title: Identification of a subset of pericytes that respond to combination therapy targeting PDGF and VEGF signaling.
abstract: The aim of our study was to further explore the use of anti-angiogenic therapy targeting the vascular endothelial growth factor receptor (VEGFR) on endothelial cells while simultaneously targeting platelet-derived growth factor receptors (PDGFRs) on adjacent pericytes. B16 mouse melanoma tumors exogenously expressing PDGF-BB (B16/PDGF-BB) display higher pericyte coverage on the vasculature compared to the parental B16 tumors (B16/mock). These models were used to investigate the effects of combination therapy targeting VEGFR and PDGFR signaling on size-matched tumors. Combination therapy using 25 mg/kg/day of the VEGFR inhibitor PTK787 and 100 mg/kg/day of the PDGFR inhibitor STI571 decreased the tumor growth rate of both tumor types, but the inhibition was only significant in the B16/PDGF-BB tumors. Combination therapy induced vessel remodeling, primarily by reducing the vessel density in B16/mock tumors, and by reducing the vessel size in B16/PDGF-BB tumors. When analyzing the effects of combination therapy on tumor vessel pericytes, it was found to primarily reduce the subpopulation of alpha-smooth muscle actin and PDGFRbeta-positive pericytes partly detached from the tumor vessels, without affecting the number of pericytes closely attached to the endothelium, which also express desmin. Taken together, these data demonstrate an increased benefit of targeting both VEGFR and PDGFR pathways in B16/PDGF-BB tumors, and demonstrates that the increased tumor growth inhibition in this model is accompanied by a reduction in a specific subset of pericytes, characterized by being loosely attached to endothelial cells and negative for the pericyte marker desmin.
authors: Ludwig Institute for Cancer Research, Uppsala University, Uppsala, Sweden.
authors: Yoko
authors: Y
authors: Hasumi
authors: Agnieszka
authors: A
authors: Kłosowska-Wardega
authors: Masao
authors: M
authors: Furuhashi
authors: Arne
authors: A
authors: Ostman
authors: Carl-Henrik
authors: CH
authors: Heldin
authors: Carina
authors: C
authors: Hellberg
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000378:metabolism; D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D000077214:Becaplermin; D001549:Benzamides; D000068877:Imatinib Mesylate; D007150:Immunohistochemistry; D008546:Melanoma, Experimental / Q000188:drug therapy* / Q000378:metabolism*; D051379:Mice; D020286:Pericytes / Q000187:drug effects* / Q000378:metabolism; D010793:Phthalazines / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000187:drug effects / Q000378:metabolism*; D020574:Proto-Oncogene Proteins c-sis; D011725:Pyridines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000187:drug effects / Q000378:metabolism*
chemical_list: D043925:Angiogenesis Inducing Agents; D020533:Angiogenesis Inhibitors; D001549:Benzamides; D010793:Phthalazines; D010879:Piperazines; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D011725:Pyridines; D011743:Pyrimidines; D042461:Vascular Endothelial Growth Factor A; D000077214:Becaplermin; C404768:vatalanib; D000068877:Imatinib Mesylate; D020797:Receptor, Platelet-Derived Growth Factor beta