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The Korean Journal of Pathology 2006;40(1): 60-65.
Expressions of Id-1 and Id-2 in Hyperplastic Thyroid Tissue and Thyroid Carcinoma.
Young A Kim, Young Joo Park, Do Joon Park, Seong Hoe Park, Ji Eun Kim
1Department of Pathology, Seoul National University Boramae Hospital, Seoul 156-707, Korea. jekim@brm.co.kr
2Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
3Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
BACKGROUND: Id proteins are a family of helix-loop-helix proteins and are regarded to be negative regulators of cell differentiation. In general, Id-1 and Id-2 expressions are upregulated during tumor development and progression in a variety of neoplasms, and these expressions may be associated with aggressive tumor behavior. However, little is known about the roles of Id-1 and Id-2 in thyroid neoplasms. METHODS: The expressions of Id-1 and Id-2 were assessed immunohistochemically in 310 normal, hyperplastic, and neoplastic thyroid tissues using tissue microarrays. RESULTS: Normal thyroid tissues rarely expressed Id-1 or Id-2. Moreover, whilst Id-1 expression was more elevated in malignant thyroid tissue than in hyperplastic thyroid tissue, Id-2 expression was more variable. No significant differences were observed between histologic subtypes of thyroid carcinomas with respect to Id-1 or Id-2 expression. Follicular adenomas showed higher expressions of Id-1 and Id-2 than thyroid carcinomas. No significant association was found between clinicopathological parameters and Id-1 expression, though Id-2 expression was significantly reduced in metastatic, stage IV tumors. CONCLUSION: The expressions of Id-1 and Id-2 were elevated in hyperplastic and neoplastic thyroid tissues. However, neither appears suitable as a marker of malignancy or an aggressive phenotype, although Id-2 expression in advanced thyroid carcinomas may reflect a favorable prognosis.
Key Words: Inhibitor of differentiation protein 1; Inhibitor of differentiation protein 2; Thyroid gland; Carcinoma, papillary; Adenocarcinoma, follicular; Adenoma