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Purpose: Most aggressive thyroid cancers are commonly associated with a BRAFV600E mutation. Preclinical and clinical data in BRAFV600E cancers suggest that combined BRAF and MEK inhibitor treatment results in a response, but resistance is common. One mechanism of acquired resistance is through persistent activation of tyrosine kinase (TK) signaling by alternate pathways. We hypothesized that combination therapy with BRAF and multitargeting TK inhibitors (MTKI) might be more effective in BRAFV600E thyroid cancer than in single-agent or BRAF and MEK inhibitors. Experimental Design: The combined drug activity was analyzed to predict any synergistic effect using high-throughput screening (HTS) of active drugs. We performed follow-up in vitro and in vivo studies to validate and determine the mechanism of action of synergistic drugs. Results: The MTKI ponatinib and the BRAF inhibitor PLX4720 showed synergistic activity by HTS. This combination significantly inhibited proliferation, colony formation, invasion, and migration in BRAFV600E thyroid cancer cell lines and downregulated pERK/MEK and c-JUN signaling pathways, and increased apoptosis. PLX4720-resistant BRAFV600E cells became sensitized to the combination treatment, with decreased proliferation at lower PLX4720 concentrations. In an orthotopic thyroid cancer mouse model, combination therapy significantly reduced tumor growth (P < 0.05), decreased the number of metastases (P < 0.05), and increased survival (P < 0.05) compared with monotherapy and vehicle control. Conclusions: Combination treatment with ponatinib and PLX4720 exhibited significant synergistic anticancer activity in preclinical models of BRAFV600E thyroid cancer, in addition to overcoming PLX4720 resistance. Our results suggest this combination should be tested in clinical trials.

Thyroid cancer is the most common endocrine cancer. The discovery of new biomarkers for thyroid cancer has significantly improved the understanding of the molecular pathogenesis of thyroid cancer, thus allowing more personalized treatments for patients with thyroid cancer. Most of the recently discovered targeted therapies inhibit the known oncogenic mechanisms in thyroid cancer initiation and progression such as MAPK pathway, PI3K/Akt-mTOR pathways, or VEGF. Despite the significant advances in molecular testing and the discoveries of new and promising therapeutics, effective treatments for advanced and metastatic, iodine-refractory thyroid cancer are still lacking. Here, we aim to summarize the current understanding of the genetic alterations and the dysregulated pathways in thyroid cancer and to discuss the most recent targeted therapies and immunotherapy for advanced thyroid cancer with a promising anti-tumor activity and clinical benefit.

Anaplastic thyroid cancer (ATC) is one of the most aggressive human malignancies, with no effective treatment currently available. Previously, we identified agents active against ATC cells, both in vitro and in vivo, using quantitative high-throughput screening of 3282 clinically approved drugs and small molecules. Here, we report that combining two of these active agents, carfilzomib, a second-generation proteasome inhibitor, and CUDC-101, a histone deacetylase and multi-kinase inhibitor, results in increased, synergistic activity in ATC cells. The combination of carfilzomib and CUDC-101 synergistically inhibited cellular proliferation and caused cell death in multiple ATC cell lines harboring various driver mutations observed in human ATC tumors. This increased anti-ATC effect was associated with a synergistically enhanced G2/M cell cycle arrest and increased caspase 3/7 activity induced by the drug combination. Mechanistically, treatment with carfilzomib and CUDC-101 increased p21 expression and poly (ADP-ribose) polymerase protein cleavage. Our results suggest that combining carfilzomib and CUDC-101 would offer an effective therapeutic strategy to treat ATC.

Background: The BRAF(V600E) mutation is the most common somatic mutation in thyroid cancer. The mechanism associated with BRAF-mutant tumor aggressiveness remains unclear. Lysyl oxidase (LOX) is highly expressed in aggressive thyroid cancers, and involved in cancer metastasis. The objective was to determine whether LOX mediates the effect of the activated MAPK pathway in thyroid cancer. Methods: The prognostic value of LOX and its association with mutated BRAF was analyzed in The Cancer Genome Atlas and an independent cohort. Inhibition of mutant BRAF and the MAPK pathway, and overexpression of mutant BRAF and mouse models of BRAF(V600E) were used to test the effect on LOX expression. Results: In The Cancer Genome Atlas cohort, LOX expression was higher in BRAF-mutant tumors compared to wild-type tumors (p

Purpose: Anaplastic thyroid cancer (ATC) is a rare but lethal malignancy without any effective therapy. The aim of this study is to use a high-throughput drug library screening to identify a novel therapeutic agent that targets dysregulated genes/pathways in ATC. ExperimentalDesign: We performed quantitative high-throughput screening (qHTS) in ATC cell lines using a compound library of 3,282 drugs. Dysregulated genes in ATC were analyzed using genome-wide expression analysis and immunohistochemistry in human ATC tissue samples and ATC cell lines. In vitro and in vivo studies were performed for determining drug activity, effectiveness of targeting, and the mechanism of action. Results: qHTS identified 100 active compounds in three ATC cell lines. One of the most active agents was the first-in-class survivin inhibitor YM155. Genome-wide expression analysis and immunohistochemistry showed overexpression of survivin in human ATC tissue samples, and survivin was highly expressed in all ATC cell lines tested. YM155 significantly inhibited ATC cellular proliferation. Mechanistically, YM155 inhibited survivin expression in ATC cells. Furthermore, YM155 treatment reduced claspin expression, which was associated with S-phase arrest in ATC cells. In vivo, YM155 significantly inhibited growth and metastases and prolonged survival. Conclusions: Our data show that YM155 is a promising anticancer agent for ATC and that its target, survivin, is overexpressed in ATC. Our findings support the use of YM155 in clinical trials as a therapeutic option in advanced and metastatic ATC. Clin Cancer Res; 21(18); 4123–32. ©2015 AACR.

// Lisa Zhang 1 , Yaqin Zhang 2 , Amit Mehta 1, 3 , Myriem Boufraqech 1 , Sean Davis 4 , Jing Wang 5 , Ze Tian 5 , Zhiya Yu 6 , Matthew B. Boxer 2 , Jeffrey A. Kiefer 7 , John A. Copland 8 , Robert C. Smallridge 8, 9 , Zhuyin Li 2 , Min Shen 2 , Electron Kebebew 1 1 Endocrine Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA 2 Division of Pre-Clinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, USA 3 Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA 4 Cancer Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA 5 Curis, Inc., Translational Science MA, USA 6 Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA 7 Division of Information Sciences, Translational Genomics Research Institute, Phoenix, AZ, USA 8 Department of Cancer Biology, Mayo Clinic, Jacksonville, FL, USA 9 Endocrinology Division, Internal Medicine Department, Mayo Clinic, Jacksonville, FL, USA Correspondence to: Electron Kebebew, e-mail: kebebewe@mail.nih.gov Keywords: CUDC-101, anaplastic thyroid cancer, quantitative high-throughput screening, EGFR, HDAC Received: January 26, 2015 Accepted: January 31, 2015 Published: April 13, 2015 ABSTRACT Anaplastic thyroid cancer (ATC) is one of the most lethal human malignancies that currently has no effective therapy. We performed quantitative high-throughput screening (qHTS) in three ATC cell lines using 3,282 clinically approved drugs and drug candidates, and identified 100 active agents. Enrichment analysis of active compounds showed that inhibitors of EGFR and histone deacetylase (HDAC) were most active. Of these, the first-in-class dual inhibitor of EGFR, HER2 and HDACs, CUDC-101, had higher efficacy and lower IC 50 than established drugs. We validated that CUDC-101 inhibited cellular proliferation and resulted in cell death by inducing cell cycle arrest and caspase-dependent apoptosis. CUDC-101 also inhibited cellular migration in vitro . Mechanistically, CUDC-101 inhibited MAPK signaling and histone deacetylation in ATC cell lines with multiple driver mutations present in human ATC. The anticancer effect of CUDC-101 was associated with increased expression of p21 and E-cadherin, and reduced expression of survivin, XIAP, β-catenin, N-cadherin, and vimentin. In an in vivo mouse model of metastatic ATC, CUDC-101 inhibited tumor growth and metastases, and significantly prolonged survival. Response to CUDC-101 treatment in vivo was associated with increased histone 3 acetylation and reduced survivin nuclear expression. Our findings provide a preclinical basis to evaluate CUDC-101 therapy in ATC.

Anaplastic thyroid cancer (ATC) is rare but it is one of the most lethal human malignancies with no effective therapy. There is a pressing need to identify new therapeutic agents for ATC. We performed quantitative high-throughput screening (qHTS) in ATC cell lines using a compound library of 3,282 drugs. qHTS identified 100 pan-active agents. Enrichment analysis of qHTS data showed drugs targeting mTOR were one of the most active drug categories, and Torin2 showed the highest efficacy. We found mTOR to be upregulated in ATC. Treatment of multiple ATC cell lines with Torin2 showed significant dose-dependent inhibition of cellular proliferation with caspase-dependent apoptosis and G1/S phase arrest. Torin2 inhibited cellular migration and inhibited the phosphorylation of key effectors of the mTOR-pathway (AKT, 4E-BP1 and 70S6K), as well as claspin and survivin expression, regulators of cell cycle and apoptosis. In our in vivo mouse model of metastatic ATC, Torin2 inhibited tumor growth and metastasis and significantly prolonged overall survival. Our findings suggest that Torin2 is a promising agent for ATC therapy and that it effectively targets upregulated pathways in human ATC.

Purpose: There is currently no standard therapy for anaplastic thyroid cancer (ATC) and poorly differentiated thyroid cancer (PDTC), which account for two-thirds of thyroid cancer–related deaths. Driver mutations in the PI3K/AKT and RAF/RAS/MEK/ERK pathways are common in ATC and PDTC. Histone deacetylases (HDAC) regulate cancer initiation and progression. Our aim was to determine the therapeutic efficacy of simultaneously targeting these pathways in thyroid cancer with a single agent and to evaluate biomarkers of treatment response. Experimental Design: CUDC-907 is a first-in-class compound, functioning as a dual inhibitor of HDACs and the PI3K/AKT pathway. We investigated its antiproliferative effect in vitro and in vivo. Results: CUDC-907 significantly inhibited cellular proliferation in thyroid cancer cell lines, induced G2–M arrest with decreased levels of the checkpoint regulators cyclin B1, AURKA, AURKB, PLK1, and increased p21 and p27. Treatment induced apoptosis with increased caspase-3/7 activity and decreased survivin levels and decreased cellular migration and invasion. CUDC-907 treatment caused H3 hyperacetylation and decreased HDAC2 expression. HDAC2 was upregulated in ATC and other thyroid cancer histologic subtypes. CUDC-907 treatment reduced both p-AKT and p-ERK1/2 levels. Finally, CUDC-907 treatment, in a metastatic mouse model of thyroid cancer, showed significant inhibition of growth and metastases, and tumors from treated mice had decreased HDAC2 expression, suggesting that this may be a useful biomarker of response. Conclusions: Dual inhibition of HDAC and the tyrosine kinase signaling pathways with CUDC-907 is a promising treatment strategy for advanced, metastatic thyroid cancer. Clin Cancer Res; 23(17); 5044–54. ©2017 AACR.

Identification of molecular factors that promote thyroid cancer progression have important clinical implications for therapy and prognostication in patients with papillary thyroid cancer (PTC). The aim of this study was to validate and determine the function of dysregulated genes that were associated increased mortality in patients with PTC. Experiemental Design: We selected the cleavage and polyadenylation specificity factor subunit 2 (CPSF2) gene from the top 5 significantly dysregulated genes associated with PTC-associated mortality from our previous study. We used 86 PTC samples enriched for aggressive disease (recurrence and mortality) by quantitative RT-PCR (qRT-PCR). In vitro functional studies of the validated gene were performed.Decreased CPSF2 gene expression was associated with shorter disease-free survival (P = .03), large tumor size (T3 and T4) (P = .03), tumor recurrence (P.01), and mortality (P.01), independent of BRAF V600E mutation status. CPSF2 knockdown increased cellular invasion by 1.8- to 3.2-fold (P.01) and increased markers of thyroid cancer stem cells (CD44 and CD133 expression). Immunohistochemistry showed an inverse correlation between CD44 protein expression in PTC samples and CPSF2 expression.Decreased CPSF2 expression is associated with increased cellular invasion and cancer stem cell population, and more aggressive disease in PTC.

Aberrant DNA methylation is known to be a major factor in oncogenesis and cancer progression, but effects of methylation in papillary thyroid cancer (PTC) are not well defined.The objective of the study was to identify altered methylation patterns, which may be associated with PTC disease behavior.This study was a genome-wide methylation analysis of PTC.The study was conducted at the National Institutes of Health Clinical Center.PTC tissue from 51 patients were analyzed and compared with normal thyroid tissue from seven patients.CpG methylation status was assessed using advanced genome-wide methylation bead chips.Altered methylation patterns in PTC were analyzed by stage, recurrence, histological subtype of tumor, and tumor genotype.PTC is globally hypomethylated compared with normal thyroid with 2837 differentially methylated CpG sites. The follicular variant of PTC demonstrated less differential methylation with only 569 differentially methylated CpG sites. Tumors with mutations in BRAF, RET/PTC, and RAS demonstrated a 3.6-fold increase in the number of differentially methylated sites compared with wild-type tumors. The differentially methylated genes were associated with oncological pathways including cellular movement, growth, and proliferation.PTC is epigenetically distinct from the follicular variant of PTC and by gene mutation status (BRAF, RET/PTC, and RAS).

Introduction: Thyroid cancer is the most common endocrine cancer in the USA and its incidence is increasing worldwide. Thyroid fine-needle aspiration biopsy (FNA) and cytologic analysis is the most cost-effective approach to distinguish between malignant and benign thyroid nodules. However, up to 30% of thyroid FNA biopsy results are inconclusive. Areas covered: In this article, the authors provide an update on the current status and emerging approaches for improving thyroid cancer diagnosis. This review covers imaging, genetic and genomic approaches being used or in development to help distinguish between malignant and benign thyroid nodules. Expert opinion: There has been considerable progress in improving thyroid cancer diagnosis. The molecular markers analysis to avoid diagnostic surgeries seems to be promising. However, the clinical utility and accuracy of some markers reported in this review are not conclusive and need to be validated as clinical diagnostic tool.

The microRNAs (miRNAs) are small non-coding RNA comprising approximately 19–25 nucleotides. miRNAs can act as tumour suppressors or oncogenes, and aberrant expression of miRNAs has been reported in several human cancers and has been associated with cancer initiation and progression. Recent evidence suggests that miRNAs play a major role in thyroid carcinogenesis. In this review, we summarize the role of miRNAs in thyroid cancer and describe the oncogenic or tumour suppressor function of miRNAs as well as their clinical utility as prognostic or diagnostic markers in thyroid cancer.

Purpose: Epithelial-to-mesenchymal transition (EMT) is important in cancer progression and metastasis. We and others have previously reported that lysyl oxidase (LOX) is overexpressed in aggressive cancers, is associated with increased mortality, and regulates EMT. However, the mechanism by which LOX mediates EMT is unknown. In this study, we investigated the effect of LOX on mediators of EMT. Experimental Design: We used chromatin immunoprecipitation and promoter luciferase assays to determine the target gene of LOX. To determine the effects of SNAI2 in vivo, we used our metastatic anaplastic thyroid cancer (ATC) mouse model. To investigate the effects of LOX and SNAI2 on MMPs and TIMPs, protein arrays were used. Primary tumors from patients with metastatic, breast and colon cancer, and tissue array for thyroid cancer were assessed for SNAI2 and TIMP4 expression by immunohistochemistry. Results: We found that LOX knockdown decreases SNAI2 expression in cancer cell lines. Furthermore, knockdown of LOX reduced SNAI2 expression in a metastatic mouse model of thyroid cancer. We also demonstrated that LOX binds and transactivates the SNAI2 promoter. We found a direct correlation in thyroid and breast cancer samples between LOX and SNAI2 expression. To understand how LOX/SNAI2 axis mediates these effects, we performed a comprehensive analysis of MMPs/TIMPs. LOX and SNAI2 depletion reduced TIMP4 secretion. Analysis of SNAI2 and TIMP4 expression showed overexpression of both proteins in aggressive thyroid, colon, and breast tumors. Conclusions: Our findings provide new evidence that LOX regulates SNAI2 expression and that SNAI2-mediated TIMP4 secretion plays a role in cancer progression. Clin Cancer Res; 22(17); 4491–504. ©2016 AACR.

Anaplastic thyroid cancer (ATC) is one of the most aggressive human malignancies. Currently, there is no standard or effective therapy for ATC. Drug repurposing for cancer treatment is an emerging approach for identifying compounds that may have antineoplastic effects. The aim of this study was to use high-throughput drug library screening to identify and subsequently validate novel therapeutic agents with anticancer effects in ATC. We performed quantitative high-throughput screening (qHTS) in ATC cell lines (SW-1736, 8505C, and C-643), using a compound library of 3282 drugs. qHTS identified 100 compounds that were active in all three ATC cell lines. Proteasome inhibitors were one of the most active drug categories according to enrichment analysis. Of the three proteasome inhibitors screened, a second-generation proteasome inhibitor, carfilzomib, was the most active. Treatment of ATC cells with carfilzomib significantly inhibited cellular proliferation and induced G2/M cell cycle arrest and caspase-dependent apoptosis. Mechanistically, carfilzomib increased expression of p27 (CDKN1B) and decreased expression of the anti-apoptotic protein ATF4. Pretreatment with carfilzomib reducedin vivometastases (lung, bone, liver, and kidney) and disease progression, and decreased N-cadherin expression. Carfilzomib treatment of mice with established, widely metastatic disease significantly increased their survival, without significant toxicity. Our findings support the use or clinical study of carfilzomib as a therapeutic option in patients with advanced and metastatic ATC.

Background Several members of the zinc finger protein family have been recently shown to have a role in cancer initiation and progression. Zinc finger protein 367 (ZNF367) is a member of the zinc finger protein family and is expressed in embryonic or fetal erythroid tissue but is absent in normal adult tissue. Methodology/Principal Findings We show that ZNF367 is overexpressed in adrenocortical carcinoma, malignant pheochromocytoma/paraganglioma and thyroid cancer as compared to normal tissue and benign tumors. Using both functional knockdown and ectopic overexpression in multiple cell lines, we show that ZNF367 inhibits cellular proliferation, invasion, migration, and adhesion to extracellular proteins in vitro and in vivo. Integrated gene and microRNA expression analyses showed an inverse correlation between ZNF367 and miR-195 expression. Luciferase assays demonstrated that miR-195 directly regulates ZNF367 expression and that miR-195 regulates cellular invasion. Moreover, integrin alpha 3 (ITGA3) expression was regulated by ZNF367. Conclusions/Significance Our findings taken together suggest that ZNF367 regulates cancer progression.

The expression and function of miR-145 in thyroid cancer is unknown. We evaluated the expression and function of miR-145 in thyroid cancer and its potential clinical application as a biomarker. We found that the expression of miR-145 is significantly downregulated in thyroid cancer as compared with normal. Overexpression of miR-145 in thyroid cancer cell lines resulted in: decreased cell proliferation, migration, invasion, VEGF secretion, and E-cadherin expression. miR-145 overexpression also inhibited the PI3K/Akt pathway and directly targetedAKT3.In vivo, miR-145 overexpression decreased tumor growth and metastasis in a xenograft mouse model, and VEGF secretion. miR-145 inhibition in normal primary follicular thyroid cells decreased the expression of thyroid cell differentiation markers. Analysis of indeterminate fine-needle aspiration samples showed miR-145 had a 92% negative predictive value for distinguishing benign from malignant thyroid nodules. Circulating miR-145 levels were significantly higher in patients with thyroid cancer and showed a venous gradient. Serum exosome extractions revealed that miR-145 is secreted. Our findings suggest that miR-145 is a master regulator of thyroid cancer growth, mediates its effect through the PI3K/Akt pathway, is secreted by the thyroid cancer cells, and may serve as an adjunct biomarker for thyroid cancer diagnosis.

There have been striking changes in the epidemiology of thyroid cancer worldwide with higher incidence rates, with low-risk or clinically less significant papillary thyroid cancer accounting for more than 80 % of new cases each year [1, 2]. During this change in epidemiology, our knowledge in the genetic and genomic alterations associated with thyroid cancer initiation and or progression has also expanded tremendously [3]. As precision medicine is becoming a reality for some solid malignancies, the application of new knowledge to the management of thyroid cancer is going to be imperative to precisely treat patients based on the genetics/genomics of their tumor, especially when it is found to be associated with disease behavior [4]. The study by Passon and colleagues from Italy reports new findings based on a careful analysis of 27 papillary thyroid cancer samples using high-resolution comparative genomic hybridization [5]. The investigators found that genomic amplifications were higher in high/intermediaterisk group tumors and that genomic deletions were higher in low-risk tumors based on the American Thyroid Association (ATA) risk stratification system. Several of these genomic amplifications and deletions were recurrent (occurred in more than 20 % of tumor samples) and several of the genes in the chromosomal loci with deletions have been implicated to be involved in thyroid cancer or their expression is dysregulated in cancer. The most frequent amplifications that were detected in 2q35, 4q26, and 4q34.1 contained FN1, PDE5A, and GALNTL6, respectively. The 2q35 locus is thought to be a breast cancer susceptibility locus, and FN1 expression was found to be restricted to thyroid cancer samples and absent in benign lesions [6, 7]. Interestingly, 60 % of the cases with 2q35 amplification were TNM Stage I according to the American Joint Committee on Cancer (AJCC) staging system, whereas more than 70 % were considered intermediate/high risk according to the ATA risk classification system. Although both systems include some of the same variables, the AJCC staging system also includes the patient’s age at diagnosis so that patients younger than 45 years even with lymph node and or distant metastases are considered as having only stage I/II disease. Also the ATA risk stratification system includes postoperative serum thyroglobulin level measurement. Thus, these factors likely explain the somewhat discrepant results. The amplification in 4q26 involving PDE5 was more prevalent in intermediate/highrisk cancers. Interestingly, studies have shown that tumors with high expression level of PDE5 have lower mRNA expression of differentiation markers or thyroid-specific genes (TG, TSHR, TPO, and NIS) [8]. Thus, PDE5 could be involved in thyroid cancer initiation, progression, or even radioiodine resistance. The authors also investigated the BRAF mutation status in the tumors analyzed but found no significant association with genomic amplifications or deletions. Most, but not all, studies have suggested that papillary thyroid cancers with BRAF mutations are more aggressive and that it is one of the most frequent genetic alterations in papillary thyroid cancer [3, 9]. Passon and colleague did find that 8 of the BRAF V600E mutant samples were in patients with ATA intermediate-risk papillary thyroid cancers. It would be interesting to know if the genomic deletion status in addition to BRAF mutation status could better stratify ATA low-risk from intermediate/high-risk papillary thyroid cancer or even outperform & Electron Kebebew kebebewe@mail.nih.gov

During childhood, the thyroid gland is one of the most sensitive organs to the carcinogenetic effects of ionizing radiation that may lead to papillary thyroid carcinoma (PTC) associated with RET/PTC oncogene rearrangement. Exposure to ionizing radiation induces a transient “oxidative burst” through radiolysis of water, which can cause DNA damage and mediates part of the radiation effects. H2O2 is a potent DNA-damaging agent that induces DNA double-strand breaks, and consequently, chromosomal aberrations. Irradiation by 5 Gy X-ray increased extracellular H2O2. Therefore, we investigated the implication of H2O2 in the generation of RET/PTC1 rearrangement after X-ray exposure. We developed a highly specific and sensitive nested reverse transcription-PCR method. By using the human thyroid cell line HTori-3, previously found to produce RET/PTC1 after γ-irradiation, we showed that H2O2, generated during a 5 Gy X-ray irradiation, causes DNA double-strand breaks and contributes to RET/PTC1 formation. Pretreatment of cells with catalase, a scavenger of H2O2, significantly decreased RET/PTC1 rearrangement formation. Finally, RET/PTC chromosomal rearrangement was detected in HTori-3.1 cells after exposure of cells to H2O2 (25 μmol/L), at a dose that did not affect the cell viability. This study shows for the first time that H2O2 is able to cause RET/PTC1 rearrangement in thyroid cells and consequently highlights that oxidative stress could be responsible for the occurrence of RET/PTC1 rearrangement found in thyroid lesions even in the absence of radiation exposure. Cancer Res; 70(10); 4123–32. ©2010 AACR.

Activated toll-like receptor (TLR) signaling pathway has been reported in several endocrine neoplasms and has been found to be associated with the upregulation of proinflammatory cytokines. These cytokines are widely known as critical mediators of tumorigenesis. The stimulation of antitumor immunity through the activation of the TLR pathway can lead to the inhibition of the carcinogenesis process. However, TLRs have been considered as putative therapeutic target in various human cancers. A chronic inflammation in the absence of infection induces oxidative stress, DNA damage, and tissue damage promoting tumorigenesis. Thus, TLRs can be viewed as having a double-edged sword function. Accumulating evidences show the association between over-activation of TLR and cancer progression and TLRsignaling molecules are often involved in tumor progression. For example, TLR4 expression has been described in several human cancer, including intestinal [1], breast, and prostate cancers [2, 3] and TLR3 in papillary thyroid cancer and cervical carcinoma [4]. Several studies support that TLR activation via TLR-adaptors such as MyD88 induces NFkB translocation to the nucleus. This induces proinflammatory cytokine secretion (IL6 and IL1), antiapoptotic factors (Bcl-XL, cIAP1, ABL), as well as, pro-angiogenic factors expression (VEGF). High expression of TLR3 has been reported in a papillary thyroid cancer cell line which is consistent with its overexpression in human papillary thyroid cancer in vivo [5]. As one of the main mediator of lipopolysaccharide action, the lack or overexpression of TLR4 has also been associated with aggressive follicular thyroid cancers [6]. In this issue of Endocrine, Kim et al. [7] report that single nucleotide polymorphism (SNP) in TLR10 is associated with tumor size in patients with papillary thyroid cancer. TLR-1-TLR6-TLR-10 is located on the same chromosome and forms a cluster, and thus was the rationale for the authors to analyze these three TLR SNPs. They found that only a missense SNP in TLR10 (rs11466653, Met326Thr) showed a significant association with small tumor size (\1 cm). SNPs in the TLR-1-TLR6-TLR-10 cluster have been associated with increased risk of prostate cancer [8]. Altered TLR-10 signaling in papillary thyroid cancer may be involved in the interplay between inflammation and tumorigenesis. For example, it has been shown by several groups that IL-6, IL-1, and VEGFA are important cytokines in thyroid carcinogenesis [9–11]. Most importantly, common somatic mutations in papillary thyroid cancer such us RET/PTC rearrangements and BRAF are involved in inflammation, where they have been shown to be involved in inflammatory response and in the infiltration of innate suppressive inflammatory cells in papillary thyroid cancer [12]. Thus, a cooperation of dysregulated TLR signaling pathway in the inflammatory response of microcarcinoma seems plausible. Based on our current knowledge, TLR-10 expression seems to be restricted to immune cells like B cells or dendritic cells. Lymphocytic and dendritic cell infiltration is higher in patients with papillary thyroid cancer as compared to those with benign thyroid tumors [13]. Thus, the missense TLR-10 SNP reported by Kim and colleagues may influence the amount of lymphocytic infiltration in patients with small papillary thyroid cancer. Although lymph node metastasis and multifocality are important M. Boufraqech C. Fassassi E. Kebebew (&) Endocrine Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 10 Center Drive, Room 4-5952, Bethesda, MD 20892, USA e-mail: kebebewe@mail.nih.gov