Valentina Cirello

BRAF mutations in an Italian cohort of thyroid cancers

objectiveu2002 Recently, a somatic point mutation of the BRAF gene (V599E) has been identified as the most common genetic event in papillary thyroid carcinoma (PTC) with a variable frequency (about 25–70%) in different series from USA, Japan, Portugal and Ukraine.

The tight relationship between papillary thyroid cancer, autoimmunity and inflammation: clinical and molecular studies

Objectiveu2002 The recent concept that oncogenes responsible for thyroid neoplastic transformation are able to elicit an inflammatory protumourigenic microenvironment raises interest in further studies on papillary thyroid cancer (PTC) associated with thyroid autoimmunity.

A High Percentage of BRAFV600E Alleles in Papillary Thyroid Carcinoma Predicts a Poorer Outcome

CONTEXTnBRAF(V600E) is considered a negative prognostic marker in papillary thyroid carcinoma (PTC), but unexplained conflicting results are present in the literature. In light of the new finding that most PTC consist of a mixture of tumor cells with wild-type and mutant BRAF, we examined the associations between the percentage of BRAF(V600E) alleles and both the clinicopathological parameters at time of diagnosis and the disease outcome in a large series of PTCs.nnnSTUDY DESIGNnTumors from 168 patients with PTC were genotyped for BRAF(V600E) using BigDye Terminator sequencing and pyrosequencing, and the clinical parameters were analyzed. The associations between clinicopathological characteristics, including disease recurrence at follow-up (median 5.1 yr) and the percentage of mutant BRAF alleles were assessed.nnnRESULTSnThe observed prevalence of BRAF(V600E) was higher when using pyrosequencing then when using BigDye Terminator sequencing (53.6 vs. 36.9%). In the PTC positive for BRAF(V600E), the percentage of mutant alleles ranged from 5.1 to 44.7% of the total BRAF alleles, with a median of 20.6%. The presence or the percentage of BRAF(V600E) alleles did not correlate significantly with sex, multicentricity, lymph node metastasis, or tumor stage. The percentage of BRAF(V600E) alleles directly correlated with age at diagnosis and tumor volume (R(2) = 0.223, P = 0.039, and R(2) = 0.166, P < 0.001, respectively). The percentage of BRAF(V600E) alleles (P = 0.014), tumor volume (P = 0.012), and lymph node metastasis (P = 0.008) predicted the disease outcome. The odds ratio of recurrence for PTC with BRAF(V600E) alleles of 30% or greater, compared with that for PTC with BRAF(V600E) alleles of less than 30%, was 5.31 (P = 0.002).nnnCONCLUSIONSnA high percentage of BRAF(V600E) alleles defines a PTC molecular subtype and predicts a poorer disease outcome. The analysis of BRAF mutations by pyrosequencing is useful to refine the risk stratification of patients with PTC.

Evidence of a Low Prevalence of RAS Mutations in a Large Medullary Thyroid Cancer Series

BACKGROUNDnApproximately 60% of sporadic medullary thyroid carcinomas (sMTC) remain orphan of a recognized genetic cause. Recently, a high percentage of RAS point mutations have been described in RET-negative sMTC. The aim of this study was to assess the prevalence of RAS point mutations in a large series of MTC collected in four Italian centers.nnnMETHODSnFor this purpose, we studied codons 12, 13, and 61 of H-, K-, and N-RAS genes in 188 MTC samples, either hereditary or sporadic, by direct sequencing. Correlations between the RAS mutational status and the clinical-pathological features of MTC patients as well as a meta-analysis of all published data were performed.nnnRESULTSnThe prevalence of RAS mutations in the present series of MTC was 10.1%, and 17.6% when considering only RET-negative cases. RAS mutations were found in MTC tumoral tissue, but not in peripheral blood indicating their somatic origin. A novel mutation in codon 72 (M72I) was found, but with a low or null transforming potential. No association was found between the presence of RAS mutations and the clinical-pathological features of the patients. Although not statistically significant, a positive association between the presence of RAS mutations and a better outcome was observed. The meta-analysis of all published studies confirmed a prevalence of 8.8% for RAS mutations in MTC.nnnCONCLUSIONSnThe prevalence of RAS mutations in our MTC series was relatively low and consistent with the meta-analysis data. Only somatic RAS mutations were found and only in RET-negative sMTC. Likewise, MTCs that harbor a RAS mutation identify a subgroup of tumors with less aggressive behavior. To our knowledge, this is the largest series of MTCs studied for the presence of mutations in RAS genes and the first meta-analysis on this specific topic.

Fetal microchimerism as an explanation of disease

Fetal cell microchimerism is defined as the persistence of fetal cells in the mother after birth without any apparent rejection. Fetal microchimeric cells (FMCs) engraft into the maternal bone marrow for decades after delivery and are able to migrate to blood and tissues. This phenomenon was hypothesized to have a detrimental role in autoimmune diseases, but data are still controversial and debated. In malignant tumors, fetal cell microchimerism has been postulated to have a positive effect on tumor burden, although some evidence suggests that FMCs may be involved in neoplastic progression. At the peripheral level, circulating FMCs are less frequently detected in patients with thyroid cancer, breast cancer or other solid, hematologic malignancies than in healthy individuals, which suggests a protective role for fetal cell microchimerism. In tissues, FMCs have been found in tumor sections from malignancies such as thyroid, breast, cervix, lung cancers and melanomas and have been shown to differentiate into epithelial, hematopoietic, endothelial and mesenchymal cells. FMCs with hematopoietic differentiation have been postulated to have a role in destroying the tumor, whereas mesenchymal and epithelial cells could participate in repair processes. Endothelial cells, on the other hand, are believed to play a part in tumor progression. This Review provides an overview of the role of fetal cell microchimerism in autoimmune and benign or malignant nonautoimmune diseases. Moreover, the mechanisms by which fetal cell microchimerism is believed to modulate the protection against cancer or tumor progression will be discussed, together with future research directions.

Telomerase in differentiated thyroid cancer: Promoter mutations, expression and localization

Telomerase-reverse-transcriptase (TERT) promoter mutations have been recently described in tumors. In the present large series, TERT mutations were found in 12% of papillary thyroid cancers (PTCs) and in 14% of follicular thyroid cancers (FTCs), and were found to significantly correlate with older age at diagnosis and poorer outcome. Interestingly, the prognostic value of TERT mutations resulted to be significantly stronger than that of BRAF(V600E). Moreover, the outcome was not different among tumors with isolated TERT mutation and those with coexistent mutations (TERT/BRAF in PTCs or TERT/RAS in FTCs). TERT rs2853669 polymorphism was found in 44.4% of tumors. At WB, TERT was significantly more expressed in tumors than in normal samples, being the highest levels of expression recorded in TERT mutated cases. At IHC, in tumors and in metastatic lymph-nodes TERT staining was significantly higher in the cytoplasm than in the nucleus, whereas in normal tissue the degree of staining did not differ in the two cellular compartments. In conclusion, TERT mutations were shown to strongly correlate with a poorer outcome in differentiated thyroid tumors, and neither BRAF nor RAS mutation were found to confer an additional effect in the disease persistence. TERT protein was found to be more expressed in neoplastic than in normal tissues, and to display a different cellular localization, suggesting that it could contribute to thyroid cancer progression by mechanisms taking place in the cytoplasm.

Fetal Cell Microchimerism in Papillary Thyroid Cancer: A Possible Role in Tumor Damage and Tissue Repair

Fetal cells enter the maternal circulation during pregnancy and can persist in the maternal blood or tissues for decades, creating a physiologic microchimerism. Because papillary thyroid cancer (PTC) is more frequent in women, the role of persisting fetal male cells in this tumor has been investigated. Tumor tissue specimens were obtained from 63 women with PTC who had a male pregnancy before the diagnosis. Male cells, identified by PCR amplification of a male-specific gene, the sex-determining region Y, was detected in 47.5% of women. By fluorescence in situ hybridization (FISH) analyses, the total number of microchimeric cells was significantly higher in neoplastic tissue than in controlateral normal sections. By combined FISH and immunohistochemistry (immuno-FISH), male cells expressing thyroglobulin were found in tumor and normal tissues, whereas male microchimeric cells stained with the CD45 antigen were detected only in tumor sections. Microchimeric cells negative for either marker were detected both in tumor and normal tissues. Moreover, both CD45(+) and Tg(+) fetal cells did not express MHC II antigens. In conclusion, fetal microchimerism has been documented in a high proportion of women with PTC. The immuno-FISH studies indicate that CD45(+)/MHC II(-) male cells found in neoplastic tissues might be committed to destroy tumor cells, whereas Tg(+)/MHC II(-) cells could have a repair function. Finally, microchimeric cells negative for either CD45 or Tg could have progenitor-like properties able to transdifferentiate in different cellular types. Although a pathogenetic mechanism cannot be excluded, the whole of the present results indicates a protective role of microchimerism in thyroid cancer.

Modifications in the Papillary Thyroid Cancer Gene Profile Over the Last 15 Years

BACKGROUNDnEvidence for an increased prevalence of BRAF(V600E) mutations has been documented in recent decades. The aim of this study was to evaluate the prevalence of both RET/PTC rearrangements and BRAF(V600E) mutations in an Italian cohort of papillary thyroid carcinoma (PTC) patients followed at the Endocrine Units of Pisa, Milano, and Perugia from 1996-2010.nnnPATIENTS AND METHODSnIn total, 401 PTC patients were examined and grouped according to the time of surgery: group 1, 1996-2000; group 2, 2001-2005; and group 3, 2006-2010. Patients were analyzed for clinical, pathological, and molecular features. In parallel, the molecular characteristics of 459 PTC from Sicily were studied.nnnRESULTSnThe genetic profiles of the three groups were significantly different (P < 0.0001). In particular, the frequency of RET/PTC rearrangements decreased from 1996-2010, occurring in 33 of 100 (33%) of the patients in group 1, 26 of 148 (17%) in group 2, and 15 of 153 (9.8%) in group 3. The incidence of BRAF(V600E) mutations increased over the same period, from 28% in group 1 (28 of 100) to 48.9% in group 2 (73 of 148) and 58.1% in group 3 (89 of 153). A consistent increase in BRAF(V600E) prevalence was observed in the Sicilian group (P < 0.0001). Moreover, a statistically significant increase in the mean age at diagnosis and decrease in tumor size over the study period was observed.nnnCONCLUSIONnThe genetic profile of PTC changed over the last 15 yr, with a significant decrease in the prevalence of RET/PTC rearrangements and an increase in BRAF(V600E) mutations. In addition, the mean age at diagnosis increased and tumor size decreased over the study period.

Fetal cell microchimerism in papillary thyroid cancer: studies in peripheral blood and tissues

Fetal cell microchimerism (FCM) is defined as the persistence, for decades after pregnancy, of fetal cells in maternal organs and circulation without any apparent rejection. We recently reported evidence, in papillary thyroid cancer (PTC) tissues, supporting a possible role of FCM in tumor damage and repair. To extend those data at the peripheral level, 106 women with a previous male pregnancy, comprising 57 with PTC and 49 healthy controls were enrolled. The presence of circulating male DNA was assessed by the amplification of the Y chromosome‐specific gene SRY, with a sensitivity of 1 male cell per 1 million female cells. Moreover, to compare the microchimeric status in blood and in tumors, the neoplastic tissues of 19 women were studied. At the blood level, a significantly lower frequency of FCM was found in parous women with PTC with respect to controls (49.1% vs. 77.6%; p = 0.002). By PCR, male DNA was identified in the tumor tissues of 6 patients, and FISH analyses confirmed the presence of microchimeric cells (range 2.1–6.9 cells/section). In some patients, FCM was negative in the blood, whereas microchimeric cells were identified in the tumor. In conclusion, the prevalence of FCM in peripheral blood was found to be significantly lower in patients than in healthy controls. The presence of microchimeric cells in the tumors, but not at the peripheral level, supports the hypothesis that fetal cells could reside in maternal niches and could be recruited to diseased areas, where they could differentiate to regenerate damaged tissues.

Role of glucocorticoid receptor polymorphism in adrenal incidentalomas

Eur J Clin Invest 2010; 40 (9): 803–811