Quantitative Analysis of Estrogen Receptor-α and -β Messenger RNA Expression in Normal and Malignant Thyroid Tissues by Real-Time Polymerase Chain Reaction

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Abstract
Objectives: We have conducted a quantitative analysis of estrogen receptor-α (ER-α) and -β (ER-β) mRNA expression in normal thyroid and tumor tissues. Methods: Normal thyroid tissues (n = 10) and tumor tissues [(follicular adenoma (n = 14), follicular carcinoma (n = 8), papillary carcinoma (n = 14), anaplastic carcinoma (n = 3) and medullary carcinoma (n = 6)] were obtained at surgery from 45 female patients. ER-α and ER-β mRNA expression has been studied by a quantitative polymerase chain reaction. Results: ER-α mRNA levels in the normal thyroid were not significantly different from those in follicular adenomas, papillary carcinomas and medullary carcinomas but were marginally (p = 0.08) higher than those in follicular and anaplastic carcinomas. ER-β mRNA levels in the normal thyroid tissues were not significantly different from those in any other tumor tissues. ER-β to ER-α mRNA ratios were significantly (p < 0.05) higher in the normal thyroid tissues than in follicular adenomas. Proportions of ER-β mRNA variants (ER-β 1, 2, 5, and 5′) did not significantly differ among the normal and tumor tissues. Conclusions: A downregulation of ER-α mRNA in follicular and anaplastic carcinomas seems to suggest that estrogens are unlikely to play an important role in the carcinogenesis and progression of these carcinomas. On the other hand, a significant decrease in ER-β to ER-α mRNA ratios in follicular adenomas suggests a possible involvement of estrogens in the pathogenesis of this disease since the same phenomenon has been reported on estrogen-dependent breast cancers.