title: Modulation of the angiogenesis response through Ha-ras control, placenta growth factor, and angiopoietin expression in mouse skin carcinogenesis.
abstract: Tumor angiogenesis is governed by a complex balance of positive and negative angiogenic factors. Development of chemically-induced mouse skin tumors appears to be highly dependent on an early burst of neovascularization. We have previously shown that Ha-ras-driven vascular endothelial growth factor (VEGF) expression plays a pivotal role in this process. However, the status of other critical positive and negative angiogenic factors throughout skin tumorigenesis has not been studied to the same extent. In the present study, we show that another VEGF family member, placenta growth factor (PlGF), was highly upregulated at all tumor stages in a ras-dependent manner. The study of angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2), ligands of receptor tyrosine kinase 2 (Tie-2), showed that while stroma-derived Ang-2 was increased, epidermal Ang-1 expression was completely abolished at early papilloma formation. Studies using epidermal tumor cell lines suggest that the disappearance of Ang-1 also depends on ras activation, extending the plethora of events controlled by this oncogene in mouse skin carcinogenesis. Our results indicated that tumor development occurred in a strong angiogenesis-prone scenario in which PlGF and Ang-2 acted cooperatively with VEGF, whereas the negative or stabilizing effect of Ang-1 was abrogated. A time-course sequence of expression of angiogenic factors expressed throughout tumor growth, as well as the identification of key signaling molecules triggering the angiogenic response, may contribute to the development and testing of antiangiogenic therapeutic strategies with this in vivo tumor model.
authors.affiliation: Project on Molecular and Cell Biology and Gene Therapy entro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Larcher
authors.forename: Marcela
authors.initials: M
authors.lastname: Franco
authors.forename: Marcela
authors.initials: M
authors.lastname: Bolontrade
authors.forename: Marcelo
authors.initials: M
authors.lastname: Rodriguez-Puebla
authors.forename: Llanos
authors.initials: L
authors.lastname: Casanova
authors.forename: Manuel
authors.initials: M
authors.lastname: Navarro
authors.forename: George
authors.initials: G
authors.lastname: Yancopoulos
authors.forename: José L
authors.initials: JL
authors.lastname: Jorcano
authors.forename: Claudio J
authors.initials: CJ
authors.lastname: Conti
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000235:genetics* / Q000378:metabolism; D042683:Angiopoietin-1; D042702:Angiopoietin-2; D000818:Animals; D002273:Carcinogens; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D016228:Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D011905:Genes, ras / Q000235:genetics*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000502:physiology; D008222:Lymphokines / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D018632:Mice, Inbred SENCAR; D009154:Mutation; D009389:Neovascularization, Pathologic / Q000235:genetics*; D010212:Papilloma / Q000098:blood supply / Q000139:chemically induced / Q000503:physiopathology*; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012878:Skin Neoplasms / Q000098:blood supply / Q000139:chemically induced / Q000503:physiopathology*; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D043925:Angiogenesis Inducing Agents; D042683:Angiopoietin-1; D042702:Angiopoietin-2; C467628:Angpt1 protein, mouse; D002273:Carcinogens; D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D008562:Membrane Glycoproteins; C000608037:Pgf protein, mouse; D011257:Pregnancy Proteins; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000072483:Placenta Growth Factor