Analysis of VEGF polymorphisms, tumor expression of VEGF mRNA and colorectal cancer susceptibility in a Swedish population

Vascular endothelial growth factor (VEGF) plays a significant role in tumor angiogenesis and is found to be overexpressed and involved in the development and progression of colorectal cancer (CRC). The VEGF gene contains several polymorphic sites known to influence VEGF expression. We examined the possible association between five polymorphisms, located in the promoter/5'-untranslated region [-2578 (C/A), -2549 (del/ins 18 bp) -1154 (G/A), -634 (G/C)] or 3'-untranslated region [+936 (C/T)] of the VEGF gene, and CRC Susceptibility and clinicopathological characteristics in 302 Swedish CRC patients and 336 healthy randomly selected controls. Both genotypes and combined haplotypes were analyzed. No significant differences were observed when VEGF genotype/haplotype frequencies in the CRC cases and controls were compared, nor were any associations found between the genotypes/haplotypes and clinicopathological characteristics. However, when the -2578 C and +936 T alleles were combined, a small but significant association with CRC susceptibility was detected (OR=1.6, 95% CI 1.3-1.9, p=0.01). In addition, VEGF mRNA expression was determined in a Subset of patients, revealing a 2-fold VEGF upregulation in CRC tissue compared to normal colonic mucosa, but no association between the genotypes or haplotypes and VEGF mRNA levels. Linkage analysis was performed, revealing that the polymorphisms in the promoter and 5'-untranslated region were in tight linkage disequilibrium (LD) (vertical bar D'vertical bar=0.91-1.00), while the +936 C/T polymorphism was only weakly associated with the others (vertical bar D'vertical bar=0.05-0.19). In conclusion, VEGF is generally upregulated in colorectal tumors. However, the single nucleotide polymorphisms examined do not appear to influence the mRNA expression of VEGF in colorectal tumors, and most likely play a limited role in CRC development and progression.