Clinical significance of the insulin-like growth factor I gene promoter (P1) polymorphism in thyroid nodular disease.

OBJECTIVES: Due to the recent increase of incidence of thyroid nodules and the known risk of malignant transformation, there is an elevated risk of thyroid cancer in Poland. Several approaches, including molecular, have been proposed to support fine needle aspiration biopsy in the early detection of malignant lesions. Although the IGF-I system in thyroid cancer has been studied, little is known about the gene and its promoter structure changes. Our aim was to assess, whether the analysis of the IGF-I gene promoter region and 5'UTR exon 1 structure may be useful in assessing the risk of thyroid carcinoma.

MATERIAL: Our study included 46 patients that underwent strumectomy due to a presence of thyroid nodules.

METHODS: All patients underwent clinical examination and laboratory investigations to assess their thyroid structure and function. Tissues obtained during the surgery were used for DNA extraction, PCR, SSCP and direct sequencing.

RESULTS: Among 46 patients, 14 had a nucleotide difference in one of the examined regions. In our study we revealed no significant difference between carcinomatous and non-carcinomatous groups of patients in terms of presence of nucleotide change, but Fisher's exact test gave a significant result in terms of the efficacy of detecting follicular adenoma. Moreover, the patients with nucleotide change had thyroid glands significantly smaller in volume.

CONCLUSIONS: We conclude that the molecular analysis of the IGF-I gene promoter is thought to be of a functional significance, but probably could not be considered useful in the assessment of risk of thyroid cancer in thyroid nodules.

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