Expression of the ring ligase PRAJA2 in thyroid cancer.

INTRODUCTION: In thyroid cells, binding of TSH to its receptor increases cAMP levels, sustaining thyrocytes growth and hormone production. The main cAMP effector enzyme is protein kinase A (PKA). Praja2 is a widely expressed RING (Really Interesting New Gene) ligase, which degrades the regulatory subunits of PKA, thus controlling the strength and duration of PKA signaling in response to cAMP. Differentiated thyroid cancer expresses a functional TSH receptor, and its growth and progression are positively regulated by TSH and cAMP signaling. AIM: We aimed to analyze the expression of praja2 in a group of 36 papillary thyroid cancer (PTC), 14 benign nodules, and six anaplastic thyroid cancers (ATC). METHODS: We measured praja2 mRNA levels by quantitative RT-PCR and praja2 expression by Western blot and immunohistochemistry. Possible association between praja2 mRNA and the presence of known mutations was evaluated. RESULTS: We found a statistical significant increase of mRNA levels in PTC tissue samples, compared with benign nodules and ATC. In particular, mRNA levels were maximal in differentiated thyroid cancer (PTC), progressively decreasing in more aggressive tumors, ATC having the lowest amount of praja2 mRNA. Accordingly, higher levels of praja2 protein were detected in lysates from PTC, compared with ATC. By immunohistochemistry, in PTC sections we observed a marked increase of cytoplasmic praja2 signal, which significantly decreased in less differentiated thyroid tumors, completely disappearing in ATC. Studies in cultured cells stably expressing RET/PTC1 oncogene or mutant BRAF revealed a direct correlation between praja2 mRNA levels and malignant phenotype of transformed cells. Similar results were obtained using thyroid cancer tissues carrying the same mutations. CONCLUSIONS: praja2 is markedly overexpressed in differentiated thyroid cancer, and its levels inversely correlate with the malignant phenotype of the tumor. Thus, praja2 is a novel cancer-related gene whose expression is linked to the histotype and mutational status of the thyroid tumor.

Telomere abnormalities and chromosome fragility in patients affected by familial papillary thyroid cancer.

INTRODUCTION: Genomic 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. AIM: We aimed to verify whether familial fPTC patients show an increased spontaneous chromosome fragility. METHODS: To 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. RESULTS: We 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. CONCLUSIONS: These 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.

Lack of mutations of the telomerase RNA component in familial papillary thyroid cancer with short telomeres.

BACKGROUND: The occurrence of familial papillary thyroid cancer (FPTC) is well established but no susceptibility genes for this disease have been discovered. Our group has recently demonstrated that patients with FPTC have shorter telomeres, not associated with mutations in telomerase reverse transcriptase, gene than patients with sporadic papillary thyroid cancer (SPTC), healthy subjects (HS), and unaffected family members (UFMs). Several diseases, however, have short telomeres associated with mutations in the telomerase RNA component (TERC) gene or in the shelterin complex (POT1, RAP1, TIN2, TPP1, TRF1, and TRF2) genes. The objective of the present study was to verify whether short telomeres observed in FPTC patients were related to mutations in TERC or shelterin genes. METHODS: Sixty-six patients with FPTC, 46 UFMs, 111 patients with SPTC, and 153 HS were analyzed by polymerase chain reaction followed by denaturing high performance liquid chromatography analysis and direct sequencing for the presence of TERC or shelterin gene mutations. When present, single-nucleotide polymorphisms were tested by χ(2) analysis at the genotypic, allelic, and haplotypic levels. RESULTS: The entire sequence of the TERC gene was analyzed with particular attention to known mutations known to be associated with short telomeres. All samples appeared to be homozygous wild type for A-771G, C-99G, G305A, G322A, C323T, C408G, G450A, T467C, G508A, A514G, G623A, and C727G substitutions and for the 378Δ→3' deletion in the TERC gene. In addition, upon analysis of all samples for shelterin proteins, we observed a significant decrease in POT1 and RAP1 protein expression in the blood of FPTC patients compared with SPTC subjects. However, no mutations or polymorphisms were found when in the coding sequences of both genes. CONCLUSIONS: To our knowledge this is the first study of TERC mutations or alterations in the shelterin complex in relation to FPTC. Shorter telomeres observed in FPTC are not linked to mutations or polymorphisms in TERC, POT1, or RAP1 genes.

Telomere length in neoplastic and nonneoplastic tissues of patients with familial and sporadic papillary thyroid cancer.

INTRODUCTION: Many studies have found an association between altered telomere length (TL), both attrition or elongation, and cancer phenotype. Recently, we have reported that patients with the familial form of papillary thyroid cancer (FPTC) have short telomeres in blood leucocytes. AIM: To evaluate relative TL (RTL) at somatic level in neoplastic and nonneoplastic tissues of patients with FPTC (n = 30) and sporadic PTC (n = 46). METHODS: RTL was measured by quantitative PCR in neoplastic thyroid tissues, in the corresponding nontumor thyroid tissues (normal contralateral thyroid), and in other extrathyroidal tissues (lymph nodes, muscles, or buccal mucosa). RTL was also measured in adenomas and hyperplastic nodules. In a subset of samples, telomerase expression was measured by quantitative PCR. RESULTS: Mean ± SD RTL of FPTC patients was short in neoplastic thyroid tissues (0.87 ± 0.2) with no difference from the normal contralateral thyroid tissues (0.85 ± 0.11) and extrathyroidal tissues (0.85 ± 0.31). On the contrary, in patients with sporadic PTC, the mean ± SD RTL in the neoplastic tissues (1.73 ± 0.63) was significantly shorter than that found in normal contralateral tissues (2.58 ± 0.89) and extrathyroidal tissues (2.5 ± 0.86). For all tissue samples (cancer, normal thyroid, and nonthyroidal tissues) the mean ± SD RTL of familial cases was shorter (P < 0.0001) than that found in tissues from sporadic PTC. RTL of FPTC was also lower (P < 0.0001) than that of 23 follicular adenomas (1.6 ± 0.7) and 24 hyperplastic nodules (2.2 ± 0.9). CONCLUSIONS: Our results demonstrate that short telomeres are a consistent feature of PTC, which in familial cases, is not restricted to the tumor tissue. This finding suggests that FPTC has a distinct, heritable, genetic background.

Lack of germline A339V mutation in thyroid transcription factor-1 (TITF-1/NKX2.1) gene in familial papillary thyroid cancer.

Thyroid cancer may have a familial predisposition but a specific germline alteration responsible for the disease has not been discovered yet. We have shown that familial papillary thyroid cancer (FPTC) patients have an imbalance in telomere-telomerase complex with short telomeres and increased telomerase activity. A germline mutation (A339V) in thyroid transcription factor-1 has been described in patients with multinodular goiter and papillary thyroid cancer. In this report, the presence of the A339V mutation and the telomere length has been studied in FPTC patients and unaffected family members. All samples analyzed displayed a pattern typical of the homozygous wild type revealing the absence of the A339V mutation. Shortening of telomeres was confirmed in all patients. We concluded that the A339V mutation in thyroid transcription factor-1 (TITF-1/NKX2.1) is not correlated with the familial form of PTC, even when the tumor was in the context of multinodular goiter.

Impact of proto-oncogene mutation detection in cytological specimens from thyroid nodules improves the diagnostic accuracy of cytology.

CONTEXT: Fine-needle aspiration cytology (FNAC) is the gold standard for the differential diagnosis of thyroid nodules but has the limitation of inadequate sampling or indeterminate lesions. OBJECTIVE: We aimed to verify whether search of thyroid cancer-associated protooncogene mutations in cytological samples may improve the diagnostic accuracy of FNAC. STUDY DESIGN: One hundred seventy-four consecutive patients undergoing thyroid surgery were submitted to FNAC (on 235 thyroid nodules) that was used for cytology and molecular analysis of BRAF, RAS, RET, TRK, and PPRgamma mutations. At surgery these nodules were sampled to perform the same molecular testing. RESULTS: Mutations were found in 67 of 235 (28.5%) cytological samples. Of the 67 mutated samples, 23 (34.3%) were mutated by RAS, 33 (49.3%) by BRAF, and 11 (16.4%) by RET/PTC. In 88.2% of the cases, the mutation was confirmed in tissue sample. The presence of mutations at cytology was associated with cancer 91.1% of the times and follicular adenoma 8.9% of the time. BRAF or RET/PTC mutations were always associated with cancer, whereas RAS mutations were mainly associated with cancer (74%) but also follicular adenoma (26%). The diagnostic performance of molecular analysis was superior to that of traditional cytology, with better sensitivity and specificity, and the combination of the two techniques further contributed to improve the total accuracy (93.2%), compared with molecular analysis (90.2%) or traditional cytology (83.0%). CONCLUSIONS: Our findings demonstrate that molecular analysis of cytological specimens is feasible and that its results in combination with cytology improves the diagnostic performance of traditional cytology.

A novel NKX2.1 mutation in a family with hypothyroidism and benign hereditary chorea.

BACKGROUND: We studied a boy with congenital hypothyroidism, benign hereditary chorea, and respiratory distress. His mother and his grandfather were affected by hypothyroidism with a late onset and benign hereditary chorea. The aim of this study was to establish the genetic defects that cause that phenotype and study the molecular mechanisms of the pathology. METHODS: NKX2.1, PAX8, NKX2.5, and TAZ genes were sequenced. RESULTS: Direct sequencing of the NKX2.1 gene showed, in all the affected, a new heterozygous mutation from cytosine to adenine in the second base of the triplet encoding for the amino acid at position 145. The mutation (C609A) is responsible for a change from serine to a stop codon (S145X). We also demonstrated that the mutant protein is predominantly in the cytoplasm and unable to translocate into the nucleus. Of note, the S145X mutation produces variable phenotypes in the affected members of the family. No mutations have been identified in the NKX2.5, PAX8, and TAZ genes. CONCLUSIONS: Our study extends the knowledge of the functional effect of NKX2.1 mutations and further highlights the complexities of genotype-phenotype correlation in the NKX2.1 deficiency syndromes.

A new case of familial nonautoimmune hyperthyroidism caused by the M463V mutation in the TSH receptor with anticipation of the disease across generations: a possible role of iodine supplementation.

OBJECTIVE: Hereditary (familial) nonautoimmune hyperthyroidism (FNAH) is caused by activating thyroid-stimulating hormone (thyrotropin) receptor (TSHR) germline mutations. We describe a family with recurrent thyrotoxicosis and goiter across three generations, including an 8-year-old girl. MAIN OUTCOME: Sequences of the TSHR gene in the index patient, her father, her paternal grandmother, and a paternal uncle demonstrated the presence of an identical germline TSHR mutation. The mutation was heterozygous and determined the substitution of valine for methionine (codon 463; ATG-->GTG) in the second transmembrane domain of the TSHR in all the affected patients, but in none of the unaffected family members. CONCLUSIONS: We compared the clinical presentation of FNAH in the family reported by us with the other cases harboring the same mutation reported in the literature. This analysis revealed high variability in the phenotypical expression of the disease. In the family reported by us, we also observed a clear anticipation of the onset of the disease across generations, and we discussed whether such a phenomenon can be the consequence of the increased iodine supplementation in the area where the family lives.