Thyroid tumorigenesis and molecular markers in thyroid cancer

EGR1/2 Inhibits Papillary Thyroid Carcinoma Cell Growth by Suppressing the Expression of PTEN and BAX

Early growth response (EGR) proteins have been reported to be involved in cell growth and apoptosis in a variety of cancer types and could inhibit tumor development. However, the role of EGR1/2 in papillary thyroid carcinoma (PTC) has not been elucidated. The expression pattern of EGR1/2 in adjacent tissues and cancer tissues and the clinical prognosis of EGR1/2 were analyzed by using the samples from TCGA database. The cell viability was detected by MTT assay. Luciferase reporter assay was used to demonstrate the binding of EGR1/2 to the target gene promotor region. Our results showed that EGR1/2 was significantly downregulated in tumor tissues and correlated with poor prognosis. Overexpression of EGR1/2 inhibited proliferation of IHH-4 and BCPAP cells, and knockdown of EGR1/2 showed a reverse effect. Overexpression of EGR1 or EGR2 promoted phosphatase and tension homolog (PTEN) or Bcl-2-associated X (BAX) expression, and EGR1 or EGR2 was able to directly bind to the promoter region of PTEN or BAX. In conclusion, we found that the altered expression of EGR1/2 affected the proliferation of PTC cells and regulated the expression of PTEN and BAX.

Thyroid tissue outside the thyroid gland: Differential diagnosis and associated diagnostic challenges

The presence of thyroid tissue outside of the thyroid gland may occur in various clinical settings and anatomic locations and includes both benign and malignant differential diagnoses. Some of these entities include thyroglossal duct cyst, lingual thyroid, parasitic nodule, thyroid tissue within a lymph node and struma ovarii. In routine daily practice, these entities do pose diagnostic challenges for the pathologists. Differential diagnostic considerations depend largely on the location of lesion and the histologic features. A definitive diagnosis may remain unclear in some cases while knowledge is still evolving in others i.e., incidentally detected bland appearing thyroid follicles in a lateral neck lymph node. This article aims to elaborate on the various entities characterized by thyroid tissue outside of the thyroid gland, both benign and malignant, and the relevant differential diagnostic considerations.

LAMB3 mediates metastatic tumor behavior in papillary thyroid cancer by regulating c-MET/Akt signals

Laminin subunit beta-3 (LAMB3) encodes one of the three subunits of LM-332, a protein of the extracellular matrix secreted by cultured human keratinocytes. While LAMB3 is involved in the invasive and metastatic abilities of several tumor types, including those found in the colon, pancreas, lung, cervix, stomach, and prostate, its mechanism of action in thyroid cancer has not been investigated previously. Our results show that LAMB3 is up-regulated in papillary thyroid cancer, and that its suppression reduces cell migration/invasion via down-regulation of epithelial‒mesenchymal transition-associated proteins (N-cadherin, vimentin, slug) and inhibition of matrix metalloproteinase 9. LAMB3 suppression also significantly decreases Akt phosphorylation and inhibits the transcription of c-MET, reducing its activation. These results suggest that LAMB3 leads to tumor invasion via Akt activation induced by the HGF/c-MET axis in papillary thyroid cancer cells. Our findings reveal a novel mechanism of action for LAMB3 in papillary thyroid cancer cells.

MicroRNA Expression Profiles in Papillary Thyroid Carcinoma, Benign Thyroid Nodules and Healthy Controls

MicroRNAs (miRNAs) represent a class of short endogenous non-coding RNAs that negatively regulate gene expression at the post-transcriptional level in many biological processes, including proliferation, differentiation, stress response and apoptosis. In this study we analyzed a set of seven miRNA molecules in sera of patients with papillary thyroid cancer, multinodular goiter and healthy controls to identify miRNA molecules that may have utility as markers for PTC. MiR-21 serum levels in the preoperative PTC and MG groups were significantly higher than the control group. Likewise, postoperative levels of miR-151-5p, miR-221 and miR-222 were significantly lower in patients with PTC. When serum miRNA levels were evaluated according to stage, postoperative levels of miR-151-5p and miR-222 were significantly lower in patients with advanced stages of the disease. The miRNA levels were also found associated with the size of the primary tumor. Our data imply that specific miRNA molecules which are differentially expressed in thyroid tumors may play role in the development of papillary thyroid carcinoma.

Correlation between polymorphisms of BRAF gene and papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC), which accounts for 80% of all thyroid cancers, has an increasing incidence over these years. Single nucleotide polymorphisms (SNPs) of BRAF were considered to be one of well-established risk factors leading to development of PTC. The aim of this study was to investigate whether the common mutations of BRAF could elevate significantly the risk of PTC in a Chinese population.

METHODS

Four SNPs (rs11762469, rs17623204, rs1267636 and rs3748093) of BRAF were selected through our filter by Haploview 4.2 software with HapMap databases. We used the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to genotype the four SNPs in blood samples of 618 subjects (206 patients with PTC and 412 healthy controls). The correlation between BRAF polymorphisms and PTC risk was assessed using student t-test and chi-square test.

RESULTS

The results showed that mutation in rs3748093 was significantly associated with an increased risk of PTC in allele model (A allele vs. T allele, OR = 1·68, 95% CI = 1·16-2·43, P = 0·006), dominant model (TA + AA vs TT, OR = 1·64, 95% CI = 1·08-2·48, P = 0·019) and homozygote model (AA vs. TT, OR = 2·94, 95% CI = 1·00-8·61, P = 0·040). However, the other three SNPs (rs11762469, rs17623204 and rs1267636) were shown to have no association with the risk of PTC.

CONCLUSIONS

Our results indicated that polymorphism of rs3748093*A was significantly correlated with an increased risk of PTC in a Chinese population. Further investigation on the aetiological mechanism of PTC is needed to validate our results.

A functional insertion/deletion polymorphism in the promoter region of the NFKB1 gene increases the risk of papillary thyroid carcinoma

This study aimed to assess whether an insertion/deletion polymorphic variation rs28362491 in the NFKB1 promoter region was related to the risk of papillary thyroid carcinoma (PTC). Genomic DNA was extracted from the peripheral venous blood of 352 patients with PTC and 459 controls. The NFKB1 rs28362491 polymorphism was genotyped by using a polymerase chain reaction assay. We found that the frequency of the heterozygous genotype ATTG1/ATTG2 was significantly higher in the cases compared to the controls (odds ratios [OR]=1.44, 95% confidence intervals [CI]=1.05-1.96, p=0.02). Moreover, the frequency of ATTG1/ATTG2+ATTG1/ATTG1 genotypes was significantly elevated in the cases compared to the controls (OR=1.38, 95% CI=1.03-1.85, p=0.03). These findings suggest that the -94 insertion/deletion ATTG polymorphism in the NFKB1 promoter might be associated with an increased risk of PTC.

PTEN: Multiple Functions in Human Malignant Tumors

PTEN is the most important negative regulator of the PI3K signaling pathway. In addition to its canonical, PI3K inhibition-dependent functions, PTEN can also function as a tumor suppressor in a PI3K-independent manner. Indeed, the PTEN network regulates a broad spectrum of biological functions, modulating the flow of information from membrane-bound growth factor receptors to nuclear transcription factors, occurring in concert with other tumor suppressors and oncogenic signaling pathways. PTEN acts through its lipid and protein phosphatase activity and other non-enzymatic mechanisms. Studies conducted over the past 10 years have expanded our understanding of the biological role of PTEN, showing that in addition to its ability to regulate proliferation and cell survival, it also plays an intriguing role in regulating genomic stability, cell migration, stem cell self-renewal, and tumor microenvironment. Changes in PTEN protein levels, location, and enzymatic activity through various molecular mechanisms can generate a continuum of functional PTEN levels in inherited syndromes, sporadic cancers, and other diseases. PTEN activity can indeed, be modulated by mutations, epigenetic silencing, transcriptional repression, aberrant protein localization, and post-translational modifications. This review will discuss our current understanding of the biological role of PTEN, how PTEN expression and activity are regulated, and the consequences of PTEN dysregulation in human malignant tumors.

Transmembrane protease serine 4 promotes thyroid cancer proliferation via CREB phosphorylation

BACKGROUND

Transmembrane protease serine 4 (TMPRSS4), one of the type II transmembrane serine proteases (TTSPs), is elevated in various cancers and is associated with multiple malignant phenotypes. However, the expression pattern and biologic significance of TMPRSS4 in thyroid cancer are largely unknown. In this study, we investigated the expression of TMPRSS4 in thyroid cancer and assessed the pro-proliferative role of TMPRSS4 in thyroid cancer.

METHODS

Immunohistochemistry and real-time reverse transcription-polymerase chain reaction (RT-PCR) assays were performed to assess the expression of TMPRSS4 in thyroid cancer. We evaluated in vitro cell proliferation using MTT, colony formation, anchorage-independent growth, flow cytometry analysis, and 5-ethynyl-2'-deoxyuridine (EdU) incorporation assays. Western blot, real-time RT-PCR, and luciferase assays were conducted to reveal the underlying mechanisms.

RESULTS

TMPRSS4 is overexpressed in thyroid cancer and is associated with the grade of malignancy. Depletion of TMPRSS4 in thyroid cancer cells significantly suppressed proliferation. Moreover, the proliferation of thyroid cancer cells with TMPRSS4 overexpression was significantly enhanced. We also show that cyclic adenosine monophosphate response element-binding protein (CREB)-cyclin D1 signaling mediates, at least partially, the role of TMPRSS4 in thyroid cancer cell proliferation.

CONCLUSIONS

TMPRSS4 is overexpressed in thyroid cancer and TMPRSS4-CREB signaling is needed to sustain thyroid cancer cell proliferation.

Aberrant expression of posterior HOX genes in well differentiated histotypes of thyroid cancers

Molecular etiology of thyroid cancers has been widely studied, and several molecular alterations have been identified mainly associated with follicular and papillary histotypes. However, the molecular bases of the complex pathogenesis of thyroid carcinomas remain poorly understood. HOX genes regulate normal embryonic development, cell differentiation and other critical processes in eukaryotic cell life. Several studies have shown that HOX genes play a role in neoplastic transformation of several human tissues. In particular, the genes belonging to HOX paralogous group 13 seem to hold a relevant role in both tumor development and progression. We have identified a significant prognostic role of HOX D13 in pancreatic cancer and we have recently showed the strong and progressive over-expression of HOX C13 in melanoma metastases and deregulation of HOX B13 expression in bladder cancers. In this study we have investigated, by immunohistochemisty and quantitative Real Time PCR, the HOX paralogous group 13 genes/proteins expression in thyroid cancer evolution and progression, also evaluating its ability to discriminate between main histotypes. Our results showed an aberrant expression, both at gene and protein level, of all members belonging to paralogous group 13 (HOX A13, HOX B13, HOX C13 and HOX D13) in adenoma, papillary and follicular thyroid cancers samples. The data suggest a potential role of HOX paralogous group 13 genes in pathogenesis and differential diagnosis of thyroid cancers.

NAD(P)H: quinone oxidoreductase 1 and NRH:quinone oxidoreductase 2 polymorphisms in papillary thyroid microcarcinoma: correlation with phenotype

PURPOSE

NAD(P)H:Quinone Oxidoreductase 1 (NQO1) C609T missense variant (NQO1*2) and 29 basepair (bp)-insertion/deletion (I29/D) polymorphism of the NRH:Quinone Oxidoreductase 2 (NQO2) gene promoter have been proposed as predictive and prognostic factors for cancer development and progression. The purpose of this study is to investigate the relationship between NQO1/NQO2 genotype and clinico-pathological features of papillary thyroid microcarcinoma (PTMC).

MATERIALS AND METHODS

Genomic DNA was isolated from 243 patients; and clinical data were retrospectively analyzed. NQO1*2 and tri-allelic polymorphism of NQO2 were investigated by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis.

RESULTS

PTMC with NQO1*2 frequently exhibited extra-thyroidal extension as compared to PTMC with wild-type NQO1 (p=0.039). There was a significant relationship between I29/I29 homozygosity of NQO2 and lymph node metastasis (p=0.042). Multivariate analysis showed that the I29/I29 genotype was associated with an increased risk of lymph node metastasis (OR, 2.24; 95% CI, 1.10-4.56; p=0.026).

CONCLUSION

NQO1*2 and I29 allele of the NQO2 are associated with aggressive clinical phenotypes of PTMC, and the I29 allele represents a putative prognostic marker for PTMC.

The risk of second cancers after diagnosis of primary thyroid cancer is elevated in thyroid microcarcinomas

BACKGROUND

Thyroid cancers have increased dramatically over the past few decades. Comorbidities may be important, and previous studies have indicated elevated second cancer risk after initial primary thyroid cancers. This study examined the risk of second cancers after development of a thyroid cancer, primary utilizing the Surveillance, Epidemiology, and End Results (SEER) program database.

METHODS

The cohort consisted of men and women diagnosed with first primary thyroid cancer who were reported to a SEER database in 1973-2008 (n=52,103). Standardized incidence ratios (SIR) were calculated for all secondary cancers. Confidence intervals and p-values are at 0.05 significance alpha level and are two-sided based on Poisson exact methods.

RESULTS

In this cohort, 4457 individuals developed second cancers. The risk of developing second cancers after a primary thyroid cancer varied from 10% to 150% depending on different cancer types. Cancers in all sites, breast, skin, prostate, kidney, brain, salivary gland, second thyroid, lymphoma, myeloma, and leukemia were elevated. The magnitude of the risk varied by histology, tumor size, calendar year of first primary thyroid cancer diagnosis, and the treatment of the primary thyroid cancer. The risk of a second cancer was elevated in patients whose first primary thyroid carcinomas were small, or were diagnosed after 1994, or in whom some form of radiation treatment was administered.

CONCLUSIONS

This large population-based analysis of second cancers among thyroid cancer patients suggests that there was an increase of second cancers in all sites, and the most commonly elevated second cancers were the salivary gland and kidney. Additionally, the increase in second cancers in patients with recently diagnosed thyroid microcarcinomas (<10 mm) suggests that aggressive radiation treatment of the first primary thyroid cancer, the environment, and genetic susceptibility, may increase the risk of a second cancer.

Rising Incidence of Small Size Papillary Thyroid Cancers with No Change in Disease-Specific Survival in Finnish Thyroid Cancer Patients

Background:

The aim of this study was to investigate trends in the incidence, diagnostics, treatment and survival of thyroid cancer in Tampere University Hospital (TAUH) region in recent decades.

Material and Methods:

New thyroid cancer cases from 1981 to 2002 were ascertained from the Finnish Cancer Registry. Follow-up data was collected from medical records of TAUH. Differentiated thyroid cancer (DTC; consisting of papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC)) patients' data was analyzed and divided into two equal time periods (1981–1991 and 1992–2002).

Results:

The total amount of thyroid cancer cases was 553, of which 427 (77%) were papillary and 72 (13%) follicular. Thyroid cancer was four times more common in females than in males and the median age at the time of diagnosis was 52 years. The incidence of DTC was 4.5/100 000 in the earlier group and 6.0/100 000 in the later group (IRR 1.33, CI 1.11–1.60). The proportion of papillary thyroid cancer rose from 81% to 89% (p = 0.02) in two study periods. Median tumour size became smaller, from 25 mm to 15 mm (p < 0.001). Surgery became more radical as total thyroidectomies were performed almost exclusively on the later group (p < 0.001). Median cumulative dose of radioiodine (I131) therapy was higher in the later group (p = 0.04). There was no difference in number of cancer recurrences (p = 0.54). The prognosis of DTC was good; 10-year disease-specific survival was 92% in the earlier group and 94% in the later group (p = 0.43).

Conclusions:

The incidence of thyroid cancer has risen and proportion of papillary cancer has increased, however, median size of tumour has decreased. No difference was seen in either all-cause or disease-specific survival.

IGF-I enhances cellular senescence via the reactive oxygen species-p53 pathway

Cellular senescence is characterized by growth arrest, enlarged and flattened cell morphology, the expression of senescence-associated β-galactosidase (SA-β-gal), and by activation of tumor suppressor networks. Insulin-like growth factor-I (IGF-I) plays a critical role in cellular growth, proliferation, tumorigenesis, and regulation of aging. In the present study, we show that IGF-I enhances cellular senescence in mouse, rat, and human primary cells in the confluent state. IGF-I induced expression of a DNA damage marker, γH2AX, the increased levels of p53 and p21 proteins, and activated SA-β-gal. In the confluent state, an altered downstream signaling of IGF-I receptor was observed. Treatment with a reactive oxygen species (ROS) scavenger, N-acetylcystein (NAC) significantly suppressed induction of these markers, indicating that ROS are involved in the induction of cellular senescence by IGF-I. In p53-null mouse embryonic fibroblasts, the IGF-I-induced augmentation of SA-β-gal and p21 was inhibited, demonstrating that p53 is required for cellular senescence induced by IGF-I. Thus, these data reveal a novel pathway whereby IGF-I enhances cellular senescence in the ROS and p53-dependent manner and may explain the underlying mechanisms of IGF-I involvement in tumorigenesis and in regulation of aging.

Evaluation of candidate diagnostic microRNAs in thyroid fine-needle aspiration biopsy samples

BACKGROUND

Thyroid cancer diagnosis in the United States has increased by 2.3-folds in the last three decades. Up to 30% of thyroid fine-needle aspiration biopsy (FNAB) results are inconclusive. Several differentially expressed microRNAs (miRNAs) have been identified as candidate diagnostic markers for thyroid nodules. We hypothesized that these differentially expressed miRNAs may improve the accuracy of FNAB in difficult to diagnose thyroid nodules.

METHODS

Expression levels of four miRNAs (miR-7, -126, -374a, and let-7g) were analyzed using quantitative real-time reverse transcription-polymerase chain reaction in 95 FNAB samples as the training set. A predictor model was formulated based on the most differentially expressed miRNA (miR-7) ΔCt value and the model was applied on a separate cohort of 59 FNAB samples as the validation set.

RESULTS

miR-7 was the best predictor to distinguish benign from malignant thyroid FNAB samples. The other three miRNAs were co-expressed and did not significantly contribute to the predictor model. miR-7 had a sensitivity of 100%, specificity of 29%, positive predictive value (PPV) of 36%, negative predictive value (NPV) of 100%, and overall accuracy of 76% when applied to the validation set. In subgroup analysis of preoperative nondiagnostic, indeterminate, or suspicious FNAB samples, the predictor model had an overall accuracy of 37% with sensitivity of 100%, specificity of 20%, PPV of 25%, and NPV of 100%.

CONCLUSIONS

miR-7 may be a helpful adjunct marker to thyroid FNAB in tumor types which are inconclusive. Given the high NPV of miR-7, a patient with a benign result based on the predictor model may be followed as opposed to performing an immediate diagnostic thyroidectomy. Future prospective clinical trials evaluating its accuracy in a larger cohort are warranted to determine its clinical utility.

Gene expression profile of human thyroid cancer in relation to its mutational status

This review describes the gene expression profile changes associated with the presence of different mutations that contribute to thyroid cell carcinogenesis. The results are discussed in the context of thyroid cancer biology and of the implications for disease prognosis, while the diagnostic aspect has been omitted. For papillary thyroid cancer (PTC), the most characteristic gene expression profile is associated with the presence of BRAF mutation. BRAF-associated PTC differ profoundly from RET/PTC or RAS-associated cancers. Simultaneously, they retain many characteristic gene expression features common for all PTCs, induced by the alternative mutations activating MAPK pathway. Although the difference between papillary and follicular thyroid cancer (FTC) is significant at the gene expression profile level, surprisingly, the RAS-related signature of FTC is not well specified. PAX8/peroxisome proliferator-activated receptor γ (PPARγ) rearrangements, which occur in FTC as an alternative to the RAS mutation, are associated with specific changes in gene expression. Furthermore, the difference between well-differentiated thyroid cancers and poorly differentiated and anaplastic thyroid cancers is mainly a reflection of tumor degree of differentiation and may not be attributed to the presence of characteristic mutations.

Expression profiling of difficult-to-diagnose thyroid histologic subtypes shows distinct expression profiles and identify candidate diagnostic microRNAs

BACKGROUND

The incidence of thyroid cancer is increasing worldwide. The findings of up to 30% of thyroid fine-needle aspiration biopsies (FNAB) are inconclusive, primarily as a result of several thyroid histologic subtypes with overlapping cytologic features. MicroRNAs (miRNAs) are small noncoding RNAs and have been implicated in carcinogenesis. We hypothesized that there are miRNAs that are differentially expressed between benign and malignant thyroid tumors that are difficult to distinguish by FNAB.

METHODS

The expression of 1263 human miRNAs was profiled in 47 tumor samples representing difficult to diagnose histologic subtypes of thyroid neoplasm (21 benign, 26 malignant). Differentially expressed miRNAs were validated by quantitative real-time reverse transcriptase-polymerase chain reaction. The area under the receiver operating characteristic curve (AUC) was used to determine the diagnostic accuracy of differentially expressed miRNAs.

RESULTS

Supervised hierarchical cluster analysis demonstrated grouping of 2 histologies (papillary and follicular thyroid carcinoma). A total of 34 miRNAs were differentially expressed in malignant compared to benign thyroid neoplasms (P<0.05). A total of 25 of the 34 nonproprietary miRNAs were selected for validation, and 15 of the 25 miRNAs were differentially expressed between benign and malignant samples with P-value<0.05. Seven miRNAs had AUC values of >0.7. miR-7 and miR-126 had the highest diagnostic accuracy with AUCs values of 0.81 and 0.77, respectively.

CONCLUSION

To our knowledge, this is the first study to evaluate the diagnostic accuracy of miRNAs in thyroid histologies that are difficult to distinguish as benign or malignant by FNAB. miR-126 and miR-7 had high diagnostic accuracy and could be helpful adjuncts to thyroid FNAB.

Differential expression of a set of genes in follicular and classic variants of papillary thyroid carcinoma

Fine-needle aspiration biopsy (FNA) is currently the best initial diagnostic test for evaluation of a thyroid nodule. FNA cytology cannot discriminate between benign and malignant thyroid nodules in up to 30% of thyroid nodules. Therefore, an adjunct to FNA is needed to clarify these lesions as benign or malignant. Using differential display-polymerase chain reaction method, the gene expression differences between follicular and classic variants of papillary thyroid carcinoma (PTC) and benign thyroid nodules were evaluated in a group of 42 patients. Computational gene function analyses via Cytoscape, FuncBASE, and GeneMANIA led us to a functional network of 17 genes in which a core sub-network of five genes coexists. Although the exact mechanisms underlying in thyroid cancer biogenesis are not currently known, our data suggest that the pattern of transformation from healthy cells to cancer cells of PTC is different in follicular variant than in classic variant.

A prospective study evaluating the accuracy of using combined clinical factors and candidate diagnostic markers to refine the accuracy of thyroid fine needle aspiration biopsy

BACKGROUND

Approximately 30% of fine needle aspiration biopsies of the thyroid have inconclusive results. We conducted a prospective trial to determine whether clinical and molecular markers could be used in combination to improve the accuracy of thyroid fine needle aspiration biopsy.

METHODS

Clinical, tumor genotyping for common somatic mutations (BRAF V600E, NRAS, KRAS, RET/PTC1, RET/PTC3, and NTRK1), and the gene expression levels of 6 candidate diagnostic markers were analyzed by univariate and multivariate methods in 341 patients to determine whether they could distinguish reliably benign from malignant thyroid neoplasms, and a scoring model was derived.

RESULTS

By a multivariate analysis, fine needle aspiration biopsy cytology classification, the presence of a NRAS mutation, and the tissue inhibitor of metalloproteinase 1 expression level were associated jointly with malignancy. The overall accuracy of the scoring model, including these 3 variables, to distinguish benign from malignant thyroid tumors was 91%, including 67% for the indeterminate and 77% for the suspicious FNA subgroups.

CONCLUSION

Fine needle aspiration biopsy cytology classification, the presence of NRAS mutation, and tissue inhibitor of metalloproteinase 1 messenger RNA expression levels in combination provide a greater diagnostic accuracy than fine needle aspiration biopsy cytology alone to allow selection of more definitive initial operative treatment. The sensitivity of the scoring model, however, was too low to avoid the need for diagnostic thyroidectomies for indeterminate fine needle aspiration biopsy findings.