Molecular classification of thyroid nodules by cytology.
OBJECTIVE
Fine needle aspiration (FNA) biopsy of thyroid nodules provides cytologic specimens whose interpretation can direct patients toward either thyroidectomy or observation. Approximately 20% of FNA specimens yield an indeterminate result. Recent studies have characterized differences in gene expression between benign and malignant conditions, most often using whole tissue. Our goal was to determine the feasibility of quantitative polymerase chain reaction (qPCR)-based gene expression analysis in cytologic samples. For five genes shown to be over-expressed in thyroid carcinomas (fibronectin, galectin-3, Met/HGFR, MUC1, and GA733-precursor), we compared expression among pathologic states.


METHODS
Prospective laboratory analysis of 20 thyroidectomy specimens.


METHODS
Routine microscopy was performed. Cytologic samples were obtained from the dominant nodules, and RNA was extracted. Preliminary analysis using fluorometry and reverse-transcriptase (RT)-PCR was performed. Expression levels of the test genes in nodules and from control samples were measured by real-time qPCR. Fold changes in gene expression were compared.


RESULTS
Only one specimen did not yield sufficient intact RNA for gene expression analysis. RT-PCR revealed satisfactory RNA recovery in all other specimens. qPCR showed significant over-expression of fibronectin in the papillary carcinomas compared with the goiters (P = .0013), follicular adenomas (P = .0014), and follicular carcinomas (P = .0001). Differences in both fibronectin and MUC1 expression between the follicular carcinomas and the follicular adenomas were also significant (P = .025 and .045, respectively).


CONCLUSIONS
Cytologic specimens were a satisfactory source of tissue for qPCR-based gene expression analysis. Both fibronectin and MUC1 were differentially expressed in follicular adenomas and follicular carcinomas, and fibronectin expression differed in papillary carcinomas compared with the other lesions. These results may form the basis of a clinical predictor for lesions with indeterminate or suspicious cytology.
Pagedar
Nitin A
NA
Department of Otolaryngology-Head and Neck Surgery, University Hospitals Case Medical Center, Case School of Medicine, Cleveland, Ohio 44106, USA.
Chen
Daniel H
DH
Wasman
Jay K
JK
Savvides
Panayiotis
P
Schluchter
Mark D
MD
Wilhelm
Scott M
SM
Lavertu
Pierre
P
D018263:Adenocarcinoma, Follicular / Q000473:pathology; D000236:Adenoma / Q000473:pathology; D000951:Antigens, Neoplasm / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D044963:Biopsy, Fine-Needle; D017252:CD3 Complex / Q000032:analysis; D002291:Carcinoma, Papillary / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000032:analysis; D000071858:Epithelial Cell Adhesion Molecule; D005240:Feasibility Studies; D005353:Fibronectins / Q000032:analysis; D037502:Galectin 3 / Q000032:analysis; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006042:Goiter / Q000473:pathology; D006801:Humans; D008967:Molecular Biology; D018396:Mucin-1 / Q000032:analysis; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D011505:Protein-Tyrosine Kinases / Q000032:analysis; D011518:Proto-Oncogene Proteins / Q000032:analysis; D019859:Proto-Oncogene Proteins c-met; D017978:Receptors, Growth Factor / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013964:Thyroid Neoplasms / Q000473:pathology; D016606:Thyroid Nodule / Q000473:pathology*
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D017252:CD3 Complex; D015815:Cell Adhesion Molecules; D000071858:Epithelial Cell Adhesion Molecule; D005353:Fibronectins; D037502:Galectin 3; C060192:MUC1 protein, human; D018396:Mucin-1; D011518:Proto-Oncogene Proteins; D017978:Receptors, Growth Factor; C491743:MET protein, human; D011505:Protein-Tyrosine Kinases; D019859:Proto-Oncogene Proteins c-met