Quantitative analysis of vascular endothelial growth factor receptors 1 and 2 in colorectal cancer

Vascular endothelial growth factor A (VEGF-A) is a key regulator of angiogenesis that binds to the receptors VEGFR-1 and VEGFR-2. It is well known that VEGF-A levels are increased in colorectal cancer (CRC) tissue compared to normal colorectal tissue, but little is known regarding the expression of the VEGFR-1 and -2 receptors. The aim of the present study was to perform a quantitative analysis of VEGFR-1 and -2 at the mRNA and protein level in tumour and normal colorectal tissue from CRC patients. Tissues were collected from 110 patients who underwent surgical resection for CRC. Receptor status was analysed at the gene expression level by real time RT-PCR using β-2-microglobulin and β-actin as reference genes. Protein analysis was performed using the ELISA technique. Gene expression and protein concentrations of VEGFR-1 and -2 were significantly increased in CRC tissue compared to normal colorectal tissue (P<10-6 for both receptors). An association between the gene expression of VEGFR-2 in CRC tissue and disease stage was detected (P=0.055). Significant correlations were also found between the gene expression of VEGFR-1 and -2 in CRC tissue and normal colorectal tissue (P<10-4). The gene expression and protein concentrations of VEGFR-1 and -2 were increased in CRC tissue compared to normal colorectal tissue, indicating that both receptors are important in CRC. The clinical implications of these findings require further investigation.