SK‑OV‑3 cells were significantly suppressed by all pharmacological inhibitors of the p110 isoform, the Syk/Src-dependent p110β isoform prominently attenuated migration activity. In contrast, the production of IL-10 and galectin-1 was mainly affected by the p110δ isoform. Gene silencing of TLR4 and galectin-1 with siRNA decreased the expression of matrix metalloproteinase-2 (MMP2) and MMP9 and reduced mesenchymal markers in LPS-treated SK‑OV‑3 cells. This study demonstrated that TLR-mediated PI3K activation modulated the invasion and metastasis of ovarian cancer through the production of galectin-1, suggesting that inhibition of the p110 isoform is a promising therapeutic approach against metastatic ovarian cancer.

Therapeutic implication of 'Iturin A' for targeting MD-2/TLR4 complex to overcome angiogenesis and invasion

Tumor angiogenesis and invasion are deregulated biological processes that drive multistage transformation of tumors from a benign to a life-threatening malignant state activating multiple signaling pathways including MD-2/TLR4/NF-κB. Development of potential inhibitors of this signaling is emerging area for discovery of novel cancer therapeutics. In the current investigation, we identified Iturin A (A lipopeptide molecule from Bacillus megaterium) as a potent inhibitor of angiogenesis and cancer invasion by various in vitro and in vivo methods. Iturin A was found to suppress VEGF, a powerful inducer of angiogenesis and key player in tumor invasion, as confirmed by ELISA, western blot and real time PCR. Iturin A inhibited endothelial tube arrangement, blood capillary formation, endothelial sprouting and vascular growth inside the matrigel. In addition, Iturin A inhibited MMP-2/9 expression in MDA-MB-231 and HUVEC cells. Cancer invasion, migration and colony forming ability were significantly hampered by Iturin A. Expressions of MD-2/TLR4 and its downstream MyD88, IKK-α and NF-κB were also reduced in treated MDA-MB-231 and HUVEC cells. Western blot and immunofluorescence study showed that nuclear accumulation of NF-κB was hampered by Iturin A. MD-2 siRNA or plasmid further confirmed the efficacy of Iturin A by suppressing MD-2/TLR4 signaling pathway. The in silico docking study showed that the Iturin A interacted well with the MD-2 in MD-2/TLR4 receptor complex. Conclusively, inhibition of MD-2/TLR4 complex with Iturin A offered strategic advancement in cancer therapy.

Combined toll-like receptor 3/7/9 deficiency on host cells results in T-cell-dependent control of tumour growth

Toll-like receptors (TLRs) are located either on the cell surface or intracellularly in endosomes and their activation normally contributes to the induction of protective immune responses. However, in cancer their activation by endogenous ligands can modulate tumour progression. It is currently unknown how endosomal TLRs regulate endogenous anti-tumour immunity. Here we show that TLR3, 7 and 9 deficiencies on host cells, after initial tumour growth, result in complete tumour regression and induction of anti-tumour immunity. Tumour regression requires the combined absence of all three receptors, is dependent on both CD4 and CD8 T cells and protects the mice from subsequent tumour challenge. While tumours in control mice are infiltrated by higher numbers of regulatory T cells, tumour regression in TLR-deficient mice is paralleled by altered vascular structure and strongly induced influx of cytotoxic and cytokine-producing effector T cells. Thus, endosomal TLRs may represent a molecular link between the inflamed tumour cell phenotype, anti-tumour immunity and the regulation of T-cell activation.

Activation of Toll-like receptor (TLR) is generally associated with increased immune activity. Here, the authors show, using syngeneic mouse models, that combined deficiency of TLR 3/7/9 in the host induces an inflamed tumour phenotype and results in T cell dependent tumour regression after an initial growth.