Survivin Delta Ex3 Overexpression in Thyroid Malignancies

Context: Thyroid cancer incidence has increased significantly during the past decades and is the most common type of endocrine malignancy. Many factors in thyroid cancers were studied as independent predictors of a poor prognosis. Objective: The objective of the study was to evaluate survivin expression - BIRC5 and its splice variants: survivin delta Ex3 and survivin 2B in benign and malignant thyroid nodules. Design: Thyroid tissues samples from a group of 50 patients consisting of: 29 patients with thyroid cancers (including medullary, papillary, follicular and undifferentiated types), as well as from 21 patients with non-cancerous thyroid tissues (including: 11 benign thyroid lesions and 10 healthy thyroid samples). Main Outcome Measures: The analysis of the survivin gene expression and evaluation of the level of splice variants were performed using quantitative RT-PCR. Results: A statistically significant higher level of expression of survivin gene - BIRC5 was detected in thyroid malignant nodules, when compared with benign lesions and healthy thyroid samples. Moreover, the comparison of survivin relative expression in different staged tumors (pT1, pT3, and pT4) revealed a much higher amount of BIRC5 transcripts in tumor tissues of pT3/pT4. The comparison of survivin expression between benign thyroid nodules and healthy thyroid did not reveal significant differences. Importantly, high expression rate of the survivin delta Ex3 splice variant characterized thyroid carcinomas. Conclusion: The results suggest that survivin, especially survivin delta Ex3 splice variant being overexpress, is a characteristic feature of thyroid malignancy.