Real-time quantitative analysis of E-cadherin expression in ret/PTC-1-activated thyroid neoplasms

Evaluation of Epithelial-Mesenchymal Transition Markers in Autoimmune Thyroid Diseases

A state of chronic inflammation is common in organs affected by autoimmune disorders, such as autoimmune thyroid diseases (AITD). Epithelial cells, such as thyroid follicular cells (TFCs), can experience a total or partial transition to a mesenchymal phenotype under these conditions. One of the major cytokines involved in this phenomenon is transforming growth factor beta (TGF-β), which, at the initial stages of autoimmune disorders, plays an immunosuppressive role. However, at chronic stages, TGF- β contributes to fibrosis and/or transition to mesenchymal phenotypes. The importance of primary cilia (PC) has grown in recent decades as they have been shown to play a key role in cell signaling and maintaining cell structure and function as mechanoreceptors. Deficiencies of PC can trigger epithelial-mesenchymal transition (EMT) and exacerbate autoimmune diseases. A set of EMT markers (E-cadherin, vimentin, α-SMA, and fibronectin) were evaluated in thyroid tissues from AITD patients and controls through RT-qPCR, immunohistochemistry (IHC), and western blot (WB). We established an in vitro TGF-β-stimulation assay in a human thyroid cell line to assess EMT and PC disruption. EMT markers were evaluated in this model using RT-qPCR and WB, and PC was evaluated with a time-course immunofluorescence assay. We found an increased expression of the mesenchymal markers α-SMA and fibronectin in TFCs in the thyroid glands of AITD patients. Furthermore, E-cadherin expression was maintained in these patients compared to the controls. The TGF-β-stimulation assay showed an increase in EMT markers, including vimentin, α-SMA, and fibronectin in thyroid cells, as well as a disruption of PC. The TFCs from the AITD patients experienced a partial transition to a mesenchymal phenotype, preserving epithelial characteristics associated with a disruption in PC, which might contribute to AITD pathogenesis.

BRAF T1799A Mutation Occurring in a Case of Malignant Struma Ovarii

Struma ovarii is an extremely rare tumor that occasionally undergoes malignant transformation. Because struma ovarii is composed of thyroid tissue, it is conceivable that the pathogenetic events involved in thyroid follicular transformation may take place also in struma ovarii. The authors describe a case of a classical variant of papillary thyroid carcinoma arising in a struma ovarii of a 22-year-old female. The tumor was heterozygous for BRAF T1799A mutation. No ret/ PTC-1 or ret/PTC-3 rearrangements were detected. This finding would suggest that malignant struma ovarii is similar histologically and genetically to primary papillary thyroid carcinoma.

Diagnostic utility of immunohistochemical panel in various thyroid pathologies

BACKGROUND

For management of thyroid nodules, distinction between benign and malignant tumours is essential. The study was performed to evaluate the diagnostic value of molecular markers in different thyroid tumours.

MATERIALS AND METHODS

Immunohistochemistry for CD56, HBME-1, COX-2, Ki-67, p53 and E-cadherin (E-CAD) was performed in 113 benign and 35 malignant thyroid lesions including 36 follicular adenomas (FA), 77 colloid goitres, 26 papillary thyroid carcinomas (PTC) and 9 follicular carcinomas (FC). The results were scored semiquantitatively by staining intensity (0-3 scale) and percentage of positive cells.

RESULTS

PTC was characterised by decreased E-CAD and CD56 expression in contrast to surrounding benign thyroid tissues. HBME-1 expression was absent in benign thyroid tissues but was notably high in PTC and occasionally in FC. The expression of E-CAD and CD56 in FA was significantly higher than in the surrounding thyroid tissues. No expression of p53 was found in any group. The expression of COX-2 was low in all lesions. The proliferation activity by Ki-67 was generally low; however, it was significantly higher in cancers.

CONCLUSIONS

The panel consisting of three markers, HBME-1, E-CAD and CD56, can be recommended as an adjunct to morphology criteria. HBME-1 is found in malignant lesions only and is the most sensitive and specific single marker in PTC. Decreased expression of E-CAD and CD56 distinguishes PTC from FA and FC. Both FA and FC are characterised by high expression of E-CAD and CD56. The practical use of Ki-67 is difficult due to low values. The role of adhesion factors in thyroid malignancies may be superior in comparison with cell proliferation.

RET/PTC rearrangement occurring in primary peritoneal carcinoma

RET/PTC rearrangements are initiating events in the development of a significant proportion of papillary thyroid carcinomas. Activated RET/PTC mutations are thought to be restricted to thyroid disease, but this study proposes that these events may also occur in nonthyroid tumors. A total of 57 nonthyroid papillary tumors were examined for RET/PTC rearrangements using interphase fluorescence in situ hybridization, Taqman reverse transcriptase polymerase chain reaction, and immunohistochemistry. Taqman single nucleotide polymorphism detection was used to analyze for expression of mutated BRAF T1799A. In all, 20% (3/15) of primary peritoneal carcinoma had detectable RET/PTC1 rearrangements by all 3 methodologies. A further case of similar histotype had an alternate RET/ PTC rearrangement. No RET/PTC1 rearrangements were detected in the remaining tumor cohort. All 57 tumors were homozygous for wild-type BRAF. The results indicate that RET/PTC rearrangements occur in a small subset of nonthyroid papillary tumors. These rearrangements may not be directly implicated in tumor growth; rather representing "passenger" mutations reflecting RET instability in secondary tumor subclones.

Geographical mapping of a multifocal thyroid tumour using genetic alteration analysis & miRNA profiling

Background

Papillary thyroid carcinoma (PTC) frequently presents as multiple tumour-foci within a single thyroid gland or pluriform, with synchronous tumours comprising different histological variants, raising questions regarding its clonality. Among the genetic aberrations described in PTC, the BRAF V600E mutation and ret/PTC activation occur most commonly. Several studies have investigated the genetic alteration status of multifocal thyroid tumours, with discordant results.

To address the question of clonality this study examined disparate geographical and morphological areas from a single PTC (classic PTC, insular and anaplastic foci, and tumour cells adjacent to vascular invasion and lymphocytic infiltrate) for the presence of ret/PTC 1 or BRAF mutations. Moreover, we wanted to investigate the consistency of miRNA signatures within disparate areas of a tumour, and geographical data was further correlated with expression profiles of 330 different miRNAs. Putative miRNA gene targets were predicted for differentially regulated miRNAs and immunohistochemistry was performed on tissue sections in an effort to investigate phenotypic variations in microvascular density (MVD), and cytokeratin and p53 protein expression levels.

Results

All of the morphological areas proved negative for ret/PTC 1 rearrangement. Two distinct foci with classic morphology harboured the BRAF mutation. All other regions, including the insular and anaplastic areas were negative for the mutation.

MiRNA profiles were found to distinguish tumours containing the BRAF mutation from the other tumour types, and to differentiate between the more aggressive insular & anaplastic tumours, and the classic variant. Our data corroborated miRNAs previously discovered in this carcinoma, and additional miRNAs linked to various processes involved in tumour growth and proliferation.

Conclusion

The initial genetic alteration analysis indicated that pluriform PTC did not necessarily evolve from classic PTC progenitor foci. Analysis of miRNA profiles however provided an interesting variation on the clonality question. While hierarchical clustering analysis of miRNA expression supported the hypothesis that discrete areas did not evolve from clonal expansion of tumour cells, it did not exclude the possibility of independent mutational events suggesting both phenomena might occur simultaneously within a tumour to enhance cancer progression in geographical micro-environments within a tumour.

Snail family transcription factors are implicated in thyroid carcinogenesis

E-Cadherin (CDH1) expression is reduced in thyroid carcinomas by primarily unknown mechanisms. In several tissues, SNAIL (SNAI1) and SLUG (SNAI2) induce epithelial-mesenchymal transition by altering target gene transcription, including CDH1 repression, but these transcription factors have not been studied in thyroid carcinoma. Recently, our group has provided direct evidence that ectopic SNAI1 expression induces epithelial and mesenchymal mouse tumors. SNAI1, SNAI2, and CDH1 expression were analyzed in thyroid-derived cell lines and samples of human follicular and papillary thyroid carcinoma by reverse transcriptase-polymerase chain reaction, Western blotting, and immunohistochemistry. The effect of SNAI1 expression on CDH1 transcription was analyzed by reverse transcriptase-polymerase chain reaction and Western blotting in ori-3 cells. Thyroid carcinoma development was analyzed in CombitTA-Snail mice, in which SNAI1 levels are up-regulated. SNAI1 and SNAI2 were not expressed in cells derived from normal thyroid tissue, or in normal human thyroid samples, but were highly expressed in cell lines derived from thyroid carcinomas, in human thyroid carcinoma samples, and their metastases. SNAI1 expression in ori-3 cells repressed CDH1 transcription. Combi-TA mice developed papillary thyroid carcinomas, the incidence of which was increased by concomitant radiotherapy. In conclusion, SNAI1 and SNAI2 are ectopically expressed in thyroid carcinomas, and aberrant expression in mice is associated with papillary carcinoma development.

[Coexistence of Hashimoto's thyroiditis and papillary thyroidal carcinoma with papillary carcinoma of thyreoglossal duct]

BACKGROUND

Simultaneous presence of Hashimoto's thyroiditis and papillary thyroidal carcinoma in thyroidal gland with papillary carcinoma association in thyroglossal duct is quite rare. The questions like where the original site of primary process, is where metastasis is, what the cause of coexisting of these diseasesis present a diagnostic dilemma.

CASE REPORT

We presented a case of a 53-year old female patient, with the diagnosis of Hashimoto's thyroiditis and symptoms of subclinical hypothyreosis and nodal changes in the right lobe of thyroidal gland, according to clinical investigation. Morphological examination of thyroidal gland, ultrasound examination and scintigraphy with technetium (Tc) confirmed the existence of nonhomogenic tissue with parenchyma nodular changes in the right lobe of thyroidal gland that weakly bonded Tc. Fine needle biopsy in nodal changes, with cytological analyses showed no evidence of atypical thyreocites. Hashimoto's thyroiditis was confirmed on the basis of the increased values of anti-microsomal antibodies, the high levels of thyreogobulin 117 ng/ml and TSH 6.29 microIU/ml. The operation near by the nodular change in the right lobe of thyroidal gland revealed pyramidal lobe spread in the thyroglossal duct. Total thyroidectomia was done with the elimination of thyroglossal duct. Final patohystological findings showed papillary carcinoma in the nodal changes pT2, N0 and in the thyroglossal duct with the presence of Hashimoto's thyroiditis in the residual parenchyme of the thyroid gland. After the surgery the whole body scintigraphy with iodine 131 (131I) did not reveal accumulation of 131I in the body, while the fixation in the neck was 1%. After that, the patient was treated with thyroxin with suppression-substitution doses.

CONCLUSION

Abnormality in embrional development of thyroidal tissue might be the source of thyroidal carcinoma or the way of spreading of metastasis of primary thyroidal carcinoma from thyroid gland. The cause of this process is most probably a hereditary mutation in RET oncogenes.

Inhibition of in vitro tumor cell proliferation by cytokines induced by combinations of TLR or TLR and TCR agonists

The objective of this study was to learn from in vitro studies how to better utilize Toll-like receptor (TLR) agonists in controlling tumor growth. One of the primary effects of TLR agonists is induction of cytokine and chemokine production. In order to identify combinations of cytokines or chemokines with optimal ability to inhibit in vitro tumor cell proliferation, a panel of 17 recombinant human or mouse cytokines that have minimal effect on primary cell survival, were tested individually or in combinations of 2, 3 or 4 on a panel of human and mouse chemotherapy sensitive and resistant tumor cell lines. A combination of high (>10 ng/ml) levels of IFNgamma with moderate concentrations of TNFalpha>IFNalpha>IL-6=IL-8 was most effective at inhibiting in vitro tumor cell viability and proliferation with minimal effect on primary cells. We also observed that similar cytokine profile could be induced in vitro PBMC culture by using certain combinations of TLR-TLR and TLR-TCR agonists. Thus, concomitant activation of TLR7/8 with TLR4 or TLR 7/8 with T cell receptor (TCR) in PBMC, amongst all possible paired TLR-TLR and TLR-TCR agonist combinations, produced cytokine mix high in IFNgamma, in combination with IFNalpha, IL-6, IL-8, TNFalpha. Such cytokine mix was equal or more effective tumor cell killing and inhibition of tumor cell proliferation than the best rec-cytokine mixture tested. These results suggest that, TLR and/or TCR agonists combinations generate an optimal mixture of cytokines and chemokines competent in regulating in vitro tumor growth, and imply that realizing such "right cytokine induction" in vivo might be more efficacious than that with individual cytokines or TLR agonists induced cytokine mix.

Molecular classification and biomarker discovery in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy, with an incidence of approximately 22,000 cases in 2004 in the USA. Incidence is increasing, with a global estimate of half a million new cases this year. PTC is found in a variety of morphologic variants, usually grows slowly and is clinically indolent, although rare, aggressive forms with local invasion or distant metastases can occur. In recent years, thyroid cancer has been at the forefront of molecular pathology as a result of the consequences of the Chernobyl disaster and the recognition of the role of Ret/PTC rearrangements in PTC. Nonetheless, the molecular pathogenesis of this disease remains poorly characterized. In the clinical setting, benign thyroid nodules are far more frequent, and distinguishing between them and malignant nodules is a common diagnostic problem. It is estimated that 5-10% of people will develop a clinically significant thyroid nodule during their lifetime. Although the introduction of fine-needle aspiration has made PTC identification more reliable, clinicians often have to make decisions regarding patient care on the basis of equivocal information. Thus, the existing diagnostic tools available to distinguish benign from malignant neoplasms are not always reliable. This article will critically evaluate recently described putative biomarkers and their potential future role for diagnostic purposes in fine-needle aspiration cytology samples. It will highlight the evolution of our understanding of the molecular biology of PTC, from a narrow focus on specific molecular lesions such as Ret/PTC rearrangements to a pan-genomic approach.

ret/PTC and BRAF act as distinct molecular, time-dependant triggers in a sporadic Irish cohort of papillary thyroid carcinoma

The purpose of this study was to assess BRAF mutation rates in various thyroid tissues and to investigate if concomitant mutations with ret/PTC activation occurred in inflammatory and neoplastic lesions. To this end, we developed a novel Taqman based screening assay for the common T1799A BRAF mutation. Heterozygous T1799A mutations were detected in 13 of 34 (44%) papillary thyroid carcinomas (PTCs) tested. No such mutations were detected in the other tissue types tested. Concomitant presence of both oncogenes was reported in 5 of the 34 PTCs. A significant temporal trend was observed, with ret/PTC chimera detected for the most part before 1997 and BRAF mutations being more prevalent after 1997. The results suggest that some environmental/etiological agent(s) may have influenced the pathobiology of thyroid tumor development, among the population examined, over time.

Hashimoto's thyroiditis with papillary thyroid carcinoma (PTC)-like nuclear alterations express molecular markers of PTC

AIMS

Focal papillary thyroid carcinoma (PTC)-like nuclear alterations have been documented in Hashimoto's thyroiditis; however, the molecular association between PTC and Hashimoto's thyroiditis is poorly understood. The aim of this study was to determine whether molecular expression patterns of PTC are present in association with PTC-like nuclear alterations in Hashimoto's thyroiditis.

METHODS AND RESULTS

The expression of four genes known to be up-regulated in PTC [LGALS3 (galectin3), CITED1, KRT19 (cytokeratin 19) and FN1 (fibronectin-1)] and the human mesothelial cell protein identified by monoclonal antibody HBME1 was evaluated. Immunohistochemistry was performed on 23 cases of Hashimoto's thyroiditis with focal or diffuse Hürthle cell change and PTC-like nuclear alterations, 37 PTC and 18 normal thyroids. Focal expression of galectin3 (GAL3), CITED1, cytokeratin 19 (CK19), HBME1 and fibronectin-1 (FN1) was seen in 87%, 65%, 43%, 26% and 17% of Hashimoto's thyroiditis, respectively, only in thyrocytes showing PTC-like nuclear alterations. In contrast, diffuse expression of GAL3, CITED1, CK19, HBME1 and FN1 was seen in 100%, 95%, 70%, 87% and 89% of PTC, respectively. Normal thyroid tissues did not express any of these proteins. Following immunohistochemistry, four Hashimoto's thyroiditis cases were found to contain foci of PTC. These foci were highlighted by the diffuse and strong expression of PTC-associated proteins, which prompted additional retrospective scrutiny of the haematoxylin and eosin-stained sections leading to appreciation of complete PTC-type nuclear atypia.

CONCLUSIONS

Focal PTC-like immunophenotypic changes in Hashimoto's thyroiditis suggest the possibility of early, focal premalignant transformation in some cases of Hashimoto's thyroiditis.

Real-time analysis of beta- and gamma-catenin mRNA expression in ret/PTC-1 activated and nonactivated thyroid tissues

Our group has previously demonstrated an association between ret/PTC-1 activation and decreased E-cadherin mRNA levels in papillary thyroid carcinoma. We also observed similarities in the E-cadherin expression profiles of Hashimoto thyroiditis and ret/PTC-1-positive papillary thyroid carcinomas and have hypothesized that ret/PTC-1 activation might cause not only the structural and nuclear peculiarities of PTC but also an immune reaction to thyroid epithelium. The objective of this study was to examine the expression of E-cadherin's ligands, beta- and gamma-catenin, in various thyroid tissue types in the context of ret/PTC-1 positivity using laser capture microdissection and TaqMan (Applied Biosystems, Foster City, CA). One-Step RT-PCR. Beta-catenin mRNA levels were found to be consistently decreased in both papillary and anaplastic carcinomas when compared with a normal/follicular adenoma group. A significant difference in expression levels was observed between papillary and follicular thyroid carcinomas with the latter having elevated mRNA levels of beta-catenin. Gamma-catenin mRNA was decreased in anaplastic carcinomas compared with normal/follicular adenoma groups. A similar expression profile of gamma-catenin as beta-catenin was observed in papillary and follicular carcinomas with the latter once again having higher mRNA levels. These results therefore suggest that although beta- and gamma-catenin may play a role in the progression of thyroid cancer in general, they do not appear to be associated with ret/PTC-1-modulated pathways.