TLR9 signaling promotes tumor progression of human lung cancer cell in vivo

Analysis of Selected Toll-like Receptors in the Pathogenesis and Advancement of Non-Small-Cell Lung Cancer

(1) Background: Non-small-cell lung cancer (NSCLC) represents a significant global health challenge, contributing to numerous cancer deaths. Despite advances in diagnostics and therapy, identifying reliable biomarkers for prognosis and therapeutic stratification remains difficult. Toll-like receptors (TLRs), crucial for innate immunity, now show potential as contributors to cancer development and progression. This study aims to investigate the role of TLR expression as potential biomarkers in the development and progression of NSCLC. (2) Materials and Methods: The study was conducted on 89 patients diagnosed with NSCLC and 40 healthy volunteers, for whom the prevalence of TLR2, TLR3, TLR4, TLR7, TLR8, and TLR9 was assessed on selected subpopulations of T and B lymphocytes in the peripheral blood of recruited patients along with the assessment of their serum concentration. (3) Result: Our study showed several significant changes in NSCLC patients at the beginning of the study. This resulted in a 5-year follow-up of changes in selected TLRs in recruited patients. Due to the high mortality rate of NSCLC patients, only 16 patients survived the 5 years. (4) Conclusions: The results suggest that TLRs may constitute real biomarker molecules that may be used for future prognostic purposes in NSCLC. However, further validation through prospective clinical and functional studies is necessary to confirm their clinical utility. These conclusions may lead to better risk stratification and tailored interventions, benefiting NSCLC patients and bringing medicine closer to precision.

MicroRNA-7: A New Intervention Target for Inflammation and Related Diseases

MicroRNAs (miRNAs) are a class of small noncoding RNA that can regulate physiological and pathological processes through post-transcriptional regulatory gene expression. As an important member of the miRNAs family, microRNA-7 (miR-7) was first discovered in 2001 to play an important regulatory role in tissue and organ development. Studies have shown that miR-7 participates in various tissue and organ development processes, tumorigenesis, aging, and other processes by regulating different target molecules. Notably, a series of recent studies have determined that miR-7 plays a key regulatory role in the occurrence of inflammation and related diseases. In particular, miR-7 can affect the immune response of the body by influencing T cell activation, macrophage function, dendritic cell (DC) maturation, inflammatory body activation, and other mechanisms, which has important potential application value in the intervention of related diseases. This article reviews the current regulatory role of miR-7 in inflammation and related diseases, including viral infection, autoimmune hepatitis, inflammatory bowel disease, and encephalitis. It expounds on the molecular mechanism by which miR-7 regulates the occurrence of inflammatory diseases. Finally, the existing problems and future development directions of miR-7-based intervention on inflammation and related diseases are discussed to provide new references and help strengthen the understanding of the pathogenesis of inflammation and related diseases, as well as the development of new strategies for clinical intervention.

Modulation of long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression in the liver of Beagle dogs by Toxocara canis infection

BACKGROUND

Long non-coding RNAs (lncRNAs) and messenger RNAs (mRNAs) play crucial roles in regulating various physiological and pathological processes. However, the role of lncRNAs and mRNAs in mediating the liver response during Toxocara canis infection remains incompletely understood.

METHODS

In the present study, the expression profile of lncRNAs and mRNAs was investigated in the liver of Beagle dogs infected by T. canis using high-throughput RNA sequencing.

RESULTS

Compared with the control groups, 876 differentially expressed (DE) lncRNAs and 288 DEmRNAs were identified at 12 h post-infection (hpi), 906 DElncRNAs and 261 DEmRNAs were identified at 24 hpi, and 876 DElncRNAs and 302 DEmRNAs were identified at 36 days post-infection (dpi). A total of 16 DEmRNAs (e.g. dpp4, crp and gnas) were commonly identified at the three infection stages. Enrichment and co-localization analyses identified several pathways involved in immune and inflammatory responses during T. canis infection. Some novel DElncRNAs, such as LNC_015756, LNC_011050 and LNC_011052, were also associated with immune and inflammatory responses. Also, LNC_005105 and LNC_005401 were associated with the secretion of anti-inflammatory cytokines, which may play a role in the healing of liver pathology at the late stage of infection.

CONCLUSIONS

Our data provided new insight into the regulatory roles of lncRNAs and mRNAs in the pathogenesis of T. canis and improved our understanding of the contribution of lncRNAs and mRNAs to the immune and inflammatory response of the liver during T. canis infection.

Mitophagy bridges DNA sensing with metabolic adaption to expand lung cancer stem-like cells

While previous studies have identified cancer stem-like cells (CSCs) as a crucial driver for chemoresistance and tumor recurrence, the underlying mechanisms for populating the CSC pool remain unclear. Here, we identify hypermitophagy as a feature of human lung CSCs, promoting metabolic adaption via the Notch1-AMPK axis to drive CSC expansion. Specifically, mitophagy is highly active in CSCs, resulting in increased mitochondrial DNA (mtDNA) content in the lysosome. Lysosomal mtDNA acts as an endogenous ligand for Toll-like receptor 9 (TLR9) that promotes Notch1 activity. Notch1 interacts with AMPK to drive lysosomal AMPK activation by inducing metabolic stress and LKB1 phosphorylation. This TLR9-Notch1-AMPK axis supports mitochondrial metabolism to fuel CSC expansion. In patient-derived xenograft chimeras, targeting mitophagy and TLR9-dependent Notch1-AMPK pathway restricts tumor growth and CSC expansion. Taken together, mitochondrial hemostasis is interlinked with innate immune sensing and Notch1-AMPK activity to increase the CSC pool of human lung cancer.

Understanding the role of Toll-like receptors in lung cancer immunity and immunotherapy

Lung cancer is currently the leading cause of cancer-related deaths worldwide. Significant improvements in lung cancer therapeutics have relied on a better understanding of lung cancer immunity and the development of novel immunotherapies, as best exemplified by the introduction of PD-1/PD-L1-based therapies. However, this improvement is limited to lung cancer patients who respond to anti-PD-1 immunotherapy. Further improvements in immunotherapy may benefit from a better understanding of innate immune response mechanisms in the lung. Toll-like receptors (TLRs) are a key component of the innate immune response and mediate the early recognition of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). TLR signaling modulates the tumor microenvironment from "cold" to "hot" leading to immune sensitization of tumor cells to treatments and improved patient prognosis. In addition, TLR signaling activates the adaptive immune response to improve the response to cancer immunotherapy through the regulation of anti-tumor T cell activity. This review will highlight recent progress in our understanding of the role of TLRs in lung cancer immunity and immunotherapy.

The Preliminary Study for Postoperative Radiotherapy Survival Associated with RUNX3 and TLR9 Expression in Lung Cancer

Background

Many studies have reported that the inflammatory immune response related to TLR9 signaling activation participates in tumor development and affects the treatment outcome. RUNX3 functions as a tumor suppressor by regulating DNA methylation. RUNX3 protein plays an important role in TGF-β signaling pathway that is involved in tumor growth inhibition and apoptosis. At present, radiotherapy is still an important treatment in lung cancer, which induces immune response and affects the therapeutic outcome. The role of TLR9 signaling activation and RUNX3 in this process is not clear.

Methods

In this study, we investigated the expression of TLR9 in tumor and RUNX3 in surrounding tissues by immunohistochemical methods and analyzed the relationship on postoperative survival in lung cancer.

Results

We found that the high expression of TLR9 was the risk factor in postoperative survival of lung cancer with no difference in lifetime. The high expression of RUNX3 in lung cancer with TLR9 signaling activation was in favor of progression-free survival and overall survival in postoperative radiotherapy. It suggested that RUNX3 played an important role in lung cancer radiotherapy. In order to determine the effect of RUNX3 in lung cancer radiation with TLR9 signaling activation, we introduced 5-Aza-2ʹ-deoxycytidine (5-Aza-CdR) and exposed lung cancer A459 cells repeatedly. The high expression of RUNX3 especially RUNX3-B in cells treated with 5-Aza-CdR was observed. We examined that 5-Aza-CdR induced more cell blocking in G2/M phase in combining irradiation.

Conclusion

The result implied that it was feasible to improve radiosensitivity of lung cancer with TLR9 signaling activation by increasing RUNX3 expression, and 5-Aza-CdR was an option in this process.

Toll-like Receptors from the Perspective of Cancer Treatment

Toll-like receptors (TLRs) represent a family of pattern recognition receptors that recognize certain pathogen-associated molecular patterns and damage-associated molecular patterns. TLRs are highly interesting to researchers including immunologists because of the involvement in various diseases including cancers, allergies, autoimmunity, infections, and inflammation. After ligand engagement, TLRs trigger multiple signaling pathways involving nuclear factor-κB (NF-κB), interferon-regulatory factors (IRFs), and mitogen-activated protein kinases (MAPKs) for the production of various cytokines that play an important role in diseases like cancer. TLR activation in immune as well as cancer cells may prevent the formation and growth of a tumor. Nonetheless, under certain conditions, either hyperactivation or hypoactivation of TLRs supports the survival and metastasis of a tumor. Therefore, the design of TLR-targeting agonists as well as antagonists is a promising immunotherapeutic approach to cancer. In this review, we mainly describe TLRs, their involvement in cancer, and their promising properties for anticancer drug discovery.

Toll-like receptor-targeted particles: A paradigm to manipulate the tumor microenvironment for cancer immunotherapy

The expression of Toll-like receptors (TLRs) on antigen presenting cells, especially dendritic cells, offers several sensitive mediators to trigger an adaptive immune response, which potentially can be exploited to detect and eliminate pathogenic objects. Consequently, numerous agonists that target TLRs are being used clinically either alone or in combination with other therapies to strengthen the immune system in the battle against cancer. This review summarizes the roles of TLRs in tumor biology, and focuses on relevant TLR-dependent antitumor pathways and the conjugation of TLR agonists as adjuvants to nano- and micro-particles for boosting responses leading to cancer suppression and eradication. STATEMENT OF SIGNIFICANCE: Toll-like receptors (TLRs), which express on antigen presenting cells, such as dendritic cells and macrophages, play an important role in sensing pathogenic agents and inducing adaptive immunity. As a result, several TLR agonists have been investigating as therapeutic agents individually or in combination with other treatment modalities for cancer treatment through boosting the immune system. This review aims to focus on the roles of TLRs in cancer and TLR-dependent antitumor pathways as well as the use of different nano- or micro-particles bearing TLR agonists for tumor inhibition and elimination.

Recent Advances in Understanding FOXN3 in Breast Cancer, and Other Malignancies

FOXN3 (forkhead box N3; CHES1: check point suppressor 1) belongs to the forkhead box (FOX) protein family. FOXN3 displays transcriptional inhibitory activity, and is involved in cell cycle regulation and tumorigenesis. FOXN3 is a tumor suppresser and alterations in FOXN3 are found in of a variety of cancers including melanoma, osteosarcoma, and hepatocellular carcinoma. While the roles of FOXN3 role in some cancers have been explored, its role in breast cancer remains unclear. Here we describe current state of knowledge of FOXN3 functions, and focus on its roles (known and potential) in breast cancer.

TLR9 signaling activation at different stages in colorectal cancer and NF-kappaB expression

Background

The relationship of inflammation and tumor is becoming more and more important in the study on the pathogenesis of colorectal cancer. The role of TLR9-mediated immune inflammation reaction in the process is not currently clear. The purpose of the study was to discuss the correlation of TLR9 signal activation with tumor progression by detecting the expression of TLR9 and its downstream molecule NF-kappaB in colorectal cancer tissues at different stages.

Methods

TLR9 expression in colorectal cancer tissues was detected by immunohistochemical streptavidin-perosidase method and Western blot.

Results

The result showed that the high expression of TLR9 was correlated with tumor poorly differentiation, invasion and liver metastasis, the abnomal increasing levels of CEA in blood. With the signal activation, the levels of TLR9 protein raised more in advanced colorectal cancer than in early colorectal cancer. Afterward, we found that the activation of specific expression of TLR9 signal was related to histologic origin. TLR9-C expression displayed in both advanced cancer and para-carcinoma tissues, and TLR9-R protein was predominat in partial sigmoid and rectal cancer tissues. With the differential expression of TLR9, the levels of its downstream molecule NF-kappaB protein increased in colon cancer tissues and decreased in rectal cancer tissues.

Conclusion

The results confirmed that TLR9 signaling activation participated in the clinical process of colorectal cancer and influenced NF-kappaB expression.

HMGB1-containing nucleosome mediates chemotherapy-induced metastasis of human lung cancer

While chemotherapy is an important and widely used therapeutic for cancer, it may facilitate cancer metastasis. Herein, we report that human lung cancer cells exert higher invasion and metastasis after chemotherapy. In a human lung cancer xenograft model, chemotherapy promotes the cancer invasion and metastasis in HMGB1-dependent manner. Further studies identify HMGB1-containing nucleosome from chemotherapy-induced apoptotic cancer cells as an effective factor. Such nucleosome functions through TLR4 and TLR9 to drive cancer invasion and metastasis. In lung cancer patients, circulating HMGB1-containing nucleosome is higher in those under chemotherapy, predicting poorly cancer cell differentiation state, enhanced cancer invasion and advanced TNM stages. These findings provide a novel mechanism by which the tumor metastasis is propagated in lung cancer patients, especially in those under chemotherapy, and a clue for developing therapeutic strategies against chemotherapy-induced metastasis.

Roles of toll-like receptors: From inflammation to lung cancer progression

Lung cancer is among the most common malignant tumors worldwide, and is characterized by a low survival rate compared with other cancers. Toll-like receptors (TLRs) are highly conserved in evolution and widely expressed on immune cells, where they serve an important role in the innate immune system by evoking inflammatory responses. Evasion of immune destruction is an important hallmark in the development of cancer. There is an established association between chronic inflammation and cancer, with TLRs serving important roles in the immune response against tumor cells. Recently, TLRs have been identified on tumor cells, where their activation may orchestrate the downstream signaling pathways that serve crucial functions in tumorigenesis and tumor progression. The present review summarizes the roles of TLRs as sensors on lung cancer cells that regulate lung cancer progression with regard to cell growth and invasion, angiogenesis and cancer stem cell behavior. This aimed to provide theoretical support for the development of therapies that target TLR signaling pathways for the treatment of lung cancer.

Anti-tumor Activity of Toll-Like Receptor 7 Agonists

Toll-like receptors (TLRs) are a class of pattern recognition receptors that play a bridging role in innate immunity and adaptive immunity. The activated TLRs not only induce inflammatory responses, but also elicit the development of antigen specific immunity. TLR7, a member of TLR family, is an intracellular receptor expressed on the membrane of endosomes. TLR7 can be triggered not only by ssRNA during viral infections, but also by immune modifiers that share a similar structure to nucleosides. Its powerful immune stimulatory action can be potentially used in the anti-tumor therapy. This article reviewed the anti-tumor activity and mechanism of TLR7 agonists that are frequently applied in preclinical and clinical investigations, and mainly focused on small synthetic molecules, including imiquimod, resiquimod, gardiquimod, and 852A, etc.

Heterogeneity of Toll-like receptor 9 signaling in B cell malignancies and its potential therapeutic application

Toll-like receptor 9 (TLR9) is expressed in a variety of B-cell malignancies and works as a bridge between innate and adaptive immunity. CpG oligodeoxynucleotides (CpG ODNs), TLR9 agonists, are able to induce anticancer immune responses and exert direct effects against cancer cells, serving as cancer therapeutic agents. Therefore, TLR9 might be a potential therapeutic target for drug development. However, several new evidences have revealed that direct effects of TLR9 agonists on B-cell malignancies is controversial. For example, CpG ODNs can induce apoptosis in certain type of chronic lymphocytic leukemia and lymphoma cells, while induce proliferation in multiple myeloma and other types of lymphoma cells. In this review, we summarize current understanding of the heterogeneity in responses of normal and malignant B cells to TLR9 agonists, due to differences in TLR9 expression levels, genetic alterations (such as MyD88 mutation), and signaling pathway activation. Especially, the downstream molecules of NF-κB signaling pathway play an important role in the heterogeneous response. In order to provide possibilities for therapeutic manipulation of TLR9 agonists in the treatment of these disorders, the preclinical and clinical advances in using CpG ODNs alone and in combination therapies are also summarized in this review.

Regulation of migration and invasion by Toll-like receptor-9 signaling network in prostate cancer

Toll-like receptors (TLRs) play an important role in tumorigenesis and progress of prostate cancer. However, the function and mechanism of Toll-like receptor-9 (TLR9) in prostate cancer is not totally understood. Here, we found that high expression of TLR9 was associated with a higher probability of lymph node metastasis and poor prognosis. Further in vitro functional study verified that silence of TLR9 inhibited migration and invasion of PC-3 cells, indicating expression of TLR9 involving in the migration and invasion of cancer cells. The data of microarray exhibited silence of TLR9 induced 205 genes with larger than 2-fold changes in expression levels, including 164 genes down-regulated and 41 genes up-regulated. Functional Gene Ontology (GO) processes annotation demonstrated that the top three scores of molecular and cellular functions were regulation of programmed cell death, regulation of locomotion and response to calcium ion. TLR9 signaling network analysis of the migration and invasion related genes identified several genes, like matrix metallopeptidase 2 (MMP2), matrix metallopeptidase 9 (MMP9), chemokine receptor 4 (CXCR4) and interleukin 8 (IL8), formed the core interaction network based on their known biological relationships. A few genes, such as odontogenic ameloblast-associated protein (ODAM), claudin 2 (CLDN2), gap junction protein beta 1 (GJB1) and Rho-associated coiled-coil containing protein kinase 1 pseudogene 1 (ROCK1P1), so far have not been found to interact with the other genes. This study provided the foundation to discover the new molecular mechanism in signaling networks of invasion and metastasis in prostate cancer.

Hypoxia induced HMGB1 and mitochondrial DNA interactions mediate tumor growth in hepatocellular carcinoma through Toll-like receptor 9

BACKGROUND & AIMS

The mechanisms of hypoxia-induced tumor growth remain unclear. Hypoxia induces intracellular translocation and release of a variety of damage associated molecular patterns (DAMPs) such as nuclear HMGB1 and mitochondrial DNA (mtDNA). In inflammation, Toll-like receptor (TLR)-9 activation by DNA-containing immune complexes has been shown to be mediated by HMGB1. We thus hypothesize that HMGB1 binds mtDNA in the cytoplasm of hypoxic tumor cells and promotes tumor growth through activating TLR9 signaling pathways.

METHODS

C57BL6 mice were injected with Hepa1-6 cancer cells. TLR9 and HMGB1 were inhibited using shRNA or direct antagonists. HuH7 and Hepa1-6 cancer cells were investigated in vitro to determine how the interaction of HMGB1 and mtDNA activates TLR9 signaling pathways.

RESULTS

During hypoxia, HMGB1 translocates from the nucleus to the cytosol and binds to mtDNA released from damaged mitochondria. This complex subsequently activates TLR9 signaling pathways to promote tumor cell proliferation. Loss of HMGB1 or mtDNA leads to a defect in TLR9 signaling pathways in response to hypoxia, resulting in decreased tumor cell proliferation. Also, the addition of HMGB1 and mtDNA leads to the activation of TLR9 and subsequent tumor cell proliferation. Moreover, TLR9 is overexpressed in both hypoxic tumor cells in vitro and in human hepatocellular cancer (HCC) specimens; and, injection in mice to knockdown either HMGB1 or TLR9 from HCC cells suppressed tumor growth in vivo.

CONCLUSIONS

Our data reveals a novel mechanism by which the interactions of HMGB1 and mtDNA activate TLR9 signaling during hypoxia to induce tumor growth.

IL-1 Receptor-Associated Kinase Signaling and Its Role in Inflammation, Cancer Progression, and Therapy Resistance

Chronic inflammation has long been associated with the development of cancer. Among the various signaling pathways within cancer cells that can incite the expression of inflammatory molecules are those that activate IL-1 receptor-associated kinases (IRAK). The IRAK family is comprised of four family members, IRAK-1, IRAK-2, IRAK-3 (also known as IRAK-M), and IRAK-4, which play important roles in both positively and negatively regulating the expression of inflammatory molecules. The wide array of inflammatory molecules that are expressed in response to IRAK signaling within the tumor microenvironment regulate the production of factors which promote tumor growth, metastasis, immune suppression, and chemotherapy resistance. Based on published reports we propose that dysregulated activation of the IRAK signaling pathway in cancer cells contributes to disease progression by creating a highly inflammatory tumor environment. In this article, we present both theoretical arguments and reference experimental data in support of this hypothesis.

Chloroquine inhibits MGC803 gastric cancer cell migration via the Toll-like receptor 9/nuclear factor kappa B signaling pathway

Stimulation of Toll‑like receptor 9 (TLR9) has been associated with invasion in various types of cancer cell in vitro. The present study aimed to evaluate the expression of TLR9 in MGC803 gastric cancer cells and investigate the effect of a non‑specific TLR9 inhibitor, chloroquine (CQ), on MGC803 cell migration via the TLR9/nuclear factor kappa B (NFκB) signaling pathway. The expression of TLR9 was investigated using reverse transcription polymerase chain reaction (RT‑PCR), flow cytometry and western blot analysis. The effects of CQ on MGC803 cell proliferation were measured by MTT colorimetric assay. The mRNA expression levels of cyclooxygenase‑2 (COX‑2), matrix metalloproteinase (MMP)‑2, MMP‑7 and NFκB p65 were evaluated by RT‑PCR in MGC803 cells stimulated by various concentrations of CQ. The migration of gastric cancer cells treated with CQ at 12, 24 and 36 h was measured by wound healing assay. The results indicated that MGC803 cells expressed TLR9 and that CQ had anti‑proliferative effects on MGC803 cells and inhibited mRNA expression of COX‑2, MMP‑2, MMP‑7 and NFκB p65 (P<0.05). Furthermore, CQ inhibited the bioactivity of NFκB p65 and prevented the migration of MGC803 cells in a dose‑dependent manner (P<0.05). In conclusion, the results indicated that the TLR9/NFκB signaling pathway was involved in gastric cancer cell migration and that CQ had anti‑tumor activity.

Prognostic value of myeloid differentiation primary response 88 and Toll-like receptor 4 in breast cancer patients

PURPOSE

Breast cancer remains a major cause of death in women worldwide, and tumor metastasis is the leading cause of death in breast cancer patients after conventional treatment. Chronic inflammation is often related to the occurrence and growth of various malignancies. This study evaluated the prognosis of breast cancer patients based on contributors to the innate immune response: myeloid differentiation primary response 88 (MyD88) and Toll-like receptor 4 (TLR4).

METHODS

We analyzed data from 205 breast invasive ductal carcinoma (IDC) patients who were treated at the Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, from 2002 to 2006. Overall survival (OS) and disease-free survival (DFS) were compared.

RESULTS

In total, 152 patients (74.15%) were disease-free without relapse or metastasis, whereas 53 (25.85%) patients developed recurrence or metastasis. A significant positive correlation was observed between MyD88 and TLR4 expression (p<0.001). Patients with high expression were more likely to experience death and recurrence/metastasis events (p<0.05). Patients with low MyD88 or TLR4 expression levels had better DFS and OS than patients with high expression levels (log-rank test: p<0.001). Patients with low MyD88 and TLR4 expression levels had better DFS and OS than patients with high expression levels of either (log-rank test: p<0.001). In a multivariate analysis, high MyD88 expression was an independent predictive factor for decreased DFS (adjusted HR, 3.324; 95% CI, 1.663-6.641; p = 0.001) and OS (adjusted HR, 4.500; 95% CI, 1.546-13.098; p = 0.006).

CONCLUSIONS

TLR4-MyD88 signaling pathway activation or MyD88 activation alone may be a risk factor for poor prognosis in breast cancer. Therefore, TLR4-MyD88 signaling pathway activation in tumor biology provides a novel potential target for breast cancer therapy.

Toll-like receptor 9 mediates invasion and predicts prognosis in squamous cell carcinoma of the mobile tongue

BACKGROUND

Toll-like receptor 9 (TLR9) is a cellular receptor, which recognizes bacterial and host-derived DNA. Stimulation of TLR9 induces cellular invasion via matrix metalloproteinase 13 (MMP-13). The aim of this study was to evaluate the role of TLR9 in invasion of oral tongue squamous cell carcinoma (OTSCC).

METHODS

The effects of TLR9 ligands on oral squamous cell carcinoma cell lines were studied with invasion and migration assays, as well as in a myoma organotypic model.

RESULTS

The TLR9 ligand, CpG-ODN, increased invasion and migration in OTSCC lines. These effects were reduced by TLR9 siRNA or inhibition with TLR9 antibodies. Immunohistochemical analysis of tissues from 195 patients with OTSCC revealed that TLR9 was expressed in 181/195 carcinomas. The expression of TLR9 was higher in the malignant cells than in the normal epithelium. High TLR9 expression was associated with high MMP-13 expression and poor differentiation. High TLR9 expression was also identified as an independent predictor of poor prognosis (HR 1.810, 95% CI [1.053-3.112]).

CONCLUSION

Toll-like receptor 9 mediates OTSCC invasion and migration in vitro and is an independent prognostic factor of OTSCC. Inhibition of TLR9 may be a novel therapeutic opportunity in oral cancer.

Functional expression of TLR9 in esophageal cancer

The Toll-like receptor 9 (TLR9) plays a crucial role in both innate and adaptive immune responses against infection and danger signals. Stimulation of TLR9 has been linked to invasion in various cancer cells in vitro. The present study evaluated the expression of TLR9 in human esophageal cancer (EC) cells and normal and malignant esophageal squamous epithelium, and examined the association between TLR9 expression, clinicopathological variables, and EC patient outcome. We further characterized the direct effects of TLR9 agonist CpG oligonucleotides (CpG ODN) and inhibitor chloroquine (CQ), on the proliferation and invasion of EC cells in vitro. RT-PCR, western blot, flow cytometry and immunohistochemical analysis were used to determine the expression of TLR9 in EC cell line TE10, and 90 cases of esophageal squamous cell carcinoma, including 30 cases of adjacent esophageal epithelium. The TLR9 expression was compared with tumor size, location, grade, stage and proliferation. We found basal expression of TLR9 in TE10 cells. Esophageal carcinomas exhibited TLR9 expression that was positively associated with tumor size, location and TNM stage (P<0.05). CpG ODN significantly enhanced the invasion of TE10 cells, which could be abrogated by a TLR9 inhibitor CQ. CpG ODN led to activation of NF‑κB and enhanced expression of matrix metalloproteinase (MMP)-2, MMP-7 and cyclooxygenase-2 (COX-2) mRNA. Expression of TLR9 in EC suggests a role of TLR9 related to cell proliferation and differentiation. Our findings indicate that TLR9 may represent a novel therapeutic target in this disease.

The stimulatory activity of plasma in patients with advanced non-small cell lung cancer requires TLR-stimulating nucleic acid immunoglobulin complexes and discriminates responsiveness to chemotherapy

Background

Therapeutic options for patients with non-small cell lung cancer (NSCLC) are often restricted to systemic chemotherapy. However, the molecular and cellular processes during chemotherapy of advanced NSCLC patients still remain unclear. Here we investigated the stimulatory activity of plasma in advanced NSCLC patients and its correlation with chemotherapy.

Methods

Whole blood samples from advanced NSCLC patients were collected before the first, second, and third cycle of chemotherapy. Plasma was isolated following centrifugation of whole blood. PBMCs were isolated from whole-blood specimens by Ficoll-Hypaque density gradient centrifugation. Immune complexes (ICs) were isolated from NSCLC plasma using the IgG Purification Kit. qRT-PCR was used to detect a broad array of cytokines and chemokines.

Results

The plasma in advanced NSCLC patients was endowed with stimulatory activity and capable of inducing proinflammatory cytokines. Both nucleic acids and immunoglobulin components were required for the stimulatory activity of NSCLC plasma. In consistent, TLR8 and TLR9 conferred the stimulatory activity of plasma in NSCLC patients. Of note, we revealed the decreased stimulatory activity of plasma in patients who responded to chemotherapy.

Conclusions

Our findings demonstrated that the plasma of advanced NSCLC patients required TLR-stimulating nucleic acid immunoglobulin complexes and could discriminate the responsiveness to chemotherapy, which might provide a novel mechanism by which the proinflammatory immune response was induced and a potential new biomarker for evaluating responsiveness to chemotherapy in NSCLC patients.

Expression of TLR9 in tumor-infiltrating mononuclear cells enhances angiogenesis and is associated with a worse survival in lung cancer

Toll-like receptors (TLRs) play a crucial role in the innate and adaptive immune responses against microbial infection, tissue injury and cancer. Ligands of TLR9 have been developed as therapy in non-small-cell lung carcinoma (NSCLC). However, phase III clinical trials in metastatic NSCLC were negative. Our objective was to determine whether TLR9 affects tumor growth. We generated a mouse model of lung adenocarcinoma (ADC) mutated for K-ras (K-ras(LA1) ), with and without TLR9 inactivation (K-ras(LA1) TLR9(-/-) and K-ras(LA1) TLR9(+/+) , respectively). TLR9 was functionally expressed only in mononuclear cells of K-ras(LA1) TLR9(+/+) mice. These mice had significantly worse survival and a higher tumor burden than K-ras(LA1) TLR9(-/-) mice. Lung tumors were analyzed for 24 cytokines/growth factors using Bio-Plex multiplex bead-based assays. Factor VIII was assessed by immunochemistry. Tumors from K-ras(LA1) TLR9(+/+) mice were characterized by an angiogenic phenotype with higher concentrations of vascular endothelial growth factor (VEGF) and higher microvessel density than from K-ras(LA1) TLR9(-/-) mice. LKR13 cells, an ADC cell line derived from K-ras(LA1) mice, were subcutaneously injected into TLR9(-/-) and TLR9(+/+) mice. Syngeneic tumors regressed in TLR9(-/-) but not in TLR9(+/+) mice. Peripheral blood mononuclear cells from TLR9(-/-) mice released less VEGF than those from TLR9(+/+) mice. In 61 patients with early-stage NSCLC, TLR9 was expressed in mononuclear cells that infiltrated tumors, as assessed by immunochemistry, and contributed to worse survival. Our results suggest that TLR9 expression in mononuclear cells was associated with an angiogenic phenotype and promoted lung cancer progression. These findings may aid clinical development of TLR9 ligands to treat cancers.

TLR9 signaling repressed tumor suppressor miR-7 expression through up-regulation of HuR in human lung cancer cells

Background

Our recent evidence showed that Toll like receptor 9 (TLR9) signaling could enhance the growth and metastatic potential of human lung cancer cells through repressing microRNA-7 (miR-7) expression. Human antigen R (HuR) has been involved in stabilizing multiple mRNAs in cellular biology. However, whether HuR also contributed to the altered expression of miR-7 in TLR9 signaling stimulated human lung cancer cells remains to be elucidated.

Methods

The expression of HuR in human lung cancer 95D cells treated with TLR9 agonist CpG Oligonucleotides (ODNs) was detected by Real-time PCR and Western blot assay. To explore the possible role of HuR on miR-7 expression, eukaryotic expression vector encoding HuR was transiently transfected into 95D cells and then the expression of miR-7 was detected by Real-time PCR assay. Moreover, RNA interference, western blot, Real-time PCR, MTT assay, BrdU labeling, invasion assay and scratch assay were employed to examine the disrupt effect of HuR on miR-7 expression in human lung cancer cells treated with CpG ODNs. Finally, inhibitors for PI3K, Akt or Erk respectively, and western blot were performed to explore the possible signaling pathway related to HuR expression in CpG ODNs treated human lung cancer cells.

Results

Our data showed that TLR9 agonist CpG ODNs could induce the expression of HuR in human lung cancer cells. Moreover, overexpression of HuR could reduce the expression of miR-7 in lung cancer cells. Notably, down-regulation of HuR using RNA interference restored miR-7 expression in CpG ODNs treated lung cancer cells, accompanied by enhanced growth and metastatic potential. Finally, CpG ODNs could induce HuR expression through Akt pathway.

Conclusion

Our findings indicated that HuR could act as regulator in regulating TLR9 signaling associated biological effect in human lung cancer cells, which might be helpful for the understanding of the potential role of HuR in tumor biology.

The Yin and Yang of Toll-like receptors in cancer

Recognition of non-self molecular patterns by pattern recognition receptors is a cornerstone of innate immunity. Toll-like receptors (TLRs) exert a key role in recognizing pathogen-associated molecular patterns (PAMPs) but have also been implicated in the recognition of damage-associated molecular patterns (DAMPs). As such, TLRs regulate a wide range of biological responses including inflammatory and immune responses during carcinogenesis. The high expression of TLRs by antigen-presenting cells, including dendritic cells, and their ability to induce antitumor mediators such as type I interferon has led to efforts to utilize TLR agonists in tumor therapy in order to convert the often tolerant immune response toward antitumor responses. However, TLRs are also increasingly recognized as regulators of tumor-promoting inflammation and promoters of tumor survival signals. Here, we will review in detail the dichotomous role of TLRs in tumor biology, focusing on relevant TLR-dependent pro- and antitumor pathways, and discuss clinical applications of TLR-targeted therapies for tumor prevention and treatment.

Expression of Toll-like receptor-9 is associated with poor progression-free survival in prostate cancer

Toll-like receptor-9 (TLR9) is a member of the innate immune system and recognizes bacterial and vertebrate DNA in cells. In addition to being expressed in cells of the immune system, it is widely expressed in various types of human cancer, including prostate cancer. We have previously demonstrated that synthetic TLR9 ligands induce invasion in TLR9-expressing prostate cancer cells in vitro. However, the role of TLR9 in the pathophysiology of prostate cancer is unclear. The expression of TLR9 in radical prostatectomy samples (n=186) was studied using immunohistochemistry. TLR9 staining scores were compared with tumor stage, Gleason score and prostate-specific antigen (PSA) concentration prior to treatment and progression-free survival. Results revealed that 124 (66.7%) of the tumors were strongly positive, 59 (31.7%) were weakly positive and 3 (1.6%) were negative, for cytoplasmic TLR9 immunostaining in cancer cells. There was no significant association between cytoplasmic TLR9 expression and distributions of pT-class, prostatectomy sample margin status, Gleason score and preoperative PSA value. Prostate cancer-specific progression-free survival was significantly longer for patients whose tumors were graded as negative for cytoplasmic TLR9 expression, as compared with patients whose tumors were strongly immunopositive for cytoplasmic TLR9 (P=0.009). In the Cox regression analysis, high TLR9 expression was an independent marker of poor prognosis in prostate cancer. Expression of TLR9 is associated with poor progression-free survival in prostate cancer patients who were treated by radical prostatectomy with curative intent.

MicroRNA-7–regulated TLR9 signaling–enhanced growth and metastatic potential of human lung cancer cells by altering the phosphoinositide-3-kinase, regulatory subunit 3/Akt pathway

This article reports that TLR9 signaling can reduce intrinsic microRNA-7 (miR-7) expression in human lung cancer cells and that overexpression of miR-7 can significantly inhibit TLR9 signaling–enhanced growth and metastatic potential of lung cancer cells in vitro and in vivo.

Recent evidence shows that microRNAs (miRNAs) contribute to the biological effects of Toll-like receptor (TLR) signaling on various cells. Our previous data showed that TLR9 signaling could enhance the growth and metastatic potential of human lung cancer cells. However, the potential role of miRNAs in the effects of TLR9 signaling on tumor biology remains unknown. In this paper, we first report that TLR9 signaling could reduce intrinsic miR-7 expression in human lung cancer cells. Furthermore, overexpression of miR-7 can significantly inhibit TLR9 signaling–enhanced growth and metastatic potential of lung cancer cells in vitro and in vivo. Notably, we identify phosphoinositide-3-kinase, regulatory subunit 3 (PIK3R3) as a novel target molecule of miR-7 in lung cancer cells by Western blotting and luciferase report assay. Further study shows that miR-7 inhibits the effects of TLR9 signaling on lung cancer cells through regulation of the PIK3R3/Akt pathway. These data suggest that miR-7 could act as a fine-tuner in regulating the biological effects of TLR9 signaling on human lung cancer cells, which might be helpful to the understanding of the potential role of miRNAs in TLR signaling effects on tumor biology.

IL-17A/IL-17RA interaction promoted metastasis of osteosarcoma cells

Osteosarcoma (OS) is the most common human primary malignant bone tumor in children and young adults with poor prognosis because of their high metastatic potential. Identification of key factors that could regulate the aggressive biologic behavior of OS, particularly with respect to metastasis, would be necessary if significant improvements in therapeutic outcome are to occur. In this study, we carefully evaluated the potential role of IL-17A/IL-17RA interaction in metastasis of OS. We found that serum IL-17A was higher in OS patients with metastasis and was associated with their clinical stage. The elevated expression of IL-17RA was observed in tumor tissue from OS patients with metastasis. Of note, we showed that IL-17A could promote the metastasis of U-2 OS cells which expression high IL-17RA, but not MG63 cells which expression low IL-17RA. Further, we revealed that downregulation of IL-17RA in U-2 cells could abrogated the enhanced metastasis induced by IL-17A, while upregulation of IL-17RA in MG63 cells could elevate their response to IL-17A and exerted enhanced metastasis. We observed that IL-17A/IL-17RA interaction promoted the expression of VEGF, MMP9 and CXCR4 in OS cells, which might partly explain the enhanced metastasis of OS cells. Furthermore, we showed that Stat3 activity was crucial for IL-17A/IL-17RA interaction to promote OS metastasis. Finally, we confirmed that IL-17A/IL-17RA interaction promoted the metastasis of OS in nude mice. Our findings might provide a mechanistic explanation for metastasis of OS in vivo, and suggested that targeting IL-17A signaling was a novel promising strategy to treat patients with OS.

MicroRNA-574-5p was pivotal for TLR9 signaling enhanced tumor progression via down-regulating checkpoint suppressor 1 in human lung cancer

Accumulating data suggested that functional expression of Toll-like receptors (TLRs) in tumor cells was involved in tumor progression. Our previous study demonstrated that TLR9 signaling could enhance the tumor progression of human lung cancer cells in vitro and in vivo. We further showed that miR-574-5p was the mostly up-regulated miRNA in human lung cancer cells under TLR9 signaling by miRNA array analysis. Here we characterized the potential role of miRNA-574-5p in enhanced tumor progression induced by TLR9 signaling in human lung cancer. We confirmed that TLR9 signaling effectively elevated the expression of miR-574-5p in human lung cancer cells. Notably, we found that down-regulation of miRNA-574-5p using miR-574-5p inhibitor in vitro or miR-574-5p sponge in vivo significantly abrogated the enhanced tumor progression induced by TLR9 signaling. Further studies showed that miR-574-5p was an important player associated with enhanced tumor progression of human lung cancer cells. Notably, we identified checkpoint suppressor 1 (Ches1) as the dominant direct target for miRNA-574-5p to confer the TLR9 signaling enhanced tumor progression. We revealed that over-expression of Ches1 significantly inhibited the cell cycle entry of human lung cancer cells. Finally, we revealed that the expression of miR-574-5p was positively correlated with TLR9 and reversely correlated with Ches1 in lung cancer patients. Our findings not only facilitated the further understanding of the crosstalk between miRNAs and TLRs in tumor biology, but also provided novel potential candidates for treatment of cancer.

IL-17 promoted metastasis of non-small-cell lung cancer cells

Non-small cell lung cancer (NSCLC) is the leading cause of cancer death worldwide. Recent data suggested that IL-17 might be a pivotal cytokine involved in tumor progression of NSCLC. However, the direct effect of IL-17 on metastasis of NSCLC cells still remains intractable. In this study, we found that the metastasis of NSCLC was significantly impaired in IL-17⁻/⁻ mice. Further, we revealed that IL-17 could directly promote the invasion of NSCLC cells both in vitro and in vivo. Furthermore, we found that IL-6-Stat3 pathway was crucial for IL-17 to enhance the invasive potential of NSCLC cells. Finally, we found that elevated expression of IL-17 in peripheral blood was associated with the TNM stage, and elevated expression of IL-17R in NSCLC cells was associated with their invasive potential in NSCLC patients. These findings could facilitate our understanding of the potential role of IL-17 in tumor biology, and provide clues for developing promising strategies against NSCLC.

Short DNA sequences and bacterial DNA induce esophageal, gastric, and colorectal cancer cell invasion

Toll-like receptor 9 (TLR9) recognizes both bacterial and self-DNA and it is abundantly expressed in the gastrointestinal tract. In this study, we investigated the influences of both bacterial DNA and specific short DNA sequences on TLR9-mediated gastrointestinal cancer cell invasion. We assessed the effect of various DNA ligands on cellular invasion and on TLR9 and matrix metalloproteinase expression of three gastrointestinal cancer cell lines. DNA-ligands described in this study include CpG-ODN M362, 9-mer (hairpin), human telomeric sequence h-Tel22 G-quadruplex, and bacterial DNAs from Escherichia coli and Helicobacter pylori. All of the DNAs studied were demonstrated to induce invasion in the studied cells. The DNA-induced invasion was inhibited with a broad-spectrum MMP inhibitor and partly also with chloroquine suggesting that it could be mediated via MMP activation, endosomal signaling, and TLR9. Interestingly, H. pylori DNA was shown to induce a more pronounced invasion in a gastric cancer cell line than in the other cell lines. Our results suggest that bacterial DNA as well as deoxynucleotides having stable secondary structures (i.e. hairpins or G-quadruplex structures) may serve as endogenous, invasion-inducing TLR9-ligands and promote local progression and metastasis of cancers in the alimentary tract.

Low TLR9 expression defines an aggressive subtype of triple-negative breast cancer

Toll-like receptor-9 (TLR9) is a DNA receptor widely expressed in cancers. Although synthetic TLR9 ligands induce cancer cell invasion in vitro, the role of TLR9 in cancer pathophysiology is unclear. We discovered that low tumor TLR9 expression is associated with significantly shortened disease-specific survival in patients with triple negative but not with ER+ breast cancers. A likely mechanism of this clinical finding involves differential responses to hypoxia. Our pre-clinical studies indicate that while TLR9 expression is hypoxia-regulated, low TLR9 expression has different effects on triple negative and ER+ breast cancer invasion in hypoxia. Hypoxia-induced invasion is augmented by TLR9 siRNA in triple negative, but not in ER+ breast cancer cells. This is possibly due to differential TLR9-regulated TIMP-3 expression, which remains detectable in ER+ cells but disappears from triple-negative TLR9 siRNA cells in hypoxia. Our results demonstrate a novel role for this innate immunity receptor in cancer biology and suggest that TLR9 expression may be a novel marker for triple-negative breast cancer patients who are at a high risk of relapse. Furthermore, these results suggest that interventions or events, which induce hypoxia or down-regulate TLR9 expression in triple-negative breast cancer cells may actually induce their spread.

HMGB1 was a pivotal synergistic effecor for CpG oligonucleotide to enhance the progression of human lung cancer cells

High-mobility group box 1 (HMGB1) has been implicated in a variety of biologically important processes, including transcription, DNA repair, differentiation, development, and extracellular signaling. However, the potential role of HMGB1 in tumor biology still remains intractable. Our previous study showed that TLR9 response to CpG oligonucleotide (ODN) in 95D human lung cancer cells could enhance their growth and invasive potential in vitro and in vivo. Here we found that CpG ODN stimulation to 95D cells induced the secretion of HMGB1 in a dose dependent manner. We further showed that blockade of extracellular HMGB1 using A box peptide and ethyl pyruvate significantly abrogated the CpG ODN enhanced progression of 95D cells. Interestingly, we found that HMGB1 alone or acted synergistic with CpG ODN could enhance the progression of 95D cells. Notably, we revealed that RAGE and TLR4 were critical for HMGB1 to exert the synergistic function. We observed a MyD88-dependent upregulation of matrix metalloproteinase (MMP) 2, MMP9 and cyclin-dependent kinase (CDK) 2 in 95D cells in response to HMGB1. These findings might further our understanding of TLR9 signaling in tumor biology and be helpful for developing HMGB1-based strategy against lung cancer.

Toll-like receptor 9 is a novel biomarker for esophageal squamous cell dysplasia and squamous cell carcinoma progression

BACKGROUND

Stimulation of Toll-like receptor 9 (TLR9) has been linked to invasion in various cancer cells in vitro. We investigated TLR9 expression in normal, dysplastic and malignant esophageal squamous epithelium.

METHODS

TLR9 expression was analyzed by immunohistochemistry in 46 cases of esophageal squamous cell carcinoma, including 12 cases with adjacent squamous dysplasia and 24 cases with normal esophageal epithelium. TLR9 expression was compared with tumor grade, stage, proliferation, apoptosis and vascular density.

RESULTS

In normal esophageal squamous epithelium, TLR9 staining intensity decreased linearly from the basal layers to the superficial layers (p < 0.001). Strong TLR9 expression was detected across full thickness of high-grade dysplasia, the intensity clearly differing from the normal squamous epithelium and squamous cell carcinoma (p < 0.001). All squamous cell carcinomas exhibited TLR9 expression that was positively associated with a high grade (p < 0.05), the presence of lymph node metastases (p < 0.05) and previously undetected distant metastases (p < 0.05).

CONCLUSIONS

Expression of TLR9 in the basal parts of normal esophageal epithelium suggests a role related to cell proliferation and differentation. TLR9 upregulation detected in dysplastic epithelium and in disseminated carcinomas indicates that this protein may serve as a novel marker for esophageal squamous dysplasia and carcinoma with metastatic potential.

Estrogen receptor-α and sex steroid hormones regulate Toll-like receptor-9 expression and invasive function in human breast cancer cells

Toll-like receptor 9 (TLR9) is a cellular DNA-receptor, which is widely expressed in cancer. Synthetic TLR9-ligands induce cancer cell invasion in vitro, but the role of TLR9 in cancer pathophysiology remains unclear. Increased TLR9 expression has been, however, detected in estrogen receptor negative (ER-) breast cancers. In this study, we investigated the effects of ERα expression and sex steroid hormones on TLR9 expression in human ER+ (MCF-7, T47-D) and ER- (MDA-MB-231) breast cancer cell lines in vitro. We also studied TLR9 mRNA expression in archival breast cancer specimens (n = 12) with qRT-PCR, using primer sets that detect only the TLR9A isoform or the isoforms A and B (TLR9A/B). The TLR9 mRNA expression was detected in 10/12 specimens with both primer sets, and in 1/12 with only the TLR9A or the TLR9A/B primer sets. The basal TLR9 mRNA expression levels were significantly lower in the ER+ cell lines as compared with the ER- MDA-MB-231 cells. The transfection of ERα cDNA into MDA-MB-231 cells also resulted in down-regulation of TLR9 expression. While sex steroids had no effect on TLR9 expression in MCF-7 cells, testosterone (10(-8) M) induced TLR9 expression in MDA-MB-231 and T47-D cells. Although bicalutamide blocked this testosterone effect in MDA-MB-231 cells, in T47-D cells bicalutamide increased TLR9 expression and only partially blocked the testosterone effects. Estradiol (10(-8) M) induced TLR9 expression in T47-D cells. The invasive effects of synthetic TLR9-ligands were augmented by testosterone in vitro. This effect was lost in TLR9 siRNA MDA-MB-231 cells and also decreased by over-expression of ERα, which also inhibited NF-κB activation by TLR9-ligands. In conclusion, expression of TLR9 isoforms A and B can be detected in clinical breast cancer specimens. The ERα and sex steroid hormones regulate TLR9 expression and invasive effects in the breast cancer cells. Also, the commonly used hormonal cancer therapy bicalutamide affects TLR9 expression.

Toll-like receptor signaling pathways--therapeutic opportunities

Toll-like receptors (TLRs) are transmembrane proteins acting mainly as sensors of microbial components. Triggering TLRs results in increased expression of multiple inflammatory genes, which then play a protective role against infection. However, aberrant activation of TLR signaling has a significant impact on the onset of cancer, allergy, sepsis and autoimmunity. Various adaptor proteins, including MyD88, IRAKs, TIRAP, TRIF, and TRAM, are involved in specific TLR signaling pathways. This article reviews the role of these molecules in TLR signaling, and discusses the impact of this pathway on various disease scenarios. Given their important role in infectious and non-infectious disease settings, TLRs and their signaling pathways emerge as attractive targets for therapeutics.

CpG-ODN increases the release of VEGF in a mouse model of lung carcinoma

Vascular endothelial-derived growth factor (VEGF) plays a fundamental role in the formation of new vessels within the tumour mass. Increasing evidence has highlighted the involvement of Toll-like receptors (TLRs) in cancer. Of interest, TLR9 is over-expressed in human lung carcinoma tissues. The aim of our study was to determine whether TLR9 activation could alter VEGF release in a mouse model of lung carcinoma. Lewis lung carcinoma cells were intravenously (i.v.) inoculated and 10 days later, tumour-bearing mice were treated with CpG-ODN (CpG, a TLR9 ligand) or PBS. CpG administration enhanced VEGF release, which was associated with increased tumour lesions in the lung. CpG induced high levels of IL-6 expression and activation of STAT3 in tumour-bearing mice. Moreover, CpG induced VEGF release from primary fibroblasts and endothelial cells, which correlated with IL-6 and TGFβ production. This may explain the large influx of fibroblasts and the production of basic fibroblast growth factor (bFGF) in the tumour mass. The administration of a monoclonal antibody against VEGF A arrested tumour progression and induced a Th1-like response in CpG-treated tumour-bearing mice. In conclusion, our study demonstrates that the combination of CpG with anti-VEGF monoclonal antibody could be of potential therapeutic in lung carcinoma.

Plasmacytoid dendritic cells alter the antitumor activity of CpG-oligodeoxynucleotides in a mouse model of lung carcinoma

The effect of CpG-oligodeoxynucleotides (CpG) has been studied on a number of tumors. Although CpG may facilitate tumor regression in mouse models of melanoma, its activity in lung cancer is unclear. The aim of our study was to elucidate the effect of CpG (0.5-50 μg/mouse) in a mouse model of Lewis lung carcinoma cell-induced lung cancer. Lung tumor growth increased at 3 and 7 d after a single administration of CpG. This was associated with a greater influx of plasmacytoid dendritic cells (pDCs), immature myeloid dendritic cells, and greater recruitment of regulatory T cells. Depletion of pDCs using a specific Ab (m927) reversed the immune-suppressive environment and resulted in a decreased lung tumor burden, accompanied by a greater influx of active myeloid dendritic cells and CD8(+) T cells, and a higher production of Th1- and Th17-like cytokines. Furthermore, the rate of apoptosis in the lungs of mice treated with CpG increased following the depletion of pDCs. CpG treatment alone does not lead to tumor regression in the lung. However, ablation of pDCs renders CpG a good adjuvant for lung cancer chemotherapy in this experimental model.

Expression of toll-like receptor-9 is increased in poorly differentiated prostate tumors

BACKGROUND

Toll-like receptor-9 (TLR9) is a cellular receptor for bacterial and vertebrate DNA. In addition to cells of the immune system, it is also expressed in various human cancer cell lines, including prostate cancer. We demonstrated previously that synthetic TLR9 ligands induce matrix metalloproteinase-13-mediated invasion in TLR9-expressing prostate cancer cells in vitro. Other studies have suggested possible sex steroid regulation of the function of the various TLRs. The role of TLR9 in the pathophysiology of prostate or any cancer is, however, unknown.

METHODS

Expression of TLR9, androgen receptor (AR), or the estrogen receptors alpha (ERalpha) and beta (ERbeta) were studied with immunohistochemistry in prostate cancer (n = 62) and benign prostatic hyperplasia (n = 45) specimens. TLR9 staining scores were compared with tumor stage, Gleason score, prostate-specific antigen (PSA) concentrations before tissue sampling and with the staining scores of AR, ERalpha, and ERbeta.

RESULTS

TLR9 expression was statistically significantly increased in prostate cancer epithelium and stroma, as compared with the same cellular compartments in benign hyperplasia. Significantly increased (P = 0.04) TLR9 expression was detected in cancers with high Gleason score (>7, n = 23), as compared with lower Gleason scores (< or =7, n = 39). No statistically significant associations were detected between TLR9 expression scores and PSA concentrations or tumor staging. Prostate adenocarcinoma cells were all positive for TLR9, AR, and ERbeta but negative for ERalpha expression. In cancer stroma cells, increased TLR9 expression was associated with increased ERalpha expression.

CONCLUSIONS

Expression of TLR9 is increased in prostate cancer specimens, especially in the most poorly differentiated forms.

Toll-like receptor 9 expression in breast and ovarian cancer is associated with poorly differentiated tumors

Toll-like receptor 9 (TLR9) activates the innate immune response when exposed to non-methylated CpG-DNA. TLR9 was recently shown to be expressed by cancer cells which have been previously characterized by global hypomethylation. We set out to examine the expression and molecular activity of TLR9 in breast and ovarian cancer cells. Firstly, we confirmed higher levels of hypomethylated DNA in the serum of patients with metastatic breast cancer (n = 18) versus age-matched tumor-free women (n = 18). In breast cancer cell lines and tissues, TLR9 mRNA expression was associated with estrogen-receptor (ER) status (n = 124, P = 0.005). Expression also correlated with increasing tumor grade in both breast (P = 0.03) and ovarian cancer specimens (n = 138, P = 0.04). Immunohistochemical analysis of formalin-fixed paraffin-embedded (FFPE) breast cancer tissues revealed higher TLR9 protein expression in hormone-receptor (HR)-negative specimens (n = 116, P < 0.001). Using an in vitro scratch assay, we observed that cell lines transfected to overexpress TLR9 demonstrated increased cellular migration when stimulated with CpG-DNA. When assessing the molecular activity of TLR9 in breast cancer, we found a strong positive correlation of nuclear factor-kappa B (NF-kappaB) activity with TLR9 mRNA expression (correlation coefficient r = 0.7, P < 0.001). Finally, immunofluorescence analysis of BT-20 and Hs578T breast cancer cell lines showed partial colocalizations of CpG-DNA with TLR9, which diminished when the cells were exposed to methylated CpG-DNA (mCpG-DNA) or control GpC-DNA. In summary we demonstrate that TLR9 expression is associated with poor differentiation in breast and ovarian cancer specimens, and that TLR9 overexpression and stimulation with hypomethylated DNA augments the migratory capacity of cancer cell lines.

Immune infiltration in human cancer: prognostic significance and disease control

The interplay between tumors and their immunologic microenvironment is complex and difficult to decipher, but its understanding is of seminal importance for the development of novel prognostic markers and therapeutic strategies. This chapter discusses tumor-immune interactions in several human cancers that illustrate various aspects of this complexity and proposes an integrated scheme of the impact of local immune reactions on clinical outcome. Thus, the fact that a strong infiltration of memory T cells with a Th1 and cytotoxic pattern is the strongest predictor for recurrence and metastasis is exemplified in colorectal cancer in which intratumoral chemokines shape an efficient immune reaction. Based on these data, we propose an immune score that predicts recurrence in early stage (UICC-TNM stage I-II) cancers. Studies on non-small lung cancers have confirmed findings of colorectal cancers and have addressed the question of the sites where antitumor immune reactions may take place. Tertiary lymphoid structures (TLS) adjacent to the tumor nest are sites of intense activity with mature dendritic cells in contact with T cells and germinal-like centers with proliferating B cells. The large number of these TLS being correlated with disease specific and overall survival tempts to postulate that they are privileged sites to mount an efficient antitumor reaction. Inflammation is a major component of human tumors and chronic inflammation is generally of bad prognosis. Head and neck cancers are highly inflammatory and two ways to modulate inflammation in these diseases are presented here: soluble IL-15 receptor α (IL-15 Rα) increases the pro-inflammatory effect of IL-15 and aggravates inflammation resulting in poor prognosis when found at high levels in the plasma of patients. By contrast, infiltration of regulatory T cells is paradoxically beneficial for local control of head and neck tumors, probably by "cooling down" the inflammatory process. The modulation of other aspects of innate immunity may also result in paradoxical effects such as the signaling through Toll like receptors 7 and 8 expressed on lung tumor cells which induce an aggressive tumoral phenotype. Finally, the analysis of primary intraocular lymphoma, which develops in the eye, exemplifies the induction of an antitumor immune reaction in an "immune sanctuary," presenting all the complexities of the tumor-immune interplay in "open" tissues such as the colon or the lung.

Selective up-regulation of CDK2 is critical for TLR9 signaling stimulated proliferation of human lung cancer cell

Accumulating data suggested that functional TLR9 was expressed in various tumor cells and TLR9 signaling could enhance the progression of tumor cells. However, the underlying mechanism of TLR9 signaling on the progression of tumors cells remains largely undefined. Our previous study demonstrated that the TLR9 agonist CpG ODNs could significantly enhance the progression of human lung cancer cells in vivo. Here we further evaluated the direct effect of CpG ODNs on the proliferation and cell cycle of human lung cancer cells. Our data showed that TLR9 agonist CpG ODNs could robustly elevate the proliferation and stimulate cell cycle entry of 95D cells in vitro, accompanied by the selectively up-regulated expression of CDK2. Furthermore, we found that down-regulation of CDK2 expression using siRNA against CDK2 could significantly inhibit the enhanced proliferation of 95D cells induced by CpG ODNs. Finally, we investigated that the CpG ODNs could selectively enhance the promoter activity of CDK2. Our findings indicated that TLR9 signaling could selectively up-regulate the expression of CDK2, which was critical for the enhanced proliferation of human lung cancer cells. Our results might provide novel insight into the understanding of functional expression of TLR9 on the progression of tumor cells.