Expressions of proliferating cell nuclear antigen, bcl-2 and c-myc proteins, and DNA ploidy in thyroid tumor cells

Objective To investigate the expressions of proliferating cell nuclear antigen (PCNA), bcl-2, and c-myc protein, and to explore diagnostic value of DNA ploidy in benign and malignant thyroid neoplasms. Methods The expressions of PCNA, bcl-2 and c-myc proteins in 36 cases of thyroid adenomas and 37 cases of thyroid carcinomas were examined by immunohistochemistry technique. DNA ploidy was measured by imaging analysis technique in 8 cases of thyroid adenomas and 17 cases of thyroid carcinomas. Results Among thyroid carcinomas, the positive rates of PCNA (43.02±31.16)% and c-myc protein 89.2% were significantly higher than those of thyroid adenomas (16.15±9.28)% and 50.0% respectively (both P0.05). Positive rate of bcl-2 in thyroid carcinoma was significantly lower than that of thyorid adenomas 64.9% vs 88.9%, (P0.05). The positive rate of PCNA in lymph node with metastasis of thyroid carcinoma was higher than that of primitive carcinoma but bcl-2 protein was negative. There were no correlations among PCNA, bcl-2, and c-myc in thyroid neoplasm. The difference in percentages of 5-ploid cells between thyroid adenoma and thyroid carcinoma was statistically significant (P0.01). Conclusion Both bcl-2 and c-myc proteins may play important roles in the occurrence and development of thyroid carcinoma. PCNA and bcl-2 assessments may be helpful in predicting biological behavior and prognosis of thyroid neoplasm. More than 8% of 5-ploid cells may be a reference index for identifying benign and malignant thyroid neoplasms.