[446] FN1, GALE, MET and QPCT mRNA Overexpression in Papillary Thyroid Carcinoma Using Routine FNAB Samples and Frozen Tissue

CAT Mitteldorf, JM Sousa-Canavez, C Massumoto, LH Camara-Lopes. Hospital Sirio Libanes, Sao Paulo, Brazil; Genoa Biotechnology S.A., Sao Paulo, Brazil; Instituto Zacarias Marques de Pesquisa, Sao Paulo, Brazil

Background: Thyroid nodules are frequent in clinical practice and fine needle aspiration biopsy (FNAB) is widely used for its evaluation. Only 5% of the cases are diagnosed as malignant, being papillary carcinoma (PC) the most common neoplasia, and approximately 20% are classified as indeterminate or suspicious for malignancy. In a prior study, we were able to apply qRT-PCR method in a series of routinely performed FNAB of thyroid nodules using individual, residual samples. In the present study, we used this series to evaluate the expression of 6 genes related to PC, comparing it with a set of frozen thyroid tissue from surgical specimens.
Design: 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 papillary carcinoma) and 46 consecutive thyroid FNAB samples previously analyzed (3 positive, 3 indeterminate and 32 negative for malignancy, 7 most probably benign and 1 suggestive of benign follicular lesion). The ΔΔCT method was used to calculate the relative expression of the 6 target genes and fold change in expression was calculated as 2-ΔΔCT.
Results: As seen on Figure 1A, FN1, GALE, MET, and QPCT mRNA expression were found to be significantly different in benign and malignant frozen thyroid samples (p = 0.0051, p = 0.0010, p = 0.0074 and p = 0.0102, respectively); FNA samples showed a similar pattern of overexpression (Figure 1B), although only 3 malignant aspirates were analyzed. H/HBA2 and MPPED2 results varied (p = 0.6442 and p = 0.549, respectively).

Conclusions: FN1, GALE, MET and QPCT are significantly overexpressed in malignant thyroid tumors, representing possible molecular markers to be used for pre-operative diagnosis. RT-PCR analysis using individual, residual samples of thyroid nodules aspirates can be employed to access gene expression, adding elements for final cytological diagnosis of indeterminate or suspicious cases, without altering the routine procedure.
Category: Cytopathology

Tuesday, March 23, 2010 1:30 PM

Platform Session: Section D, Tuesday Afternoon


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