Comparison of telomerase and CD44 expression as diagnostic tumor markers in lesions of the thyroid

The analysis of the tissue expression patterns of both the telomerase enzym e and the adhesion molecule CD44 has highlighted these molecules as potenti al tumor markers, In this study, the expression of these markers was analyz ed in frozen tissue samples of the same human thyroid lesions, and the data were compared to evaluate their application to tumor diagnosis. The study analyzed 12 malignant specimens, including 5 papillary, 3 follicular, 2 ana plastic, 1 medullary, and 1 low-grade Hurthle cell carcinoma and 17 specime ns from benign lesions, including cases of adenoma, hyperplasia, and Graves ' disease. Telomerase expression was analyzed by assay of enzyme activity u sing the telomeric repeat amplification protocol and by reverse transcripti on-PCR detection of human telomerase reverse transcriptase (hTERT) mRNA, Ni ne of 12 (75%) malignant samples and the two Graves' disease samples were e valuated as positive for telomerase activity by the telomeric repeat amplif ication protocol assay. The presence of hTERT mRNA was detected in 8 (67%) of 12 malignant tissues and in 5 (29%) of 17 benign thyroid tissue samples. The expression of CD44 transcripts containing variant exons 7, 8, and 11 w as evaluated by reverse transcription-PCR/Southern blot analysis. Of the 12 malignant samples, 9 (75%) included transcripts containing exon 7, 10 (83% ) included transcripts containing exon 11, and 11 (92%) included transcript s containing exon 8, However, these CD44 exons were also present in transcr ipts in a high proportion of benign samples. Five (28%), 10 (59%), and 6 (3 5%) benign samples contained CD44 transcripts, including variant exons 7, 8 , and ii, respectively. The measurement of telomerase activity proved to be the most specific for the detection of thyroid carcinoma in frozen tissue samples as a single analyte, but diagnostic accuracy was increased by the c ombination of telomerase and CD44 analyses.