Exp Mol Med.  2004 Apr;36(2):122-129.

Microsatellite instability and its correlation with clinicopathological features in a series of thyroid tumors prevalent in iodine deficient areas

• Vaish M
• Mishra A
• Kaushal M
• Mishra SK
• Mittal B

Abstract

Thyroid tumors display diverse spectrum of histopathological groups with geographic variation in its prevalence. Influence of iodine deficiency (a major causative factor) in its etiology, prevalence, or aggressiveness is debatable which reflects the existence of various genetic events in pathogenesis. The present study was undertaken to study the role of Microsatellite instability (MSI) or LOH (loss of heterozygosity), an indicator of defective mismatch repair system as a genetic change and to explore it as a prognostic marker in thyroid tumors. Tumor tissues from total thyroidectomy surgical specimens and blood (matched control) of 36 patients from iodine deficient areas (10 benign; 26 malignant) were obtained after their consent. Urinary iodine analysis was done by alkali ash method for which 10 ml of urine was collected from 18 patients before surgery. Genomic DNA, isolated from tumor tissue and blood was amplified by polymerase chain reaction (PCR) using mono and dinucleotide markers - BAT-26, BAT-40, TGF(RII, IGFIIR, hMSH3, BAX, D2S123, D9S283, D9S851 and D18S58. PCR products were analysed on 8% denaturing polyacrylamide gel followed by autoradiography. Of total, 66.6% of tumors [70% (7/10) benign and 65.4% malignant cases (17/26)] showed MSI/LOH. Strong association of MSI/LOH with low iodine (P=0.01) and with AMES risk groups i.e. age (P=0.02), tumor size (P=0.04) and metastases (P=0.002) in thyroid tumors was observed. This may help in predicting the biological behaviour and strengthening the hypothesis that iodine deficiency has influence on MSI in thyroid tumors. Our results further substantiate the risk group classification and help in deciding the treatment modality in particular patient.

Keyword

Iodine deficiency; Microsatellite markers; Risk group; Thyroid cancer

MeSH Terms

Adult
Aged
DNA, Neoplasm/*genetics
Female
Genomic Instability/*genetics
Humans
Iodine/*deficiency/urine
Loss of Heterozygosity/genetics
Male
Microsatellite Repeats/*genetics
Middle Aged
Predictive Value of Tests
Prevalence
Research Support, Non-U.S. Gov't
Risk Factors
Thyroid Neoplasms/epidemiology/etiology/*genetics/pathology/therapy/urine
Thyroidectomy
Tumor Markers, Biological/*genetics