Matrix metalloproteinase-9 (MMP-9) promoter -1562C/T functional polymorphism is associated with an increased risk to develop micropapillary thyroid carcinoma.

Abstract

Matrix metalloproteinase-9 (MMP-9) is an important mediator of tumor initiation and progression. The MMP-9 promoter -1562C/T functional polymorphism increases gene expression and was identified as a susceptibility factor for various cancers. To evaluate the influence of the MMP-9 promoter genotype on the risk of developing papillary thyroid cancer (PTC) and to correlate cancer patient genotype with the clinical and pathological phenotype. We evaluated 236 patients with nodular thyroid disease pre-thyroidectomy (119 benign disease, 117 PTC). Genomic DNA was isolated from whole blood and the MMP-9 -1562C/T genotype was evaluated by PCR-RFLP analysis. Genotype frequencies were in Hardy-Weinberg equilibrium for all groups. The T allele was significantly more frequent in cancer compared to benign disease (17.5% vs 10.1%), p= 0.019. Patients with the CT or CT+TT genotype had an increased risk of developing PTC, specifically micropapillary thyroid carcinoma (MPTC) (CT genotype: OR = 6.467, p= 0.00006; CT+TT: OR = 6.859, p= 0.00002), but not more advanced stages (CT: p= 0.094; CT+TT: p= 0.157). The -1562C/T genotype did not significantly correlate with tumor histological subtype, invasion or TNM stage. The MMP-9 -1562C/T functional polymorphism may indicate susceptibility to develop thyroid cancer, specifically intrathyroidal clinically non-relevant MPTC. This suggests that although this genotype might be a predisposing factor, other genetic/epigenetic events are needed for cancer progression.