Comparison of MicroRNA Expression in Thyroid Neoplasms: An Aid for Diagnostic Evaluation?
Y Li, GA Barkan, S Alkan. Loyola University Medical Center, Maywood, IL; Miami, Miami, FL
Background: MicroRNAs (miRNAs) is a class of small non-coding RNA molecules that regulate target gene expression. Aberrant expression of miRNAs plays a role as tumor suppressors or oncogenes in cancer. Thyroid cancer is the most common endocrine malignancy, and miRNA deregulation has be reported in common human thyroid cancer. miRNA-221 and miRNA-222 are found upregulated in certain human cancers. We have previously reported marked overexpression of miRNA-221 and 222 in papillary thyroid carcinoma (PTC), and slight upregulation in other thyroid cancer including follicular carcinoma (FC), follicular variant of papillary thyroid carcinoma (FVPTC). To compare the miRNA regulation in benign and malignant thyroid neoplasms, we extended our study to include follicular adenoma (FA).
Design: An electronic database search was performed from 1999 to 2008 in our institution for thyroid neoplasms including FA. The surgical slides were examined, neoplastic and normal thyroid tissue was taken as paired samples from the same specimen. miRNA was extracted from paraffin-embedded thyroid tissue, and was quantified by RT-PCR (Taqman assay). miRNA-RNU was used as an internal control for calculation of Ct (cycle threshold) values. Unpaired t-test was used for statistical analysis.
Results: The expression of miRNA-221 and 222 in the studied thyroid tumors are illustrated in Figure 1. Our results showed miRNA-221 and 222 are both significantly upregulated in PTC compared to normal thyroid and other thyroid tumors. miRNA-221is also slightly overexpressed in FVPTC, FC and FA. However, miRNA-222 expression did not show statistical difference in FVPTC or FC or FA. There is no significant difference in expression levels of miRNA-221 and miRNA-222 among FVPTC, FC, or FA.
Conclusions: We studied expression levels of miRNA-221 and 222 in thyroid tumors (PTC, FVPTC, FC and FA). Both miRNAs remain as highly sensitive diagnostic markers for PTC. However, other thyroid tumors, FVPTC, FC and FA, also showed certain levels of upregulation of both miRNAs, especially miRNA-221. Further investigation is required to understand the biology and to apply biomarker signatures in diagnostic evaluation of thyroid neoplasms.
Tuesday, March 23, 2010 1:00 PM
Poster Session IV # 35, Tuesday Afternoon