COX-2 is induced by HGF stimulation in Met-positive thyroid papillary carcinoma cells and is involved in tumour invasiveness

Crosstalk between Thyroid Carcinoma and Tumor-Correlated Immune Cells in the Tumor Microenvironment

Thyroid cancer (TC) is the most common malignancy in the endocrine system. Although most TC can achieve a desirable prognosis, some refractory thyroid carcinomas, including radioiodine-refractory differentiated thyroid cancer, as well as anaplastic thyroid carcinoma, face a myriad of difficulties in clinical treatment. These types of tumors contribute to the majority of TC deaths due to limited initial therapy, recurrence, and metastasis of the tumor and tumor resistance to current clinically targeted drugs, which ultimately lead to treatment failure. At present, a growing number of studies have demonstrated crosstalk between TC and tumor-associated immune cells, which affects tumor deterioration and metastasis through distinct signal transduction or receptor activation. Current immunotherapy focuses primarily on cutting off the interaction between tumor cells and immune cells. Since the advent of immunotherapy, scholars have discovered targets for TC immunotherapy, which also provides new strategies for TC treatment. This review methodically and intensively summarizes the current understanding and mechanism of the crosstalk between distinct types of TC and immune cells, as well as potential immunotherapy strategies and clinical research results in the area of the tumor immune microenvironment. We aim to explore the current research advances to formulate better individualized treatment strategies for TC patients and to provide clues and references for the study of potential immune checkpoints and the development of immunotherapy technologies.

Aspirin Use Is Not Associated with Lower Thyroid Cancer Risk: A Nationwide Nested Case-Control Study

Background: While aspirin use is known to be associated with reduced incidence of various cancer types, it is unclear whether this benefit extends to thyroid cancer. We aimed to evaluate the association between aspirin use and thyroid cancer development. Methods: This nested case-control study used nationwide data from the Korean National Health Insurance Service-National Sample Cohort 2002-2015. In total, 4547 individuals with newly developed thyroid cancer were matched with 13,641 controls based on age, sex, and follow-up period. Odds ratios (ORs) and 95% confidence intervals (CIs) for thyroid cancer development according to aspirin use were analyzed using a multivariable conditional logistic regression model. Results: The number of days for which patients with thyroid cancer used aspirin (the proportions of no use, <30 days/year, 30-90 days/year, and ≥90 days/year were 93.03%, 6.51%, 0.31%, and 0.15%, respectively) was comparable with that of the controls (p = 0.371, chi-squared test). The risk of thyroid cancer development was not associated with the duration of aspirin use (ORs [CI] for aspirin use <30 days/year, 30-90 days/year, and ≥90 days/year were 1.11 [0.96-1.28], 1.01 [0.54-1.88], and 1.23 [0.50-3.06], respectively, compared with no use) after adjusting for body mass index, smoking status, hypertension, Charlson comorbidity index, and number of outpatient visits per year. In addition, subgroup analyses stratified by age, sex, and follow-up duration did not reveal any significant association between aspirin use and thyroid cancer. Conclusions: Our findings suggest that even extended aspirin use may not impact the prevention or onset of thyroid cancer.

Senescent thyrocytes and thyroid tumor cells induce M2-like macrophage polarization of human monocytes via a PGE2-dependent mechanism

BACKGROUND

Thyroid carcinoma includes several variants characterized by different biological and clinical features: from indolent microcarcinoma to undifferentiated and aggressive anaplastic carcinoma. Inflammation plays a critical role in thyroid tumors. Conditions predisposing to cancer, as well as oncogene activity, contribute to the construction of an inflammatory microenvironment that facilitates thyroid tumor progression. Moreover, oncogene-induced senescence, a mechanism tightly connected with inflammation, and able to restrain or promote cancer progression, is involved in thyroid cancer. The interactions between thyroid tumor cells and the microenvironment are not completely clarified.

METHODS

We characterize in vitro the interplay between macrophages and senescent thyrocytes and tumor-derived cell lines, modeling early and late thyroid tumor stages, respectively. Purified peripheral blood-derived human monocytes were exposed to thyroid cell-derived conditioned medium (CM) and assessed for phenotype by flow cytometry. The factors secreted by thyroid cells and macrophages were identified by gene expression analysis and ELISA. The protumoral effect of macrophages was assessed by wound healing assay on K1 thyroid tumor cells. The expression of PTGS2 and M2 markers in thyroid tumors was investigated in publicly available datasets.

RESULTS

Human monocytes exposed to CM from senescent thyrocytes and thyroid tumor cell lines undergo M2-like polarization, showing high CD206 and low MHC II markers, and upregulation of CCL17 secretion. The obtained M2-like macrophages displayed tumor-promoting activity. Among genes overexpressed in polarizing cells, we identified the prostaglandin-endoperoxide synthase enzyme (PTGS2/COX-2), which is involved in the production of prostaglandin E2 (PGE2). By using COX-2 inhibitors we demonstrated that the M2-like polarization ability of thyroid cells is related to the production of PGE2. Co-expression of PTGS2 and M2 markers is observed a significant fraction of human thyroid tumors.

CONCLUSIONS

Our results demonstrate that both senescent thyrocytes and thyroid tumor cell lines trigger M2-like macrophage polarization that is related to PGE2 secretion. This suggests that the interaction with the microenvironment occurs at both early and late thyroid tumor stages, and favors tumor progression. The co-expression of PTGS2 gene and M2 markers in human thyroid carcinoma highlights the possibility to counteract tumor growth through COX-2 inhibition.

MET overexpression and activation favors invasiveness in a model of anaplastic thyroid cancer

In thyroid cancers, MET receptor overexpression has been associated with higher risk of metastatic progression. In this study, it was shown that the anaplastic thyroid cancer (ATC)-derived TTA1 cell line overexpressed MET. By using FISH and relative quantification by qPCR, it was demonstrated that this overexpression resulted from a MET amplification with more than 20 copies. As expected, MET overexpression led to its constitutive activation and upregulated signaling towards the MAPK, PI3K/AKT, STAT3 and NF-κB pathways. Since the usual feature of MET-amplified cell lines is the "MET addiction" for their cell proliferation, the effect of the highly selective ATP competitive MET inhibitor PHA665752 was analyzed. While PHA665752 strongly inhibited the MAPK pathway, it did not reduce cell proliferation in TTA1 cells (IC₅₀ = 4100 nM). This resistance to PHA665752 of the TTA1 cell line was demonstrated to be related to EGFR-MET functional cross-talk and PI3K/AKT and NF-κB signaling. Nevertheless, PHA665752 suppressed the anchorage-independent growth capacity of the TTA1 cell line and reduced cell migration and invasion in a transwell assay. The role of activated MET in these neoplastic properties of the TTA1 cells was also proved with si-MET-RNA targeting. Thus, this work highlights the TTA1 cell line as the first model of MET amplification in an ATC cell line, which leads to MET constitutive activation and underlies its neoplastic properties. Besides being a useful model for MET inhibitors screening, the TTA1 cell line also supports the argument for searching for MET amplification in ATC, as it could have therapeutic implications.

Cyclooxygenase-2 (COX-2) gene polymorphism in patients with differentiated thyroid carcinomas in the Turkish population

Background/aim: The most common thyroid malignancies are papillary and follicular thyroid carcinomas. They account for approximately 85%-90% of all thyroid cancers. Recent studies have reported the relevance of cyclooxygenase-2 (COX-2) gene polymorphism in human carcinogenesis. The aim of this study was to investigate the relationship between thyroid carcinoma and COX-2 gene polymorphism in the Turkish population.Materials and methods: We included a total of 96 differentiated thyroid cancer patients (mean age: 46.9 ± 10.3 years; 14 males, 82 females) and 83 healthy control subjects (mean age: 46.0 ± 10.6 years; 39 males, 44 females). The frequency of -765G>C, -8473T>C, and 1195A>G gene polymorphisms in the COX-2 promoter region was investigated in thyroid cancer patients and the control group using the high-resolution melting method. Results: COX-2-765G>C and COX-2-1195A>G gene polymorphisms were similar between thyroid cancer patients and the control group. There was a statistically significant difference between COX-2-8473T>C gene polymorphism in the thyroid cancer group and the control group (P = 0.012).Conclusion: The single nucleotide gene polymorphism COX-2-8473T>C might contribute to genetic susceptibility to differentiated thyroid cancer in the Turkish population.

Hepatocyte Growth Factor/C-Met Axis in Thyroid Cancer: From Diagnostic Biomarker to Therapeutic Target

The hepatocyte growth factor (HGF)/c-met axis plays a crucial role in cancer development by promoting cellular proliferation, motility, and morphogenesis, as well as angiogenesis. Different cellular distributions of both the ligand and the receptor in benign vs malignant lesions indicate this biological system as a candidate for a diagnostic biomarker of malignancy occurring in endocrine glands, such as the thyroid and pituitary. Furthermore, the HGF/c-met expression may help to identify a subset of patients eligible for potential targeted therapies with HGF/c-met inhibitors or antagonists in thyroid tumour, as well as in other malignancies. This may be relevant for iodine-refractory cancers, the treatment of which is still a major challenge. With this in mind, HGF/c-met expression in thyroid cancer tissue may be useful for prognostic and therapeutic stratification of patients.

Thyroid Cancer and Nonsteroidal Anti-Inflammatory Drug Use: A Pooled Analysis of Patients Older Than 40 Years of Age

BACKGROUND

Cyclooxygenase (COX-2) has been associated with tumor growth and metastasis in several cancers, including thyroid cancer. For this reason, several investigators have studied COX-2 inhibitors in preclinical models of thyroid cancer and found antineoplastic effects. Thus, the primary aim of this study was to assess if the use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced incidence of thyroid cancer. A second aim of the study was to determine additional risk or protective factors for thyroid cancer.

METHODS

Three large prospective population-based studies (the NIH-AARP Diet and Health Study; the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial; and the U.S. Radiologic Technologists Study) were pooled to investigate the association between self-reported frequency of aspirin and nonaspirin NSAID use one year prior to baseline (no use, ≤ 2/week, >2-6/week, and ≥ 7/week) and subsequent risk of thyroid cancer. A Cox regression proportional hazard model was used to estimate aggregated hazard ratios (HR) adjusted for cohort, sex, race/ethnicity, weight, smoking status, and alcohol intake.

RESULTS

There were 388,577 participants in the pooled cohort, with 481 cases of thyroid cancer. No significant risk reduction was observed with regular use of nonaspirin NSAIDs (HR = 1.14 [confidence interval (CI) 0.84-1.55]), and/or regular use of aspirin (HR = 1.06 [CI 0.82-1.39]). The multivariate regression analysis confirmed as previously reported in the literature that female sex, obesity class I (body mass index [BMI] = 30-34.99 kg/m(2)), and obesity class II (BMI = 35-35.99 kg/m(2)) were independently associated with an increased thyroid cancer risk. Current smoking status and moderate and excessive alcohol use were also confirmed as independent risk factors associated with a reduced thyroid cancer risk.

CONCLUSIONS

Neither nonaspirin NSAIDs nor aspirin use is associated with a reduced risk of thyroid cancer. Women and obesity are associated with an increased risk of thyroid cancer, whereas smoking and alcohol use are associated with decreased risk of thyroid cancer.

Directed random walks and constraint programming reveal active pathways in hepatocyte growth factor signaling

An effective means to analyze mRNA expression data is to take advantage of established knowledge from pathway databases, using methods such as pathway-enrichment analyses. However, pathway databases are not case-specific and expression data could be used to infer gene-regulation patterns in the context of specific pathways. In addition, canonical pathways may not always describe the signaling mechanisms properly, because interactions can frequently occur between genes in different pathways. Relatively few methods have been proposed to date for generating and analyzing such networks, preserving the causality between gene interactions and reasoning over the qualitative logic of regulatory effects. We present an algorithm (MCWalk) integrated with a logic programming approach, to discover subgraphs in large-scale signaling networks by random walks in a fully automated pipeline. As an exemplary application, we uncover the signal transduction mechanisms in a gene interaction network describing hepatocyte growth factor-stimulated cell migration and proliferation from gene-expression measured with microarray and RT-qPCR using in-house perturbation experiments in a keratinocyte-fibroblast co-culture. The resulting subgraphs illustrate possible associations of hepatocyte growth factor receptor c-Met nodes, differentially expressed genes and cellular states. Using perturbation experiments and Answer Set programming, we are able to select those which are more consistent with the experimental data. We discover key regulator nodes by measuring the frequency with which they are traversed when connecting signaling between receptors and significantly regulated genes and predict their expression-shift consistently with the measured data. The Java implementation of MCWalk is publicly available under the MIT license at: https://bitbucket.org/akittas/biosubg.

Expression of prostaglandin E2 and EP receptors in human papillary thyroid carcinoma

The objective of the present study is to determine the role of prostaglandin E2 (PGE2) and downstream EP receptors in the development of human papillary thyroid carcinoma (PTC). A total of 90 thyroid specimens excised from patients undergoing total or subtotal thyroidectomy in the Department of General Surgery, the Fifth Affiliated Hospital of Sun Yat-sen University, China, from August 2013 to September 2014, were analyzed. The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemical analyses were employed to examine the messenger RNA (mRNA) and protein expression, respectively. The expressions and significances of cyclooxygenase-2 (COX-2), microsomal prostaglandin E synthase-1 (mPGES-1), PGE2, and EP receptors in PTC and nodular goiter were investigated. The COX-2 mRNA and protein expression level significantly increased in the PTC tissues than in the paired noncarcinoma tissues adjacent to the PTC or nodular goiter tissues. The mPGES-1 protein expression was also significantly upregulated in the PTC tissues. All the four subtypes of EP receptors (EP1-4) could express in the thyroid tissues, while only the EP4 mRNA and protein levels significantly increased in the PTC tissues. The local production of PGE2 had a higher-level expression in the PTC tissues than in the noncarcinoma thyroid tissues adjacent to the PTC lesion and the benign nodular goiter tissues. The induction of PGE2 biosynthesis as well as the overexpression of EP4 in PTC suggested that this pathway might play an important role in the carcinogenesis and progression of PTC. These observations raise the possibility that pharmacological inhibition of mPGES-1 and/or EP4 may hold therapeutic promise in this common cancer.

The Pathogenetic Role of the HGF/c-Met System in Papillary Carcinoma of the Thyroid

The MET oncogene encodes for Met protein, a trans-membrane tyrosine kinase identified as the high affinity receptor for hepatocyte growth factor (HGF). Immunohistochemical studies have demonstrated that Met protein is intensely expressed in tumor cells of >95% cases of thyroid papillary carcinoma. High density of Met protein in tumor cells is the result of increased transcription of a normal MET gene, probably due to a combination of intracellular and extracellular signals. Over-expression of Met protein is more pronounced at the invading front of the tumor and can profoundly affect the tumorigenesis of papillary carcinoma of the thyroid. In fact, Met protein-positive papillary carcinoma cells are highly responsive to hepatocyte growth factor (HGF), which is effective in stimulating tumor cell adhesion, migration and invasiveness. In addition, HGF stimulation of papillary carcinoma of the thyroid (PTC) cells causes up-regulation of COX-2 and down-regulation of CD82/KAI-1; both these molecules have a major role in controlling tumor cell invasiveness. Finally, HGF stimulation of tumor cells may significantly affect the tumor microenvironment. In fact, HGF induces tumor cells to release chemokines active in the recruitment of dendritic cells, and is involved in regulating the production of proangiogenic factors.

Immune response in thyroid cancer: widening the boundaries

The association between thyroid cancer and thyroid inflammation has been repeatedly reported and highly debated in the literature. In fact, both molecular and epidemiological data suggest that these diseases are closely related and this association reinforces that the immune system is important for thyroid cancer progression. Innate immunity is the first line of defensive response. Unlike innate immune responses, adaptive responses are highly specific to the particular antigen that induced them. Both branches of the immune system may interact in antitumor immune response. Major effector cells of the immune system that directly target thyroid cancer cells include dendritic cells, macrophages, polymorphonuclear leukocytes, mast cells, and lymphocytes. A mixture of immune cells may infiltrate thyroid cancer microenvironment and the balance of protumor and antitumor activity of these cells may be associated with prognosis. Herein, we describe some evidences that immune response may be important for thyroid cancer progression and may help us identify more aggressive tumors, sparing the vast majority of patients from costly unnecessary invasive procedures. The future trend in thyroid cancer is an individualized therapy.

Papillary carcinoma of the thyroid: high expression of COX-2 and low expression of KAI-1/CD82 are associated with increased tumor invasiveness

BACKGROUND

We have previously demonstrated that expression of COX-2 is upregulated by hepatocyte growth factor in thyroid papillary carcinoma (TPC) cells and is associated with increased invasiveness of tumor cells. COX-2 upregulation was associated with downregulation of KAI-1/CD82, a metastasis suppressor molecule that has been associated with the metastatic potential of several solid tumors. In the present study, we have investigated the possibility that downregulation of KAI-1/CD82 may contribute to the invasiveness of papillary carcinoma cells.

METHODS

Expression of KAI-1/CD82 and its relation to COX-2 levels were investigated in 6 primary cultures of TPC, in 2 tumor cell lines (TPC-1 and K1), and in 55 tumor samples of TPC. The biological role of KAI-1/CD82 in regulating tumor invasiveness was investigated in TPC cell lines and primary cultures transfected with a pCDNA3.1/Hygro.KAI-1; transfected cells were tested in functional studies of cell migration and invasiveness. Finally, the role of KAI-1/CD82 in influencing TPC metastasis was investigated in vivo using nu/nu mice injected with K1-transfected cells.

RESULTS

We provide evidence that COX-2 and KAI-1/CD82 are inversely regulated in TPC primary cultures and in TPC-1 tumor cells. In fact, inhibition of COX-2 with NS398 is associated with a 2-9-fold upregulation of KAI-1/CD82 RNA. Moreover, a possible relation between COX-2 and KAI-1/CD82 was confirmed by the presence of a statistically significant inverse correlation in the expression of the two genes in 55 tumor samples of TPC (r = -0.513; p = 0.001). In 36 of 55 cases, tumor areas contained lower levels of KAI-1/CD82 RNA as compared with the corresponding normal tissue. Low expression of KAI-1/CD82 RNA in the tumor area was associated with extrathyroid extension of the disease in 16 of 19 cases (p < 0.04) and with lymph node metastasis in 11 of 14 cases (not significant). KAI-1/CD82 re-expression in tumor cells was associated with a significant decrease in their migratory (50-76% reduction) and invasive (46-65% reduction) capacity, even after hepatocyte growth factor stimulation. Finally, nu/nu mice injected with KAI-1/CD82-transfected K1 TPC cells developed fewer and smaller metastasis as compared with mice injected with vector-transfected K1 cells (p=0.016).

CONCLUSION

Our findings raise the possibility that downregulation of KAI-1/CD82 in TPC cells is one of the molecular mechanisms regulating their invasive and metastatic potential.

Treatment with the vascular disruptive agent OXi4503 induces an immediate and widespread epithelial to mesenchymal transition in the surviving tumor

Epithelial to mesenchymal transition (EMT) is considered an important mechanism in tumor resistance to drug treatments; however, in vivo observation of this process has been limited. In this study we demonstrated an immediate and widespread EMT involving all surviving tumor cells following treatment of a mouse model of colorectal liver metastases with the vascular disruptive agent OXi4503. EMT was characterized by significant downregulation of E-cadherin, relocation and nuclear accumulation of β-catenin as well as significant upregulation of ZEB1 and vimentin. Concomitantly, significant temporal upregulation in hypoxia and the pro-angiogenic growth factors hypoxia-inducible factor 1-alpha, hepatocyte growth factor, vascular endothelial growth factor and transforming growth factor-beta were seen within the surviving tumor. The process of EMT was transient and by 5 days after treatment tumor cell reversion to epithelial morphology was evident. This reversal, termed mesenchymal to epithelial transition (MET) is a process implicated in the development of new metastases but has not been observed in vivo histologically. Similar EMT changes were observed in response to other antitumor treatments including chemotherapy, thermal ablation, and antiangiogenic treatments in our mouse colorectal metastasis model and in a murine orthotopic breast cancer model after OXi4503 treatment. These results suggest that EMT may be an early mechanism adopted by tumors in response to injury and hypoxic stress, such that inhibition of EMT in combination with other therapies could play a significant role in future cancer therapy.

Spatial morphological and molecular differences within solid tumors may contribute to the failure of vascular disruptive agent treatments

Background

Treatment of solid tumors with vascular disrupting agent OXi4503 results in over 90% tumor destruction. However, a thin rim of viable cells persists in the tumor periphery following treatment, contributing to subsequent recurrence. This study investigates inherent differences in the microenvironment of the tumor periphery that contribute to treatment resistance.

Methods

Using a murine colorectal liver metastases model, spatial morphological and molecular differences within the periphery and the center of the tumor that may account for differences in resistance to OXi4503 treatment were investigated. H&E staining and immunostaining were used to examine vessel maturity and stability, hypoxia and HIF1α levels, accumulation of immune cells, expression of proangiogenic factors/receptors (VEGF, TGF-β, b-FGF, and AT1R) and expression of EMT markers (ZEB1, vimentin, E-cadherin and β-catenin) in the periphery and center of established tumors. The effects of OXi4503 on tumor vessels and cell kinetics were also investigated.

Results

Significant differences were found between tumor periphery and central regions, including association of the periphery with mature vessels, higher accumulation of immune cells, increased growth factor expression, minimal levels of hypoxia and increased evidence of EMT. OXi4503 treatment resulted in collapse of vessels in the tumor center; however vasculature in the periphery remained patent. Similarly, tumor apoptosis and proliferation were differentially modulated between centre and periphery after treatment.

Conclusions

The molecular and morphological differences between tumor periphery and center may account for the observed differential resistance to OXi4503 treatment and could provide targets for drug development to totally eliminate metastases.

Prostaglandin synthases influence thyroid follicular cell proliferation but not carcinogenesis in rats initiated with N-bis(2-hydroxypropyl)nitrosamine

To clarify roles of prostaglandin synthases in rat thyroid follicular carcinogenesis, effects of an antithyroid agent, sulfadimethoxine (SDM), and two prostaglandin H synthase (COX) inhibitors, indomethacin and nimesulide, on prostaglandin synthase expression, follicular cell proliferation, and tumor induction in thyroids of rats with or without N-bis(2-hydroxypropyl)nitrosamine (DHPN) initiation were examined. In experiment 1, F344 male rats were allowed free access to drinking water containing SDM (0.1%), SDM + indomethacin (0.0025% in diet), or SDM + nimesulide (0.04% in diet) for 4 weeks. Both COX inhibitors suppressed goitrogenic activity of SDM, but they did not significantly affect microsomal prostaglandin E synthase-2 (mPGES-2) expression levels enhanced by SDM. In experiment 2, all rats received an injection of DHPN (2800 mg/kg body weight), and starting 1 week later, they were treated as in experiment 1 for 4 or 10 weeks. Cell proliferation was suppressed or showed a tendency for suppression by the COX inhibitors in the follicular preneoplastic/neoplastic lesions and surrounding parenchyma, and this was obviously thyroid stimulating hormone independent at least at week 4. However, neither of the COX inhibitors altered the incidence or multiplicity of preneoplastic/neoplastic lesions. Immunohistochemistry revealed significant reduction and elevation of COX-2 and mPGES-2 expression, respectively, in the lesions, but these were also not changed by the COX inhibitors. These results suggest that COX-2 and PGES, and in turn PGE(2), might play important roles in follicular cell proliferation but do not affect tumor induction in this rat thyroid carcinogenesis model. Further studies are needed to clarify the significance of the reduction of COX-2 expression in preneoplastic/neoplastic lesions.

PGE(2)-driven induction and maintenance of cancer-associated myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) are critical mediators of tumor-associated immune suppression, with their numbers and activity strongly increased in most human cancers and animal models. MDSCs suppress anti-tumor immunity through multiple mechanisms, including the manipulation of arginine and tryptophan metabolism by such factors as arginase (Arg), inducible nitric oxide synthase (iNOS/NOS2), and indoleamine-2,3-dioxygenase (IDO). Prostaglandin E(2) (PGE(2)), a mediator of chronic inflammation and tumor progression, has emerged as a key molecule in MDSC biology. PGE(2) promotes MDSC development and their induction by additional factors, directly suppresses T cell immune responses and participates in the induction of other MDSC-associated suppressive factors, including Arg, iNOS and IDO. It further promotes MDSC recruitment to tumor environments through the local induction of CXCL12/SDF-1 and the induction and stabilization of the CXCL12 receptor, CXCR4, on tumor-associated MDSCs. The establishment of a positive feedback loop between PGE(2) and cyclooxygenase 2 (COX-2), the key regulator of PGE(2) synthesis, stabilizes the MDSC phenotype and is required for their suppressive function. The central role of PGE(2) in MDSC biology provides for a feasible target for counteracting MDSC-mediated immune suppression in cancer.

BRAFV600E mutation in papillary thyroid carcinoma: a potential target for therapy?

This article reviews the therapeutic significance of the close genotype-phenotype association in papillary thyroid carcinoma, namely regarding the association between genetic alterations in RET, BRAF or RAS genes and the histopathological variants of papillary thyroid carcinoma. Based upon the aforementioned review on morphology and molecular pathology, the most recent prognostic and therapeutic data are reviewed and the role of targeted therapies, namely those interfering with BRAF-activated pathways are discussed, which may play a role in the treatment of patients with papillary thyroid carcinoma unresponsive to radioactive iodine.