FN1, GALE, MET, and QPCT Overexpression in Papillary Thyroid Carcinoma: Molecular Analysis Using Frozen Tissue and Routine Fine-Needle Aspiration Biopsy Samples

Thyroid nodules are a common clinical problem, and fine-needle aspiration biopsy (FNAB) is widely used for its evaluation. Only 5% are malignant, being papillary carcinoma (PC) the most frequent neoplasia. Approximately 20% are classified as indeterminate or suspicious for malignancy. Gene-expression pattern may be useful for diagnosing PC in difficult or ambiguous cases. In our prior study, we were able to apply RT-PCR method in a series of routinely performed FNAB of thyroid nodules using individual, residual samples. In this study, a total of 70 thyroid samples were evaluated for the expression of MPPED2, H/HBA2, MET, FN1, GALE, and QPCT genes, including 24 cases of frozen thyroid tissue, 12 nodular hyperplasia and 12 PC, and the 46 consecutive thyroid FNAB samples, previously analyzed (3 positive, 10 indeterminate and 32 negative for malignancy, and 1 insufficient). FN1, GALE, MET, and QPCT mRNA expression were significantly different in benign and malignant samples, with similar pattern of overexpression in aspirates compared to frozen tissue. H/HBA2 and MPPED2 expression varied. Histological correlation was possible in five indeterminate cases, revealing one PC and four benign lesions. In conclusion, FN1, GALE, MET, and QPCT were significantly overexpressed in thyroid PC. RT-PCR method could be applied to routine FNAB, showing a similar pattern of overexpression. Despite the small number of cases evaluated, our results suggest that molecular analysis may be of assistance in patients with indeterminate/suspicious cytology, adding elements for preoperative diagnosis and better management of these patients. Diagn. Cytopathol. 2011;39:556-561. (C) 2010 Wiley-Liss, Inc.