Paola Caria

Telomere Abnormalities and Chromosome Fragility in Patients Affected by Familial Papillary Thyroid Cancer

INTRODUCTIONnGenomic instability has been proposed to play a role in cancer development and can occur through different mechanisms including telomere association and telomere loss. Studies carried out in our unit have demonstrated that familial papillary thyroid cancer (fPTC) patients display an imbalance, at the germinal level, in telomere-telomerase complex.nnnAIMnWe aimed to verify whether familial fPTC patients show an increased spontaneous chromosome fragility.nnnMETHODSnTo this purpose, we compared telomeric fusions and associations as well as other chromosomal fragility features by conventional and molecular cytogenetic analyses, in phytohemagglutinin stimulated T-lymphocytes from fPTC patients, unaffected family members, sporadic papillary thyroid cancer patients, and healthy subjects.nnnRESULTSnWe demonstrate that fPTC patients have a significant increase in spontaneous telomeric associations and telomeric fusions compared with healthy subjects and sporadic cases in the frame of an otherwise common spontaneous chromosome fragility pattern. A quantitative fluorescence in situ hybridization analysis demonstrates that familial cases display a significant decrease in the telomeric peptide nucleic acid-fluorescence in situ hybridization signal intensity in the metaphase chromosome. Moreover, three copies of the hTERT gene were found only in familial cases, although the result was not statistically significant.nnnCONCLUSIONSnThese results contribute in defining familial thyroid cancer as a clinical entity characterized by an altered telomere stability, which may be associated with the predisposition to develop the familial form of thyroid cancer.

Cytogenetic and molecular events in adenoma and well-differentiated thyroid follicular-cell neoplasia.

In spite of its simple organization, the thyroid gland can give rise to a wide spectrum of neoplasms, ranging from innocuous to highly malignant lesions. Approximately 94% of the malignancies is represented by well-differentiated thyroid carcinoma originating from follicular cells. These neoplasms are divided into two main categories, papillary thyroid carcinoma and follicular thyroid carcinoma. Despite their origin from the same type of cells, the two neoplasias show different biological behavior and a different set of genetic features, including specific cytogenetic patterns. Thyroid adenoma is the benign counterpart of follicular carcinoma. No benign counterpart of papillary carcinoma has yet been identified. The chromosomes of thyroid nodules have been investigated since 1965, and different cytogenetic subgroups have been recognized, some of which show structural chromosomal rearrangements. These structural changes lead to the formation of fusion genes RET-PTC, TRK(-T), and BRAF-AKAP9, which originate as a result of intrachromosomal or interchromosomal rearrangements and are found in papillary thyroid carcinoma. Fusion genes involving PPARγ are caused mainly by translocations and are characteristic of follicular neoplastic tissue. Radiation exposure and the particular architectural arrangement of chromatin regions in which the affected genes lie during interphase are thought to favor the formation of fusion genes in papillary thyroid carcinoma and possibly also in follicular thyroid carcinoma.

Assessing RET/PTC in thyroid nodule fine needle aspirates: the FISH point of view

RET/PTC rearrangement and BRAF(V600E) mutation are the two prevalent molecular alterations associated with papillary thyroid carcinoma (PTC), and their identification is increasingly being used as an adjunct to cytology in diagnosing PTC. However, there are caveats associated with the use of the molecular approach in fine-needle aspiration (FNA), particularly for RET/PTC, that should be taken into consideration. It has been claimed that a clonal or sporadic presence of this abnormality in follicular cells can distinguish between malignant and benign nodules. Nevertheless, the most commonly used PCR-based techniques lack the capacity to quantify the number of abnormal cells. Because fluorescence in situ hybridization (FISH) is the most sensitive method for detecting gene rearrangement in a single cell, we compared results from FISH and conventional RT-PCR obtained in FNA of a large cohort of consecutive patients with suspicious nodules and investigated the feasibility of setting a FISH-FNA threshold capable of distinguishing non-clonal from clonal molecular events. For this purpose, a home brew break-apart probe, able to recognize the physical breakage of RET, was designed. While a ≥3% FISH signal for broken RET was sufficient to distinguish nodules with abnormal follicular cells, only samples with a ≥6.8% break-apart FISH signal also exhibited positive RT-PCR results. On histological analysis, all nodules meeting the ≥6.8% threshold proved to be malignant. These data corroborate the power of FISH when compared with RT-PCR in quantifying the presence of RET/PTC in FNA and validate the RT-PCR efficiency in detecting clonal RET/PTC alterations.

Leukocyte telomere length positively correlates with duration of lithium treatment in bipolar disorder patients.

Bipolar disorder (BD) has been suggested to be associated with accelerated aging and premature cell senescence. While findings on shorter telomeres in BD are controversial, a recent study showed that long-term lithium treatment correlates with longer telomeres in BD. In our study, we sought to investigate the correlation between leukocyte telomere length (LTL) and long-term lithium treatment in a sample of 200 BD patients characterized for lithium response. We also compared data from two different methods commonly used to measure telomere length, quantitative PCR (qPCR) and quantitative fluorescence in situ hybridization (Q-FISH). We also measured, for the first time, the effect of lithium in vitro on the expression of the telomerase gene in human-derived neural progenitor cells (NPCs). Our findings showed that LTL correlated negatively with age (p=0.0002) and was independent of sex, diagnosis, age at onset, suicidal behavior, number of mood episodes, response to lithium and use of other psychotropic medications. After correcting for age, LTL was positively correlated with lithium treatment duration in patients treated for more than two years (n=150, R=0.17, p=0.037). There was a significant correlation between data measured with qPCR and Q-FISH (p=0.012, R=0.826). Lithium treatment increased telomerase expression in NPCs, though this effect was not statistically significant. Our data support previous findings showing that long-term lithium treatment associates with longer telomeres in BD, though this effect appeared to be independent from clinical response to the treatment. Moreover, we suggested for the first time that lithium increases the expression of telomerase gene in human neural progenitor cells.

An alternative approach in endocrine pathology research: MALDI-IMS in papillary thyroid carcinoma

To the Editor, Many different molecular techniques (polymerase chain reaction (PCR), DNA sequencing, fluorescence in situ hybridization (FISH)) have been introduced in thyroid pathology [1]. Fewer studies evaluated the role of proteomic analysis in the research of new useful targets [2, 3]. Matrixassisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) is a unique technology that explores the spatial distribution of biomolecules directly in situ, thus integrating molecular and morphological information. Therefore, we are investigating the potential role of MALDIIMS in detecting new diagnostic targets in papillary thyroid carcinoma (PTC). We have addressed the issue of molecular stratification of PTC in a small cohort of samples, evaluating both the genomic profile of the main genes of interest (BRAF, N-H-K RAS point mutations, and PAX8/PPARγ or RET/PTC rearrangements) and the proteomic profile shown byMALDIIMS analysis. We have collected ex vivo cytological specimens (see “Technical Note”), in order to analyse a sample perfectly mimicking the in vivo fine-needle aspiration (FNA) biopsy, while respecting the ethical requirements. Unsupervised proteomic analysis of the samples was followed by comparison with histopathology and genetic classification of the patients (Table 1). Data generated by MALDI-IMS were submitted to hierarchical cluster analysis (HCA), in order to evaluate the different proteomic expressions in the cases under study. HCA allowed to cluster proteomic spectra based on their similarity on a dendrogram: spectra showing comparable features were grouped under the same node of the dendrogram; then, it was possible to select nodes and assign them a specific colour (Fig. 1) [4]. Node A groups together three cytological specimens (two collected from patient 1 and one from patient 2), all histologically diagnosed as hyperplastic benign nodules. Node B groups together specimens collected from patients 3, 4 and 5, who were affected by PTC comparable for stage and histotype (Table 1). Node C, instead, groups a microcarcinoma (follicular variant (fv) of PTC), from patient 6, and a nodule histologically classified as uncertain malignant potential (UMP) tumour (patient 7). The last one, originated in a multinodular goitre environment and showed ambiguous morphological features, defined as borderline between a hyperplastic nodule and an “incipient” fv,PTC. The three distinct nodes (A, B, C) generated by HCA analysis confirmed that MALDI-IMS can potentially discriminate between benign and malignant thyroid lesions. Moreover, the homologies between cases 6 and 7 highlight that MALDI-IMS is able to identify a PTC even when the classic diagnostic morphological aspects are still unclear and ambiguous (mild nuclear clearing, rare grooves, no pseudoinclusions). This finding is in agreement Veronica Mainini and Fabio Pagni equally contributed to this paper.

A mutation screening of oncogenes, tumor suppressor gene TP53 and nuclear encoded mitochondrial complex I genes in oncocytic thyroid tumors

BackgroundThyroid neoplasias with oncocytic features represent a specific phenotype in non-medullary thyroid cancer, reflecting the unique biological phenomenon of mitochondrial hyperplasia in the cytoplasm. Oncocytic thyroid cells are characterized by a prominent eosinophilia (or oxyphilia) caused by mitochondrial abundance. Although disruptive mutations in the mitochondrial DNA (mtDNA) are the most significant hallmark of such tumors, oncocytomas may be envisioned as heterogeneous neoplasms, characterized by multiple nuclear and mitochondrial gene lesions. We investigated the nuclear mutational profile of oncocytic tumors to pinpoint the mutations that may trigger the early oncogenic hit.MethodsTotal DNA was extracted from paraffin-embedded tissues from 45 biopsies of oncocytic tumors. High-resolution melting was used for mutation screening of mitochondrial complex I subunits genes. Specific nuclear rearrangements were investigated by RT-PCR (RET/PTC) or on isolated nuclei by interphase FISH (PAX8/PPARγ). Recurrent point mutations were analyzed by direct sequencing.ResultsIn our oncocytic tumor samples, we identified rare TP53 mutations. The series of analyzed cases did not include poorly- or undifferentiated thyroid carcinomas, and none of the TP53 mutated cases had significant mitotic activity or high-grade features. Thus, the presence of disruptive TP53 mutations was completely unexpected. In addition, novel mutations in nuclear-encoded complex I genes were identified.ConclusionsThese findings suggest that nuclear genetic lesions altering the bioenergetics competence of thyroid cells may give rise to an aberrant mitochondria-centered compensatory mechanism and ultimately to the oncocytic phenotype.

Deep fibrous histiocytoma with a clonal karyotypic alteration: molecular cytogenetic characterization of a t(16;17)(p13.3;q21.3)

Deep fibrous histiocytoma, a rare lesion occuring in deep soft tissues, has recently been formally characterized as a diagnostically distinguishable variant of the benign fibrous histiocytoma spectrum with distinct morphological features. Nevertheless, because of the small number of cases published, information on their clinical behavior, including propensity for local recurrence and metastasis, is quite limited, and no molecular genetic or cytogenetic data are available. We report a 46,XY,t(16;17)(p13.3;q21.3) karyotype in a deep fibrous histiocytoma. Fluorescence in situ hybridization using bacterial artificial chromosome (BAC) clones refined the translocation breakpoints within 119.9 kb at 16p13.3 and 214 kb at 17q21.3. Moreover, to ascertain whether they may be nonrandomly involved in changes in this rare tumor type, we designed two dual-color break-apart probes with BAC clones, mapping proximally and distally to the two breakpoints, to be tested in additional archival cases by interphase fluorescence in situ hybridization. No break-apart signals were observed in the six additional cases studied, indicating either that the translocation is sporadic or that it is rare in deep fibrous histiocytoma. In conclusion, our data show that chromosome aberrations may be found in deep fibrous histiocytoma and that, as with cutaneous lesions, they may have clonal, at present nonrecurrent, chromosome changes.

Novel 2-pheynlbenzofuran derivatives as selective butyrylcholinesterase inhibitors for Alzheimer’s disease

Alzheimer’s disease (AD) is a neurodegenerative disorder representing the leading cause of dementia and is affecting nearly 44 million people worldwide. AD is characterized by a progressive decline in acetylcholine levels in the cholinergic systems, which results in severe memory loss and cognitive impairments. Expression levels and activity of butyrylcholinesterase (BChE) enzyme has been noted to increase significantly in the late stages of AD, thus making it a viable drug target. A series of hydroxylated 2-phenylbenzofurans compounds were designed, synthesized and their inhibitory activities toward acetylcholinesterase (AChE) and BChE enzymes were evaluated. Two compounds (15 and 17) displayed higher inhibitory activity towards BChE with IC50 values of 6.23u2009μM and 3.57u2009μM, and a good antioxidant activity with EC50 values 14.9u2009μM and 16.7u2009μM, respectively. The same compounds further exhibited selective inhibitory activity against BChE over AChE. Computational studies were used to compare protein-binding pockets and evaluate the interaction fingerprints of the compound. Molecular simulations showed a conserved protein residue interaction network between the compounds, resulting in similar interaction energy values. Thus, combination of biochemical and computational approaches could represent rational guidelines for further structural modification of these hydroxy-benzofuran derivatives as future drugs for treatment of AD.

Simultaneous occurrence of PAX8-PPARg and RET-PTC3 rearrangements in a follicular variant of papillary thyroid carcinoma.

Specific genotype-phenotype correlations have been identified in conventional-type papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC). In contrast, the genetic alterations underlying the pathogenesis of the follicular variant of PTC (FV-PTC), which shares some clinicopathologic and molecular features with both PTC and FTC, remain to be clarified. This entity shows a PAX8-PPARg fusion gene (associated with FTC), more frequently than BRAF or RET-PTC alterations (associated with PTC). Herein, we report, for the first time, an FV-PTC with the simultaneous occurrence of both RET-PTC and PAX8-PPARg alterations. Neoplastic cells were of the wild type for BRAF and H,K,N-RAS, had an apparently normal karyotype by conventional cytogenetics, and had a balanced genome by array comparative genomic hybridization analysis. In fact, submicroscopic chromosome rearrangements producing RET-PTC3 and PAX8-PPARg chimeric genes were found by interphase fluorescence in situ hybridization. We demonstrated that these 2 genetic alterations coexisted in the same tumor and were confined to 2 different clones. Our findings indicate that molecular heterogeneity, although an uncommon phenomenon, may occur in thyroid carcinoma and demonstrate the coexistence in a case of FV-PTC not only of the histologic but also of the molecular features of both PTC (RET-PTC) and FTC (PAX8-PPARg).

Centrosomal and mitotic abnormalities in cell lines derived from papillary thyroid cancer harboring specific gene alterations

BackgroundDifferentiated thyroid carcinoma offers a good model to investigate the possible correlation between specific gene mutations and chromosome instability. Papillary thyroid neoplasms are characterized by different mutually exclusive genetic alterations, some of which are associated with aneuploidy and aggressive phenotype.ResultsWe investigated the centrosome status and mitotic abnormalities in three thyroid carcinoma-derived cell lines, each maintaining the specific, biologically relevant gene alteration harbored by the parental tumors: RET/PTC1 rearrangement in TPC1; heterozygous and homozygous BRAFV600E mutation in K1 and in B-CPAP, respectively. B-CPAP cells showed a statistically significant (P < 0.01) higher frequency of abnormal mitotic figures compared to TPC1 and K1 cells.ConclusionsOur data indicate that RET/PTC1 oncogenic activity is not related to mitotic chromosome impairment and missegregation whereas, based on the consistent difference in types/frequencies of centrosome and spindle abnormalities observed between K1 and B-CPAP cells, the hetero/homozygous allelic status of BRAFV600E mutation seems to be not irrelevant in respect to chromosomal instability development.