Background & objective: Vascular endothelial growth factor (VEGF) play an important role in tumor angiogenesis through a paracrine mechanism, but the importance of its autocrine has not been fully elucidated. This study was designed to explore the gene coexpression pattern of VEGF and its receptors (Flt-1 and KDR) in variety of human malignant cell lines.
Methods: After isolation of RNA from thirty tumor cell lines and four endothelial cells, gene expressions of VEGF and its receptors were measured by semi-quantitative reverse transcriptase polymerase chain reaction using the transcriptional level of the house-keeping gene for internal calibration.
Results: VEGF transcript was detected in the majority of tumor cell lines (29/30) and in all endothelial cell lines at moderate or high level, while the expression of VEGF was low in human umbilical vein endothelial cell (HUVEC). Moreover, Flt-1 gene expression was found in 50% of hematopoietic malignancies (6/12), 28% of solid tumors (5/18), and endothelial cells (EA. hy926 and HUVEC). In contrast, the expression of KDR gene was found in 2 (16.7%) hematopoietic cell lines and 6 (33.3%) solid tumor lines. In endothelial cells, KDR gene expression was detectable in HMEC-1 and HUVEC only. However, ECV304 cells express neither Flt-1 nor KDR gene.
Conclusion: Overexpression of VEGF gene in all tumor cell lines provides a potential biological marker for malignancies and the coexpression of VEGF with its receptors suggesting an autocrine pathway exists in tumor cells.