title: TNF-alpha downregulates vascular endothelial Flk-1 expression in human melanoma xenograft model.
abstract: High-dose TNF with melphalan has significant antitumor activity in regional perfusion of the limbs and liver in human malignancies. TNF is believed to target tumor vasculature, but the precise molecular mechanism is unknown. The present study demonstrates that TNF downregulates the VEGF receptor, fetal liver kinase-1 (Flk-1), on tumor endothelium in a human melanoma xenograft model. NIH1286 human melanoma cells were transduced with a 720-bp fragment of the human VEGF(121) gene to develop well-vascularized tumors that served as an amplified system for measuring Flk-1 expression changes. We injected 5 x 10(6) cells subcutaneously, each of two distinct single cell clones (NIH1286/3 and NIH1286/15), into athymic nude mice to produce tumors approximately 10 mm in size. Each animal then received either BSA or TNF in BSA by tail vein. Tumors harvested at different time points post-TNF were analyzed for Flk-1 mRNA and protein expression. Data obtained showed that intravascular TNF downregulated Flk-1 expression in tumor endothelial cells. This effect could contribute to the antitumor activity of TNF known to target tumor vasculature.
authors.affiliation: Harrison Department of Surgical Research, School of Medicine, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: Chandrakala
authors.initials: C
authors.lastname: Menon
authors.forename: Malini
authors.initials: M
authors.lastname: Iyer
authors.forename: Indira
authors.initials: I
authors.lastname: Prabakaran
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Canter
authors.forename: Shannon C
authors.initials: SC
authors.lastname: Lehr
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Fraker
mesh_terms: D000818:Animals; D015536:Down-Regulation; D016228:Endothelial Growth Factors / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008222:Lymphokines / Q000235:genetics; D008545:Melanoma / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D012333:RNA, Messenger / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism*; D042442:Vascular Endothelial Growth Factors
chemical_list: D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D012710:Serum Albumin, Bovine; D040301:Vascular Endothelial Growth Factor Receptor-2