Expression of p21 (WAF1/CIP1) protein in clinical thyroid tissues

Abstract

Summary p21 (WAF1/CIP1) protein expression in various thyroid tissues, including thyroid carcinoma, was studied by means of immunohistochemistry using anti-p21 monoclonal antibody. Normal follicles and hyperplasias rarely expressed p21, whereas immunohistochemically positive cells were also too rarely found in follicular adenomas to justify these cases being classified as positive. Twenty eight of the 93 carcinomas examined (30.1%), however, were positive for p21. Of the p21-positive cases, 80% of the undifferentiated and 28.6% of the poorly differentiated carcinomas showed lesions co-expressing p21 and p53. If diffuse immunoreactivity of p53 reflects the p53 mutation, our results indicate that p21 in these carcinomas can be induced by p53-independent as well as by p53-dependent pathways. On the other hand, well-differentiated carcinomas did not co-express these two proteins and it therefore remains unclear whether p53-independent or p53-dependent pathways are predominant in this type of carcinoma. The incidence of expression of p21 was very similar in undifferentiated (26.3%), poorly (28.0%) and well-differentiated carcinomas (32.7%), even though they are characterised by different degrees of malignancy. Furthermore, no correlation between p21 expression and either clinical parameters or patient's prognosis could be established. These results suggest that p21 is only marginally related to the characteristics of thyroid carcinoma and can play only an adjuvant role in regulating the progression of this carcinoma.

p21^{WAF–1/CIP–1}, a Downstream Regulator of Functional p53 Loss, in Transitional Cell Carcinoma of Urothelium

“…They could neither detect any relationship of p21 nuclear immunoreactivity with pathological findings such as histological type and depth of the tumor invasion. Ito et al [15]reported similar results for thyroid carcinoma. For small–cell lung carcinoma, Marchetti et al [5]reported no clinical significance of p21 overexpression.…”

Expression of the Components of the Cip/Kip Family in Malignant Lymphoma of the Thyroid

“…In normal follicular cells, p27 expression was observed at a high incidence, whereas the immunoreactivity of p57 and p21 was only occasionally observed (data not shown), which was not different from the findings in previous studies [16][17][18]. In follicular cells forming small follicles and infiltrating lymphocytes, p57 immunoreactivity was diffusely observed (fig.…”

p21/WAF1 expression as related to p53, cell proliferation and prognosis in epithelial ovarian cancer

“…In the present study, the lower p21/WAF1 expression was a significant predictor of poorer overall survival in the univariate survival analysis (47% vs 31% of 5-year survival rate, P = 0.012) but not of the recurrence-free survival in either univariate or multivariate survival analyses. This prognostic significance of p21/WAF1 expression has been reported in some neoplasias (Gomyo et al, 1997;Ito et al, 1997;Jiang et al, 1997;Ogawa et al, 1997;Wagasuki et al, 1997), whereas other authors have failed to establish any such prognostic value (Ito et al, 1996;Backe et al, 1997;Diab et al, 1997). The mechanisms by which the expression of p21/WAF1 is associated with better prognosis is not known in any detail as yet.…”