Research
A fiber-modified adenoviral vector interacts with immunoevasion molecules of the B7 family at the surface of murine leukemia cells derived from dormant tumors
- † Equal contributors
1 INSERM UMR 837, 1, rue Polonovski, 59045 Lille, France
2 Univ. Lille Nord de France, 59000 Lille, France
3 Institut de Recherches sur le Cancer de Lille, Place de Verdun, 59045 Lille, France
4 Univ. Lille Nord de France, UDSL, Faculté de Médecine, IMPRT, JPARC, Place de Verdun, 59045 Lille, France
5 INSERM UMR 761, Biostructures & Drug Discovery, Université de Lille 2, Institut Pasteur de Lille, Faculté de Pharmacie de Lille, 3, rue du Professeur Laguesse. Institut Pasteur de Lille, IFR 142 - PRIM, 59000 Lille, France
6 Université Lyon 1 & UMR INRA-754, Rétrovirus & Pathologie Comparée, 50, avenue Tony Garnier, 69366 Lyon Cedex 07, France
7 Unit of Virus Host Cell Interactions (UVHCI), UMI 3265 (CNRS/UJF/EMBL), 6, rue Jules Horowitz, 38042 Grenoble, France
8 Service des Maladies du Sang, Centre Hospitalier et Universitaire de Lille, Rue Polonovski, 59000 Lille, France
Molecular Cancer 2011, 10:105 doi:10.1186/1476-4598-10-105
Published: 31 August 2011Abstract
Tumor cells can escape the immune system by overexpressing molecules of the B7 family, e.g. B7-H1 (PD-L1 or CD86), which suppresses the anti-tumor T-cell responses through binding to the PD-1 receptor, and similarly for B7.1 (CD80), through binding to CTLA-4. Moreover, direct interactions between B7-H1 and B7.1 molecules are also likely to participate in the immunoevasion mechanism. In this study, we used a mouse model of tumor dormancy, DA1-3b leukemia cells. We previously showed that a minor population of DA1-3b cells persists in equilibrium with the immune system for long periods of time, and that the levels of surface expression of B7-H1 and B7.1 molecules correlates with the dormancy time. We found that leukemia cells DA1-3b/d365 cells, which derived from long-term dormant tumors and overexpressed B7-H1 and B7.1 molecules, were highly permissive to Ad5FB4, a human adenovirus serotype 5 (Ad5) vector pseudotyped with chimeric human-bovine fibers. Both B7-H1 and B7.1 were required for Ad5FB4-cell binding and entry, since (i) siRNA silencing of one or the other B7 gene transcript resulted in a net decrease in the cell binding and Ad5FB4-mediated transduction of DA1-3b/d365; and (ii) plasmid-directed expression of B7.1 and B7-H1 proteins conferred to Ad5FB4-refractory human cells a full permissiveness to this vector. Binding data and flow cytometry analysis suggested that B7.1 and B7-H1 molecules played different roles in Ad5FB4-mediated transduction of DA1-3b/d365, with B7.1 involved in cell attachment of Ad5FB4, and B7-H1 in Ad5FB4 internalization. BRET analysis showed that B7.1 and B7-H1 formed heterodimeric complexes at the cell surface, and that Ad5FB4 penton, the viral capsomere carrying the fiber projection, could negatively interfere with the formation of B7.1/B7-H1 heterodimers, or modify their conformation. As interactors of B7-H1/B7.1 molecules, Ad5FB4 particles and/or their penton capsomeres represent potential therapeutic agents targeting cancer cells that had developed immunoevasion mechanisms.
