Toll-like receptors and cancer, particularly oral squamous cell carcinoma

Salivary exosomal microRNA profile as biomonitoring tool for diagnosis and prognosis of patients with head and neck squamous cell carcinoma: a systematic review

OBJECTIVE

Exosomes are extracellular vesicles found in saliva and other body fluids. These vesicles range in size from 30 to 150 nm and play a crucial role in intercellular communication, transporting different biomolecules, actively targeting cells. These vesicles regulate both physiological and pathological processes within recipient cells. MicroRNAs (miRs) are transported within exosomes and are delivered to target cells where they influence signaling pathways, taking on a crucial regulatory role in oncogenesis; for example, they are implicated in progression and infiltration of various cancers, such as head and neck squamous cell carcinoma (HNSCC).

MATERIAL AND METHODS

A systematic literature search based on specific keywords, according to the PRISMA guidelines, was carried out on PubMed, Web of Science, Scopus, and Google Scholar. Only original articles were selected during this review. The risk of bias was assessed by QUADAS-2.

RESULTS

At the end of the selection process 9 articles were included. In these studies, 41 miRs showed differential expression between healthy subjects and patient with HNSCC. The techniques varied among studies for the extraction and analysis of exosomal miRs. We presented also salivary exosomal miRs pathways, to give insights about pathogenetic mechanisms.

CONCLUSIONS

Exosomal microRNA are promising biomarkers for HNSCC detection. MiR-10b-5p, miR-486-5p, miR-24-3p, miR-412-3p, and miR-512-3p are the most promising markers applicable to diagnostics, while miR-1307-5p and miR-519c-3p resulted overexpressed and correlated to worse survival outcomes.

The HPV viral regulatory mechanism of TLRs and the related treatments for HPV-associated cancers

Infection with human papillomavirus (HPV) typically leads to cervical cancer, skin related cancers and many other tumors. HPV is mainly responsible for evading immune tumor monitoring in HPV related cancers. Toll like receptors (TLRs) are particular pattern recognition molecules. When the body is facing immune danger, it can lead to innate and direct adaptive immunity. TLR plays an important role in initiating antiviral immune responses. HPV can affect the expression level of TLR and interfere with TLR related signaling pathways, resulting in sustained viral infection and even carcinogenesis. This paper introduces the HPV virus and HPV related cancers. We discussed the present comprehension of TLR, its expression and signaling, as well as its role in HPV infection. We also provided a detailed introduction to immunotherapy methods for HPV related diseases based on TLR agonists. This will provide insights into methods that support the therapeutic method of HPV related conditions with TLR agonists.

Role of toll-like receptor in the pathogenesis of oral cancer

Toll-like receptors are important molecules of innate immunity. They are known as pattern recognition receptors. They recognise certain molecules known as pathogen-associated molecular pattern on a pathogen and release chemicals that causes inflammation. Toll-like receptors (TLR) help in the removal of the infected cell and thus stop the spread of infection and are being studied for their association with cancer. Oral carcinoma has emerged as a major problem of our country today; it is found ranks first in men and third in women. Toll-like receptors have been implicated in the development of cancer. Certain polymorphisms in toll-like receptor can make a cell more susceptible to develop oral cancer. The identification of toll-like receptors and the different genotypes that are involved in the development of cancer can be utilised for using them as biomarkers of the disease. The study revealed that toll-like receptors like TLR7 and TLR5 are found to have a role in suppression of oral cancer while toll-like receptors like TLR4 and TLR2 are found to be associated with the progression of oral cancer. Toll-like receptors can turn out as important target molecules in the future in designing therapeutic strategies for oral cancer.

Spatial subsetting enables integrative modeling of oral squamous cell carcinoma multiplex imaging data

Oral squamous cell carcinoma (OSCC), a prevalent and aggressive neoplasm, poses a significant challenge due to poor prognosis and limited prognostic biomarkers. Leveraging highly multiplexed imaging mass cytometry, we investigated the tumor immune microenvironment (TIME) in OSCC biopsies, characterizing immune cell distribution and signaling activity at the tumor-invasive front. Our spatial subsetting approach standardized cellular populations by tissue zone, improving feature reproducibility and revealing TIME patterns accompanying loss-of-differentiation. Employing a machine-learning pipeline combining reliable feature selection with multivariable modeling, we achieved accurate histological grade classification (AUC = 0.88). Three model features correlated with clinical outcomes in an independent cohort: granulocyte MAPKAPK2 signaling at the tumor front, stromal CD4+ memory T cell size, and the distance of fibroblasts from the tumor border. This study establishes a robust modeling framework for distilling complex imaging data, uncovering sentinel characteristics of the OSCC TIME to facilitate prognostic biomarkers discovery for recurrence risk stratification and immunomodulatory therapy development.

The emerging role of oral microbiota in oral cancer initiation, progression and stemness

Oral squamous cell carcinoma (OSCC) is the most prevalent malignancy among the Head and Neck cancer. OSCCs are highly inflammatory, immune-suppressive, and aggressive tumors. Recent sequencing based studies demonstrated the involvement of different oral microbiota in oral cavity diseases leading OSCC carcinogenesis, initiation and progression. Researches showed that oral microbiota can activate different inflammatory pathways and cancer stem cells (CSCs) associated stemness pathways for tumor progression. We speculate that CSCs and their niche cells may interact with the microbiotas to promote tumor progression and stemness. Certain oral microbiotas are reported to be involved in dysbiosis, pre-cancerous lesions, and OSCC development. Identification of these specific microbiota including Human papillomavirus (HPV), Porphyromonas gingivalis (PG), and Fusobacterium nucleatum (FN) provides us with a new opportunity to study the bacteria/stem cell, as well as bacteria/OSCC cells interaction that promote OSCC initiation, progression and stemness. Importantly, these evidences enabled us to develop in-vitro and in-vivo models to study microbiota interaction with stem cell niche defense as well as CSC niche defense. Thus in this review, the role of oral microbiota in OSCC has been explored with a special focus on how oral microbiota induces OSCC initiation and stemness by modulating the oral mucosal stem cell and CSC niche defense.

Association of oral microbiome and pancreatic cancer: a systematic review and meta-analysis

BACKGROUND

Oral microbiota reported to be associated with pancreatic diseases, including pancreatic cancer. However, the association of oral microbiome and pancreatic cancer has not been reviewed systematically.

OBJECTIVES

To systematically investigate the association between the oral microbiome and pancreatic cancer risk.

DESIGN

A systematic review and meta-analysis.

DATA SOURCES AND METHODS

Systemic searches were conducted using PubMed, Medline, Cochrane Library, and Embase databases without any language restriction from conception to August 29, 2020. The studies that evaluated the association of oral microbiome and pancreatic cancer risk were included in this meta-analysis.

RESULTS

The six included studies encompassed a total of 863 pancreatic cancer cases and 906 controls. Four studies reported the overall oral microbiome in pancreatic cancer cases. A total of 12-17 species/clusters were correlated with pancreatic cancer. Three studies reported the odds ratios (ORs) or relative abundance of several oral microbiomes pieces/clusters, and the majority were associated with pancreatic cancer.

CONCLUSIONS

Overall, this study supports the hypothesis of associations of variations of patients' oral microbiota to pancreatic cancer. Nonetheless, due to all included studies were conducted in USA or Europe, additional original studies and meta-analysis particular studies from other countries are essential for an in-depth investigation into the role of oral bacteria in pancreatic cancer.

Association between Tissue Expression of Toll-Like Receptor and Some Clinicopathological Indices in Oral Squamous Cell Carcinoma

BACKGROUND

The oral squamous cell carcinoma (OSCC) composes about 90% of all head and neck cancers. The toll-like receptor (TLR)⁺ immune cells have potential of invasion and malignancy transformation. The aim of this study was assessment of possible associations between clinicopathological indices and TLR2 and TLR9 gene expression in OSCC.

METHODS

Forty-two OSCC samples with related healthy margins including 25 early and 17 advanced stages were gathered. The samples were classified histologically from grade I to II. The expression of TLR2 and TLR2 was evaluated by Real-time PCR. The patient's disease-free survival (DFS) and overall survival (OS) were analyzed using SPSS V.23 software.

RESULTS

The expression of TLR2 and TLR9 genes in tumor tissues (especially in grade I and II) were higher than healthy surgical margin tissue (p< 0.001). TLR9 expression in grade II was statistically significant than grade I in tumor tissue (p< 0.001). TLR9 expression in advanced stage was statistically significant in compare to early stage (p= 0.012). In advanced stage both overall survival (p= 0.029) and disease-free survival (p= 0.012) were statistically lower than early stage. The follow-up time to recurrence in advanced stage was statistically lower than early stage (p= 0.007).

CONCLUSION

Overexpression of TLRs 2, 9 play role in the pathogenesis and tumor development of OSCC and can be applied as biomarker in prognostic approaches.

TLR4 Expression in Ex-Lichenoid Lesions—Oral Squamous Cell Carcinomas and Its Surrounding Epithelium: The Role of Tumor Inflammatory Microenvironment

Toll-like receptors (TLRs) regulate innate and adaptive immune responses. Moreover, TLRs can induce a pro-survival and pro-proliferation response in tumor cells. This study aims to investigate the expression of TLR4 in the epithelium surrounding oral squamous cell carcinomas (OSCC) in relation to its inflammatory microenvironment. This study included 150 human samples: 30 normal oral control (NOC), 38 non-lichenoid epithelium surrounding OSCC (NLE-OSCC), 28 lichenoid epithelium surrounding OSCC (LE-OSCC), 30 OSCC ex-non oral lichenoid lesion (OSCC Ex-NOLL), and 24 OSCC ex-oral lichenoid lesion (OSCC Ex-OLL). TLR4 expression was investigated by immunohistochemistry and the percentage of positive cells was quantified. In addition, a semiquantitative analysis of staining intensity was performed. Immunohistochemical analysis revealed that TLR4 is strongly upregulated in LE-OSCC as compared to normal control epithelium and NLE-OSCC. TLR4 expression was associated with the inflammatory environment, since the percentage of positive cells increases from NOC and NLE-OSCC to LE-OSCC, reaching the highest value in OSCC Ex–OLL. TLR4 was detected in the basal third of the epithelium in NLE-OSCC, while in LE-OSCC, TLR4 expression reached the intermediate layer. These results demonstrated that an inflammatory microenvironment can upregulate TLR4, which may boost tumor development.

Serum and Tissue Level of TLR9 in EBV-Associated Oropharyngeal Cancer

Simple Summary

The Epstein–Barr virus (EBV) is associated with the development and progression of various epithelial malignancies including cancer in the head and neck region. Toll-like receptors (TLRs) are molecules distinguishing self and non-self antigens. They are required for congenital immune response to infections with viruses such as EBV because, during viral infection, the congenital immunity is the first line of human defense preventing the replication of the virus. Moreover, TLR response may influence the transformation to malignancy. The aim of our study was to assess TLR9 level in patients with diagnosed oropharyngeal cancer with or without EBV infection. We wanted to know whether infection with EBV influences TLR9 level and maybe changes the immune response which may lead to malignant transformation. The results obtained in our research may improve understanding of the role viral infections play in head and neck cancers and influence future diagnosis, prevention and treatment strategies in these malignancies.

Abstract

The Epstein–Barr virus (EBV) is associated with the development of various epithelial malignancies including cancer in the head and neck region. Several studies have shown that Toll-like receptors (TLRs) are required for an innate immune response to infection with human DNA viruses, e.g., EBV. During viral infections, TLR response may influence the transformation to malignancy. The aim of the study was to assess TLR9 serum and tissue level in EBV(+) and EBV(−) oropharyngeal cancer patients. The study involved 78 patients: 42 EBV(+) and 36 EBV(−). EBV DNA was detected in fresh frozen tumor tissue. TLR9 level was measured in homogenate of tumor tissue and in serum. Moreover, in serum samples IL-10, VEGF, TGFβ, TNFα and antibodies against EBV were detected using ELISA test. TLR9 level was significantly lower in EBV(+) patients, both in tissue and serum, while EBVCA, EBNA and VEGF level was statistically higher in EBV(+) patients. An increase in EBVCA and EBNA antibodies titer was correlated with a TLR9 level decrease. TLR9 level was higher in poorly-differentiated tumors (G3), in tumor of larger dimensions (T3-T4) and with lymph nodes involvement (N3-N4) but without statistical significance. High levels of anti-EA antibodies in the majority of EBV(+) patients may point to the reactivation of EBV infection.

Oral Versus Gastrointestinal Mucosal Immune Niches in Homeostasis and Allostasis

Different body systems (epidermis, respiratory tract, cornea, oral cavity, and gastrointestinal tract) are in continuous direct contact with innocuous and/or potentially harmful external agents, exhibiting dynamic and highly selective interaction throughout the epithelia, which function as both a physical and chemical protective barrier. Resident immune cells in the epithelia are constantly challenged and must distinguish among antigens that must be either tolerated or those to which a response must be mounted for. When such a decision begins to take place in lymphoid foci and/or mucosa-associated lymphoid tissues, the epithelia network of immune surveillance actively dominates both oral and gastrointestinal compartments, which are thought to operate in the same immune continuum. However, anatomical variations clearly differentiate immune processes in both the mouth and gastrointestinal tract that demonstrate a wide array of independent immune responses. From single vs. multiple epithelia cell layers, widespread cell-to-cell junction types, microbial-associated recognition receptors, dendritic cell function as well as related signaling, the objective of this review is to specifically contrast the current knowledge of oral versus gut immune niches in the context of epithelia/lymphoid foci/MALT local immunity and systemic output. Related differences in 1) anatomy 2) cell-to-cell communication 3) antigen capture/processing/presentation 4) signaling in regulatory vs. proinflammatory responses and 5) systemic output consequences and its relations to disease pathogenesis are discussed.

Salivary exosomal microRNAs as biomarkers for head and neck cancer detection-a literature review

Background

MicroRNAs (miRs) are small, non-coding mRNA molecules which regulate cellular processes in tumorigenesis. miRs were discovered in extracellular environment and biological fluids, carrying marks of head and neck squamous cell carcinoma (HNSCC). They were also identified in abundance in salivary exosomes, in which they are protected by exosome lipid barrier against enzymatic injuries and therefore, the accuracy of exosomal miR-based cancer detection increase. This systematic review aimed to reveal and inventorize the most reliable exosomal miRNAs in saliva samples which can be used as novel biomarkers for early detection of HNSCC.

Materials and methods

A systematic literature search, according to PRISMA guideline, was performed on Pubmed and Google Academic libraries, based on specific keywords. Original articles published between 2010 and 2021 were selected. The quality of each paper was assessed using the Quality Evaluation Scoring Tool.

Results

At the end of selection process, five studies met the inclusion criteria. These studies analyzed twelve salivary exosomal miRs, presenting different methods of exosome and miR identification for HNSCC detection. A comprehensive explanation of the miR pathways of action was drawn and illustrated in this review.

Conclusion

Exosomal miRs are promising biomarkers for oral cavity and oropharyngeal cancer detection. miR-10b-5p, miR-486-5p, miR-24-3p and miR-200a stand as the most useful ones in saliva sample examination.

Expression of p16, p53, and TLR9 in HPV-Associated Head and Neck Squamous Cell Carcinoma: Clinicopathological Correlations and Potential Prognostic Significance

Purpose

To investigate the association of human papillomavirus (HPV) status with p16, p53, and TLR9 expression in head and neck squamous cell carcinoma (HNSCC) and to evaluate these proteins as potential surrogate prognostic markers.

Methods

Expression of p16, p53, and TLR9 was assessed by immunohistochemistry, and HPV status was analyzed by in situ hybridization in 85 tumors of patients with HNSCC. Chi-square test was performed to evaluate the correlations of HPV infection with p16, p53, and TLR9 expression. Kaplan–Meier method and Cox regression analyses were applied to evaluate the associations between the expression levels of these proteins and patient outcomes.

Results

Overall, 24 of the 85 HNSCC specimens were associated with HPV infection. High expression of p16, p53, and TLR9 in tumor cells was observed in 31.76%, 61.18%, and 49.41% of the specimens, respectively. p16 showed a higher diagnostic odds ratio for the prediction of HPV DNA positivity than p53 and TLR9. Improved 5-year overall and disease-free survival correlated with HPV positivity and high p16, low p53, and low TLR9 expression. Associations with improved outcomes were also observed for marker combinations high p16/low p53 and high p16/low p53/low TLR9. In a multivariate analysis, the high p16/low p53 signature showed the lowest hazard ratio regarding death.

Conclusion

The expression of p16, p53, and TLR9 in HNSCC is associated with HPV status. High p53 and TLR9 expression may be related to poor outcomes. The two-marker signature high p16/low p53 in tumor cells is a reliable tool for patient survival prognostication in HNSCC.

The role of Toll-like receptors (TLRs) in virus-related cancers: a mini review

The modulation of the host innate immune system is a well-established carcinogenesis feature of several tumors, including human Epstein-Barr (EBV) and Papillomavirus-(HPV) related cancers. These viruses are able to interrupt the initial events of the immune response, including the expression of Toll-like receptors (TLRs), cytokines, and inflammation. The aim of the study is to review current data and summarize knowledge on the TLRs and their role in the development of cancer, especially viral-related cancers (EBV and HPV). Research work shows a correlation between the TLRs polymorphism and the development of oropharyngeal and gastric cancer (GC), especially related to viral infections. Many studies suggest the important role for TLRs in inflammatory, autoimmune disease and human cancers. However, further efforts are necessary to draw a precise conclusion.

Food Processing, Dysbiosis, Gastrointestinal Inflammatory Diseases, and Antiangiogenic Functional Foods or Beverages

Foods and beverages provide nutrients and alter the gut microbiota, resulting in eubiosis or dysbiosis. Chronic consumption of a diet that is high in saturated or trans fats, meat proteins, reducing sugars, and salt and low in fiber induces dysbiosis. Dysbiosis, loss of redox homeostasis, mast cells, hypoxia, angiogenesis, the kynurenine pathway, transglutaminase 2, and/or the Janus kinase pathway are implicated in the pathogenesis and development of inflammatory bowel disease, celiac disease, and gastrointestinal malignancy. This review discusses the effects of oxidative, carbonyl, or glycative stress-inducing dietary ingredients or food processing-derived compounds on gut microbiota and gastrointestinal epithelial and mast cells as well as on the development of associated angiogenic diseases, including key signaling pathways. The preventive or therapeutic potential and the biochemical pathways of antiangiogenic or proangiogenic foods or beverages are also described. The outcomes of the interactions between disease pathways and components of food are critical for the design of foods and beverages for healthy lives.

Inhibition of kinase IKKβ suppresses cellular abnormalities induced by the human papillomavirus oncoprotein HPV 18E6

Human papillomavirus (HPV) is the leading cause of cervical cancer and has been implicated in several other cancer types including vaginal, vulvar, penile, and oropharyngeal cancers. Despite the recent availability of a vaccine, there are still over 310,000 deaths each year worldwide. Current treatments for HPV-mediated cancers show limited efficacy, and would benefit from improved understanding of disease mechanisms. Recently, we developed a Drosophila 'HPV 18 E6' model that displayed loss of cellular morphology and polarity, junctional disorganization, and degradation of the major E6 target Magi; we further provided evidence that mechanisms underlying HPV E6-induced cellular abnormalities are conserved between humans and flies. Here, we report a functional genetic screen of the Drosophila kinome that identified IKK[Formula: see text]-a regulator of NF-κB-as an enhancer of E6-induced cellular defects. We demonstrate that inhibition of IKK[Formula: see text] reduces Magi degradation and that this effect correlates with hyperphosphorylation of E6. Further, the reduction in IKK[Formula: see text] suppressed the cellular transformation caused by the cooperative action of HPVE6 and the oncogenic Ras. Finally, we demonstrate that the interaction between IKK[Formula: see text] and E6 is conserved in human cells: inhibition of IKK[Formula: see text] blocked the growth of cervical cancer cells, suggesting that IKK[Formula: see text] may serve as a novel therapeutic target for HPV-mediated cancers.

Curcumin-Loaded Bacterial Cellulose/Alginate/Gelatin as A Multifunctional Biopolymer Composite Film

Multifunctional biopolymer composites comprising mechanically-disintegrated bacterial cellulose, alginate, gelatin and curcumin plasticized with glycerol were successfully fabricated through a simple, facile, cost-effective mechanical blending and casting method. SEM images indicate a well-distributed structure of the composites. The water contact angles existed in the range of 50-70°. Measured water vapor permeability values were 300-800 g/m2/24 h, which were comparable with those of commercial dressing products. No release of curcumin from the films was observed during the immersion in PBS and artificial saliva, and the fluid uptakes were in the range of 100-700%. Films were stretchable and provided appropriate stiffness and enduring deformation. Hydrated films adhered firmly onto the skin. In vitro mucoadhesion time was found in the range of 0.5-6 h with porcine mucosa as model membrane under artificial saliva medium. The curcumin-loaded films had substantial antibacterial activity against E. coli and S. aureus. The films showed non-cytotoxicity to human keratinocytes and human gingival fibroblasts but exhibited potent anticancer activity in oral cancer cells. Therefore, these curcumin-loaded films showed their potential for use as leave-on skin applications. These versatile films can be further developed to achieve desirable characteristics for local topical patches for wound care, periodontitis and oral cancer treatment.

Assessment of TLR4 and TLR9 signaling and correlation with human papillomavirus status and histopathologic parameters in oral tongue squamous cell carcinoma

OBJECTIVES

Toll-like receptors (TLRs) may promote or inhibit tumor progression. The aim of this study was to assess the expression of TLR4 and TLR9 and their downstream targets in oral tongue squamous cell carcinoma (OTSCC) in correlation with histopathologic parameters and human papillomavirus (HPV) status.

STUDY DESIGN

OTSCC (fully or superficially invasive and in situ) were studied. Immunohistochemical expression of TLR4, TLR9, nuclear factor-κΒ (NF-κΒ/p65), and interferon-β (IFN-β) was evaluated in tumor and inflammatory cells and in adjacent morphologically normal mucosa. HPV status was also determined.

RESULTS

TLR4 showed increased expression levels in tumor and infiltrating inflammatory cells compared with adjacent mucosa, especially in fully invasive cases; a negative correlation between TLR4 levels in inflammatory cells and tumor grade was observed. TLR9 was upregulated in tumor and infiltrating inflammatory cells compared with the adjacent mucosa; its expression in inflammatory cells was higher in well differentiated tumors. NF-κΒ and IFN-β were elevated in cancerous tissues, especially in fully invasive cases, and positively correlated with TLR4 and/or TLR9. HPV positivity (detected in 15.9% of the cases) demonstrated positive correlation with TLR9 and NF-κΒ levels.

CONCLUSIONS

TLR4 and TLR9 are upregulated in OTSCC and its microenvironment and, by affecting important downstream molecules, such as NF-κB and IFN-β, may play a role in oral cancer development 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.

Targeting Toll-Like Receptors for Cancer Therapy

The immune system encompasses a broad array of defense mechanisms against foreign threats, including invading pathogens and transformed neoplastic cells. Toll-like receptors (TLRs) are critically involved in innate immunity, serving as pattern recognition receptors whose stimulation leads to additional innate and adaptive immune responses. Malignant cells exploit the natural immunomodulatory functions of TLRs, expressed mainly by infiltrating immune cells but also aberrantly by tumor cells, to foster their survival, invasion, and evasion of anti-tumor immune responses. An extensive body of research has demonstrated context-specific roles for TLR activation in different malignancies, promoting disease progression in certain instances while limiting cancer growth in others. Despite these conflicting roles, TLR agonists have established therapeutic benefits as anti-cancer agents that activate immune cells in the tumor microenvironment and facilitate the expression of cytokines that allow for infiltration of anti-tumor lymphocytes and the suppression of oncogenic signaling pathways. This review focuses on the clinical application of TLR agonists for cancer treatment. We also highlight agents that are undergoing development in clinical trials, including investigations of TLR agonists in combination with other immunotherapies.

Toll-like receptor 6 expression, sequence variants, and their association with colorectal cancer risk

This is the first study to examine the potential correlation of the rs3796508 and rs5743810 SNPs of the TLR6 gene in patients with colorectal cancer (CRC) in a subset of the Saudi population. TLR6 gene expression was studied by real-time PCR assaysin 10 matching normal and cancer colon tissues. TLR6 expression at the protein level was determined by immunohistochemistry. A case-control search was conductedon 115 case patients and 102 controls. All samples were genotyped with the TaqMan assay for the TLR6 gene. Odds ratios and 95% confidence interval were computed from logistic regression models after adjusting for age, sex, and tumor localization. Our findings showed a decrease in TLR6 expression (p <0.001) in colon cancer tissues when compared to normal colon tissues. Global analysis revealed no significant association between the TLR6 rs3796508 and rs5743810 and CRC in this population. However, the Val/Met genotype of rs3796508 had a significantly higher frequency in the control group than in the cases for the male group (OR= 0.095, and p= 0.03385) or the volunteers aged more than 57 years OR= 0.152; and p= 0.04069, respectively). Two non-synonymous single nucleotide polymorphisms (SNP; S249P and V327M) were common in a few patients and were predicted as damaging by SIFT and Polyphen and were further analyzed for their protein stability and function using advanced bioinformatics tools. The results suggest that TLR6 rs3796508 has a crucial role as a protective factor against colorectal cancer in the older Saudi male population.

Surrogates of immunologic cell death (ICD) and chemoradiotherapy outcomes in head and neck squamous cell carcinoma (HNSCC)

OBJECTIVES

Chemoradiation can induce immunogenic (ICD) or tolerogenic cell death. ICD relies on the generation of damage-associated molecular patterns which can stimulate toll-like receptors (TLRs). We sought to determine whether we can predict responses to chemoradiation by measuring surrogate biomarkers of ICD in a cohort of patients with locally advanced (LA) head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

In a cohort of 113 LA HNSCC pts we evaluated expression of TLR4, TLR7 and TLR9 in the EpCAM + circulating tumor cell (CTC) fraction at baseline and after cisplatin chemoradiation. We also quantified changes in chemokines CXCL10, CXCL16 and IL-2R in the serum.

RESULTS

Seventy three patients had evaluable specimens. Among cases with biomarker assessment at baseline and post treatment, 36.8% had an increase in CXCL10 levels (p = 0.022), 73.7% had an increase in CXCL16 levels (p = 0.002) and 63.8% had an increase in IL2Ra levels (p = 0.032) with treatment. 52.0% of evaluable cases at baseline and post-treatment had an increase in TLR4 levels (p = 0.996), 42.9% had an increase in TLR7 levels (p = 0.042) and 27.7% had increase in TLR9 levels (p = 0.011) with treatment. CXCL10 levels at baseline were significantly associated with PFS and OS (p = 0.010 and p = 0.032, respectively).

CONCLUSIONS

Our results suggest that chemoradiation leads to quantifiable effects in surrogate markers of ICD. These effects may inform trials combining chemoradiation with immune checkpoint inhibitors. In addition, CXCL10 has prognostic effect in pts treated with chemoradiation.

Genetic variations of TLRs and their association with HPV/EBV, co-infection along with nicotine exposure in the development of premalignant/malignant lesions of the oral cavity in Indian population

BACKGROUND

Despite being most preventable malignancies associated with smoked and smokeless tobacco products, squamous cell carcinoma of oral cavity is one of the most common malignancy in India. The aim of the present study was to evaluate the role of TLRs in oral pre-cancerous, cancerous cases and their genotypic correlation with HPV/EBV, co-infection & lifestyle habits in Indian population.

METHODS

The present study was conducted on 300 subjects (100 OSCC, 50 pre-cancer & 150 controls). The amplification of TLRs gene and HPV/EBV co-infection was assessed by Nested PCR, PCR-RFLP and further confirmation by direct sequencing.

RESULTS

The TLR 9(-1486 T/C), revealed that the TT vs. CT + CC genotype had a ˜5-fold increased risk for the development of pre-cancerous lesions as compared to controls (p = 0.0001). Further analysis showed that the risk of cancer was extremely pronounced in HPV/EBV, co-infection (p = 0.0141), implicating the possible interaction between TLR 9(-1486T/C) genotype and HPV infection in increasing cancer/pre-cancer risk. The 'G' allele of TLR 4(+896A/G) was also a higher risk of developing pre-cancerous lesions with 4.5 fold and statistically significant (p = 0.0001). The genotypic association of TLR 9(-1486T/C) in OSMF cases showed ˜8 fold increased risk and TLR 4(+896A/G) showed fourteen fold higher risk for leukoplakia (p < 0.0001, OR = 14.000).

CONCLUSION

Genetic polymorphism of TLR 9(-1486 T/C) and TLR 4(+896A/G) may influence the effects of HPV/EBV, co-infection and play the significant role in development of the disease. The significance of these TLRs seemed to be enhanced by tobacco chewing and smoking habits also, which act as an important etiological risk factor for OSCC.

Treponema denticola chymotrypsin-like proteinase is present in early-stage mobile tongue squamous cell carcinoma and related to the clinicopathological features

BACKGROUND

Certain periodontopathogenic bacteria have been linked to cancers. Treponema denticola (Td) is associated with severe periodontitis. Chymotrypsin-like proteinase (CTLP), a major virulence factor of Td, can degrade various host proteins and peptides, and modulate inflammatory responses. However, the role of Td in the tongue carcinogenesis remains unknown. This study aimed to investigate the presence of Td-CTLP in early-stage mobile tongue squamous cell carcinoma (MTSCC) and its relation to clinical and pathological characteristics.

METHODS

The immunopositivity of Td-CTLP was assessed in samples obtained from 60 patients with MTSCC and associated with their clinicopathological data. Additionally, Td-CTLP expression was compared with immunoexpression of matrix metalloproteinases (MMP-8 and MMP-9), toll-like receptors (TLR-2, TLR-4, TLR-7 and TLR-9), c-Myc, Ki-67, Bmi-1 and Snail.

RESULTS

Treponema denticola-chymotrypsin-like proteinase was present in 95% of MTSCC tumours of which many (40.4%) showed high immunopositivity. Td-CTLP positivity was significantly associated with invasion depth, tumour diameter and the expression of TLR-7, TLR-9 and c-Myc. High Td-CTLP immunopositivity in younger patients (≤ 60 years old) predicted early relapse.

CONCLUSION

Our data indicate that Td and its CTLP are present in early-stage MTSCC carcinoma and may contribute to carcinogenesis, and therefore provide novel perspectives into intervention and therapeutic measures of MTSCC.

Viral Modulation of TLRs and Cytokines and the Related Immunotherapies for HPV-Associated Cancers

The modulation of the host innate immune system is a well-established carcinogenesis feature of several tumors, including human papillomavirus- (HPV-) related cancers. This virus is able to interrupt the initial events of the immune response, including the expression of Toll-like receptors (TLRs), cytokines, and inflammation. Both TLRs and cytokines play a central role in HPV recognition, cell maturation and differentiation as well as immune signalling. Therefore, the imbalance of this sensitive control of the immune response is a key factor for developing immunotherapies, which strengthen the host immune system to accomplish an efficient defence against HPV and HPV-infected cells. Based on this, the review is aimed at exposing the HPV immune evasion mechanisms involving TLRs and cytokines and at discussing existing and potential immunotherapeutic TLR- and cytokine-related tools.

Toll-Like Receptor 7 Staining in Malignant Epithelial Tumors

BACKGROUND

As important players of the innate immune system, Toll-like receptors (TLRs) and their role for tumorigenesis have been in the focus of research. In particular TLR7 is an interesting candidate, as TLR7 agonists are broadly used for the treatment of cutaneous tumors. However, data addressing the baseline expression of TLR7 in both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) on the protein level are lacking, while on the genomic level significantly elevated expression of TLR7 in SCC but not in BCC has been demonstrated.

AIM

Our aim was to characterize the immunohistochemical staining pattern of TLR7 in SCC and BCC. Besides, we aimed to clarify if, in case of different TLR7 expression between SCC and BCC, TLR7 expression would help to define basosquamous carcinoma (BSC), a tumor entity sharing characteristics of both SCC and BCC.

METHODS

We examined histopathological samples from 23 BCC, 4 BSC, and 24 SCC and characterized the expression of TLR7 by immunohistochemistry and immunofluorescence.

RESULTS

We found that TLR7 was not expressed by the tumor tissue of SCC, BCC, and BSC, but by inflammatory cells located within the tumoral and/or peritumoral tissue. Whereas the overall expression of TLR7 did not differ between BCC and SCC (30.4% vs. 45.8%, respectively), we found that within the group of SCC, the well-differentiated SCC showed strong tumoral and/or peritumoral immunocellular TLR7 reactivity in contrast to the poorly differentiated SCC (73.33% vs. 11.1%, respectively). Besides, immunofluorescence double staining revealed the expression of TLR7 in immune cells closely interacting with T cells and natural killer cells.

CONCLUSIONS

In contrast to genomic data, we did not find a general difference between baseline TLR7 expression of SCC and BCC on the protein level. Nevertheless, the expression of TLR7 by the inflammatory infiltrate associated with SCC may correlate with the degree of differentiation of SCC possibly indicating better outcome.

Comprehensive microRNA-sequencing of exosomes derived from head and neck carcinoma cells in vitro reveals common secretion profiles and potential utility as salivary biomarkers

Exosomes are nano-scale, membrane encapsulated vesicles that are released by cells into the extracellular space and function as intercellular signaling vectors through horizontal transfer of biologic molecules, including microRNA (miRNA). There is evidence that cancer-derived exosomes enable the tumor to manipulate its microenvironment, thus contributing to the capacity of the tumor for immune evasion, growth, invasion, and metastatic spread. The objective of this study was to characterize differential secretion of exosomal miRNA by head and neck squamous cell carcinoma (HNSCC) and identify a set of candidate biomarkers that could be detected in non-invasive saliva samples. We isolated exosomes from conditioned media from 4 HNSCC cell lines and oral epithelial control cells and applied miRNA-sequencing to comprehensively characterize their miRNA cargo and compare transcript levels of each HNSCC cell line to that of oral epithelial control cells. A candidate set of miRNA differentially secreted by all 4 HNSCC cell lines was further evaluated in saliva collected from HNSCC patients and healthy controls. We observed extensive differences in exosomal miRNA content between HNSCC cells when compared to normal oral epithelial control cells, with a high degree of overlap in exosomal miRNA profiles between the 4 distinct HNSCC cell lines. Importantly, several of the exosomal miRNA secreted solely by cancer cells in culture were detected at substantially elevated levels in saliva from HNSCC patients relative to saliva from healthy controls. These findings provide important insight into tumor biology and yields a promising set of candidate HNSCC biomarkers for use with non-invasive saliva samples.

Two SNPs in the promoter region of Toll-like receptor 4 gene are not associated with smoking in Saudi Arabia

Defects in the innate immune system, particularly in Toll-like receptors (TLRs), have been reported in several cigarette smoke-promoted diseases. The aim of this study was to examine the impact of tobacco smoke on allelic frequencies of TLR4 single-nucleotide polymorphisms (SNPs) and to compare the genotypic distribution of these SNPs in a Saudi Arabian population with that in previously studied populations. DNA was extracted from 303 saliva samples collected from smokers and nonsmokers. Two transitional SNPs in the promoter region of TLR4 were selected, rs2770150 (T/C) and rs10759931 (G/A). Genotype frequencies were determined using quantitative polymerase chain reaction. Our results showed a slight effect of smoking on the distribution of rs2770150 and rs10759931. However, the differences were not significant. Thus, we conclude that the SNPs selected for this study were independent of smoking and may not be related to smoking-induced diseases.

Effect of smoking on the genetic makeup of toll-like receptors 2 and 6

Background

Cigarette smoking is a major risk factor for lung cancer, asthma, and oral cancer, and is central to the altered innate immune responsiveness to infection. Many hypotheses have provided evidence that cigarette smoking induces more genetic changes in genes involved in the development of many cigarette-related diseases. This alteration may be from single-nucleotide polymorphisms (SNPs) in innate immunity genes, especially the toll-like receptors (TLRs).

Objective

In this study, the genotype frequencies of TLR2 and TLR6 in smoking and nonsmoking population were examined.

Methods

Saliva samples were collected from 177 smokers and 126 nonsmokers. The SNPs used were rs3804100 (1350 T/C, Ser450Ser) and rs3804099 (597 T/C, Asn199Asn) for TLR2 and rs3796508 (979 G/A, Val327Met) and rs5743810 (745 T/C, Ser249Pro) for TLR6.

Results

Results showed that TLR2 rs3804100 has a significant effect in short-term smokers (OR =2.63; P=0.04), and this effect is not observed in long-term smokers (>5 years of smoking). Therefore, this early mutation may be repaired by the DNA repair system. For TLR2 rs3804099, the variation in genotype frequencies between the smokers and control patients was due to a late mutation, and its protective role appears only in long-term smokers (OR =0.40, P=0.018). In TLR6 rs5743810, the TT genotype is significantly higher in smokers than in nonsmokers (OR =6.90). The effect of this SNP is observed in long-term smokers, regardless of the smoking regime per day.

Conclusion

TLR2 (rs3804100 and rs3804099) and TLR6 (rs5743810) can be used as a potential index in the diagnosis and prevention of more diseases caused by smoking.

Biopathological Significance of TLR9 Expression in Cancer Cells and Tumor Microenvironment Across Invasive Breast Carcinomas Subtypes

Toll-like receptors (TLRs) are pattern recognition receptors mainly expressed by cells of the immune system but also by epithelial tumor cells. Little is known about expression patterns of TLR genes in breast tumors, and their clinical significance is unclear. The aim of our study was to investigate expression of TLRs pathway components in pre-invasive breast lesions and invasive breast carcinomas (IBCs). We used RT-PCR assays to quantify mRNA levels of the 10 TLR genes and genes involved in TLR pathways in 350 breast tumors from patients with known clinical/pathological status and long-term outcome. Sets of 158 breast samples were also analyzed by immunochemistry including; 40 early noninvasive breast lesions, 38 IBCs and 80 triple negative carcinomas subtype (TNCs). We identified TLR9 as the major TLR gene family member upregulated in breast tumors and more particularly in TNCs. Immunohistochemical studies demonstrated that TLR9 protein was expressed in tumor epithelial and stromal cells of the TLR9 mRNA-overexpressing tumors. TLR9 overexpression appears very early during breast carcinogenesis. High TLR9 levels were associated with favorable outcome in the TNC sub-group. TLR9 overexpression was associated with alterations of down-stream components of the TLR9 signaling pathway, epithelio-mesenchymal transition (EMT) induction and EGFR pathway deregulation. TNCs with TLR9 overexpression were significantly correlated with development of a fibrous and inflammatory microenvironment with variable status of nuclear phosphoSTAT3. Our results suggest that TLR9 could play a role in TNC carcinogenesis and could be useful as predictive biomarker and therapeutic target.

Gambogenic acid inhibits LPS-simulated inflammatory response by suppressing NF-κB and MAPK in macrophages

Inflammation is a response of body tissues to injury and infection. Compounds that can inhibit inflammation have been shown to have potential therapeutic clinical application. Gambogenic acid (GEA) has potent antitumor and anti-inflammatory activities. Herein, the molecular mechanisms of GEA's anti-inflammatory effect were investigated in lipopolysaccharide (LPS)-stimulated macrophage cells. The results showed that pretreatment with GEA could markedly inhibit interleukin (IL)-1α, IL-1β, tumor necrosis factor-α, IFN-β, IL-12b, and IL-23a production in a dose-dependent manner in LPS-induced model. Furthermore, this drug significantly reduced the release of nitric oxide (NO), and impaired the protein level of inducible NO synthase and the cyclooxygenase 2. The finding also showed that the effect of GEA may be related to the suppression of the nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathway. These results indicate that GEA could suppress LPS-simulated inflammatory response partially by attenuating NO synthesis and NF-κB and MAPK activation, suggesting that it may become a potent therapeutic agent for the treatment of inflammatory diseases.

Clinical relevance of the tumor microenvironment and immune escape of oral squamous cell carcinoma

BACKGROUND

Changes in the tumor microenvironment and immune surveillance represent crucial hallmarks of various kinds of cancer, including oral squamous cell carcinoma (OSCC), and a close crosstalk of hypoxia regulating genes, an activation of chemokines and immune cells has been described.

METHODS

A review about the pivotal role of HIF-1, its crosstalk to various cornerstones in OSCC tumorigenesis is presented.

RESULTS

Hypoxia is a frequent event in OSCC and leads to a reprogramming of the cellular metabolism in order to prevent cell death. Hypoxic OSCC cells induce different adaptive changes such as anaerobic glycolysis, pH stabilisation and alterations of the gene and protein expression profile. This complex metabolic program is orchestrated by the hypoxia inducible factor (HIF)-1, the master regulator of early tumor progression. Hypoxia-dependent and -independent alterations in immune surveillance lead to different immune evasion strategies, which are partially mediated by alterations of the tumor cells, changes in the frequency, activity and repertoire of immune cell infiltrates and of soluble and environmental factors of the tumor micromilieu with consecutive generation of an immune escape phenotype, progression of disease and poor clinical outcome of OSCC patients.

CONCLUSIONS

This review focusses on the importance of HIF-1 in the adaption and reprogramming of the metabolic system to reduced oxygen values as well as on the role of the tumor microenvironment for evasion of OSCC from immune recognition and destruction.

Targeted Therapy in Locally Advanced and Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma (LA-R/M HNSCC)

Surgery and radiotherapy are the standard treatment options for patients with squamous cell carcinoma of the head and neck (SCCHN). Chemoradiotherapy is an alternative for patients with locally advanced disease. In recurrent/metastatic disease and after progression to platin-based regimens, no standard treatments other than best supportive care are currently available. Most SCCHN tumours overexpress the epidermal growth factor receptor (EGFR). This receptor is a tyrosine-kinase membrane receptor that has been implicated in angiogenesis, tumour progression and resistance to different cancer treatments. In this review, we analysed the different drugs and pathways under development to treat SCCHN, especially recurrent/metastatic disease. Until now, the EGFR signalling pathway has been considered the most important target with respect to new drugs; however, new drugs, such as immunotherapies, are currently under study. As new treatments for SCCHN are developed, the influence of therapies with respect to overall survival, progression free survival and quality of life in patients with this disease is changing.

Downregulation of toll-like receptor 4 induces suppressive effects on hepatitis B virus-related hepatocellular carcinoma via ERK1/2 signaling

Background

Hepatitis B virus (HBV) infection is a major risk factor which can lead to development of hepatocellular carcinoma (HCC). In this study, we aimed to explore the effects of toll-like receptor 4 (TLR4) downregulation on the growth and survival of HBV-related HCC cells and to examine the molecular mechanisms been involved.

Methods

The expression levels of TLR4 were examined in a panel of HCC cell lines (HepG2, SMMC7721, Huh7, HepG2.2.15 and Hep3B). The effects of TLR4 downregulation on the proliferation, apoptosis, and tumorigenicity of HBV-related HepG2.2.15 cells were determined. The effects of TLR4 downregulation on multiple signaling pathways were also measured. Co-immunoprecipitation and immunofluoresence staining assays were performed to investigate the interaction between TLR4 and HBV X protein (HBx).

Results

The mRNA and protein levels of TLR4 were significantly increased in HepG2.2.15 cells than those in the other cells which have been studied. Downregulation of TLR4 significantly decreased the proliferation and induced G2/M cell cycle arrest and apoptosis in HepG2.2.15 cells. TLR4 depletion inhibited HepG2.2.15 cell colony formation and tumor growth in nude mice. TLR4 silencing decreased the phosphorylation of ERK1/2 but not JNK1/2, p38, or NF-κB. Chemical inhibition of ERK1/2 approximately phenocopied the growth-suppressive effect of TLR4 downregulation on HepG2.2.15 cells. In addition, TLR4 showed a physical interaction with HBx.

Conclusions

Taken together, TLR4 plays a tumor-promoting role in HBV-related HCC cells, which is associated with regulation of ERK1/2 activation and interaction with HBx. Therefore, TLR4 may be a potential therapeutic target for HBV-related HCC.

Toll-like receptor 4 expression in the epithelium of inflammatory periapical lesions. An immunohistochemical study

Toll-like receptors (TLR) are essential for the innate immune response against invading pathogens and have been described in immunocompetent cells of areas affected by periapical disease. Besides initiating the inflammatory response, they also directly regulate epithelial cell proliferation and survival in a variety of settings. This study evaluates the in situ expression of TLR4 in periapical granulomas (PG) and radicular cysts, focusing on the epithelial compartment.

Twenty-one periapical cysts (PC) and 10 PG were analyzed; 7 dentigerous non-inflamed follicular cyst (DC) served as control. TLR4 expression was assessed by immunohistochemistry. TLR4 immunoreaction products were detected in the epithelium of all specimens, with a higher percentage of immunostained cells in PG. Although TLR4 overexpression was detected in both PG and PC, there were differences that seemed to be related to the nature of the lesion, since in PG all epithelial cells of strands, islands and trabeculae were strongly immunoreactive for TLR4, whereas in PC only some areas of the basal and suprabasal epithelial layers were immunostained. This staining pattern is consistent with the action of TLR4: in PG it could promote formation of epithelial cell rests of Malassez and in epithelial strands and islands the enhancement of cell survival, proliferation and migration, whereas in PC TLR4 could protect the lining epithelium from extensive apoptosis. These findings go some way towards answering the intriguing question of why many epithelial strands or islands in PG and the lining epithelium of apical cysts regress after non-surgical endodontic therapy, and suggest that TLR4 plays a key role in the pathobiology of the inflammatory process related to periapical disease.

Strategies for combining immunotherapy with radiation for anticancer therapy

Radiation therapy controls local disease but also prompts the release of tumor-associated antigens and stress-related danger signals that primes T cells to promote tumor regression at unirradiated sites known as the abscopal effect. This may be enhanced by blocking inhibitory immune signals that modulate immune activity through a variety of mechanisms. Indeed, abscopal responses have occurred in patients with lung cancer or melanoma when given anti-CTLA4 antibody and radiation. Other approaches involve expanding and reinfusing T or NK cells or engineered T cells to express receptors that target specific tumor peptides. These approaches may be useful for immunocompromised patients receiving radiation. Preclinical and clinical studies are testing both immune checkpoint-based strategies and adoptive immunotherapies with radiation.

Chemokine function in periodontal disease and oral cavity cancer

The chemotactic cytokines, or chemokines, comprise a superfamily of polypeptides with a wide range of activities that include recruitment of immune cells to sites of infection and inflammation, as well as stimulation of cell proliferation. As such, they function as antimicrobial molecules and play a central role in host defenses against pathogen challenge. However, their ability to recruit leukocytes and potentiate or prolong the inflammatory response may have profound implications for the progression of oral diseases such as chronic periodontitis, where tissue destruction may be widespread. Moreover, it is increasingly recognized that chronic inflammation is a key component of tumor progression. Interaction between cancer cells and their microenvironment is mediated in large part by secreted factors such as chemokines, and serves to enhance the malignant phenotype in oral and other cancers. In this article, we will outline the biological and biochemical mechanisms of chemokine action in host–microbiome interactions in periodontal disease and in oral cancer, and how these may overlap and contribute to pathogenesis.

Differential expression of TLR3 and TLR4 in keratocystic odontogenic tumor (KCOT): A comparative immunohistochemical study in primary, recurrent, and nevoid basal cell carcinoma syndrome (NBCCS)--associated lesions

BACKGROUND

Toll-like receptors (TLRs) play an essential role in the activation of innate immunity and they can promote cancer cell survival and tumor progression. It has been claimed that TLRs can somehow predict the clinical behavior in oral squamous cell carcinoma (OSCCs).

AIM

To elucidate the molecular basis underlying keratocystic odontogenic tumor (KOCTs) aggressive behavior and recurrence we carried out this immunohistochemical study on TLR3 and TLR4 expression in sporadic primary KCOTs (sp-KCOTs), sporadic recurrent KCOTs (sp-KCOTs), and NBCCS-associated KCOTs (NBCCS-KCOTs).

METHOD

40 cases of KOCTs removed from 23 men and 17 women were the sample. Paraffin-embedded blocks were processed for immunohistochemistry. Sections were incubated with TLR3 and TLR4 antibodies and immunoreactivity evaluated on a semi-quantitative score.

RESULTS

Both TLR3 and TLR4 were expressed in KCOTs epithelium, although with a different extent. TLR3 was not expressed in sp-KCOTs and sr-KCOTs, but it showed a faint staining in NBCCS-KCOTs. On the other hand, both cytoplasmic and nuclear staining for TLR4 was detected in all the 3 types of lesions; however being significantly more expressed in sr-KCOT and NBCCS-KCOTs (p < 0.0001). Our results, demonstrated an association between TLR4, but not TLR3 expression to recurrence behavior of KCOTs. In fact, TLR4 was up-regulated in sr-KCOTs and NBCCS-KCOTs but not in sp-KCOTs.

CONCLUSIONS

According these findings it seems conceivable to assume that the up-regulation of TLR4 in some KCOTs can be correlated somehow to their tendency recurrence.