Project description:Well-differentiated tumours (WDT) of the thyroid gland can be difficult to diagnose. Focal nuclear clearing can be suggestive of a papillary thyroid carcinoma (PTC), while questionable vascular or capsular penetration may raise the possibility of diagnosis of a follicular thyroid carcinoma (FTC). The recently proposed term “thyroid tumours of uncertain malignant potential” (TT-UMP) defines cases showing inconclusive morphological evidence of malignancy. We use microRNA (miRNA) expression profiling to analyze 42 well differentiated thyroid tumours including 7 follicular tumours of uncertain malignant potential (FT-UMP), 6 well differentiated tumours of uncertain malignant potential (WDT-UMP), 7 follicular thyroid adenomas (FTA), 5 follicular variant of papillary thyroid carcinoma (FV-PTC) 6 follicular thyroid carcinoma (FTC), and 11 conventional papillary thyroid carcinoma (C-PTC) with 6 C-PTC mutated for BRAFV600E (C-PTC-mut) and 5 not mutated: wild type (C-PTC-wt). Comparison of these 13 tumours of uncertain malignant potential (7 FT-UMP and 6 WDT-UMP) with those obtained from 16 PTC (11 C-PTC and 5 FV-PTC), 6 FTC and 7 FTA is performed in order to clarify the relationships between TT-UMP and the morphologically well characterized categories of thyroid tumours (i.e. C-PTC, FV-PTC, FTC and FTA). In first, each pathological sample (“L” for Lesional tissue) is compared with its matched control (“S” for Safe tissue) for the 42 patients (84 miRNA microarray slides). This control was taken from the same patient at a large distance from the tumour. Secondly, the perilesional tissue from the same patients but 2 (1 PTC and 1 adenoma, without enough RNA left) is compared to normal thyroid tissue (safe tissue reference) obtained from a patient who underwent total thyroidectomy for a laryngeal carcinoma that partially invaded the thyroid gland, to search for microRNA signatures of perilesional tissues (80 miRNA microarray slides).Experiments is performed with a miRNA microarray, referenced in GEO under the accession number GPL4717 (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GPL4717).

Project description:Anaplastic thyroid carcinomas (ATC) are rare, but represent the most lethal malignancy of the thyroid. Selective molecular markers and drivers distinguishing ATC from other thyroid carcinomas of follicular origin remain largely unknown, limiting advances in diagnosis and treatment. In a retrospective study, we analyzed gene expression in 36 ATC, 18 poorly-differentiated, 132 papillary and 55 follicular thyroid carcinoma, as well as 124 paired and un-paired normal thyroid tissues in three independent cohorts by RNA-sequencing and immunohistochemistry. RNA-sequencing data in the test cohort suggested selective ATC protein biomarkers. Evaluation of these revealed that ATCs are characterized by the de novo expression of various testis antigens, including melanoma-associated antigen A3 (MAGEA3), but most importantly the oncofetal IGF2 mRNA binding protein 1 (IGF2BP1). Shallow whole genome-sequencing essentially excluded, that IGF2BP1 upregulation results from gene copy number alterations. Immunohistochemical analyses in all three tumor cohorts confirmed selective de novo expression of IGF2BP1 protein in ATC. In sum, 75 % (27/36) of all tested ATC and 0.5 % (1/204) of poorly and well-differentiated thyroid carcinoma tissue samples were positive for IGF2BP1 protein. This indicates that IGF2BP1 protein expression identifies ATC with a diagnostic odds ratio of 612 (95 % CI: 74.6 to 5021). In addition, we found that MAGEA3 is exclusively, although less consistently upregulated in ATC, presenting with an odds ratio of 411 (95 % CI: 23.8 to 7098.7). Importantly, we provide confirmatory evidence that IGF2BP1 and MAGEA3 expression distinguishes ATC from partially differentiated thyroid carcinomas (PDTCs). IGF2BP1 furthermore identified ATC foci within low-grade follicular thyroid carcinoma. In conclusion, IGF2BP1 represents the most promising single-gene marker available for ATC, followed by MAGEA3, improving on current techniques. Robust markers are essential to help distinguish this high-grade malignancy from other thyroid carcinomas, to guide surgical decision making, therapy and post-resection/therapy monitoring strategies.

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