title: Neutrophil-mediated experimental metastasis is enhanced by VEGFR inhibition in a zebrafish xenograft model.
abstract: Inhibition of VEGF signalling effectively suppresses localized tumour growth but accelerates tumour invasiveness and micrometastasis by unknown mechanisms. To study the dynamic and reciprocal interactions between tumour cells and their microenvironment during these processes, we established a xenograft model by injecting tumour cells into the blood circulation of transparent zebrafish embryos. This reproducibly results in rapid simultaneous formation of a localized tumour and experimental micrometastasis, allowing time-resolved imaging of both processes at single-cell resolution within 1 week. The tumour vasculature was initiated de novo by remodelling of primitive endothelial cells into a functional network. Roles of myeloid cells in critical tumourigenesis steps such as vascularization and invasion were revealed by genetic and pharmaceutical approaches. We discovered that the physiological migration of neutrophils controlled tumour invasion by conditioning the collagen matrix and forming the metastatic niche, as detected by two-photon confocal microscopy and second harmonic generation. Administration of VEGFR inhibitors blocked tumour vascularization and a localized tumour growth but enhanced migration of neutrophils, which in turn promoted tumour invasion and formation of micrometastasis. This demonstrates the in vivo cooperation between VEGF signalling and myeloid cells in metastasis and provides a new mechanism underlying the recent findings that VEGFR targeting can promote tumour invasiveness.
authors.affiliation: Institute of Biology, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
authors.forename: Shuning
authors.initials: S
authors.lastname: He
authors.forename: Gerda Em
authors.initials: GE
authors.lastname: Lamers
authors.forename: Jan-Willem M
authors.initials: JW
authors.lastname: Beenakker
authors.forename: Chao
authors.initials: C
authors.lastname: Cui
authors.forename: Veerander Ps
authors.initials: VP
authors.lastname: Ghotra
authors.forename: Erik Hj
authors.initials: EH
authors.lastname: Danen
authors.forename: Annemarie H
authors.initials: AH
authors.lastname: Meijer
authors.forename: Herman P
authors.initials: HP
authors.lastname: Spaink
authors.forename: B Ewa
authors.initials: BE
authors.lastname: Snaar-Jagalska
mesh_terms: D000818:Animals; D001507:Beclomethasone / Q000494:pharmacology; D001943:Breast Neoplasms / Q000473:pathology; D002465:Cell Movement / Q000502:physiology; D002471:Cell Transformation, Neoplastic; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000473:pathology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D051379:Mice; D022423:Myeloid Cells / Q000473:pathology / Q000502:physiology; D009362:Neoplasm Metastasis / Q000503:physiopathology*; D009504:Neutrophils / Q000473:pathology / Q000502:physiology*; D011758:Pyrroles / Q000494:pharmacology; D040262:Receptors, Vascular Endothelial Growth Factor / Q000037:antagonists & inhibitors* / Q000187:drug effects; D015398:Signal Transduction / Q000502:physiology; D000077210:Sunitinib; D023041:Xenograft Model Antitumor Assays; D015027:Zebrafish / Q000196:embryology*
chemical_list: D007211:Indoles; D011758:Pyrroles; D040262:Receptors, Vascular Endothelial Growth Factor; D001507:Beclomethasone; D000077210:Sunitinib