Small interfering RNA-directed targeting of Toll-like receptor 4 inhibits human prostate cancer cell invasion, survival, and tumorigenicity

The immune function of TLR4-1 gene in Octopus sinensis revealed by RNAi and RNA-seq

Toll-like receptors (TLRs) are a class of conserved pattern recognition receptors (PRRs) that are crucial for initiating the innate immune response and aiding in the clearance of pathogenic organisms. Many studies have identified TLR4 as a distinctive member of the TLR family, capable of activating both the Myeloid differentiation factor 88-dependent signaling pathway (MyD88-dependent) and the TIR-domain-containing adaptor inducing IFN-β dependent signaling pathway (TRIF-dependent). Nevertheless, the role of TLR4 in Cephalopoda is still largely unexplored. To elucidate the immune function of the OsTLR4-1 gene in Octopus sinensis, the OsTLR4-1 gene was first validated and analyzed in this study. The cDNA comprises a 2475 bp ORF region, encoding 824 amino acids. Evolutionary tree analysis indicated a high homology and a close phylogenetic relationship between the Octopus sinensis and other mollusks. RNA interference (RNAi) experiments demonstrated that the expression level of OsTLR4-1 gene and its protein in the lymphocytes of the RNAi group treated with OsTLR4-1 dsRNA was extremely significantly lower than that of the blank control group and negative control group (P < 0.01), and the expression of downstream genes of OsTLR4-1, including ligand MyD88, IRAK4, TRAF6, MKK6, Hsp90, COX2, TRAF3, and RIP1, were significantly down-regulated compared to the blank and negative control group (P < 0.01). Additionally, OsTLR4-1 expression in lymphocytes was highly significantly up-regulated in the LPS-treated group compared to the blank control group (P < 0.01), while its expression was extremely significantly lower in the LPS-treated group after OsTLR4-1 interference than in the blank control group (P < 0.01). The expression of its downstream effector genes Big Defensin (Big-Def) and histone H2A.V (H2A.V) was highly significantly up-regulated in lymphocytes in the LPS-treated group compared to the blank control group (P < 0.01), while their expression in the LPS-treated group after OsTLR4-1 interference was extremely significantly lower than that in the blank control group (P < 0.01). Through comparative transcriptome analysis of the RNAi group and the blank control group, it was found that differentially expressed genes were enriched in the Toll-like receptor signaling pathway, PI3K-AKT signaling pathway, P53 signaling pathway, MAPK signaling pathway, and NF-κB signaling pathway. qRT-PCR results of key genes in these pathways revealed a decrease in all genes except IκB and Jun2 genes. This study enhances our understanding of the immune function of the TLR gene family in O. sinensis and provides a foundation for further research into innate immune signaling pathways in cephalopods.

Re-exploration of immunotherapy targeting EMT of hepatocellular carcinoma: Starting from the NF-κB pathway

Hepatocellular carcinoma (HCC) is the fifth most common malignancies worldwide, and its high morbidity and mortality have brought a heavy burden to the global public health system. Due to the concealment of its onset, the limitation of treatment, the acquisition of multi-drug resistance and radiation resistance, the treatment of HCC cannot achieve satisfactory results. Epithelial mesenchymal transformation (EMT) is a key process that induces progression, distant metastasis, and therapeutic resistance to a variety of malignant tumors, including HCC. Therefore, targeting EMT has become a promising tumor immunotherapy method for HCC. The NF-κB pathway is a key regulatory pathway for EMT. Targeting this pathway has shown potential to inhibit HCC infiltration, invasion, distant metastasis, and therapeutic resistance. At present, there are still some controversies about this pathway and new ideas of combined therapy, which need to be further explored. This article reviews the progress of immunotherapy in improving EMT development in HCC cells by exploring the mechanism of regulating EMT.

SARS-CoV-2 Omicron Spike shows strong binding affinity and favourable interaction landscape with the TLR4/MD2 compared to other variants

Emergences of SARS-CoV-2 variants have made the pandemic more critical. Toll-like receptor 4 (TLR4) recognizes the molecular patterns of pathogens and activates the production of proinflammatory cytokines to restrain the infection. We have identified a molecular basis of interaction between the Spike and TLR4 of SARS-CoV-2 and its present and past VOCs (variant- of concern) through in silico analysis. The interaction of wild type Spike with TLR4 showed 15 number hydrogen bonds formation. Similarly, the Alpha variants' Spike with the TLR4 has illustrated that 14 hydrogen bonds participated in the interaction. However, the Delta Spike and TLR4 interaction interface showed that 17 hydrogen bonds were formed during the interaction. Furthermore, Omicron S-glycoprotein and TLR4 interaction interface was depicted (interaction score: -170.3), and 16 hydrogen bonds were found to have been formed in the interaction. Omicron S-glycoprotein shows stronger binding affinity with the TLR4 than wild type, Alpha, and Delta variants. Similarly, the Alpha Spike shows higher binding affinity with TLR4 than the wild type and Delta variant. Now, it is an open question of the molecular basis of the interaction of Spike and TLR4 and the activated downstream signaling events of TLR4 for SARS-CoV-2 and its variants.

TLR9 Monotherapy in Immune-Competent Mice Suppresses Orthotopic Prostate Tumor Development

Prostate cancer is ranked second in the world for cancer-related deaths in men, highlighting the lack of effective therapies for advanced-stage disease. Toll-like receptors (TLRs) and immunity have a direct role in prostate cancer pathogenesis, but TLR9 has been reported to contribute to both the progression and inhibition of prostate tumorigenesis. To further understand this apparent disparity, we have investigated the effect of TLR9 stimulation on prostate cancer progression in an immune-competent, syngeneic orthotopic mouse model of prostate cancer. Here, we utilized the class B synthetic agonist CPG-1668 to provoke a TLR9-mediated systemic immune response and demonstrate a significant impairment of prostate tumorigenesis. Untreated tumors contained a high abundance of immune-cell infiltrates. However, pharmacological activation of TLR9 resulted in smaller tumors containing significantly fewer M1 macrophages and T cells. TLR9 stimulation of tumor cells in vitro had no effect on cell viability or its downstream transcriptional targets, whereas stimulation in macrophages suppressed cancer cell growth via type I IFN. This suggests that the antitumorigenic effects of CPG-1668 were predominantly mediated by an antitumor immune response. This study demonstrated that systemic TLR9 stimulation negatively regulates prostate cancer tumorigenesis and highlights TLR9 agonists as a useful therapeutic for the treatment of prostate cancer.

Cold Atmospheric Plasma Conveys Selectivity Against Hepatocellular Carcinoma Cells via Triggering EGFR(Tyr1068)-Mediated Autophagy

Hepatocellular carcinomas remain as a global health threat given its high mortality rate. We have previously identified the selectivity of cold atmospheric plasma (CAP) against multiple types of malignant tumors and proposed it as a promising onco-therapeutic strategy. Here, we investigated its roles in controlling hepatocellular carcinoma malignancy and one possible driving molecular mechanism. By focusing on post-translational modifications including acetylation, phosphorylation, and ubiquitination, we identified the crosstalk between EGFR acetylation and EGFR(Tyr1068) phosphorylation and their collective roles in determining LC3B ubiquitination and proposed the EGFR/p-JNK/BIRC6/LC3B axis in CAP-triggered autophagy. Our study not only demonstrated the selectivity of CAP against hepatocellular carcinoma malignancy and confirmed its roles as an onco-therapeutic tool but also opened the horizon of translating CAP into clinics toward a broader scope that included human longevity and anti-aging.

Microbial-Derived Toll-like Receptor Agonism in Cancer Treatment and Progression

Simple Summary

Toll like receptors (TLRs) are a group of transmembrane receptors belonging to the class of pattern recognition receptors (PRR), which are involved in recognition of pathogen associated molecular patterns (PAMPs), inducing immune response. During the past decade, a number of preclinical and clinical breakthroughs in the field of TLR agonists has immerged in cancer research and some of these agents have performed exceptionally well in clinical trials. Based on evidence from scientific studies, we draw attention to several microbial based TLR agonists and discuss their relevance in various cancer and explore various microbial based TLR agonists for developing effective immunotherapeutic strategies against cancer.

Abstract

Toll-like receptors (TLRs) are typical transmembrane proteins, which are essential pattern recognition receptors in mediating the effects of innate immunity. TLRs recognize structurally conserved molecules derived from microbes and damage-associated molecular pattern molecules that play an important role in inflammation. Since the first discovery of the Toll receptor by the team of J. Hoffmann in 1996, in Drosophila melanogaster, numerous TLRs have been identified across a wide range of invertebrate and vertebrate species. TLR stimulation leads to NF-κB activation and the subsequent production of pro-inflammatory cytokines and chemokines, growth factors and anti-apoptotic proteins. The expression of TLRs has also been observed in many tumors, and their stimulation results in tumor progression or regression, depending on the TLR and tumor type. The anti-tumoral effects can result from the activation of anti-tumoral immune responses and/or the direct induction of tumor cell death. The pro-tumoral effects may be due to inducing tumor cell survival and proliferation or by acting on suppressive or inflammatory immune cells in the tumor microenvironment. The aim of this review is to draw attention to the effects of TLR stimulation in cancer, the activation of various TLRs by microbes in different types of tumors, and, finally, the role of TLRs in anti-cancer immunity and tumor rejection.

A Humanized Monoclonal Antibody Targeting Extracellular Nicotinamide Phosphoribosyltransferase Prevents Aggressive Prostate Cancer Progression

Prostate cancer (PCa) is the major cause of cancer-related death in males; however, effective treatments to prevent aggressive progression remain an unmet need. We have previously demonstrated that secreted extracellular nicotinamide phosphoribosyltransferase (eNAMPT) is a multifunctional innate immunity regulator that promotes PCa invasion. In the current study, we further investigate the therapeutic effects of an eNAMPT-neutralizing humanized monoclonal antibody (ALT-100 mAb) in preclinical PCa orthotopic xenograft models. We utilized human aggressive PCa cells (DU145 or PC3) for prostate implantation in SCID mice receiving weekly intraperitoneal injections of either ALT-100 mAb or IgG/PBS (control) for 12 weeks. Prostatic tumors and solid organs were examined for tumor growth, invasion, and metastasis and for biochemical and immunohistochemistry evidence of NFκB activation. ALT-100 mAb treatment significantly improved overall survival of SCID mice implanted with human PCa orthotopic prostate xenografts while inducing tumor necrosis, decreasing PCa proliferation and reducing local invasion and distal metastases. The ALT-100 mAb inhibits NFκB phosphorylation and signaling in PCa cells both in vitro and in vivo. This study demonstrates that eNAMPT neutralization effectively prevents human PCa aggressive progression in preclinical models, indicating its high potential to directly address the unmet need for an effective targeted therapy for patients with aggressive PCa.

Light-Inducible Spatio-Temporal Control of TLR4 and NF-κB-Gluc Reporter in Human Pancreatic Cell Line

Augmented Toll-like receptor 4 (TLR4) expression was found in nearly 70% of patients with pancreatic adenocarcinoma, which is correlated with increased tumorigenesis and progression. In this study, we engineered a new light-oxygen-voltage-sensing (LOV) domain-based optogenetic cell line (opto-TLR4 PANC-1) that enables time-resolved activation of the NF-κB and extracellular-signal regulated kinases (ERK)1/2 signalling pathway upon blue light-sensitive homodimerisation of the TLR4-LOV fusion protein. Continuous stimulation with light indicated strong p65 and ERK1/2 phosphorylation even after 24 h, whereas brief light exposure peaked at 8 h and reached the ground level 24 h post-illumination. The cell line further allows a voltage-dependent TLR4 activation, which can be continuously monitored, turned on by light or off in the dark. Using this cell line, we performed different phenotypic cell-based assays with 2D and 3D cultures, with the aim of controlling cellular activity with spatial and temporal precision. Light exposure enhanced cell attachment, the formation and extension of invadopodia, and cell migration in 3D spheroid cultures, but no significant changes in proliferation or viability could be detected. We conclude that the opto-TLR4 PANC-1 cell line is an ideal tool for investigating the underlying molecular mechanisms of TLR4, thereby providing strategies for new therapeutic options.

Toll-like receptor 4 signaling activates ERG function in prostate cancer and provides a therapeutic target

The TMPRSS2–ERG gene fusion and subsequent overexpression of the ERG transcription factor occurs in ∼50% of prostate tumors, making it the most common abnormality of the prostate cancer genome. While ERG has been shown to drive tumor progression and cancer-related phenotypes, as a transcription factor it is difficult to target therapeutically. Using a genetic screen, we identified the toll-like receptor 4 (TLR4) signaling pathway as important for ERG function in prostate cells. Our data confirm previous reports that ERG can transcriptionally activate TLR4 gene expression; however, using a constitutively active ERG mutant, we demonstrate that the critical function of TLR4 signaling is upstream, promoting ERG phosphorylation at serine 96 and ERG transcriptional activation. The TLR4 inhibitor, TAK-242, attenuated ERG-mediated migration, clonogenic survival, target gene activation and tumor growth. Together these data indicate a mechanistic basis for inhibition of TLR4 signaling as a treatment for ERG-positive prostate cancer.

Association between the anticancer efficacy of cabazitaxel and toll-like receptor 4 mediating signaling pathways in metastatic castration-resistant prostate cancer cells

BACKGROUND

We evaluated the effect of cabazitaxel (CAB) as a third-line taxane on Toll-like receptor 4 (TLR4)-mediated signaling pathways, especially NF-κB activity, in metastatic castration-resistant prostate cancer (mCRPC) cells.

METHODS

CAB cytotoxicity was determined by WST-1 assay. To assess the relationship between CAB efficacy and TLR4 signaling pathways, RT-PCR, western blot and immunofluorescence analysis were performed. Additionally, CAB-mediated apoptotic cell death was assessed by Annexin V and RT-PCR analysis.

RESULTS

Our results demonstrated that CAB exerted considerably cytotoxic and apoptotic effects on PC-3 mCRPC cells (p < 0.05). CAB treatment altered TLR4 expression level in a dose-dependent manner. Furthermore, 1 nM CAB treatment significantly induced NF-κB activity through p65 nuclear localization and increased the expression level of caspase-3, Bax and p53. Interestingly, total apoptotic cell death and IRF3 protein levels were increased at 5 nM concentration of CAB despite a decrease in the levels of both NF-κB and pro-apoptotic genes.

CONCLUSIONS

Therefore, NF-κB activity may be a potential target for the efficacy of CAB in mCRPC cells.

The role of toll-like receptor 4 (TLR4) in cancer progression: A possible therapeutic target?

The toll-like receptor (TLR) family consists of vital receptors responsible for pattern recognition in innate immunity, making them the core proteins involved in pathogen detection and eliciting immune responses. The most studied member of this family, TLR4, has been the center of attention regarding its contributory role in many inflammatory diseases including sepsis shock and asthma. Notably, mounting pieces of evidence have proved that this receptor is aberrantly expressed on the tumor cells and the tumor microenvironment in a wide range of cancer types and it is highly associated with the initiation of tumorigenesis as well as tumor progression and drug resistance. Cancer therapy using TLR4 inhibitors has recently drawn scientists' attention, and the promising results of such studies may pave the way for more investigation in the foreseeable future. This review will introduce the key proteins of the TLR4 pathway and how they interact with major growth factors in the tumor microenvironment. Moreover, we will discuss the many aspects of tumor progression affected by the activation of this receptor and provide an overview of the recent therapeutic approaches using various TLR4 antagonists.

Identification of hub genes associated with the pathogenesis of diffuse large B-cell lymphoma subtype one characterized by host response via integrated bioinformatic analyses

Background

Host response diffuse large B-cell lymphoma (HR DLBCL) shares features of histologically defined T-cell/histiocyte-rich B-cell lymphoma, including fewer genetic abnormalities, frequent splenic and bone marrow involvement, and younger age at presentation. HR DLBCL is inherently less responsive to the standard treatment for DLBCL. Moreover, the mechanism of infiltration of HR DLBCL with preexisting abundant T-cells and dendritic cells is unknown, and their associated underlying immune responses incompletely defined. Here, hub genes and pathogenesis associated with HR DLBCL were explored to reveal molecular mechanisms and treatment targets.

Methods

Differentially expressed genes were identified in three datasets (GSE25638, GSE44337, GSE56315). The expression profile of the genes in the GSE53786 dataset was used to constructed a co-expression network. Protein-protein interactions analysis in the modules of interest identified candidate hub genes. Then screening of real hub genes was carried out by survival analysis within the GSE53786 and GSE10846 datasets. Expression of hub genes was validated in the Gene expression profiling interactive analysis, Oncomine databases and human tissue specimens. Functional enrichment analysis and Gene set enrichment analysis were utilized to investigate the potential mechanisms. Tumor Immune Estimation Resource and The Cancer Genome Atlas were used to mine the association of the hub gene with tumor immunity, potential upstream regulators were predicted using bioinformatics tools.

Results

A total of 274 common differentially expressed genes were identified. Within the key module, we identified CXCL10 as a real hub gene. The validation of upregulated expression level of CXCL10 was consistent with our study. CXCL10 might have a regulatory effect on tumor immunity. The predicted miRNA (hsa-mir-6849-3p) and transcription factor (IRF9) might regulate gene expression in the hub module.

Role of secreted extracellular nicotinamide phosphoribosyltransferase (eNAMPT) in prostate cancer progression: Novel biomarker and therapeutic target

BACKGROUND

There remains a serious need to prevent the progression of invasive prostate cancer (PCa). We previously showed that secreted extracellular nicotinamide phosphoribosyltransferase (eNAMPT) is a multifunctional innate immunity regulator via TLR4 ligation which has been implicated in PCa progression. Here we investigate the role of eNAMPT as a diagnostic biomarker and therapeutic target in the progression of PCa.

METHODS

Tumor NAMPT expression and plasma eNAMPT level were evaluated in human subjects with various PCa tumor stages and high risk subjects followed-up clinically for PCa. The genetic regulation of NAMPT expression in PCa cells and the role of eNAMPT in PCa invasion were investigated utilizing in vitro and in vivo models.

FINDINGS

Marked NAMPT expression was detected in human extraprostatic-invasive PCa tissues compared to minimal expression of organ-confined PCa. Plasma eNAMPT levels were significantly elevated in PCa subjects compared to male controls, and significantly greater in subjects with extraprostatic-invasive PCa compared to subjects with organ-confined PCa. Plasma eNAMPT levels showed significant predictive value for diagnosing PCa. NAMPT expression and eNAMPT secretion were highly upregulated in human PCa cells in response to hypoxia-inducible factors and EGF. In vitro cell culture and in vivo preclinical mouse model studies confirmed eNAMPT-mediated enhancement of PCa invasiveness into muscle tissues and dramatic attenuation of PCa invasion by weekly treatment with an eNAMPT-neutralizing polyclonal antibody.

INTERPRETATION

This study suggests that eNAMPT is a potential biomarker for PCa, especially invasive PCa. Neutralization of eNAMPT may be an effective therapeutic approach to prevent PCa invasion and progression.

Role of Toll like receptor in progression and suppression of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common type of head and neck squamous cell carcinoma and one of the multifactorial process that consists of most contributing factors such as tobacco smoking, chewing and alcohol consumption that altered the intracellular environment. Recent studies have shown relevance of Toll like receptor (TLR) associated with carcinogenesis. This review aim’s to explore that how TLR associates with progression and suppression of OSCC. This review is a classical review that has confined to articles published in the past 19 years (i.e. 2000-2019) and has summarized the perspective of the authors. 62 articles were reviewed and it was found that progression and suppression of OSCC is associated with different TLRs promoting tumor development and also inhibiting the progression of oral neoplasm. It was found that TLR2, TLR3, TLR4, TLR5, TLR7 and TLR9 are associated with tumor development i.e. in progression of OSCC, where as suppression of OSCC through TLR3 and TLR7. We authors would like to conclude that literature survey has indicated effective TLR’s against OSCC development and can be explored to investigate other TLRs that can be used for therapeutic purposes in near future.

The effect of TLR4 on the growth and local inflammatory microenvironment of HPV-related cervical cancer in vivo

BACKGROUND

Cervical cancer is the most common malignancy of the female lower genital tract. In our previous study, we found that TLR4 promotes cervical cancer cell growth in vitro. The aim of this study was to further explore the role of TLR4 in HPV-related cervical cancer in vivo by using a nude mouse xenograft model.

METHODS

Cervical cancer-derived HeLa and CaSki cells (5 × 107/mL) were either stimulated with an optimal concentration of LPS for the appropriate time (HeLa cells were treated with 1 μg/mL LPS for 1 h, and CaSki cells were treated with 2 μg/mL LPS for 1.5 h) or transfected with TLR4 shRNA and then injected subcutaneously into the dorsal right posterior side of nude mice. The shortest width and longest diameter of the transplanted tumors in the nude mice were measured every 3 days.TLR4, IL-6,iNOS, IL-8,COX-2, MIP-3α, TGF-β1 and VEGF expression levels in the transplanted tumor tissue were detected by immunohistochemistry.

RESULTS

The tumor formation rate was 100% in both HeLa and CaSki nude mouse groups. The tumors grew faster, and the cachexia symptoms were more serious in the LPS groups than in the control group. In contrast, the tumors grew slower, and the cachexia symptoms were milder in the TLR4-silenced groups. TLR4, iNOS, IL-6, MIP-3α and VEGF were highly expressed in the transplanted tumor tissues from the LPS groups, and their expression levels were decreased in the TLR4-silenced groups.

CONCLUSION

TLR4 expression is closely associated with the tumorigenesis and growth of HPV-positive cervical cancer; TLR4 promotes HPV-positive cervical tumor growth and facilitates the formation of a local immunosuppressive microenvironment. Eventually, these conditions may lead to cervical cancer development.

Anti-inflammatory effects of nobiletin on TLR4/TRIF/IRF3 and TLR9/IRF7 signaling pathways in prostate cancer cells

Background: Toll-like receptors (TLRs) are often expressed in natural immune cells as well as in tumor cells. TLR4 exhibits both tumor promoting and tumor-suppressing roles and higher TLR9 expression is an important marker of poor prognosis in prostate cancer (PCa). Nobiletin (NOB) is an O-methylated flavonoid and NOB has been proven to have anti-cancer effect in PCa cells. However, there is no study in the literature investigating the potential anti-inflammatory effects of NOB on the TLR signaling pathways in cancer. Therefore, we aimed to explore the potential anti-inflammatory effects of NOB on the TLR4/TRIF/IRF3 and TLR9/IRF7 signaling pathways in different types of PCa cell lines, for the first time.Material and methods: In the current study, the cytotoxic effect of NOB PC-3 (hormone-independent and metastatic) and LNCaP cells (hormone-dependent) was evaluated by WST-1 assay. Furthermore, the inhibitory effects of NOB on TLR4/TRIF/IRF3 and TLR9/IRF7signaling pathway were determined by RT-PCR, western blotting and ELISA analysis.Results: NOB demonstrated an inhibitory effect on PCa cell growth and LNCaP cells were more sensitive to NOB than PC-3 cells due to androjen receptor status. Furthermore, NOB alone could suppress TLR4/TRIF/IRF3 and TLR9/IRF7 signaling pathways through the downregulation of their associated pathways (mRNA and related protein levels) and the release of IFN-α and IFN-β compared to LPS or CpG-ODN stimulated PCa cells.Conclusions: NOB potentially inhibited TLR4 and TL9-dependent signaling pathway in PCa cells. However, the efficacy of NOB was different in PCa cells due to the hormone status and aggressive features.

Increased Preoperative Plasma Level of Microbial 16S rDNA Translocation Is Associated With Relapse After Prostatectomy in Prostate Cancer Patients

Background: The environmental factors for promoting prostate cancer (PCa) recurrence remain unknown. Methods: A retrospective cross-sectional study was conducted in healthy men (n = 12) and PCa patients undergoing prostatectomy (n = 27). Plasma preoperative level of total cell-free bacterial 16S rDNA, a marker of microbial translocation, was evaluated by qPCR. Plasma levels of prostate-specific antigen (PSA) were evaluated by ELISA. Results: Similar degrees of microbial translocation were found in healthy men and patients. However, the levels of microbial 16S rDNA were increased in patients with cancer relapse (n = 10) compared to patients without relapse (n = 17) after prostatectomy. Furthermore, the levels of microbial 16S rDNA were marginally increased in patients with pT3 or pT4 tumors compared to those with pT 2 or less. The levels of microbial 16S rDNA tended to increase in patients with higher pathologic tumor stage, Gleason score, and margin and lymph node involvements; but these differences did not reach significance. Conclusion: The plasma 16S rDNA levels increased in patients with PCa who have biochemical recurrence and 16S rDNA levels were higher in patients with higher-grade PCa.

TLR4 Polymorphisms and Expression in Solid Cancers

Toll-like receptors (TLRs) are a type of pattern-recognition receptor (PRR) that are part of the innate immune system known to recognize pathogen-associated molecular patterns and thereby play a crucial role in host immune response. Among the various known TLRs, TLR4 is one of the most extensively studied PRRs expressed by immune, certain nonimmune, and tumor cells. When TLR4 binds with the bacterial lipopolysaccharide, it induces production of proinflammatory cytokines, chemokines, and effector molecules as part of the immune response. Continuous exposure to pathogens and TLR4 signaling results in chronic inflammation that may further lead to malignant transformation. TLR4 is a highly polymorphic gene, and genetic variations are known to influence host immune response, leading to dysregulation of signaling pathway, which may affect an individual's susceptibility to various diseases, including cancer. Furthermore, TLR4 expression in different tumor types may also serve as a marker for tumor proliferation, differentiation, metastasis, prognosis, and patient survival. This review aims to summarize various reports related to TLR4 polymorphisms and expression patterns and their influences on different cancer types with a special focus on solid tumors.

SP1-induced lncRNA AGAP2-AS1 expression promotes chemoresistance of breast cancer by epigenetic regulation of MyD88

BACKGROUND

Resistance to trastuzumab has become a leading cause of mortality in breast cancer patients and is one of the major obstacles for improving the clinical outcome. Cell behavior can be modulated by long non-coding RNAs (lncRNAs), but the contribution of lncRNAs in trastuzumab resistance to breast cancer is largely unknown. To this end, the involvement and regulatory function of lncRNA AGAP2-AS1 in human breast cancer are yet to be investigated.

METHODS

Trastuzumab-resistant SKBR-3 and BT474 cells were obtained by continuous culture with 5 mg/mL trastuzumab for 6 months. RT-qPCR assay was used to determine the expression of AGAP2-AS1 in tissues and cells. RNA fluorescence in situ hybridization was used to investigate the subcellular location of AGAP2-AS1 in breast cancer cells. Bioinformatic analysis, chromatin immunoprecipitation (ChIP), RNA immunoprecipitation (RIP), western blotting, and immunofluorescence were carried out to verify the regulatory interaction of AGAP2-AS1, CREB-binding protein (CBP), and MyD88. In addition, a series of in vitro assays and a xenograft tumor model were used to analyze the functions of AGAP2-AS1 in breast cancer cells.

RESULTS

AGAP2-AS1 was upregulated and transcriptionally induced by SP1 in breast cancer. Overexpression of AGAP2-AS1 promoted cell growth, suppressed apoptosis, and caused trastuzumab resistance, whereas knockdown of AGAP2-AS1 showed an opposite effect. MyD88 was identified as a downstream target of AGAP2-AS1 and mediated the AGAP2-AS1-induced oncogenic effects. Mechanistically, the RIP assay revealed that AGAP2-AS1 could bind to CBP, a transcriptional co-activator. ChIP assays showed that AGAP2-AS1-bound CBP increased the enrichment of H3K27ac at the promoter region of MyD88, thus resulting in the upregulation of MyD88. Gain- and loss-of-function assays confirmed that the NF-κB pathway was activated by MyD88 and AGAP2-AS1. Furthermore, high AGAP2-AS1 expression was associated with poor clinical response to trastuzumab therapy in breast cancer patients.

CONCLUSION

AGAP2-AS1 could promote breast cancer growth and trastuzumab resistance by activating the NF-κB signaling pathway and upregulating MyD88 expression. Therefore, AGAP2-AS1 may serve as a novel biomarker for prognosis and act as a therapeutic target for the trastuzumab treatment.

The Pathologic Role of Toll-Like Receptor 4 in Prostate Cancer

Toll-like receptor (TLR) 4 is expressed on normal and malignant prostate epithelial cells. The TLR4 and its downstream signaling pathways mediate innate immune responses in the host against invading pathogens. However, multiple lines of evidence shows that TLR4 expression is increased in prostate tissues from prostate cancer patients, and altered TLR4 signals may promote cancer development, as well as antitumor effects. In this review, we have summarized key features of the TLR4 signaling pathway and its associated immune responses and focused on the pathologic role of TLR4 in prostate carcinogenesis and tumor progression.

Peroxiredoxin 1 - an antioxidant enzyme in cancer

Peroxiredoxins (PRDXs), a ubiquitous family of redox‐regulating proteins, are reported of potential to eliminate various reactive oxygen species (ROS). As a major member of the antioxidant enzymes, PRDX1 can become easily over‐oxidized on its catalytically active cysteine induced by a variety of stimuli in vitro and in vivo. In nucleus, oligomeric PRDX1 directly associates with p53 or transcription factors such as c‐Myc, NF‐κB and AR, and thus affects their bioactivities upon gene regulation, which in turn induces or suppresses cell death. Additionally, PRDX1 in cytoplasm has anti‐apoptotic potential through direct or indirect interactions with several ROS‐dependent (redox regulation) effectors, including ASK1, p66^Shc, GSTpi/JNK and c‐Abl kinase. PRDX1 is proven to be a versatile molecule regulating cell growth, differentiation and apoptosis. Recent studies have found that PRDX1 and/or PRDX1‐regulated ROS‐dependent signalling pathways play an important role in the progression and metastasis of human tumours, particularly in breast, oesophageal and lung cancers. In this paper, we review the structure, effector functions of PRDX1, its role in cancer and the pivotal role of ROS in anticancer treatment.

Statin pretreatment inhibits the lipopolysaccharide-induced epithelial-mesenchymal transition via the downregulation of toll-like receptor 4 and nuclear factor-κB in human biliary epithelial cells

BACKGROUND AND AIM

Epithelial-mesenchymal transition (EMT) of biliary epithelial cells (BECs) plays an important role in biliary fibrosis. This study investigated the effects of simvastatin on the lipopolysaccharide (LPS)-induced EMT and related signal pathways in BECs.

METHODS

Biliary epithelial cells were exposed to LPS (2 µg/mL) or transforming growth factor β1 (TGF-β1) (5 ng/mL) for 5 days. The EMT was assessed by a gain of mesenchymal cell markers (vimentin, N-cadherin, slug, and Twist-1) and a loss of epithelial cell markers (E-cadherin). The effects of simvastatin on the EMT induced by LPS or TGF-β1 were determined by the changes in the levels of EMT markers and TLR4 and in the c-Jun N-terminal kinase (JNK), p38, and nuclear factor-κB (NF-κB) signaling pathways.

RESULTS

Compared with the BECs treated with LPS alone, co-treatment with simvastatin and LPS induced an increase in the expression of E-cadherin and decreases in the expression levels of mesenchymal cell markers. The LPS-induced TLR4 expression level was slightly decreased by co-treatment with simvastatin. LPS-induced BEC growth was markedly inhibited by co-treatment with simvastatin. Furthermore, pretreatment with simvastatin inhibited the LPS-induced EMT in BECs by downregulating NF-κB and JNK phosphorylation. The suppressive effects of simvastatin pretreatment on the induction of the EMT by TGF-β1 were also demonstrated in H69 cells.

CONCLUSIONS

Our results demonstrate that LPS or TGF-β1 promote the EMT in BECs that that pretreatment with simvastatin inhibited the induced EMT by downregulating toll-like receptor 4 and NF-κB phosphorylation. This finding suggests that simvastatin can be considered a new agent for preventing biliary fibrosis associated with the EMT of BECs.

Effects of TLR4 gene silencing on the proliferation and apotosis of hepatocarcinoma HEPG2 cells

Toll-like receptors (TLRs) are key factors in the innate immune system and initiate an inflammatory response to foreign pathogens, such as bacteria, fungi and viruses. TLR4-mediated signaling has been implicated in tumor cell proliferation and apoptosis in numerous cancers. The present study aimed to investigate the biological effect of TLR4 on the proliferation and apoptosis of human liver cancer cells and the mechanisms responsible for the regulation of cellular responses following TLR4 gene knockdown. Three TLR4 small interfering (si)RNA constructs, consisting of TLR4-siRNA-1, TLR4-siRNA-2 and TLR4-siRNA-3, were transiently transfected into HepG2 cells using Lipofectamine 2000. TLR4 knockdown was confirmed using reverse transcription-polymerase chain reaction and western blotting. The effect of the TLR4 siRNA on tumor cell proliferation was monitored by methyl thiazolyl tetrazolium assay and cell apoptosis was observed by flow cytometry. The expression of TLR4-associated proteins, consisting of myeloid differentiation primary response 88 (MyD88), Toll-interleukin-1R-domain-containing adapter-inducing interferon-β (TRIF), interferon regulatory factor-3 (IRF3), nuclear factor (NF)-κB, NF-κB inhibitor α (IκBα), phosphorylated IκBα (p-IκBα), extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), was detected by western blot analysis. TLR4-siRNA-1 had the strongest knockdown effect and inhibited TLR4 messenger RNA and protein expression. TLR4 knockdown with TLR4-siRNA-1 reduced cell proliferation and promoted cell apoptosis. MyD88, TRIF, IRF3, IκBα, JNK and ERK were markedly suppressed in the cells transfected with TLR4 siRNA. However, nuclear expression of NF-κB and p-IκBα increased in HepG2 cells with TLR4 gene knockdown. The present study revealed that TLR4-mediated signaling plays a key role in the proliferation and apoptosis of cultured hepatocarcinoma cells. Therefore, RNA interference-directed targeting of TLR4 may raise the potential of the application of TLR4 knockdown for liver cancer therapy.

Epigenetic modification of TLR4 promotes activation of NF-κB by regulating methyl-CpG-binding domain protein 2 and Sp1 in gastric cancer

Toll-like receptor 4 (TLR4) is important in promoting the immune response in various cancers. Recently, TLR4 is highly expressed in a stage-dependent manner in gastric cancer, but the regulatory mechanism of TLR4 expression has been not elucidated it. Here, we investigated the mechanism underlying regulation of TLR4 expression through promoter methylation and histone modification between transcriptional regulation and silencing of the TLR4 gene in gastric cancer cells. Chromatin immunoprecipitation was carried out to screen for factors related to TLR4 methylation such as MeCP2, HDAC1, and Sp1 on the TLR4 promoter. Moreover, DNA methyltransferase inhibitor 5-aza-deoxycytidine (5-aza-dC) induced demethylation of the TLR4 promoter and increased H3K4 trimethylation and Sp1 binding to reactivate silenced TLR4. In contrast, although the silence of TLR4 activated H3K9 trimethylation and MeCP2 complex, combined treatment with TLR4 agonist and 5-aza-dC upregulated H3K4 trimethylation and activated with transcription factors as Sp1 and NF-κB. This study demonstrates that recruitment of the MeCP2/HDAC1 repressor complex increases the low levels of TLR4 expression through epigenetic modification of DNA and histones on the TLR4 promoter, but Sp1 activates TLR4 high expression by hypomethylation and NF-κB signaling in gastric cancer cells.

Biological Response Modifier in Cancer Immunotherapy

Biological response modifiers (BRMs) emerge as a lay of new compounds or approaches used in improving cancer immunotherapy. Evidences highlight that cytokines, Toll-like receptor (TLR) signaling, and noncoding RNAs are of crucial roles in modulating antitumor immune response and cancer-related chronic inflammation, and BRMs based on them have been explored. In particular, besides some cytokines like IFN-α and IL-2, several Toll-like receptor (TLR) agonists like BCG, MPL, and imiquimod are also licensed to be used in patients with several malignancies nowadays, and the first artificial small noncoding RNA (microRNA) mimic, MXR34, has entered phase I clinical study against liver cancer, implying their potential application in cancer therapy. According to amounts of original data, this chapter will review the regulatory roles of TLR signaling, some noncoding RNAs, and several key cytokines in cancer and cancer-related immune response, as well as the clinical cases in cancer therapy based on them.

Mitochondrial Dynamics and Heart Failure

Mitochondrial dynamics, fission and fusion, were first identified in yeast with investigation in heart cells beginning only in the last 5 to 7 years. In the ensuing time, it has become evident that these processes are not only required for healthy mitochondria, but also, that derangement of these processes contributes to disease. The fission and fusion proteins have a number of functions beyond the mitochondrial dynamics. Many of these functions are related to their membrane activities, such as apoptosis. However, other functions involve other areas of the mitochondria, such as OPA1's role in maintaining cristae structure and preventing cytochrome c leak, and its essential (at least a 10 kDa fragment of OPA1) role in mtDNA replication. In heart disease, changes in expression of these important proteins can have detrimental effects on mitochondrial and cellular function.

Mechanisms and pathways of innate immune activation and regulation in health and cancer

Research on innate immune signaling and regulation has recently focused on pathogen recognition receptors (PRRs) and their signaling pathways. Members of PRRs sense diverse microbial invasions or danger signals, and initiate innate immune signaling pathways, leading to proinflammatory cytokines production, which, in turn, instructs adaptive immune response development. Despite the diverse functions employed by innate immune signaling to respond to a variety of different pathogens, the innate immune response must be tightly regulated. Otherwise, aberrant, uncontrolled immune responses will lead to harmful, or even fatal, consequences. Therefore, it is essential to better discern innate immune signaling and many regulators, controlling various signaling pathways, have been identified. In this review, we focus on the recent advances in our understanding of the activation and regulation of innate immune signaling in the host response to pathogens and cancer.

Knockdown of PLCε inhibits inflammatory cytokine release via STAT3 phosphorylation in human bladder cancer cells

Phospholipase Cε (PLCε) is a multifunctional enzyme implicated in inflammatory functions. There are limited data, however, on how PLCε can alter inflammatory cytokine by affecting downstream pathways. Recent studies suggest that inflammation is likely to have an important role in transitional cell carcinoma of bladder (TCCB) and cancer disease progression. Here, we showed that PLCε and p-STAT3 expression were both elevated in TCCB tissues compared to adjacent tissues, and the increase of PLCε level was associated with the increase of p-STAT3 level. Then, knockdown of PLCε using adenovirus-shPLCε significantly decreased inflammatory cytokine (IL-6, TNF-α, IL-1β) expression and inflammation-associated gene (TLR4, MyD88, p-STAT3) expression. Furthermore, we demonstrated that PLCε knockdown blocked LPS-induced inflammatory cytokine and p-STAT3 expression. Additionally, we found that combined treatment of STAT3 inhibitor S3I-201 with adenovirus-shPLCε exhibited synergistic inhibitory effects on expression of p-STAT3. Our results suggested that STAT3 phosphorylation is involved in PLCε-mediated inflammatory cytokine release. Our research is of potential importance in drug development programs using PLCε as a therapeutic target for TCCB.

Toll-like receptor 4 regulates hepatitis B virus related hepatic carcinoma cell proliferation by controlling cyclin-dependent kinase 4/6 expression

AIM: To explore the effect of Toll-like receptor 4 (TLR4) on the proliferation of hepatitis B virus (HBV) related hepatic carcinoma cells and the underlying mechanism.

METHODS: The expression of TLR4, cyclin-dependent kinase (CDK) 4 and CDK6 protein in 36 HBV-related hepatic carcinoma tissues and matched adjacent tissues were detected by Western blot, and their correlations in carcinoma tissues were analyzed. Three TLR4 specific siRNAs and a negative control were synthesized and transfected into hepatoma cells Hep-3B using liposomes. The siRNA sequence with the best performance was selected for Western blot analysis. The expression of TLR4, CDK4 and CDK6 proteins was measured by Western blot assay before and after transfection. The proliferation of hepatoma cells was observed by MTT assay and colony formation assay.

RESULTS: The overall expression levels of TLR4, CDK4 and CDK6 proteins in HBV-related hepatic carcinoma were significantly higher than those in the matched adjacent tissues (P < 0.05). There was a positive correlation between TLR4 and CDK4 expression (r = 0.66, P < 0.05), and between TLR4 and CDK6 expression (r = 0.57, P < 0.05). Using the best interference sequence (TLR4-siRNA-03), it was found that the protein levels of CDK4 and CDK6 were significantly decreased in the TLR4-siRNA group (P < 0.05), compared to the control group. In addition, the proliferation of Hep-3B cells and the colony formation rate were both decreased (P < 0.05) in the TLR4-siRNA group.

CONCLUSION: TLR4 may regulate the proliferation of HBV-related hepatic carcinoma cells by controlling the expression of CDK4 and CDK6.

TLR4 activation by lipopolysaccharide confers survival advantage to growth factor deprived prostate cancer cells

BACKGROUND

Prostate cancer (PCa) cells express Toll-like receptor-4 (TLR4), a known pro-tumorigenic molecule for different cancer cells. The cancer cells residing in the avascular region of the tumor confront various metabolic stresses and continuously adapt mechanisms to overcome them. We hypothesized that TLR4 activation might provide direct survival advantage to metabolically stressed PCa cells.

METHODS

We first investigated the effect of LPS on survival of serum deprived PCa cells. To understand the molecular mechanisms involved in TLR4 mediated PCa survival, we next investigated change in expression of markers for apoptosis, senescence and autophagy. Ultimately, the effect of LPS on established prostate tumors was confirmed in vivo using a syngeneic rat model for PCa.

RESULTS

Lipopolysaccharide (LPS)-mediated TLR4 activation significantly enhanced survival of serum deprived (SD) PC3, DU145 and MAT-LyLu PCa cells. TLR4 inhibition by a specific inhibitor resulted in rapid death of SD-PC3 cells, which was significantly suppressed by LPS. Interestingly, LPS treatment suppressed macroautophagy in SD-PC3 cells and increased expression of CCL2 (C-C motif ligand-2), a known autophagy inhibitor and pro-survival factor. Intra-tumor LPS injection resulted in increased tumor mass, induced TLR4 activation, suppressed autophagy, and increased the macrophage population in MAT-LyLu-tumors.

CONCLUSIONS

Our study reveals that bacterial LPS enhance survival of PCa cells under conditions of nutrient stress through TLR4 activation. Moreover, LPS induces overexpression of CCL2 involved in the suppression of starvation-induced macroautophagy in PCa cells, and enhanced macrophage population in prostate tumors in vivo. Taken together, the current study suggests the importance of bacterial infection or TLR4-activation in prostate cancer pathogenesis.

TLR4 mutation and HSP60-induced cell death in adult mouse cardiac myocytes

Extracellular (ex) HSP60 is increasingly recognized as an agent of cell injury. Previously, we reported that low endotoxin exHSP60 causes cardiac myocyte apoptosis. Our findings supported a role for Toll-like receptor (TLR) 4 in HSP60 mediated apoptosis. To further investigate the involvement of TLR4 in cardiac injury, we studied adult cardiac myocytes from C3H/HeJ (HeJ) mice, which have a mutant, nonfunctional TLR4, and compared the results with parallel studies using wild-type (WT) mice. Nuclear factor κB (NFκB) activation is an early step downstream of TLR4. NFκB was activated 1 h after treatment with HSP60 in WT, but not HeJ mouse myocytes. ExHSP60 caused apoptosis in cardiac myocytes from WT mice, but not in myocytes from the HeJ mutants. To further elucidate the importance of exHSP60 in cardiac myocyte injury, both WT and HeJ mutant isolated mouse adult cardiac myocytes were exposed to hypoxia/reoxygenation. Anti-HSP60 antibody treatment reduced apoptosis in the WT group, but had no effect on the HeJ mutant myocytes. Unexpectedly, necrosis was also decreased in the HeJ mutants. Necrosis after hypoxia/reoxygenation in WT cardiac myocytes was mediated in part by TLR2 and TLR4 through rapid activation of PKCα, followed by increased expression of Nox2, and this was ameliorated by blocking antibodies to TLR2/4. These studies provide further evidence that TLR4 mediates exHSP60-associated apoptosis and that exHSP60 has an important role in cardiac myocyte injury, both apoptotic and necrotic.

Esophageal cancer-related gene-4 (ECRG4) interactions with the innate immunity receptor complex

OBJECTIVE AND DESIGN

The human c2orf40 gene encodes a tumor suppressor gene called esophageal cancer-related gene-4 (ECRG4) with pro- and anti-inflammatory activities that depend on cell surface processing. Here, we investigated its physical and functional association with the innate immunity receptor complex.

METHODS

Interactions between ECRG4 and the innate immunity receptor complex were assessed by flow cytometry, immunohistochemistry, confocal microscopy, and co-immunoprecipitation. Phage display was used for ligand targeting to cells that overexpress the TLR4-MD2-CD14.

RESULTS

Immunoprecipitation and immunohistochemical studies demonstrate a physical interaction between ECRG4 and TLR4-MD2-CD14 on human granulocytes. Flow cytometry shows ECRG4 on the cell surface of a subset of CD14(+) and CD16(+) leukocytes. In a cohort of trauma patients, the C-terminal 16 amino acid domain of ECRG4 (ECRG4(133-148)) appears to be processed and shed, presumably at a thrombin-like consensus sequence. Phage targeting this putative ligand shows that this peptide sequence internalizes into cells through the TLR4/CD14/MD2 complex, but modulates inflammation through non-canonical, NFκB signal transduction.

CONCLUSIONS

ECRG4 is present on the surface of human monocytes and granulocytes. Its interaction with the human innate immunity receptor complex supports a role for cell surface activation of ECRG4 during inflammation and implicates this receptor in its mechanism of action.

Lipopolysaccharide enhances OSCC migration by promoting epithelial-mesenchymal transition

BACKGROUND

This study was performed to examine whether lipopolysaccharide can influence cell migration and epithelial-mesenchymal transition of oral squamous cell carcinoma.

METHODS

Three oral squamous cell carcinoma cell lines (HSC3, CAL27, and SCC4) were obtained for the study. TLR4 expression in three cell lines was analyzed by Q-PCR and Western blot. After cells treated with LPS, cell migration was analyzed by wound-healing and chemotaxis cell migration assay. Changes of E-cadherin and vimentin expression were tested by Western blot and immunofluorescence staining. To examine NF-κB activation, NF-κB nuclear translocation was investigated.

RESULTS

TLR4 was expressed in all three cell lines and was highest in HSC3 while lowest in SCC4. TLR4 ligand lipopolysaccharide accelerated wound healing and enhanced cell migration. Also, it stimulated epithelial-mesenchymal transition demonstrated by decreased E-cadherin and increased vimentin expression. Lipopolysaccharide also provoked NF-κB nuclear translocation. Either TLR4 or NF-κB blocking reverted these effects.

CONCLUSIONS

Lipopolysaccharide can induce TLR4-mediated epithelial-mesenchymal transition and cell migration in oral squamous cell carcinoma. These responses could further affect tumor progressing by inducing tumor cell metastasis.

Polymorphisms of an innate immune gene, toll-like receptor 4, and aggressive prostate cancer risk: a systematic review and meta-analysis

BACKGROUND

Toll-like receptor 4 (TLR4) is one of the best known TLR members expressed on the surface of several leukocytes and tissue cells and has a key function in detecting pathogen and danger-associated molecular patterns. The role of TLR4 in the pathophysiology of several age-related diseases is also well recognized, such as prostate cancer (PCa). TLR4 polymorphisms have been related to PCa risk, but the relationship between TLR4 genotypes and aggressive PCa risk has not been evaluated by any systematic reviews.

METHODS

We performed a systematic review and meta-analysis of candidate-gene and genome-wide association studies analyzing this relationship and included only white population. Considering appropriate criteria, only nine studies were analyzed in the meta-analysis, including 3,937 aggressive PCa and 7,382 controls.

RESULTS

Using random effects model, no significant association was found in the ten TLR4 SNPs reported by at least four included studies under any inheritance model (rs2737191, rs1927914, rs10759932, rs1927911, rs11536879, rs2149356, rs4986790, rs11536889, rs7873784, and rs1554973). Pooled estimates from another ten TLR4 SNPs reported by three studies also showed no significant association (rs10759930, rs10116253, rs11536869, rs5030717, rs4986791, rs11536897, rs1927906, rs913930, rs1927905, and rs7045953). Meta-regression revealed that study type was not a significant source of between-study heterogeneity.

CONCLUSIONS

TLR4 polymorphisms were not significantly associated with the risk of aggressive PCa.

Links between Toll-like receptor 4 and breast cancer

Toll-like receptors (TLRs) have generated an extraordinary amount of interest in cancer research since the last decade. TLRs are a family of pattern recognition receptors that is involved in the host defense against microbial infections. It is well known that the activation of TLRs leads to the production of biological factors that drive inflammatory responses and activate the adaptive immune system. More recently, TLR-mediated signaling pathways have been shown to support tumor cell growth in vitro and in vivo. In this review, we describe recently emerged links between TLR4 and breast cancer oncogenesis, and future perspectives for the targeting of TLR4 in breast cancer therapy.

Toll-like receptor 4 prompts human breast cancer cells invasiveness via lipopolysaccharide stimulation and is overexpressed in patients with lymph node metastasis

Toll-like receptor (TLR)4-mediated signaling has been implicated in tumor cell invasion, survival, and metastasis in a variety of cancers. This study investigated the expression and biological role of TLR4 in human breast cancer metastasis. MCF-7 and MDA-MB-231 are human breast cancer cell lines with low and high metastatic potential, respectively. Using lipopolysaccharide (LPS) to stimulate MCF-7 and MDA-MB-231 cells, expression of TLR4 mRNA and protein increased compared with that in control cells. TLR4 activation notably up-regulated expression of matrix metalloproteinase (MMP)-2, MMP-9 and vascular endothelial growth factor(VEGF) mRNA and their secretion in the supernatants of both cell lines. LPS enhanced invasion of MDA-MB-231 cells by transwell assay and MCF-7 cells by wound healing assay. LPS triggered increased expression of TLR4 downstream signaling pathway protein myeloid differentiation factor 88(MyD88) and resulted in interleukin (IL)-6 and IL-10 higher production by human breast cancer cells. Stimulation of TLR4 with LPS promoted tumorigenesis and formed metastatic lesions in liver of nude mice. Moreover, expression of TLR4 and MyD88 as well as invasiveness and migration of the cells could be blocked by TLR4 antagonist. Combined with clinicopathological parameters, TLR4 was overexpressed in human breast cancer tissue and correlated with lymph node metastasis. These findings indicated that TLR4 may participate in the progression and metastasis of human breast cancer and provide a new therapeutic target.

DNA methylation status of key cell-cycle regulators such as CDKNA2/p16 and CCNA1 correlates with treatment response to doxorubicin and 5-fluorouracil in locally advanced breast tumors

PURPOSE

To explore alterations in gene promoter methylation as a potential cause of acquired drug resistance to doxorubicin or combined treatment with 5-fluorouracil and mitomycin C in human breast cancers.

EXPERIMENTAL DESIGN

Paired tumor samples from locally advanced breast cancer patients treated with doxorubicin and 5-fluorouracil-mitomycin C were used in the genome-wide DNA methylation analysis as discovery cohort. An enlarged cohort from the same two prospective studies as those in the discovery cohort was used as a validation set in pyrosequencing analysis.

RESULTS

A total of 469 genes were differentially methylated after treatment with doxorubicin and revealed a significant association with canonical pathways enriched for immune cell response and cell-cycle regulating genes including CDKN2A, CCND2, CCNA1, which were also associated to treatment response. Treatment with FUMI resulted in 343 differentially methylated genes representing canonical pathways such as retinoate biosynthesis, gαi signaling, and LXR/RXR activation. Despite the clearly different genes and pathways involved in the metabolism and therapeutic effect of both drugs, 46 genes were differentially methylated before and after treatment with both doxorubicin and FUMI. DNA methylation profiles in genes such as BRCA1, FOXC1, and IGFBP3, and most notably repetitive elements like ALU and LINE1, were associated with TP53 mutations status.

CONCLUSION

We identified and validated key cell-cycle regulators differentially methylated before and after neoadjuvant chemotherapy such as CDKN2A and CCNA1 and reported that methylation patterns of these genes may be potential predictive markers to anthracycline/mitomycine sensitivity.

Mycoplasma hyorhinis induces epithelial-mesenchymal transition in gastric cancer cell MGC803 via TLR4-NF-κB signaling

Our previous works showed chronic infection of Mycoplasma hyorhinis (M. hyorhinis) was associated with gastric cancer metastasis, but the mechanisms were unknown. Herein, we found M. hyorhinis induced epithelial-mesenchymal transition (EMT) in gastric cancer cell MGC803, which was counteracted by inhibitor of NF-κB signaling or p65 knockdown. Furthermore, we found that TLR4 associated with p37, a membrane protein of M. hyorhinis. Knock-down or inhibition of TLR4 antagonized M. hyorhinis-induced NF-κB signaling, EMT, and cell migration. Thus, M. hyorhinis induces EMT and promotes cell migration via TLR4-NF-κB signaling, which provides a clue to the pathogenesis of M. hyorhinis in gastric cancer.

Toll-like receptors and prostate cancer

Prostate cancer is the second leading cause of cancer-related death in men after lung cancer. Immune responses clearly play a critical role in the tumorigenesis and in the efficacy of radiation therapy and chemotherapy in prostate cancer; however, the underlying molecular mechanisms are still poorly understood. Toll-like receptors (TLRs) are a well-known family of pattern recognition receptors that play a key role in host immune system. Recent studies demonstrate that there are links between TLRs and cancer; however, the function and biological importance of TLRs in prostate cancer seems complex. To elucidate the role of TLRs and innate immunity in prostate cancer might provide us with a better understanding of the molecular mechanisms of this disease. Moreover, utilizing the agonists or antagonists of TLRs might represent a promising new strategy against prostate cancer. In this review, we summarize recent advances on the studies of association between TLR signaling and prostate cancer, TLR polymorphisms and prostate cancer risk, and provide some insights about TLRs as potential targets for prostate cancer immunotherapy.

Knockdown of toll-like receptor 4 inhibits human NSCLC cancer cell growth and inflammatory cytokine secretion in vitro and in vivo

Toll-like receptor 4 (TLR4)-mediated signaling has been implicated in tumor cell invasion, survival and metastasis in several types of cancers. However, the expression of TLR4 in patients with non-small cell lung cancer (NSCLC) and its biological function in the development and progression of NSCLC have not been elucidated to date. Here, we sought to characterize the expression of TLR4 in patients with NSCLC and to investigate the biological roles of TLR4 in lung metastasis, cell invasion and survival. In this study, we found that TLR4 expression was elevated in most patients with NSCLC, and its expression levels correlated with key pathological characteristics, including tumor differentiation, stage and metastasis. Our data also showed that downregulation of TLR4 expression using an RNA silencing approach in A549 tumor cells significantly suppressed cell proliferation, cell migration and cell invasion, and induced tumor apoptosis in vitro, and suppressed tumor growth in vivo. In addition, we also found that downregulation of TLR4 expression significantly decreased cell TNF-α and IL-6 levels. Furthermore, we found that knockdown of TLR4 was able to significantly suppress constitutive phosphorylation of Akt and PI3K, which may contribute to the inhibition of tumor growth. These data suggest that TLR4 plays an important role in tumorigenic properties of human NSCLC, and that RNA interference-directed targeting of TLR4 could be used as a potential anticancer therapeutic target in NSCLC.

Activation of Toll-like receptor-9 promotes cellular migration via up-regulating MMP-2 expression in oral squamous cell carcinoma

PURPOSE

Activation of Toll like receptors (TLRs) signaling has been implicated in promoting malignant cell invasion and metastatic potential. Previously we demonstrated that increased TLR-9 expression predicted poor survival in oral cancer patients. The objective of this study is to further investigate the roles and potential molecular mechanisms of TLR-9 signaling in human oral cancer cell invasion.

METHODS

Cell migration, invasion and protein expression were detected by wound healing assay, Transwell chambers model and western blot. The secretion and activity levels of metalloproteinases-2/9 were quantified by ELISA and Gelatin zymography. EMSA and ChIP assays were employed to detect the activity of AP-1signal pathway. TLR-9 siRNA transfection was used to regulate the expression and activity of TLR-9 in oral cancer cell line HB cells.

RESULT

The results of both wound healing assay and in vitro Transwell assay revealed that activation of TLR-9 induced dose- and time- dependent migration and invasion of HB cells. An increased expression, secretion and activity of MMP-2 were observed upon the treatment of CpG-ODN. The TLR-9 signaling-mediated MMP-2 expression appeared to be a consequence of AP-1 activation, because that their DNA binding activity was enhanced by CpG-ODN treatment. All these influences were efficiently repressed by the knockdown of TLR-9 through siRNA or pretreatment of an AP-1 inhibitor.

CONCLUSION

Activation of TLR-9 signaling could promote human oral cancer HB cells invasion with the induction of MMP-2 presentation by attenuating AP-1 binding activity, suggesting a novel anti-metastatic application for TLR-9 targeted therapy in oral cancer in the future.

Chlamydia trachomatis infection increases the expression of inflammatory tumorigenic cytokines and chemokines as well as components of the Toll-like receptor and NF-κB pathways in human prostate epithelial cells

Inflammation has been reported to play a major role in prostate carcinogenesis. Several bacterial infections can lead to prostate inflammation; however, until now, the precise molecular and cellular mechanisms linking inflammation to carcinogenesis have remained unclear. We therefore investigated the initiation of inflammation induced by Chlamydia trachomatis (C. trachomatis) infection in human prostate epithelial cells using an in vitro culture system in which human androgen-independent PC-3 prostate cancer epithelial cells were infected with C. trachomatis serovar L2. The expression levels of VEGF, ICAM-1, IL-6, IL-8, IL-1β, TNFα, CCL5, CCL2 and iNOS inflammation-related genes, as well as genes involved in the Toll-like receptor (TLR) pathway (TLR2, TLR4, CD14 and MyD88), were evaluated at the mRNA level in infected PC-3 cells 24 h after infection with C. trachomatis serovar L2. The expression levels of components of the NF-κB pathway (p65 and IκBα) were evaluated at the mRNA level in infected PC-3 cells at different time points (1, 6, 12 and 24 h) after infection. The expression levels of inflammation-related genes, components of the Toll-like receptor pathway and genes involved in NF-κB activation were analyzed in infected and uninfected cells using semi-quantitative RT-PCR. We detected a significant increase (p < 0.001) in inflammation-related cytokines in infected PC-3 cells. During infection, PC-3 cells elicited a proinflammatory response, as shown by NF-κB activation, TLR2 and TLR4 upregulation and the increased expression of inflammation-related genes. Furthermore, we observed significant upregulation of the adhesion molecules ICAM-1 and VEGF, which are two biomarkers correlated with tumor progression and immune system evasion. The present study suggests that human prostate cancer epithelial cells are susceptible to C. trachomatis infection and upregulate proinflammatory markers during infection.

Fragmented sleep accelerates tumor growth and progression through recruitment of tumor-associated macrophages and TLR4 signaling

Sleep fragmentation (SF) is a highly prevalent condition and a hallmark of sleep apnea, a condition that has been associated with increased cancer incidence and mortality. In this study, we examined the hypothesis that sleep fragmentation promotes tumor growth and progression through proinflammatory TLR4 signaling. In the design, we compared mice that were exposed to sleep fragmentation one week before engraftment of syngeneic TC1 or LL3 tumor cells and tumor analysis four weeks later. We also compared host contributions through the use of mice genetically deficient in TLR4 or its effector molecules MYD88 or TRIF. We found that sleep fragmentation enhanced tumor size and weight compared with control mice. Increased invasiveness was apparent in sleep fragmentation tumors, which penetrated the tumor capsule into surrounding tissues, including adjacent muscle. Tumor-associated macrophages (TAM) were more numerous in sleep fragmentation tumors, where they were distributed in a relatively closer proximity to the tumor capsule compared with control mice. Although tumors were generally smaller in both MYD88(-/-) and TRIF(-/-) hosts, the more aggressive features produced by sleep fragmentation persisted. In contrast, these more aggressive features produced by sleep fragmentation were abolished completely in TLR4(-/-) mice. Our findings offer mechanistic insights into how sleep perturbations can accelerate tumor growth and invasiveness through TAM recruitment and TLR4 signaling pathways.

Should a Toll-like receptor 4 (TLR-4) agonist or antagonist be designed to treat cancer? TLR-4: its expression and effects in the ten most common cancers

Toll-like receptor 4 (TLR-4) is well known for its host innate immunity. Despite the fact that TLR-4 activation confers antitumor responses; emerging evidence suggests that TLR-4 is associated with tumor development and progression. It is now clear that overactivation of TLR-4, through various immune mediators, may cause immune response dysfunction, resulting in tumorigenesis. Different cancers could have different extents of TLR-4 involvement during tumorigenesis or tumor progression. In this review, we focus on infection- and inflammation-related TLR-4 activation in noncancer and cancer cells, as well as on the current evidence about the role of TLR-4 in ten of the most common cancers, viz, head and neck cancer, lung cancer, gastrointestinal cancer, liver cancer, pancreatic cancer, skin cancer, breast cancer, ovarian cancer, cervical cancer, and prostate cancer.