Endocrine Abstracts

Expression gene profile may be useful for the diagnosis of thyroid malignancies

Pamela Piampiani¹, Cristina Romei¹, Barbara Cosci¹, Agnese Vivaldi¹, Raffaele Ciampi¹, David Viola¹, Valeria Bottici¹, Riccardo Giannini², Fulvio Basolo², Aldo Pinchera¹ & Rossella Elisei¹

¹Department of Endocrinology, University of Pisa, Pisa, Italy; ²Department of Oncology, University of Pisa, Pisa, Italy.

Although 20% of follicular neoplasms are papillary thyroid carcinoma (PTC), their cytological diagnosis is not diagnostic. A different profile of gene expression between malignant and benign thyroid tumors has been reported. Aim of this study was to identify a gene expression profile to be used in distinguishing malignant from benign thyroid neoplasms. By real-time RT-PCR we analyzed mRNA expression of 6 thyroid differentiation genes (TTF-1, PAX8, TPO, TSHr, NIS and Tg) and 5 genes known to be involved in thyroid tumorigenesis [PPARγ, Gal3, EGFR, MET and oncofibronectin (onfFN)] in 174 human thyroid tissues (87 tumor samples and 87 corresponding normal tissues) belonging to 72 patients affected with PTC and 15 patients affected with benign nodular disease (BND). Our results indicate that thyroid differentiation genes and PPARγ were significantly less expressed in PTC samples than in normal tissue (TPO, 61/72 cases, P<0.0001; NIS, 64/72 cases, P<0.0001; Tg, 59/72 cases, P=0.0002; TSHr, 57/72 cases, P=0.0169; TTF1, 47/72 cases, P=0.002; PAX8, 55/72 cases, P=0.0001; PPARγ, 57/72 case, P<0.0001). On the contrary, 3 genes were more expressed in the tumor than in normal tissue (onfFN, 64/72 cases, P<0.0001; MET, 55/72 cases, P=0.0018; Gal3, 53/72, P<0.0001). No statistically significant difference was observed for the mRNA expression of EGFR between tumoral and normal tissues. In BND a statistically significant difference between mRNA expression in tumoral and normal tissue was observed only for PPARγ as observed in PTC specimen. Summarising, our data show that 10/11 selected genes are differentially expressed in the tumor tissue with respect to normal. On the contrary only 1/11 was differentially expressed in BND with respect to its normal tissue. In conclusion, 9/11 of these genes are characterized by a gene expression profile that was specific for the malignant neoplasms. The analysis of the levels of expression of these genes in Fine Needle Aspiration material might represent a helpful and innovative method for the presurgical diagnosis of citologically indeterminate thyroid nodules.

Endocrine Abstracts (2007) 14 OC1.2