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Inactivation of the APC Gene is Constant in Adrenocortical Tumors from Patients with Familial Adenomatous Polyposis but not Frequent in Sporadic Adrenocortical Cancers
source: Clinical cancer research
year: 2010
authors: Gaujoux S, Pinson S, Gimenez-Roqueplo A P, Amar L, Ragazzon B, Launay P, Meatchi T, Libé R, Bertagna X, Audebourg A, Zucman-Rossi J, Tissier F, Bertherat J
summary/abstract:PURPOSE : In adrenocortical tumors (ACT), Wnt/β-catenin pathway activation can be explained by β-catenin somatic mutations only in a subset of tumors. ACT is observed in patients with familial adenomatous polyposis (FAP) with germline APC mutations, as well as in patients with Beckwith-Wiedemann syndrome with Wilms’ tumors reported to have WTX somatic mutations. Both APC and WTX are involved in Wnt/β-catenin pathway regulation and may play a role in ACT tumorigenesis. The aim of this study was to report if APC and WTX may be associated with FAP-associated and sporadic ACT.
EXPERIMENTAL DESIGN : ACTs from patients with FAP and sporadic adrenocortical carcinomas (ACC) with abnormal β-catenin localization on immunohistochemistry but no somatic β-catenin mutations were studied. APC was analyzed by denaturing high-performance liquid chromatography followed by direct sequencing and by multiplex ligation-dependent probe amplification when allelic loss was suspected. WTX was studied by direct sequencing.
RESULTS : Four ACTs were observed in three patients with FAP and were ACC, adrenocortical adenoma, and bilateral macronodular adrenocortical hyperplasia, all with abnormal β-catenin localization. Biallelic inactivation of APC was strongly suggested by the simultaneous existence of somatic and germline alterations in all ACTs. In the 20 sporadic ACCs, a silent heterozygous somatic mutation as well as a rare heterozygous polymorphism in APC was found. No WTX mutations were observed.
CONCLUSIONS : ACT should be considered a FAP tumor. Biallelic APC inactivation mediates activation of the Wnt/β-catenin pathway in the ACTs of patients with FAP. In contrast, APC and WTX genetic alterations do not play a significant role in sporadic ACC.
organisation: Université Paris Descartes-Faculté de médecineDOI: 10.1158/1078-0432.CCR-10-1497
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