title: Failure of anti tumor-derived endothelial cell immunotherapy depends on augmentation of tumor hypoxia.
abstract: We have previously demonstrated that Tenascin-C (TNC)(+) human neuroblastoma (NB) cells transdifferentiate into tumor-derived endothelial cells (TDEC), which have been detected both in primary tumors and in tumors formed by human NB cell lines in immunodeficient mice. TDEC are genetically unstable and may favor tumor progression, suggesting that their elimination could reduce tumor growth and dissemination. So far, TDEC have never been targeted by antibody-mediated immunotherapy in any of the tumor models investigated. To address this issue, immunodeficient mice carrying orthotopic NB formed by the HTLA-230 human cell line were treated with TDEC-targeting cytotoxic human (h)CD31, that spares host-derived endothelial cells, or isotype-matched mAbs. hCD31 mAb treatment did not affect survival of NB-bearing mice, but increased significantly hypoxia in tumor microenvironment, where apoptotic and proliferating TDEC coexisted, indicating the occurrence of vascular remodeling. Tumor cells from hCD31 mAb treated mice showed i) up-regulation of epithelial-mesenchymal transition (EMT)-related and vascular mimicry (VM)-related gene expression, ii) expression of endothelial (i.e. CD31 and VE-cadherin) and EMT-associated (i.e. Twist-1, N-cadherin and TNC) immunophenotypic markers, and iii) up-regulation of high mobility group box-1 (HMGB-1) expression. In vitro experiments with two NB cell lines showed that hypoxia was the common driver of all the above phenomena and that human recombinant HMGB-1 amplified EMT and TDEC trans-differentiation. In conclusion, TDEC targeting with hCD31 mAb increases tumor hypoxia, setting the stage for the occurrence of EMT and of new waves of TDEC trans-differentiation. These adaptive responses to the changes induced by immunotherapy in the tumor microenvironment allow tumor cells to escape from the effects of hCD31 mAb.
authors.affiliation: Laboratorio di Oncologia, Istituto Giannina Gaslini, Genova, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Pezzolo
authors.affiliation: Laboratorio di Oncologia, Istituto Giannina Gaslini, Genova, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: Marimpietri
authors.affiliation: Laboratorio di Oncologia, Istituto Giannina Gaslini, Genova, Italy.
authors.forename: Lizzia
authors.initials: L
authors.lastname: Raffaghello
authors.affiliation: Laboratorio di Oncologia, Istituto Giannina Gaslini, Genova, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Cocco
authors.affiliation: Unità di Epidemiologia e Biostatistica Istituto Giannina Gaslini, Genova, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Pistorio
authors.affiliation: Laboratorio di Anatomia Patologica Istituto Giannina Gaslini, Genova, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Gambini
authors.affiliation: Animal Research Facility, IRCCS-AOU San Martino-IST Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Cilli
authors.affiliation: Laboratorio di Immunogenetica, Università di Torino, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Horenstein
authors.affiliation: Laboratorio di Immunogenetica, Università di Torino, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Malavasi
authors.affiliation: Laboratorio di Oncologia, Istituto Giannina Gaslini, Genova, Italy.
authors.forename: Vito
authors.initials: V
authors.lastname: Pistoia
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D017209:Apoptosis / Q000187:drug effects; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D054338:Cell Transdifferentiation; D042783:Endothelial Cells / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005260:Female; D024243:HMGB1 Protein / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000139:chemically induced; D007167:Immunotherapy / Q000009:adverse effects / Q000379:methods*; D008819:Mice, Nude; D009447:Neuroblastoma / Q000276:immunology / Q000628:therapy*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism*; D019063:Tenascin / Q000378:metabolism; D017211:Treatment Failure; D019139:Tumor Escape; D059016:Tumor Microenvironment; D066253:Vascular Remodeling; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D024243:HMGB1 Protein; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D019063:Tenascin