Quantitative Real-Time Reverse Transcription–PCR Study of the Expression of Vascular Endothelial Growth Factor (VEGF) Splice Variants and VEGF Receptors (VEGFR-1 and VEGFR-2) in Non–Small Cell Lung Cancer

Abstract

Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis and its expression is increased in non-small cell lung cancer (NSCLC). We aimed to determine the expression pattern of VEGF splice variants in NSCLC and its correlation with the clinicopathological characteristics of tumors. We used real-time reverse transcription PCR to quantify the mRNA expression of total VEGF, 4 VEGF splice variants (VEGF(121), VEGF(165), VEGF(183), and VEGF(189)), and 2 VEGF receptors (VEGFR-1 and VEGFR-2) in 27 pairs of cancerous and adjacent noncancerous tissues originating from patients with NSCLC. Total VEGF, VEGF(121), and VEGF(165) were expressed in all specimens, whereas VEGF(183) and VEGF(189) were present in small amounts in certain samples. Total VEGF, VEGF(121), and VEGF(165) mRNA was upregulated in cancerous compared with healthy tissues, whereas VEGF(183) and VEGF(189) expression tended to be higher in healthy tissues. The expression of VEGFRs was similar between matched specimens. No correlation was found between the expression of total VEGF or VEGF splice variants and the clinicopathological characteristics of tumors. The expression patterns of VEGF splice variants differed between tissue pairs. VEGF(121) was the major variant expressed in all samples; however, its relative expression was higher in cancerous tissues. The relative expression of VEGF(183) and VEGF(189) was upregulated in healthy lung tissues, whereas the ratio of VEGF(165) to total VEGF was similar between matched specimens. The expression pattern of certain VEGF splice variants is altered during tumorigenesis. Our data support the hypothesis that during malignant progression an angiogenic switch favoring the shorter diffusible isoforms occurs.