005), suggesting that the cyclin D1 expression may play a role in tumor progression and may have prognostic significance in thyroid cancer. This study demonstrates a significant overexpression of cyclin D1 in ATC compared CPC (P <. On the other hand, 28 of 32 ATCs showed cyclin D1 immunostaining. Seven of 10 MIFCs were cyclin D1 positive, five (71%) were 1+, and the remaining two (29%) were 2+ positive. Twenty-eight out of the 34 CPCs were cyclin D1 positive, 24 (70%) were 1+, 3 (9%) were 2+, and one (3%) were 3+ positive. Kruskal-Wallis one-way ANOVA and Wilcoxon Rank Sum/Mann-Whitney U Test was used to assess the difference in the expression of cyclin D1 between the study groups. Cyclin D1 staining was classified by staining score as 0, negative 1+, less than 25% 2+, 25 to 50% and 3+, more than 50% tumor cells staining positive. We studied the expression of cyclin D1 by immunohistochemistry in 34 cases of conventional papillary carcinoma (CPC), 10 cases of minimally invasive follicular carcinoma (MIFC), and 32 cases of more aggressive thyroid carcinoma (ATC), which included 11 tall cell variants, one columnar cell variant of papillary carcinoma, seven insular carcinomas, and 13 anaplastic carcinomas. The role of cyclin D1 in malignant progression of thyroid carcinoma has yet to be established. These results indicate that CDKIs may have an important role in the carcinogenesis of the thyroid and that they probably have a limited role in malignant progression of the thyroid cancer. Our previous studies have demonstrated decreased p27 expression in both papillary and more aggressive carcinomas of the thyroid compared to thyroid adenoma and almost similar level of cyclin D1 expression between thyroid adenoma and papillary carcinoma. more Cell cycle progression is facilitated by cyclin-dependent kinases that are activated by cyclins including cyclin D1 and inactivated by cyclin-dependent kinase inhibitors (CDKIs) such as p27. This study shows a significant underexpression of p27 in FVPC compared with FA, suggesting that a decrease in p27 expression plays a more important role than overexpression of cyclins D1 and E alone in thyroid carcinogenesis and that p27 immunostaining may be helpful in the diagnosis of FVPC.Д¬ell cycle progression is facilitated by cyclin-dependent kinases that are activated by cyclins i. This difference in the grade of p27 staining between FVPC and FA was statistically significant (P <. Conversely, all 57 FA were p27 positive, 53 were 4+, and four were 3+ positive. Of the 59 FVPC, 53 (89%) showed p27-positive cells of these, 33 were 1+, nine were 2+, seven were 3+ and only four were 4+ positive. 284) staining was seen between FVPC and FA. No significant differences in the grade of cyclins D1 (P =. Cyclin E-positive cells were seen in 51 (86%) FVPC and 47 (82%) FA.

Cyclin D1 expression was seen in 37 (63%) FVPC and 34 (60%) FA. The positive staining was divided into four grades: 1+ if less than 10%, 2+ if 11% to 25%, 3+ if 26% to 50%, and 4+ if greater than 50% of the nuclei of tumor cells stained positively. We studied the expression of cyclins D1 and E, and the CDKI, p27 by immunohistochemistry in 116 cases, including 59 cases of follicular variant of papillary carcinoma (FVPC) and 57 cases of follicular adenoma (FA). The overexpression of the positive regulators (cyclins) or the underexpression of the negative regulators including p27 has been seen in a variety of neoplasms, but their role and interaction in thyroid carcinogenesis is yet to be established. CDK inhibitors (CDKIs) such as p27 inhibit cyclin-CDK complexes and function as a negative cell cycle regulator. CDKs phosphorylate certain substrates to facilitate the proliferating cells through the cell cycle. more The cell cycle is controlled in part by cyclin-dependent kinases (CDKs), which are activated by forming complexes with cyclins. The cell cycle is controlled in part by cyclin-dependent kinases (CDKs), which are activated by f.

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