Background: Previous studies have demonstrated that two members of the Rb family, pRb and p130, are expressed in thyroid neoplasms. However, our knowledge about the expression and physiological role of the third member of this family, p107, remains poor. We therefore investigated p107 expression in various thyroid neoplasms.
Materials and methods: We immunohistochemically investigated p107 expression in 16 anaplastic carcinomas, 50 papillary carcinomas, 15 follicular carcinomas and 17 follicular adenomas using a rabbit polyclonal antibody against p107.
Results: Normal follicular cells only occasionally expressed p107. In papillary carcinoma, p107 was positive in 84.0% of the cases, regardless of various biological characteristics. Follicular carcinoma less frequently expressed p107 than follicular adenoma (p = 0.0278). Furthermore, only 12.5% of anaplastic carcinomas were p107-positive and the incidence was significantly less than that in papillary carcinoma (p < 0.0001).
Conclusion: Our findings suggest that p107 plays a constitutive role in the progression of papillary carcinoma and that decreased p107 expression may contribute to the transformation from follicular adenoma to follicular carcinoma and anaplastic transformation.