Strong and Significant Associations of Single Nucleotide Variants (SNVs) in the Promoter and 3'-Untranslated Region (3'-UTR) of Vascular Endothelial Growth Factor (VEGF) Gene with Head and Neck Cancers

Vascular Endothelial Growth Factor (VEGF) has a potent role in tumorigenesis and metastasis. VEGF gene is highly polymorphic. Specific variants have been associated with risk and disease progression in disorders with microvascular involvement such as diabetes mellitus and cancer. However, no study has reported association analysis of common single nucleotide variants (SNVs) in the promoter and 3 untranslated region (3-UTR) with head and neck cancers (HNCs). The present study addresses this gap. It investigates the association of two SNVs, -2578 C/A (rs699947) in the promoter region and +936 C/T (rs3025039) in 3-UTR of the VEGF gene, with risk of HNCs and tumour characteristics. After the ethical approval and informed consent, 323 participants were enrolled in the study. In the case-control component of the study, there were 121 HNC patients and 202 controls. Demographic details and medical history were recorded. Peripheral blood samples (10ml) were collected in ACD-coated vacutainers. DNA isolation was carried out by organic-solvent method. PCR-RFLP methods were optimized for the genotyping of selected SNVs. The protocol was validated by Sanger sequencing. The susceptibility association was determined by using genetic models applying Hardy-Weinberg equilibrium. Statistical analyses included Chi-squared test of independence or Fishers Exact test with significance at p-value <0.05, and odds ratios with 95% confidence interval. VEGF -2578 A-allele, A-carrier genotype (dominant model), and AA genotype (co-dominant model) were significantly associated with protective effect against HNCs (p-values <0.01, <0.042, and < 0.009, respectively). The odds ratios (95% CI) were: 0.651 (0.469 - 0.904), 0.613 (0.381 - 0.985), and 0.393 (0.193 - 0.804), respectively. The association analysis of VEGF +936 C/T polymorphism showed that T-allele, CT (over-dominant model), and T-carrier (dominant model) genotypes were significantly associated with the risk for head and neck cancers (p-values < 0.047, < 0.037, and < 0.038, respectively). The odds ratios (95% CI) were 1.882 (1.001 - 3.536); 2.060 (1.035 - 4.102); and 2.023 (1.032 - 3.966), respectively. Additionally, VEGF +936 CT and T-carrier genotypes showed significant associations with higher tumour grade (p-value <0.029, and <0.037). The odds ratios (95% CI) were 10.00 (1.435 - 72.806) and 9.00 (1.294 - 62.594), respectively. VEGF -2578 C/A and +936 C/T may be further investigated as susceptibility genetic markers for HNCs. Specifically, -2578 A-variant has a protective effect, whereas +936 T-variant increases the risk. Furthermore, +936 CT and T-carrier genotypes are also associated with higher tumour grade. The present study is the first positive association analysis report of both selected SNVs with HNCs in any population.