title: Decrease of endogenous vascular endothelial growth factor may not affect glioma cell proliferation and invasion.
abstract: Vascular endothelial growth factor (VEGF) is abundantly produced by glioma cells especially glioblastoma, the most malignant form of astrocytoma. VEGF, a well known angiogenic factor, acts in a paracrine fashion on endothelial cells to develop tumor vasculature. However, recent studies have found that several tumor cells express VEGF receptors, and an autocrine action of VEGF on tumor cells has been suggested. To test this hypothesis, three human glioma cell lines (U251n, U87 and A172) were checked for VEGF and VEGFR expression. These cells express 0.1-0.6 ng/ml VEGF165 in cell culture medium within 24 hours. Western blot analysis showed that these cells express all of the VEGF receptors, VEGFR-1/Flt-1, VEGFR-2/KDR, Neuropilin-1 (NRP-1) and Neuropilin-2(NRP-2), even though tyrosine kinase receptor VEGFR-2/KDR exhibited baseline levels of expression. VEGF expression was significantly down regulated by phosphorothioate oligodeoxynucleotide (PS-ODN) and VEGF RNAi transfection. However, VEGF RNAi transfection as well as VEGF and VEGFR2 neutralization antibody treatment did not decrease cell proliferation detected by MTT and CyQuant NF proliferation assay except that PS-ODN transfection caused a non-specific decrease on cell proliferation. VEGF RNAi transfection did not alter cell invasion, as demonstrated in a matrigel invasion assay. Matrix metalloproteinase-2 (MMP-2) and MMP-9, facilitating cell invasion and over expressed in glioma cells, were not altered by VEGF RNAi transfection, as shown by zymographic assays. Our data indicate that the decrease of endogenous VEGF expression may not affect glioma cell proliferation and invasion.
authors.affiliation: Department of Neurosurgery, Henry Ford Health Science Center, Detroit, MI 48202, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Hong
authors.forename: Feng
authors.initials: F
authors.lastname: Jiang
authors.forename: Steven N
authors.initials: SN
authors.lastname: Kalkanis
authors.forename: Zheng Gang
authors.initials: ZG
authors.lastname: Zhang
authors.forename: Xuepeng
authors.initials: X
authors.lastname: Zhang
authors.forename: Xuguang
authors.initials: X
authors.lastname: Zheng
authors.forename: Tom
authors.initials: T
authors.lastname: Mikkelsen
authors.forename: Hao
authors.initials: H
authors.lastname: Jiang
authors.forename: Michael
authors.initials: M
authors.lastname: Chopp
mesh_terms: D001485:Basement Membrane / Q000378:metabolism; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000235:genetics / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004797:Enzyme-Linked Immunosorbent Assay; D005109:Extracellular Matrix / Q000378:metabolism; D014644:Genetic Variation; D005910:Glioma / Q000235:genetics / Q000473:pathology*; D006801:Humans; D007202:Indicators and Reagents; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D034622:RNA Interference / Q000502:physiology; D040262:Receptors, Vascular Endothelial Growth Factor / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology
chemical_list: D007202:Indicators and Reagents; D020319:Oligodeoxyribonucleotides, Antisense; D042461:Vascular Endothelial Growth Factor A; D040262:Receptors, Vascular Endothelial Growth Factor; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9