MEN1 mutations in Hürthle cell (oncocytic) thyroid carcinoma.

CONTEXT AND OBJECTIVE Oncocytic thyroid carcinoma, also known as Hürthle cell thyroid carcinoma, accounts for only a small percentage of all thyroid cancers. However, this malignancy often presents at an advanced stage and poses unique challenges to patients and clinicians. Surgical resection of the tumor accompanied in some cases by radioactive iodine treatment, radiation, and chemotherapy are the established modes of therapy. Knowledge of the perturbed oncogenic pathways can provide better understanding of the mechanism of disease and thus opportunities for more effective clinical management. DESIGN AND PATIENTS Initially, two oncocytic thyroid carcinomas and their matched normal tissues were profiled using whole genome sequencing. Subsequently, 72 oncocytic thyroid carcinomas, one cell line, and five Hürthle cell adenomas were examined by targeted sequencing for the presence of mutations in the multiple endocrine neoplasia I (MEN1) gene. RESULTS Here we report the identification of MEN1 loss-of-function mutations in 4% of patients diagnosed with oncocytic thyroid carcinoma. Whole genome sequence data also revealed large regions of copy number variation encompassing nearly the entire genomes of these tumors. CONCLUSION Menin, a ubiquitously expressed nuclear protein, is a well-characterized tumor suppressor whose loss is the cause of MEN1 syndrome. Menin is involved in several major cellular pathways such as regulation of transcription, control of cell cycle, apoptosis, and DNA damage repair pathways. Mutations of this gene in a subset of Hürthle cell tumors point to a potential role for this protein and its associated pathways in thyroid tumorigenesis.