title: Topotecan inhibits VEGF- and bFGF-induced vascular endothelial cell migration via downregulation of the PI3K-Akt signaling pathway.
abstract: Angiogenesis plays a crucial role in tumor growth and metastases. The extent of angiogenesis correlates with the increased invasion and metastasis in a variety of human neoplasms. Vascular endothelial cell proliferation and migration are critical steps in angiogenesis and are regulated by various growth factors, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). The topoisomerase I inhibitor topotecan (10-hydroxy-9-dimethylaminomethyl-(S)-camptothecin) is a water-soluble camptothecin analogue and possesses an indirect in vivo antitumor effect mediated through the inhibition of angiogenesis. We found that topotecan inhibited VEGF- and bFGF-induced migration of human umbilical vein endothelial cells (HUVECs) in vitro. The migration of HUVECs was also inhibited by a phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002. Thus, we investigated the possibility that topotecan's antiangiogenic property might be mediated by its inhibitory effect on VEGF- and bFGF-induced activation of the PI3K-Akt signaling pathway. We found that topotecan treatment decreased the amount of the phosphorylated (activated) form of Akt, but not the amount of Akt protein, in HUVECs. Moreover, transient transfection of constitutive active akt cDNA into HUVECs reversed the topotecan-mediated decrease in HUVEC migration. These results suggest that the antiangiogenic activity of topotecan is mediated in part by downregulating the PI3K-Akt signaling pathway.
authors.affiliation: Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nakashio
authors.forename: Naoya
authors.initials: N
authors.lastname: Fujita
authors.forename: Takashi
authors.initials: T
authors.lastname: Tsuruo
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D015536:Down-Regulation; D016228:Endothelial Growth Factors / Q000037:antagonists & inhibitors*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D016222:Fibroblast Growth Factor 2 / Q000037:antagonists & inhibitors*; D006801:Humans; D008222:Lymphokines / Q000037:antagonists & inhibitors*; D020780:Matrix Metalloproteinase 9 / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D019772:Topotecan / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D000970:Antineoplastic Agents; D016228:Endothelial Growth Factors; D016222:Fibroblast Growth Factor 2; D008222:Lymphokines; D020780:Matrix Metalloproteinase 9; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019772:Topotecan; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C494918:AKT1 protein, human