An immunohistochemical analysis of cyclin D1, p53. and p21waf1/cip1 proteins in tumors originating from the follicular epithelium of the thyroid gland

This study aimed at clarifying the factors closely related to the tumor progression of thyroid neoplasms. We examined the immunoreactivity of cyclin D1, p53, and p21(waf1/cip1) proteins in 179 thyroid tumors originating from the follicular epithelium using an immunohistochemical technique. Cyclin D1 positivity was frequent in well-differentiated thyroid carcinomas (39/122 cases), but it was rarely seen in follicular adenomas (1/33 cases), (p < 0.05). Positivity for p53 was more frequent in poorly differentiated carcinomas (7/19 cases) and undifferentiated carcinomas (4/5 cases) than in well-differentiated carcinomas (14/122 cases) (p < 0,05, respectively). P21(waf1/cip1) positivity was more frequent in well-differentiated thyroid carcinomas (43/122 cases) than in follicular adenomas (4/33 cases) (p < 0.05). Regarding the relationships of these proteins, co-positivity for cyclin D1 and p53 was observed more often in poorly differentiated carcinomas (5/7 cases) than in well-differentiated carcinomas (7/39 cases) (p < 0.05). Most cases with cyclin D1 positivity did not show p21(waf1/cip1) expression in poorly differentiated carcinomas (6/7 cases). Three cases examined showed co-positivity of p53 and p21(waf1/cip1). Our results suggest that cyclin D1 is invoved in thyroid oncogenesis. Moreover, p53 might be closely related to the development of poorly differentiated carcinomas and undifferentiated carcinomas originating from well-differentiated carcinomas.