|Titolo:||A subgroup of thyroid lesions with PTC-FV features is characterized by trisomy 17 and lack of RET disruprion, PAX8/PPARgamma1 fusion and BRAF mutations.|
|Data di pubblicazione:||2007|
|Abstract:||Papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) are encapsulated follicular patterned lesions which may be of difficult classification. PTC is the most common type of endocrine malignancy and may show simple rearranged karyotypes, usually in the diploid range (Mitelman et al. 2006). Activation of the RET proto-oncogene via chromosomal inversion or translocation, referred to as RET/PTC, has been reported as a cancer causative event (Grieco et al. 1990). Moreover, inv(7) (q21Y22q34), resulting in the AKAP9-BRAF gene fusion, has been observed in 11% of post Chernobyl PTCs (Ciampi et al. 2005). Recently, the gene fusion PAX8/PPARgamma1 has been found also in PTC of the follicular variant (PTC-FV) (Castro et al. 2006). Numerical chromosome changes in PTC are rare and not representative of specific morphological or cytogenetic subgroups. In order to understand whether cases with trisomy 17 as the only karyotypic change (sporadically reported in PTC) could represent a cytogenetic subset of thyroid lesions, we selected from our cytogenetic files, containing 318 nodules, the 9 lesions sharing trisomy 17 as the sole change (irrispectively of the final diagnosis), and 31 nodules with disomy 17 and a final diagnosis of PTC (controls). Re-evaluation of histology and cytogenetics, was done. Cytogenetic re-evaluation was achieved on nuclei isolated from archivial paraffin embedded material by probing chromosome X,7,8,17 and TP53 gene copy number, as well as RET disruption and PAX8/PPARgamma1gene fusion. BRAF mutations was excluded by DNA sequencing. The correlation between the histopathologic and cytogenetic re-evaluations seems to support the view that trisomy 17, lack of RET and PAX8/PPARgamma1 rearrangements, and BRAF mutations, characterizes a rare and peculiar subset of follicular nodules within which PTC-FV and oncocytic features may develop. Supported in part by AIRC and RAS. We thank M Rocchi and YE Nikiforov for probes and control material.|
|Tipologia:||1.5 Abstract in rivista|
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