Gene expression profiling associated with the progression to poorly differentiated thyroid carcinomas

Poorly differentiated thyroid carcinomas (PDTC) represent a heterogeneous, aggressive entity, presenting features that suggest a progression from well-differentiated carcinomas. To elucidate the mechanisms underlying such progression and identify novel therapeutical targets, we assessed the genome-wide expression in normal thyroid tissues, well-differentiated thyroid carcinomas and PDTC. RNA were extracted from 2 normal thyroid tissues taken from the opposite lobe of thyroid tumors, and 24 thyroid carcinomas: 5 PDTC, 7 classic papillary thyroid carcinomas (cPTC), 8 follicular variants of PTC (fvPTC) and 4 follicular thyroid carcinomas (FTC). All samples were obtained at time of surgery and immediately frozen in liquid nitrogen. We also hybridized a commercial pool of human thyroid total RNA (BD Bioscience). PTC were screened for BRAF mutations and rearrangements of RET/PTC and, in addition, follicular variants were also analyzed for RAS mutations and PAX8-PPARG rearrangements. FTC were screened for RAS and PAX8-PPARG rearrangements. PDTC were analyzed for BRAF, RAS and PAX8-PPARG genes.