Analysis of cyclin D1 and retinoblastoma protein immunoreactivity in follicular thyroid tumors.

Protein products of cyclin D1 and retinoblastoma (Rb) genes play crucial roles in regulation of G1/S transition in the cell cycle. In this study we analyzed, using immunohistochemical methods, the expression of cyclin D1 and Rb proteins in material from medical archives (12 cases of follicular thyroid carcinoma, 57 cases of follicular adenoma and 17 nodular goiter cases). A positive nuclear reaction for cyclin D1 was observed in 83.3% (10/12) of the follicular carcinomas, in 96.5% (55/57) of the follicular adenomas and in 23.5% (4/17) of nodular goiters. Overexpression of cyclin Dl (more than 50% of positively staining cells) was noted in 25% (3/12) of the follicular carcinomas and in 22.8% (13/57) of the follicular adenomas. No overexpression of cyclin D1 was noted among nodular goiters. The number of carcinoma cases with cyclin D1 overexpression did not differ statistically in any significant way from the follicular adenoma group (p = 1.000). A positive nuclear reaction for Rb protein was noted in 100% of the follicular carcinomas (12/12), in 96.5% of the follicular adenomas (55/57) and in 47.1% of the cases (8/17) of nodular goiter. Rb protein overexpression (more than 50% of positively staining cells) was found in 83.3% (10/12) of the follicular carcinomas, in 68.4% (39/57) of the follicular adenomas and in 11.8% (2/17) of the nodular goiters. The number of cases with Rb protein overexpression in the follicular carcinoma group did not differ significantly from that in the follicular adenoma group (p = 0.486). A positive correlation was found in the groups studied between the expressions of Rb protein and cyclin D1. However, the correlation was statistically significant only in the nodular goiter group (Rs = 0.567; p = 0.018). In the follicular carcinoma group, that correlation was borderline (Rp = 0.437; p = 0.072) and, in the follicular adenoma group, it was statistically insignificant (Rs = 0.217; p = 0.105). Our results confirm the existence of mutual regulation mechanisms of Rb and cyclin D1 protein expressions, which are observed in cells from various carcinomas.

Analysis of P53 and P21WAF1 proteins expression in follicular thyroid tumors.

The expression of P53 and P21WAF1 proteins was analyzed immunohistochemically in archival material derived from 12 cases of follicular thyroid carcinoma, 57 cases of follicular adenoma and 17 cases of nodular goiter. In the follicular carcinoma group 6 out of 12 cases (50%) were positive for P53 protein and 4 out of 12 cases (33.3%) were positive for P21WAF1 protein. In the follicular adenoma group, 18 out of 57 cases (31.6%) were positive for P53 and 16 out of 57 cases (28.1%) were positive for P21WAF1 protein. No positive cases of P53 or P21WAF1 proteins presence were found in the nodular goiter group. Positive correlation between the expression of P53 and P21WAF1 proteins was found for follicular carcinoma and adenoma groups (p = 0.034 and p = 0.002, respectively). The obtained results demonstrate that simultaneous immunohistochemical detection of P53 and P21WAF1 proteins expression may be useful in determining functional status of P53 protein, helping to interpret expression of P53 protein in thyroid follicular carcinoma cells.

Analysis of P161NK4A protein expression in follicular thyroid tumors.

PI6INK4A (P16) protein expression was analyzed immunohistochemically in archival material derived from 12 cases of follicular thyroid carcinoma, 57 cases of follicular adenoma and 17 cases of nodular goiter. Among follicular carcinomas, 11 out of 12 examined cases (91.7%) were positive for P161NK4A protein. Among follicular adenomas the percentage of immunopositivity was 76.5% (45/57) and among nodular goiter cases it was 19.3% (13/17). Overexpression of P16INK4A protein was found in 66.7% (8/12) of follicular carcinomas and in 19.3% (11/57) of follicular adenomas; the values of this parameter were statistically significantly higher in the follicular carcinoma group (p < 0.005). No P16INK4A protein overexpression was noted in nodular goiter cells. High immunohistochemically-detected expression of P16INK4A protein in follicular thyroid carcinoma cells suggests that the altered expression pattern of P16INK4A protein may disturb the regulatory mechanisms of thyreocyte cell cycle and plays a significant role in the formation of benign neoplasms and their malignant counterparts derived from follicular thyroid cell.

Analysis of nm23-H1 protein immunoreactivity in follicular thyroid tumors.

Immunohistochemical analysis employing a monoclonal antibody nm23-H1 (the antibody against nm-23 protein) was performed on archival material, consisting of 12 cases of follicular thyroid carcinoma (FTC), 57 cases of follicular thyroid adenoma (FTA) and 17 cases of nodular goiter (NG). Both cytoplasmic and nuclear immunoreactions for nm-23H1 were observed in cells of FTCs, FTAs and NGs. In oxyphilic adenomas cytoplasmic staining was observed. Eleven (91.7%) cases of FTC, 55 (98.2%) cases of FTA and 14 (82.4%) cases of NG were found to be positive for nm23-H1 protein. There were no statistically significant differences in the mean percentage values of immunopositive cells between carcinomas and adenomas. A significant increase in the number of cases with high percentage (more than 50) of positive cells was found in both carcinomas (FTCs) and adenomas (FTAs)--mainly microfollicular ones, in comparison with nodular goiter. It can be concluded that highly positive immunoreaction for the nm23-H1 protein in the cells of carcinomas (FTCs) and microfollicular adenomas indicates for a high proliferation rate of these tumors.

Frequency of proliferation, apoptosis, and their ratio during rat colon carcinogenesis and their characteristic pattern in the dimethylhydrazine-induced colon adenoma and carcinoma.

The imbalance between the cell proliferation and cell loss plays a crucial role in the carcinogenesis and tumor progression. However, the direction of these changes is still the matter of discussion. Thus, the aim of this study was to evaluate the proliferative activity, apoptotic activity, and proliferation/apoptosis ratio (P/A) assessed every 6 weeks in the colonic epithelium during 21 weeks of dimethylhydrazine (DMH) treatment in male Wistar rats. Moreover, it is necessary to answer the question whether these analyzed parameters correlate with the grade of differentiation or dysplasia of the induced tumors. It was found that DMH administration enhanced the proliferation in week 12 and 18 when compared with week 6. The proliferation in the control group did not change during the study. Up to week 12 of the experiment, there were no statistically significant differences between proliferative activity in the control and DMH-treated groups. In week 18, the proliferation in DMH-treated group was higher than in the control group. At all time points of the study, the apoptotic activity in the DMH-treated groups was significantly higher than in controls and in both groups, they dropped during the study. In the control group, apoptotic activity decreased in week 18 and was lower in comparison to that in week 6 and 12. In the group treated with DMH, apoptosis dropped at week 12 and was lower than in week 6. The P/A ratio did not change during the study in the control group, but increased in the DMH-treated group. After 21 weeks of DMH administration, 28 cases of colon adenocarcinoma and nine cases of colon adenoma were obtained and classified according to the WHO classification (1989) for human colon tumors. The adenocarcinomas were divided into four groups: well, moderately, poorly differentiated, and signet-ring cell carcinoma. The colon adenomas were divided into three groups: adenoma with mild, moderate, and severe grade of dysplasia. The proliferative activity in signet-ring cell carcinoma was significantly smaller than in well, moderately, and poorly differentiated adenocarcinoma and apoptotic activity was smaller than in well-differentiated adenocarcinoma. A weak (statistically nonsignificant) negative correlation was also observed between the proliferative and apoptotic activity in adenocarcinoma or adenoma and their grade of dedifferentiation or dysplasia, respectively.