BRAF mutation associated with other genetic events identifies a subset of aggressive papillary thyroid carcinoma

Fusion Oncogenes in Patients With Locally Advanced or Distant Metastatic Differentiated Thyroid Cancer

CONTEXT

Fusion oncogenes are involved in the underlying pathology of advanced differentiated thyroid cancer (DTC), and even the cause of radioactive iodine (RAI)-refractoriness.

OBJECTIVE

We aimed to investigation between fusion oncogenes and clinicopathological characteristics involving a large-scale cohort of patients with advanced DTC.

METHODS

We collected 278 tumor samples from patients with locally advanced (N1b or T4) or distant metastatic DTC. Targeted next-generation sequencing with a 26-gene ThyroLead panel was performed on these samples.

RESULTS

Fusion oncogenes accounted for 29.86% of the samples (72 rearrangement during transfection (RET) fusions, 7 neurotrophic tropomyosin receptor kinase (NTRK) fusions, 4 anaplastic lymphoma kinase (ALK) fusions) and occurred more frequently in pediatric patients than in their adult counterparts (P = .003, OR 2.411, 95% CI 1.329-4.311) in our cohort. DTCs with fusion oncogenes appeared to have a more advanced American Joint Committee on Cancer (AJCC)_N and AJCC_M stage (P = .0002, OR 15.47, 95% CI 2.54-160.9, and P = .016, OR 2.35, 95% CI 1.18-4.81) than those without. DTCs with fusion oncogenes were associated with pediatric radioactive iodine (RAI) refractoriness compared with those without fusion oncogenes (P = .017, OR 4.85, 95% CI 1.29-15.19). However, in adult DTCs, those with fusion oncogenes were less likely to be associated with RAI refractoriness than those without (P = .029, OR 0.50, 95% CI 0.27-0.95), owing to a high occurrence of the TERT mutation, which was the most prominent genetic risk factor for RAI refractoriness in multivariate logistic regression analysis (P < .001, OR 7.36, 95% CI 3.14-17.27).

CONCLUSION

Fusion oncogenes were more prevalent in pediatric DTCs than in their adult counterparts and were associated with pediatric RAI refractoriness, while in adult DTCs, TERT mutation was the dominant genetic contributor to RAI refractoriness rather than fusion oncogenes.

Harnessing Immunity to Treat Advanced Thyroid Cancer

The incidence of thyroid cancer (TC) has increased over the past 30 years. Although differentiated thyroid cancer (DTC) has a good prognosis in most patients undergoing total thyroidectomy followed by radioiodine therapy (RAI), 5-10% of patients develop metastasis. Anaplastic thyroid cancer (ATC) has a low survival rate and few effective treatments have been available to date. Recently, tyrosine kinase inhibitors (TKIs) have been successfully applied to RAI-resistant or non-responsive TC to suppress the disease. However, TC eventually develops resistance to TKIs. Immunotherapy is a promising treatment for TC, the majority of which is considered an immune-hot malignancy. Immune suppression by TC cells and immune-suppressing cells, including tumor-associated macrophages, myeloid-derived suppressor cells, and regulatory T cells, is complex and dynamic. Negative immune checkpoints, cytokines, vascular endothelial growth factors (VEGF), and indoleamine 2,3-dioxygenase 1 (IDO1) suppress antitumor T cells. Basic and translational advances in immune checkpoint inhibitors (ICIs), molecule-targeted therapy, tumor-specific immunotherapy, and their combinations have enabled us to overcome immune suppression and activate antitumor immune cells. This review summarizes current findings regarding the immune microenvironment, immunosuppression, immunological targets, and immunotherapy for TC and highlights the potential efficacy of immunotherapy.

Integrated analysis of tumor microenvironment features to establish a diagnostic model for papillary thyroid cancer using bulk and single-cell RNA sequencing technology

BACKGROUND

Characterizing tumor microenvironment using single-cell RNA sequencing has been a promising strategy for cancer diagnosis and treatment. However, a few studies have focused on diagnosing papillary thyroid cancer (PTC) through this technology. Therefore, our study explored tumor microenvironment (TME) features and identified potential biomarkers to establish a diagnostic model for papillary thyroid cancer.

METHODS

The cell types were identified using the markers from the CellMarker database and published research. The CellChat package was conducted to analyze the cell-cell interaction. The SCEVAN package was used to identify malignant thyroid cells. The SCP package was used to perform multiple single-cell downstream analyses, such as GSEA analysis, enrichment analysis, pseudotime trajectory analysis, and differential expression analysis. The diagnostic model of PTC was estimated using the calibration curves, receiver operating characteristic curves, and decision curve analysis. RT-qPCR was performed to validate the expression of candidate genes in human papillary thyroid samples.

RESULTS

Eight cell types were identified in the scRNA-seq dataset by published cell markers. Extensive cell-cell interactions like FN1/ITGB1 existed in PTC tissues. We identified 26 critical genes related to PTC progression. Further, eight subgroups of PTC tumor cells were identified and exhibited high heterogeneity. The MDK/LRP1, MDK/ALK, GAS6/MERTK, and GAS6/AXL were identified as potential ligand-receptor pairs involved in the interactions between fibroblasts/endothelial cells and tumor cells. Eventually, the diagnostic model constructed by TRPC5, TENM1, NELL2, DMD, SLC35F3, and AUTS2 showed a good efficiency for distinguishing the PTC and normal tissues.

CONCLUSIONS

Our study comprehensively characterized the tumor microenvironment in papillary thyroid cancer. Through combined analysis with bulk RNA-seq, six potential diagnostic biomarkers were identified and validated. The diagnostic model we constructed was a promising tool for PTC diagnosis. Our findings provide new insights into the heterogeneity of thyroid cancer and the theoretical basis for diagnosing thyroid cancer.

Correlation between low expression of protein disulfide isomerase A3 and lymph node metastasis in papillary thyroid carcinoma and poor prognosis: a clinicopathological study of 1,139 cases with long-term follow-up

The incidence of papillary thyroid carcinoma (PTC) is increasing worldwide. The biomarkers to identify aggressive types of PTC are limited, illustrating the need to establish reliable novel biomarkers. Protein disulfide isomerase A3 (PDIA3) is a chaperone protein that modulates the folding of newly synthesized glycoproteins and stress-responsive proteins in the endoplasmic reticulum. Although the role of PDIA3 in various cancers such as breast, uterine cervix, head and neck, and gastrointestinal tract has been examined, its expression in thyroid cancer has not been reported. We retrospectively reviewed accumulated data with long-term follow-up of 1,139 PTC patients, and investigated the correlation between immunohistochemical expression of PDIA3 in PTC patients and clinicopathological features and prognosis. PDIA3 expression was significantly lower in PTCs compared to normal thyroid tissues (NTT; n = 80, p = 0.002). In PTCs, correlation between low PDIA3 expression and lymph node metastasis (p = 0.018) and the number of positive nodes (p = 0.004) was observed. Patients with low PDIA3 expression exhibited worse cause-specific survival compared to those with high PDIA3 expression (p = 0.013). Our findings indicate that low PDIA3 expression is related to poor clinical outcome in PTC patients, and that PDIA3 may potentially be a novel ancillary biomarker. Further clarification of the biological role of PDIA3 in PTC is warranted for the future clinical application.

Putative homeostatic role of cancer driver mutations

Somatic mutations have traditionally been associated with cancer, yet more recently, it was realized that they also appear in nontransformed cells beginning in early life. Remarkably, some of these mutations, commonly viewed as cancer driver mutations, are widely spread among cells of noncancerous tissues, sometimes affecting the majority of the tissue cells. This spreading process intensifies upon aging or exposure to extrinsic insults, such as UV irradiation, inhaling smoke, and inflammatory cues. Whereas classic driver mutations in normal cells are mostly viewed as a first step in the carcinogenesis process, here, we speculate that in certain states, they can play beneficial homeostatic roles while confronting stress and aging tissue repair.

Correlation of the Expression of BRAF V600E Mutation With Various Phenotypic Expressions of Thyroid Neoplasms

Aims We aimed to assess the incidence of the BRAF V600E mutation in thyroid neoplasms at a tertiary care center and its association with various phenotypic features. Methods and material We included all cases diagnosed as thyroid neoplasm in the past decade at the Department of Pathology of our institute and obtained their clinical details from the medical records department of the institute after obtaining permission from the authorities and due International Human Epigenome Consortium clearance. We included data on age, sex, clinical presentation, hormone status, and T and N status of the malignant neoplasms. Hematoxylin and eosin (H&E) slides of all cases were evaluated for the type of neoplasm, nuclear features, invasion into the capsule and vascular spaces, extrathyroidal extension, lymph node metastases, mitoses, necrosis, and presence/absence of amyloid. Paraffin blocks of sections with high tumor density and less normal tissue were chosen for evaluation after H&E staining. The slides showing tumors with large areas of hemorrhage, cystic change, or necrosis were excluded. Two primers were used to amplify a 339-bp fragment containing the V600E mutation in exon 15 of BRAF. Tissues were prepared from formalin-fixed paraffin-embedded (FFPE) blocks, and DNA was isolated using a standard protocol BRAF NF and BRAF NR Primer Standardized Protocol For FFPE Tissue DNA. Percentages and tables have been used for data presentation. Results Among 47 identified cases, 14 were positive for the BRAF V600E mutation and had papillary carcinoma (n = 9) or follicular neoplasms (n = 5; follicular adenoma, n = 3; follicular carcinoma, n = 2). In the BRAF-positive papillary carcinomas, five cases were aged 20-30 years, eight were female, eight (88.88%) were euthyroid, and one was hypothyroid. Furthermore, 55.55% (5/9 cases) of BRAF-positive cases were stage I, 33.3% (3/9 cases) were stage II, and 0.02% (1/9 cases) were stage III. Conclusions In our cohort, 31% of cases of papillary thyroid carcinoma (PTC) and 18.72% of follicular neoplasms expressed the BRAF V600E mutation. BRAF V600E mutation-positive papillary thyroid carcinomas consistently showed all characteristic nuclear features, such as nuclear crowding, overlapping, and grooves. Considering the greater prevalence in the younger age group, the importance of mutation surveillance in PTCs for a total thyroidectomy may be warranted in mutation-positive patients.

The Genomic Landscape of Thyroid Cancer Tumourigenesis and Implications for Immunotherapy

Thyroid cancer is the most prevalent endocrine malignancy that comprises mostly indolent differentiated cancers (DTCs) and less frequently aggressive poorly differentiated (PDTC) or anaplastic cancers (ATCs) with high mortality. Utilisation of next-generation sequencing (NGS) and advanced sequencing data analysis can aid in understanding the multi-step progression model in the development of thyroid cancers and their metastatic potential at a molecular level, promoting a targeted approach to further research and development of targeted treatment options including immunotherapy, especially for the aggressive variants. Tumour initiation and progression in thyroid cancer occurs through constitutional activation of the mitogen-activated protein kinase (MAPK) pathway through mutations in BRAF, RAS, mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway and/or receptor tyrosine kinase fusions/translocations, and other genetic aberrations acquired in a stepwise manner. This review provides a summary of the recent genetic aberrations implicated in the development and progression of thyroid cancer and implications for immunotherapy.

Clinicopathological features and immunohistochemical utility of NTRK-, ALK-, and ROS1-rearranged papillary thyroid carcinomas and anaplastic thyroid carcinomas

NTRK1/3, ALK, and ROS1 translocations have been reported in a minor subset of papillary thyroid carcinomas (PTCs). We aimed to elucidate the prevalence and clinicopathological characteristics of these gene rearrangements and the utility of immunohistochemistry (IHC) in PTC and anaplastic thyroid carcinoma (ATC). We screened nonradiation-exposed cases of 307 PTCs and 16 ATCs by IHC for pan-Trk, ALK, and ROS1, followed by fluorescence in situ hybridization (FISH). In the PTC group, IHC for pan-Trk, ALK, and ROS1 was positive in 18 cases (5.9%), 1 case (0.3%), and 12 cases (3.9%), respectively. Among the pan-Trk IHC-positive cases (n = 18), 2 cases (11.1%; 0.7% of all PTCs) had NTRK1 or NTRK3 gene rearrangement with conventional PTC histology. The ALK IHC-positive case (n = 1) was the follicular variant of PTC with consistent ALK gene rearrangement. ROS1 gene rearrangement was not detectable in the ROS1 IHC-positive PTCs (0/12) by FISH. Most (approximately 70%) of the pan-Trk or ROS1 IHC-positive/FISH-negative cases had BRAF gene mutation with conventional PTC morphology. In the ATC group, neither ALK nor ROS1 IHC was positive, whereas pan-Trk IHC was positive in 1 case (6.3%) in which NTRK1 gene rearrangement was confirmed by FISH. These results suggest that NTRK, ALK, and ROS1 rearrangements are rare molecular events in nonradiation-exposed Japanese patients with PTC and ATC. Although IHC is not an entirely specific surrogate for these abnormalities and does not serve as a stand-alone companion diagnosis, the combined use of IHC and molecular testing may be helpful for determining promising therapeutic strategies with tyrosine kinase inhibitors.

Acquired Secondary RAS Mutation in BRAFV600E-Mutated Thyroid Cancer Patients Treated with BRAF Inhibitors

Background: The BRAF^V600E mutation is the most common driver mutation in papillary thyroid cancer (PTC) and anaplastic thyroid cancer (ATC). This mutation is considered actionable and, for BRAF^V600E-mutated ATC, a BRAF inhibitor (dabrafenib) in combination with an MEK inhibitor (trametinib) is FDA approved. BRAF inhibitors have also shown efficacy in BRAF^V600E-mutated PTC. However, as with all targeted therapies, resistance to these drugs eventually develops. It is essential that we understand the mechanisms of resistance to the BRAF inhibitors in thyroid cancer to develop future strategies to effectively treat these patients and improve survival. Patients: Herein, we describe four patients with thyroid cancer treated with selective BRAF inhibitors, who developed a RAS mutation in addition to the BRAF^V600E mutation at progression. Results: Patients 1 and 3 acquired a KRAS^G12V mutation in the progressive tumor, patient 2 acquired a NRAS^Q61K mutation in a progressive lymph node, and patient 4 acquired NRAS^G13D mutation on liquid biopsy performed at the time of radiographic disease progression. Conclusion: Similar to the melanoma experience, the emergence of RAS mutations appears to act as a mechanism of resistance to BRAF inhibitors in thyroid cancers.

Highly Sensitive and Specific Molecular Test for Mutations in the Diagnosis of Thyroid Nodules: A Prospective Study of BRAF-Prevalent Population

Molecular testing offers more objective information in the diagnosis and personalized decision making for thyroid nodules. In Korea, as the BRAF V600E mutation is detected in 70–80% of thyroid cancer specimens, its testing in fine-needle aspiration (FNA) cytology specimens alone has been used for the differential diagnosis of thyroid nodules until now. Thus, we aimed to develop a mutation panel to detect not only BRAF V600E, but also other common genetic alterations in thyroid cancer and to evaluate the diagnostic accuracy of the mutation panel for thyroid nodules in Korea. For this prospective study, FNA specimens of 430 nodules were obtained from patients who underwent thyroid surgery for thyroid nodules. A molecular test was devised using real-time PCR to detect common genetic alterations in thyroid cancer, including BRAF, N-, H-, and K-RAS mutations and rearrangements of RET/PTC and PAX8/PPARr. Positive results for the mutation panel were confirmed by sequencing. Among the 430 FNA specimens, genetic alterations were detected in 293 cases (68%). BRAF V600E (240 of 347 cases, 69%) was the most prevalent mutation in thyroid cancer. The RAS mutation was most prevalently detected for indeterminate cytology. Among the 293 mutation-positive cases, 287 (98%) were diagnosed as cancer. The combination of molecular testing and cytology improved sensitivity from 72% (cytology alone) to 89% (combination), with a specificity of 93%. We verified the excellent diagnostic performance of the mutation panel applicable for clinical practice in Korea. A plan has been devised to validate its performance using independent FNA specimens.

MiR-221/222 promote migration and invasion, and inhibit autophagy and apoptosis by modulating ATG10 in aggressive papillary thyroid carcinoma

MicroRNA (miRNA) has been reported to exert important functions in papillary thyroid carcinomas (PTC). However, the role of miRNA in aggressive PTC (APTC) remains unclear. Here, we investigated the diagnostic potentials and mechanisms of miR-221/222 in APTC. Results showed that miR-221/222 were markedly up-regulated in PTC, compared with the adjacent normal tissue (ANT). A high expression of miR-221/222 were associated with a primary tumor, regional lymph node, and distant metastasis (TNM) stage, multicentricity, lymph node metastasis, and extra-thyroidal extension. Receiver operating characteristic (ROC) curve analysis indicated that miR-221/222 could be used as APTC diagnostic markers. Moreover, miR-221/222 tremendously promoted migration and invasion and inhibited apoptosis and autophagy in PTC cells. A luciferase assay showed that miR-221/222 inhibited the fluorescent activity of autophagy-related protein 10 (ATG10). Furthermore, miR-221/222 decreased ATG10 mRNA and protein levels. Silencing of ATG10 significantly abrogated the effect of miR-221/222 on apoptosis and autophagy. We suggested that miR-221/222 can promote migration and invasion, and inhibit autophagy and apoptosis by targeting ATG10 in APTC.

BRAF and KRAS mutations in papillary thyroid carcinoma in the United Arab Emirates

Background

Papillary thyroid carcinoma (PTC) is the most common malignant thyroid neoplasm comprising 80–90% of all thyroid malignancies. Molecular changes in thyroid follicular cells are likely associated with the development of PTC. Mutations in serine/threonine-protein kinase (BRAF) and Rat sarcoma viral oncogene homolog (RAS) are commonly seen in PTC.

Methods

In total, 90 cases of PTC are randomly selected from archive paraffin blocks and 10μm sections were cut and processed for DNA extraction. BRAF^V600E mutation and 8 types of KRAS mutations were investigated using Real Time PCR.

Results

BRAF^V600E mutation was identified in 46% of PTC while KRAS mutations were seen in 11% of PTC. There was significant correlation between BRAF^V600E mutation and PTC larger than 5cm in diameter, positive surgical margin and lymph node metastasis. BRAF^V600E mutation was significantly higher in patients with less than 55-year of age than those more than 55-year of age. BRAF^V600E mutation was significantly higher in patients with family history of thyroid cancer than those without. There was no significant difference in BRAF^V600E mutation between males and females, PTC classic and follicular variants, unifocal and multifocal PTC. There was a significant higher percentage of BRAF^V600E mutation in classic PTC than papillary microcarcinoma variant. There was no significant age, gender, histologic type, tumor size, lymph node metastasis, tumor focality, and surgical margin status differences between KRAS mutated and non-mutated PTC.

Conclusion

BRAF^V600E and KRAS mutation are seen in a significant number of PTC in the UAE. BRAF mutation is significantly correlated with large tumor size, positive surgical margins and lymph node metastasis suggesting an association between BRAF^V600E mutation and tumor growth and spread.

Prognostic Impact of the Turin Criteria in Poorly Differentiated Thyroid Carcinoma

BACKGROUND

The Turin criteria including solid, trabecular, and/or insular architecture, lack of typical nuclear features of papillary carcinoma, and mitoses, necrosis, or convoluted nuclei were adopted in the recent 4th edition of the World Health Organization classification published in 2017.

MATERIALS AND METHODS

Between 2006 and 2017, 11,001 cases underwent initial surgery for primary malignant thyroid tumor derived from follicular cells. A total of 75 (0.7%) cases were diagnosed with PDTC according to the 2004 WHO classification. Based on the Turin criteria, 30 (40%) cases were re-classified as PDTC-Turin (+) and 45 (60%) cases were PDTC-Turin (-). Clinicopathological features and prognosis were compared between PDTC-Turin (+) and PDTC-Turin (-).

RESULTS

Seventy-five patients (48 females and 27 males) had a median age at the time of surgery of 57 years. Preoperative diagnosis was benign in 16 (21%), follicular tumor in 40 (53%), and malignant in 19 (25%). The 5-year cause-specific survival (CSS) and disease-free survival (DFS) rates were 97% and 44% for PDTC-Turin (+) and 100% and 88% for PDTC-Turin (-). On univariate analysis, CSS and DFS rates were significantly worse in the PDTC-Turin (+) than in the PDTC-Turin (-) (p = 0.0096, and p = 0.0016). Multivariate analysis showed that Turin criteria status, Ki-67 labeling index ≥ 10%, and age 55 ≥ years were the independent prognostic factors for recurrence.

CONCLUSIONS

The prevalence of PDTC diagnosed with the Turin criteria was low, but it showed more aggressive behavior. The 2017 WHO classification reflects the prognosis more accurately than the 2004 WHO classification.

A novel gene panel for prediction of lymph-node metastasis and recurrence in patients with thyroid cancer

BACKGROUND

Although well-differentiated papillary thyroid cancer may remain indolent, lymph node metastases and the recurrence rates are approximately 50% and 20%, respectively. No current biomarkers are able to predict metastatic lymphadenopathy and recurrence in early stage papillary thyroid cancer. Hence, identifying prognostic biomarkers predicting cervical lymph-node metastases would prove very helpful in determining treatment.

METHODS

The database of the Cancer Genome Atlas included 495 papillary thyroid cancer samples. Using this database, we developed a machine learning model to define a gene signature that could predict lymph-node metastasis (N0 or N1). Kruskal-Wallis tests, univariate and multivariate logistic and Cox regression models, and Kaplan-Meier analyses were performed to correlate the gene signature with clinical outcomes.

RESULTS

We identified a panel of 25 genes and constructed a risk score that can differentiate N0 and N1 papillary thyroid cancer samples (P < .001) with a sensitivity of 86%, a specificity of 62%, a positive predictive value of 93%, and a negative predictive value of 42%. This panel represents an independent biomarker to predict metastatic lymphadenopathy (OR = 8.06, P < .001) specifically in patients with T1 lesions (OR = 7.65, P = .002) and disease-free survival (HR = 2.64, P = .043).

CONCLUSION

This novel 25-gene panel may be used as a potential prognostic marker for accurately predicting lymph-node metastasis and disease-free survival in patients with early-stage papillary thyroid cancer.

Predictive Value of BRAFV600E Mutation for Lymph Node Metastasis in Papillary Thyroid Cancer: A Meta-analysis

BRAF^V600E mutation has been thought to be a valuable molecular marker that may predict a worse prognosis for papillary thyroid cancer (PTC). But whether BRAF^V600E mutation is associated with lymph node metastasis (LNM) remains controversial. Different surgical strategies may bring a bias in demonsstrating the association between them. In order to delineate a risk stratification to guide a tailored initial approach to tumors that express BRAF^V600E mutation, we performed this meta-analysis by using the articles in which total or near-total thyroidectomy plus bilateral central lymph node dissection was routinely performed to avoid the bias from the surgical strategy. We searched the Medline, Embase and CNKI database for eligible studies from January 2003 to May 2018. Meta-analysis was performed using the STATA 12.0 software. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated under fixed-effects or randomeffects models. Fifteen clinical studies were included with a total of 4909 PTC patients. Our meta-analysis results reported that BRAFV600E mutation was associated with LNM (OR=1.34; 95% CI: 1.09-1.65; P=0.005), as well as central LNM (OR=1.59; 95% CI: 1.35-1.88; P<0.00001). Moreover, in patients with papillary thyroid microcarcinoma, we also confirmed the predictive value of BRAF^V600E mutation for LNM (OR=3.49; 95% CI: 2.02-6.02; P<0.00001). This meta-analysis demonstrates that BRAF^V600E mutation is closely related to LNM in PTC patients. The results suggest that BRAF^V600E mutation can be considered as a risk factor for LNM in PTC. Moreover, combining BRAF^V600E mutation with other risk factors to determine the initial surgical treatment may bring benefits for PTC patients.

Identification of key genes of papillary thyroid cancer using integrated bioinformatics analysis

OBJECTIVE

To identify novel clinically relevant genes in papillary thyroid carcinoma from public databases.

METHODS

Four original microarray datasets, GSE3678, GSE3467, GSE33630 and GSE58545, were downloaded. Differentially expressed genes (DEGs) were filtered from integrated data. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed, followed by protein-protein interaction (PPI) network construction. The CentiScape pug-in was performed to scale degree. The genes at the top of the degree distribution (≥ 95% percentile) in the significantly perturbed networks were defined as central genes. UALCAN and The Cancer Genome Atlas Clinical Explorer were used to verify clinically relevant genes and perform survival analysis.

RESULT

225 commonly changed DEGs (111 up-regulated and 114 down-regulated) were identified. The DEGs were classified into three groups by GO terms. KEGG pathway enrichment analysis showed DEGs mainly enriched in the PI3K-Akt signaling pathway, pathways in cancer, focal adhesion and proteoglycans in cancer. DEGs' protein-protein interaction (PPI) network complex was developed; six central genes (BCL2, CCND1, FN1, IRS1, COL1A1, CXCL12) were identified. Among them, BCL2, CCND1 and COL1A1 were identified as clinically relevant genes.

CONCLUSION

BCL2, CCND1 and COL1A1 may be key genes for papillary thyroid carcinoma. Further molecular biological experiments are required to confirm the function of the identified genes.

Prediction of central lymph node metastasis in papillary thyroid microcarcinoma according to clinicopathologic factors and thyroid nodule sonographic features: a case-control study

Background

Preoperative diagnosis of central lymph node metastasis (CLNM) poses to be a challenge in clinical node-negative papillary thyroid microcarcinoma (PTMC). This research work aims at investigating the association existing between BRAF mutation, clinicopathological factors, ultrasound characteristics, and CLNM, in addition to establishing a predictive model for CLNM in PTMC.

Materials and methods

The study included 673 PTMC patients, already undergone total thyroidectomy or lobectomy with prophylactic central lymph node dissection. The predictor factors were identified through univariate and multivariate analyses. The support vector machine was put to use to develop statistical models, which could predict CLNM on the basis of independent predictors.

Results

Tumor size (>5 mm), lower location, no well-defined margin, contact of >25% with the adjacent capsule, display of enlarged lymph nodes, and BRAF mutation were independent predictors of CLNM. Through the use of the predictive model, 79.6% of the patients were classified accurately, the sensitivity and specificity amounted to be 85.1% and 75.8%, respectively, and the positive predictive value and negative predictive value stood at 71.6% and 87.6%, respectively.

Conclusions

We established a predictive model in order to predict CLNM preoperatively in PTMC when preoperative diagnosis of CLNM was not clear.

Thyroid cancers of follicular origin in a genomic light: in-depth overview of common and unique molecular marker candidates

In recent years, thyroid malignances have become more prevalent, especially among women. The most common sporadic types of thyroid tumors of follicular origin include papillary, follicular and anaplastic thyroid carcinomas. Although modern diagnosis methods enable the identification of tumors of small diameter, tumor subtype differentiation, which is imperative for the correct choice of treatment, is still troublesome. This review discusses the recent advances in the field of molecular marker identification via next-generation sequencing and microarrays. The potential use of these biomarkers to distinguish among the most commonly occurring sporadic thyroid cancers is presented and compared. Geographical heterogeneity might be a differentiator, although not necessarily a limiting factor, in biomarker selection. The available data advocate for a subset of mutations common for the three subtypes as well as mutations that are unique for a particular tumor subtype. Tumor heterogeneity, a known issue occurring within solid malignancies, is also discussed where applicable. Public databases with datasets derived from high-throughput experiments are a valuable source of information that aid biomarker research in general, including the identification of molecular hallmarks of thyroid cancer.

Molecular pathology of thyroid tumours of follicular cells: a review of genetic alterations and their clinicopathological relevance

Thyroid cancer is the most common endocrine malignancy. Knowledge of the molecular pathology of thyroid tumours originating from follicular cells has greatly advanced in the past several years. Common molecular alterations, such as BRAF p.V600E, RAS point mutations, and fusion oncogenes (RET-PTC being the prototypical example), have been, respectively, associated with conventional papillary carcinoma, follicular-patterned tumours (follicular adenoma, follicular carcinoma, and the follicular variant of papillary carcinoma/non-invasive follicular thyroid neoplasm with papillary-like nuclear features), and with papillary carcinomas from young patients and arising after exposure to ionising radiation, respectively. The remarkable correlation between genotype and phenotype shows how specific, mutually exclusive molecular changes can promote tumour development and initiate a multistep tumorigenic process that is characterised by aberrant activation of mitogen-activated protein kinase and phosphoinositide 3-kinase-PTEN-AKT signalling. Molecular alterations are becoming useful biomarkers for diagnosis and risk stratification, and as potential treatment targets for aggressive forms of thyroid carcinoma. What follows is a review of the principal genetic alterations of thyroid tumours originating from follicular cells and of their clinicopathological relevance.

Long-term vemurafenib treatment drives inhibitor resistance through a spontaneous KRAS G12D mutation in a BRAF V600E papillary thyroid carcinoma model

The BRAF V600E mutation is commonly observed in papillary thyroid cancer (PTC) and predominantly activates the MAPK pathway. Presence of BRAF V600E predicts increasing risk of recurrence and higher mortality rate, and treatment options for such patients are limited. Vemurafenib, a BRAF V600E inhibitor, is initially effective, but cells inevitably develop alternative mechanisms of pathway activation. Mechanisms of primary resistance have been described in short-term cultures of PTC cells; however, mechanisms of acquired resistance have not. In the present study, we investigated possible adaptive mechanisms of BRAF V600E inhibitor resistance in KTC1 thyroid cancer cells following long-term vemurafenib exposure. We found that a subpopulation of KTC1 cells acquired resistance to vemurafenib following 5 months of treatment with the inhibitor. Resistance coincided with the spontaneous acquisition of a KRAS G12D activating mutation. Increases in activated AKT, ERK1/2, and EGFR were observed in these cells. In addition, the resistant cells were less sensitive to combinations of vemurafenib and MEK1 inhibitor or AKT inhibitor. These results support the KRAS G12D mutation as a genetic mechanism of spontaneously acquired secondary BRAF inhibitor resistance in BRAF V600E thyroid cancer cells.

Current Standards in Treatment of Radioiodine Refractory Thyroid Cancer

OPINION STATEMENT

Radioiodine refractory differentiated thyroid cancer (RAI-R DTC) is a challenging malignancy with limited prognosis and treatment options. Recently, clinical trials with targeted therapies have advanced the outlook of these patients, and inhibition of the vascular endothelial growth factor (VEGF) axis has led to the approval of small-molecule tyrosine kinase inhibitors (TKIs) for first-line treatment of radioiodine refractory disease. In addition to approved therapies (sorafenib and lenvatinib), other multi-targeted tyrosine kinase inhibitors that are commercially available have been recognized as viable treatment options for RAI-R DTC. Our preference is to initially use lenvatinib, given the dramatic progression-free survival (PFS) improvement versus placebo, with the caveat that 24 mg daily is not often tolerated and lower doses often used. In patients with BRAF V600E mutation, BRAF inhibitors are now considered for treatment, especially if patients are at high risk from antiangiogenic therapy. Research is continuing to evolve in identifying mechanisms related to radioiodine refractoriness, and trials are evaluating therapeutic molecules to overcome this resistance. Clinical care of patients with RAI-R DTC requires careful consideration of both patient and disease characteristics. Many patients with asymptomatic and indolent disease can be followed for years without treatment while others with high volume or rapidly progressive disease merit early intervention.

Association between the BRAF V600E mutation and ultrasound features of the thyroid in thyroid papillary carcinoma

The aim of the present study was to investigate the association between the BRAF V600E mutation and ultrasound features of the thyroid in papillary thyroid carcinoma (PTC). Fresh thyroid carcinoma tissue and paracarcinoma tissue were obtained from 34 patients undergoing surgery for PTC. The BRAF V600E mutation was detected by PCR amplification and direct DNA sequencing. The thyroid ultrasound results were compared between patients with and without the BRAF V600E mutation. Eighteen out of 34 cases were identified with the BRAF V600E mutation (52.9%), while 16 cases did not have the BRAF V600E mutation (47.1%). Additionally, no BRAF V600E mutation was detected in paracarcinoma tissue in the 34 cases. The results of ultrasound imaging suggested that there were no significant differences in tumor size, whether the border was clear, or in tumor calcification (presence or absence) between patients with and without BRAF V600E mutation (P>0.05). The BRAF V600E mutation rate was high in patients with PTC. There was no significant correlation between BRAF V600E mutation and thyroid ultrasound features. Thyroid ultrasound features are therefore unable to predict the presence of the BRAF V600E mutation in patients with PTC.

Molecular Pathology of Anaplastic Thyroid Carcinomas: A Retrospective Study of 144 Cases

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is a rare tumor, with poorly defined oncogenic molecular mechanisms and limited therapeutic options contributing to its poor prognosis. The aims of this retrospective study were to determine the frequency of anaplastic lymphoma kinase (ALK) translocations and to identify the mutational profile of ATC including TERT promoter mutations.

METHODS AND MATERIALS

One hundred and forty-four ATC cases were collected from 10 centers that are a part of the national French network for management of refractory thyroid tumors. Fluorescence in situ hybridization analysis for ALK rearrangement was performed on tissue microarrays. A panel of 50 genes using next-generation sequencing and TERT promoter mutations using Sanger sequencing were also screened.

RESULTS

Fluorescence in situ hybridization was interpretable for 90 (62.5%) cases. One (1.1%) case was positive for an ALK rearrangement with a borderline threshold (15% positive cells). Next-generation sequencing results were interpretable for 94 (65.3%) cases, and Sanger sequencing (TERT) for 98 (68.1%) cases. A total of 210 mutations (intronic and exonic) were identified. TP53 alterations were the most frequent (54.4%). Forty-three percent harbored a mutation in the (H-K-N)RAS genes, 13.8% a mutation in the BRAF gene (essentially p.V600E), 17% a PI3K-AKT pathway mutation, 6.4% both RAS and PI3K pathway mutations, and 4.3% both TP53 and PTEN mutations. Nearly 10% of the cases showed no mutations of the RAS, PI3K-AKT pathways, or TP53, with mutations of ALK, ATM, APC, CDKN2A, ERBB2, RET, or SMAD4, including mutations not yet described in thyroid tumors. Genes encoding potentially druggable targets included: mutations in the ATM gene in four (4.3%) cases, in ERBB2 in one (1.1%) case, in MET in one (1.1%) case, and in ALK in one (1.1%) case. A TERT promoter alteration was found in 53 (54.0%) cases, including 43 C228T and 10 C250T mutations. Three out of our cases did not harbor mutations in the panel of genes with therapeutic interest.

CONCLUSION

This study confirms that ALK rearrangements in ATC are rare and that the mutational landscape of ATC is heterogeneous, with many genes implicated in the follicular epithelial cell dedifferentiation process. This may explain the limited effectiveness of targeted therapeutic options tested so far.

A meta-analysis of prognostic roles of molecular markers in papillary thyroid carcinoma

The prognostic role of molecular markers in papillary thyroid carcinoma (PTC) is a matter of ongoing debate. The aim of our study is to investigate the impact of RAS, BRAF, TERT promoter mutations and RET/PTC rearrangements on the prognosis of PTC patients. We performed a search in four electronic databases: PubMed, Scopus, Web of Science and Virtual Health Library (VHL). Data of hazard ratio (HR) and its 95% confidence interval (CI) for disease-specific survival (DSS) and disease-free survival (DFS) were directly obtained from original papers or indirectly estimated from Kaplan-Meier curve (KMC). Pooled HRs were calculated using random-effect model weighted by inverse variance method. Publication bias was assessed by using Egger's regression test and visual inspection of funnel plots. From 2630 studies, we finally included 35 studies with 17,732 patients for meta-analyses. TERT promoter mutation was significantly associated with unfavorable DSS (HR = 7.64; 95% CI = 4.00-14.61) and DFS (HR = 2.98; 95% CI = 2.27-3.92). BRAF mutations significantly increased the risk for recurrence (HR = 1.63; 95% CI = 1.27-2.10) but not for cancer mortality (HR = 1.41; 95% CI = 0.90-2.23). In subgroup analyses, BRAF mutation only showed its prognostic value in short-/medium-term follow-up. Data regarding RAS mutations and RET/PTC fusions were insufficient for meta-analyses. TERT promoter mutation can be used as an independent and reliable marker for risk stratification and predicting patient's outcomes. The use of BRAF mutation to assess patient prognosis should be carefully considered.

The evolution of differentiated thyroid cancer

Differentiated thyroid tumours of follicular cell derivation have traditionally been classified based on architecture, cytology, or both. The features that distinguish the various entities are controversial and diagnostic criteria are inconsistent and often irreproducible. The complexity of classification schemes has not been substantiated by molecular profiling. In this review, a simplistic approach to the diagnosis of well differentiated thyroid neoplasia is provided to challenge the dogma. The proposed classification matches the molecular profiles of these lesions and simplifies the criteria for diagnosis. This approach can be used to support rational treatment algorithms.

Genetic Alterations and Their Clinical Implications in High-Recurrence Risk Papillary Thyroid Cancer

Purpose

Papillary thyroid carcinomas (PTCs) frequently involve genetic alterations. The objective of this study was to investigate genetic alterations and further explore the relationships between these genetic alterations and clinicopathological characteristics in a high-recurrence risk (node positive, N1) PTC group.

Materials and Methods

Tumor tissue blocks were obtained from 240 surgically resected patients with histologically confirmed stage III/IV (pT3/4 or N1) PTCs. We screened gene fusions using NanoString’s nCounter technology and mutational analysis was performed by direct DNA sequencing. Data describing the clinicopathological characteristics and clinical courses were retrospectively collected.

Results

Of the 240 PTC patients, 207 (86.3%) had at least one genetic alteration, including BRAF mutation in 190 patients (79.2%), PIK3CA mutation in 25 patients (10.4%), NTRK1/3 fusion in six patients (2.5%), and RET fusion in 24 patients (10.0%). Concomitant presence of more than two genetic alterations was seen in 36 patients (15%). PTCs harboring BRAF mutation were associated with RET wild-type expression (p=0.001). RET fusion genes have been found to occur with significantly higher frequency in N1b stage patients (p=0.003) or groups of patients aged 45 years or older (p=0.031); however, no significant correlation was found between other genetic alterations. There was no trend toward favorable recurrence-free survival or overall survival among patients lacking genetic alterations.

Conclusion

In the selected high-recurrence risk PTC group, most patients had more than one genetic alteration. However, these known alterations could not entirely account for clinicopathological features of high-recurrence risk PTC.

BRAF V600E mutation in prognostication of papillary thyroid cancer (PTC) recurrence

Papillary thyroid cancer (PTC) offers excellent prognosis, however relapse risk or persistent disease is related to ~30%. Currently, attention is paid to the possibility of patient group selection of different risk of unfavorable outcome to match a particular therapeutic approach. Therefore, interest in new prognostic and predictive markers known preoperatively is observed. BRAF V600E mutation is such a marker. Many studies analyzing the prevalence of the mutation and its relationship with other clinico-pathological risk factors were reported but with controversial conclusions. The prognostic significance of BRAF mutation was confirmed by some single centre studies, a few meta-analyses and a large multicenter retrospective international study. They confirmed a correlation between the mutation and the risk of recurrence. The strongest argument against using BRAF mutation as an independent prognostic and predictive factor in PTC is its high prevalence (30-80%). At present it seems that BRAF mutation is one of the factors influencing the prognosis and it should be analyzed in correlation with other prognostic factors. The most recent ATA recommendations do not indicate a routine application of BRAF status for initial risk stratification in differentiated thyroid cancer due to a lack of evident confirmation of a direct influence of mutation on the increase in relapse risk. However, ATA demonstrates the continuous risk scale for the relapse risk assessment, considering BRAF and/or TERT status. At present, researchers are working on determining the role of BRAF mutation in patients from a low-risk group and its correlations with others molecular events. Currently, BRAF mutation cannot be used as a single, independent predictive factor. However, its usefulness in the context of other molecular and clinico-pathological risk factors cannot be excluded. They may be used to make modern prognostic scales of relapse risk and be applied to individualized diagnostic and therapeutic strategy for PTC patients.

BRAFV600E Mutation: Has It a Role in Cervical Lymph Node Metastasis of Papillary Thyroid Cancer?

BACKGROUND

The BRAF^V600E mutation is common in papillary thyroid cancer (PTC). Lymph node metastasis (LNM) may be associated with poor prognosis. However, the LNM mechanism remains unclear.

OBJECTIVES

Our aim was to evaluate the prevalence of the BRAF^V600E mutation in primary tumors and accompanying LNM at the time of diagnosis.

METHODS

This retrospective study included 51 PTC patients (40 women, 11 men; mean age 40.0 ± 16.5 years; range 6-81) who underwent total thyroidectomy accompanied by a lateral neck dissection due to preoperatively detected LNM. Real-time PCR was used for the detection of the BRAF^V600E mutation in specimens from primary thyroid tumors and metastatic lymph node tumors.

RESULTS

The prevalence of the BRAF^V600E mutation was 64.7% (n = 33) in primary tumors and 47.1% (n = 24) in metastatic lymph nodes. Of 33 patients with BRAF^V600E-positive primary tumors, 18 (54.5%) had BRAF^V600E-positive metastatic lymph nodes. Of 18 patients with BRAF^V600E-negative primary tumors, 6 (33.3%) had BRAF^V600E-positive metastatic lymph nodes. The presence of the BRAF^V600E mutation in the primary tumor did not affect the tumor size, but the diameter of metastatic lymph nodes significantly increased (by nearly 3 mm) with the presence of BRAF^V600E in LNM (p = 0.01).

CONCLUSIONS

In our study, the BRAF^V600E mutation did not show a one-to-one correspondence. This indicates that the presence of BRAF^V600E in the primary tumor is not clonal and addresses the role of intratumor heterogeneity in PTC tumorigenesis. This supports the theses that mutations occur in the later stages of tumorigenesis, might be subclonal, and develop de novo, or that some other factors may be involved in the development of metastasis.

Classical V600E and other non-hotspot BRAF mutations in adult differentiated thyroid cancer

BACKGROUND

BRAF is the most frequently mutated gene in differentiated thyroid cancer (DTC). Previous studies on DTC have well documented high rates of the BRAF (V600E) mutation in patients of mixed ages. Previous studies either included a mix of pediatric and adult patients or pediatric patients only. However, the prevalence of hotspot and non-hotspot BRAF mutations and its significance in pure adult DTCs is not yet well determined. In this study we determine the frequency of this classical BRAF mutation and other rare BRAF mutations in pure adult DTCs.

METHODS

A total of 204 adult DTC samples (Age >18 years) were analyzed for mutations in exon 15 of the BRAF gene by performing polymerase chain reaction (PCR) amplification of tumor genomic DNAs and direct sequencing of amplicons using Sanger sequencing. Obtained results were correlated to clinical and pathological characteristics of DTCs. Statistical analyses were performed using SPSS (The Statistical Package for Social Sciences) version 20 software.

RESULTS

Overall, BRAF mutations were identified in 48.5 % (99/204) of adult DTCs. Three rare non-hotspot mutations (T599I, T599dup and K601E) were detected in four tumor samples (2 %). One (K601E) of these non-hotspot mutations occurred in conventional papillary thyroid cancer (CPTC) and other three (T599I, T599dup and K601E) were found in follicular variant PTC. We found significant association between BRAF (V600E) mutation and age (P < 0.0001), extrathyroidal invasion (P = 0.017), lymph node metastasis (P = 0.038) and TNM stage III/IV (P = 0.001).

CONCLUSIONS

Our study is the first to report BRAF mutations in a pure adult sample of DTCs of Saudi Arabian ethnicity. Our results show a high rate and a strong prognostic role of the classical BRAF (V600E) mutation and also suggest a common occurrence of non-hot spot mutations in adult DTC from this highly inbred population.

Clinical impact of BRAF mutation on the diagnosis and prognosis of papillary thyroid carcinoma: a systematic review and meta-analysis

BACKGROUND

The possible role of BRAF(V) (600E) mutation in the diagnosis and prognosis of papillary thyroid carcinoma (PTC) remains controversial. A systematic review to investigate the diagnostic and prognostic role of BRAF(V) (600E) mutation in patients with PTC is urgently needed.

METHODS

A systematic review of relevant literatures was performed in PubMed, EMBASE and CENTRAL. The incremental accuracy (IA) of fine needle aspiration biopsy plus BRAF(V) (600E) mutation analysis over fine needle aspiration biopsy alone, and the statistical data about the association of BRAF(V) (600E) mutation and the prognosis of PTC (risk ratios (RR) for dichotomous data, standard mean differences for continuous data and hazard ratios (HRs) for disease-free survival (DFS) were pooled. Subgroup analysis was performed to explain the heterogeneities.

RESULTS

A total of 67 studies were included. The pooled IA was 2% (95% confidence interval (CI): 0·5-4%). The pooled RR for gender, multifocality, lymph node metastasis, extrathyroidal invasion and pathological stage was 1·11 (95% CI: 0·98-1·25), 1·17 (95% CI: 1·09-1·24), 1·36 (95% CI: 1·20-1·53), 1·60 (95% CI: 1·41-1·82), and 1·49 (95% CI: 1·33-1·68), respectively. The pooled standard mean differences for age and tumour size were 0·14 (95% CI: 0·04-0·23) and 0·21 (95% CI: 0·1-0·32), respectively. The pooled HR for DFS was 1·96 (95% CI: 1·62-2·37). Subgroup analysis showed that these statistical results were affected by the geographical background of patients, study design and detection methods.

CONCLUSIONS

BRAF(V) (600E) mutation analysis can not only be used in the diagnosis of PTC, but can also predict its prognosis.

Comparison of the clinicopathological behavior of the follicular variant of papillary thyroid carcinoma and classical papillary thyroid carcinoma: A systematic review and meta-analysis

The follicular variant of papillary thyroid carcinoma (FV-PTC) is the second most common type of papillary thyroid carcinoma (PTC), and it has been increasingly diagnosed in recent years. However, whether FV-PTC behaves differently from classical PTC (C-PTC) remains controversial. To address this controversy, a meta-analysis was performed to determine the potential differences between FV-PTC and C-PTC in their clinicopathological behavior. The relevant published studies between January 1, 2003 and August 31, 2014 were reviewed according to the defined selection criteria using the PubMed database. Review Manager was used to calculate the pooled odds ratio (OR) or the mean difference (MD) with a 95% confidence interval (CI), using a random- or fixed-effect model for all analyses. In total, 112 studies were identified and examined; finally, only 36 studies met the inclusion criteria. In the 36 studies, compared to the clinicopathological behavior of patients with C-PTC, patients with FV-PTC had the following parameters: Similar mean age and similar prevalence of gender, tumor size ≥10 mm, multifocality, capsular invasion, vascular invasion, lymphocytic and/or Hashimoto's thyroiditis, and clinical stage; a larger mean tumor size and higher prevalence of age ≥45 years; and lower prevalence of extrathyroidal extensions, lymph node metastases, BRAF mutation and recurrence. The meta-analysis suggested that patients with FV-PTC have a more favorable clinicopathological behavior and improved prognosis compared to patients with C-PTC. Thus, patients with FV-PTC and C-PTC may be managed differently, and the two types of PTC should be clearly distinguished in future retrospective or prospective studies.

Prognostic value of genetic mutations in thyroid cancer: a meta-analysis

BACKGROUND

Genetic mutations have been found to be associated with thyroid cancer. Previous studies have been focused on the relation between genetic mutations and thyroid cancer. We sought to evaluate the prognostic value of the three most common genetic mutations (BRAF, RAS, and RET) in patients with thyroid cancer.

METHODS

Sources from MEDLINE (inception to December 2013) and EMBASE (inception to December 2013) were searched. Studies of thyroid cancer with results of genetic mutations and studies that reported survival data were included and two authors performed the data extraction independently. Any discrepancies were resolved by a consensus.

RESULTS

Fourteen studies assessing BRAF mutations, 6 RAS mutations, 4 RET mutations, and 1 with analysis of both BRAF and RAS mutations were included in this meta-analysis. Patients with papillary thyroid cancer with BRAF mutations showed a 1.59-fold higher risk of events or a 2.66-fold higher risk of death than patients with papillary thyroid cancer without a BRAF mutation. Also, patients with RAS mutations showed a 2.90-fold higher risk of death by thyroid cancer than patients without a RAS mutation. In addition, patients with medullary thyroid cancer with RET mutations showed a 5.82-fold higher risk of death by the disease than without a RET mutation.

CONCLUSIONS

Genetic mutations should be considered as a poor prognostic marker in thyroid cancer and may lead to better management of individual patients. However, the use of genetic mutations as prognostic markers should not be generalized, but individualized in the specific clinic setting.

Concomitant RAS, RET/PTC, or BRAF mutations in advanced stage of papillary thyroid carcinoma

BACKGROUND

RET/PTC rearrangement, RAS, and BRAF mutations are considered to be mutually exclusive in papillary thyroid carcinoma (PTC). However, although concomitant mutations of RET/PTC, RAS, or BRAF have been reported recently, their significance for tumor progression and survival remains unclear. We sought to examine the prognostic value of concomitant mutations in PTC.

METHODS

We investigated 88 PTC for concomitant mutations. Mutation in BRAF exon 15, KRAS, NRAS, and HRAS were studied by polymerase chain reaction (PCR)-sequencing of tumor DNA; RET/PTC rearrangement was determined by reverse transcription (RT)-PCR-sequencing of tumor cDNA.

RESULTS

BRAF(V600E) was detected in 39 of 82 classic PTC (CPTC) and in all three tall-cell variants (49%, 42/85). KRAS mutation (p.Q61R and p.S65N) was detected in two CPTC (2%, 2/88) and NRAS(Q61R) in one CPTC and two follicular variant PTC (FVPTC; 3%, 3/88). KRAS(S65N) was identified for the first time in thyroid cancer and could activate mitogen-associated protein kinase (MAPK). RET/PTC-1 was detected in nine CPTC, one tall-cell variant, and two FVPTC. Concomitant BRAF(V600E) and KRAS, or BRAF(V600E) and RET/PTC-1 mutations were found in two CPTC, and six CPTC and one tall-cell variant, respectively. In total, 11 concomitant mutations were found in 88 PTC samples (13%), and most of them were in the advanced stage of disease (8/11, 73%; p<0.01).

CONCLUSIONS

Our data show that concomitant mutations are a frequent event in advanced PTC and are associated with poor prognosis. The concomitant mutations may represent intratumor heterogeneity and could exert a gene dosage effect to promote disease progression. KRAS(S65N) can constitutively activate the MAPK pathway.

Evaluation of PTEN, PI3K, MTOR, and KRAS expression and their clinical and prognostic relevance to differentiated thyroid carcinoma

Aim of the study

Important signalling pathways play fundamental roles in the pathogenesis of thyroid carcinoma (TC). PTEN, mTOR, PI3K-p85 and K-Ras are the principal factors involved in these signalling pathways. To immunohistochemically examine the expressions of PI3K, mTOR and PTEN in patients suffering from follicular TC, papillary TC or variants thereof, as well as to investigate KRAS mutations via PCR to determine their clinical and prognostic relevance to differentiated thyroid cancer.

Material and methods

The expression of PTEN, PI3K-p85 and mTOR was immunohistochemically examined, and the mutation of K-Ras was examined via PCR. The results obtained were compared to the clinico-pathologic characteristics of the patients.

Results

A significant correlation was found between p85 expression and lymphovascular invasions and between PTEN expression and multifocality (p = 0.048 and p = 0.04, respectively), and a correlation between p85 and capsular invasion was found, with a borderline statistical significance (p = 0.056). No expression of PTEN, p85 or Mtor was detected in normal tissue. K-Ras mutation was examined in 66 of the 101 patients (57.4%), and the percentage of patients exhibiting a K-Ras mutation was 17.4%. All of the patients exhibiting a K-Ras mutation were women (p = 0.047). The disease-free survival was 44.6 months (95% CI: 37.9–51.3) and was statistically significantly higher in the group that displayed level 1 or lower expression of p85 (p = 0.043).

Conclusions

The expression levels of the aforementioned markers were significantly higher in TC cells than in normal tissue. A significant correlation was detected between K-Ras mutation and gender. This study demonstrates that p85 and PTEN are markers that should be evaluated in further studies of TC.

Time to re-consider the meaning of BRAF V600E mutation in papillary thyroid carcinoma

The BRAF V600E mutation, resulting from the BRAFT1799A transversion, is the most common genetic mutation in papillary thyroid carcinoma (PTC), with a mean frequency close to 50% among all cases. A large number of studies in the past decade have tried to dissect the relevance and the function of the V600E mutation in controlling oncogenesis and progression of thyroid cancer. However, several works published in the latest years have provided new evidence, in partial conflict with the previous knowledge, suggesting the need of reconsidering the meaning of the BRAF V600E mutation in PTC. In this work, we attempt to discuss some of the most recent molecular, preclinical and clinical evidence to construct a more exhaustive model of function for the BRAF V600E in development, progression and therapeutic approach of thyroid cancer.

Prognostic value of the BRAF V600E mutation in papillary thyroid carcinoma

The aim of the present study was to investigate the prevalence of the BRAF V600E mutation in papillary thyroid carcinoma (PTC) and to determine the correlation between this mutation and indicators of poor prognosis and outcome in patients with PTC. The BRAF V600E mutation status was analyzed in 187 tumor samples using the multiplex allele-specific PCR method. Univariate and multivariate analyses were performed to investigate the association of the BRAF V600E mutation with clinical features and patient outcome. The sensitivity of the multiplex allele-specific PCR combined with denaturing high-performance liquid chromatography reached ~1%. The BRAF V600E mutation was observed in 63.6% (119/187) of tumor tissues, predominantly in PTC specimens, and no BRAF mutation was identified in other benign-type thyroid diseases. The univariate analysis indicated that the BRAF V600E mutation was associated with age, tumor stage and prognosis (P<0.05). In addition, the frequency of the BRAF V600E mutation was significantly different in the central (75.3%) and lateral neck (49.3%) lymph nodes of patients with lymph node metastasis. Multivariate logistic regression analysis showed that the BRAF V600E mutation (HR, 2.471; 95% CI, 1.149–5.312) and lymph node metastasis (HR, 3.003; 95% CI, 1.027–8.771) are independent factors that predict tumor prognosis. Thus, the BRAF V600E mutation is an independent risk factor that may be used to predict thyroid cancer persistence/recurrence.

Molecular pathogenesis and mechanisms of thyroid cancer

Thyroid cancer is a common endocrine malignancy. There has been exciting progress in understanding its molecular pathogenesis in recent years, as best exemplified by the elucidation of the fundamental role of several major signalling pathways and related molecular derangements. Central to these mechanisms are the genetic and epigenetic alterations in these pathways, such as mutation, gene copy-number gain and aberrant gene methylation. Many of these molecular alterations represent novel diagnostic and prognostic molecular markers and therapeutic targets for thyroid cancer, which provide unprecedented opportunities for further research and clinical development of novel treatment strategies for this cancer.

Signaling pathways in follicular cell-derived thyroid carcinomas (review)

Thyroid carcinoma is the most common malignant endocrine neoplasia. Differentiated thyroid carcinomas (DTCs) represent more than 90% of all thyroid carcinomas and comprise the papillary and follicular thyroid carcinoma subtypes. Anaplastic thyroid carcinomas correspond to less than 1% of all thyroid tumors and can arise de novo or by dedifferentiation of a differentiated tumor. The etiology of DTCs is not fully understood. Several genetic events have been implicated in thyroid tumorigenesis. Point mutations in the BRAF or RAS genes or rearranged in transformation (RET)/papillary thyroid carcinoma (PTC) gene rearrangements are observed in approximately 70% of papillary cancer cases. Follicular carcinomas commonly harbor RAS mutations and paired box gene 8 (PAX8)-peroxisome proliferator-activated receptor γ (PPARγ) rearrangements. Anaplastic carcinomas may have a wide set of genetic alterations, that include gene effectors in the mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K) and/or β-catenin signaling pathways. These distinct genetic alterations constitutively activate the MAPK, PI3K and β-catenin signaling pathways, which have been implicated in thyroid cancer development and progression. In this context, the evaluation of specific genes, as well as the knowledge of their effects on thyroid carcinogenesis may provide important information on disease presentation, prognosis and therapy, through the development of specific tyrosine kinase targets. In this review, we aimed to present an updated and comprehensive review of the recent advances in the understanding of the genetic basis of follicular cell-derived thyroid carcinomas, as well as the molecular mechanisms involved in tumor development and progression.