Oncogene Amplification and Overexpression of Oncoproteins in Thyroid Papillary Cancer

Abstract

Background: Several oncogene aberrations have been found in papillary thyroid cancer, the incidence of which has increased after the accident in Chernobyl. The occurrence and prognostic significance of these aberrations may have importance in therapeutic strategies. Materials and Methods: Tumour tissues from 24 patients were investigated by Dot-blot DNA hybridisation for c-myc, Ha-ras amplification and p53 deletion, and by immunohistochemical method for cyclin D1, p53 and p21 overexpression. Results: Overexpression of p53 protein was detected in 66.6%, with p21 expression (25%) without any influence on tumour phenotype. Cyclin D1 overexpression was found in 50% to be associated with p21, in inverse relation to lymphocytic infiltration. Overexpression of estrogen receptor was shown in 4 cyclin D1-positive samples (17%). Conclusion: Our results suggest that cyclin D1 overexpression is associated with poor prognosis. The co-expression of cyclin D1 and p21 causes a CDK-independent, estrogen receptor-mediated effect of the cyclin D1 also described in breast cancer.