title: Modality of tumor endothelial VEGFR2 silencing-mediated improvement in intratumoral distribution of lipid nanoparticles.
abstract: The vascular endothelial growth factor (VEGF)-mediated enhancement in vascular permeability is considered to be a major factor in tumor-targeting delivery via the enhanced permeability and retention (EPR) effect. We previously reported that the silencing of the endothelial VEGF receptor (VEGFR2) by a liposomal siRNA system (RGD-MEND) resulted in an enhanced intratumoral distribution of polyethylene glycol (PEG)-modified liposomes (LPs) in a renal cell carcinoma, a type of hypervascularized cancer, although the inhibition of VEGF signaling would be expected to decrease the permeability of the tumor vasculature. We herein report that the enhancement in the intratumoral distribution of LPs by VEGFR2 inhibition was dependent on the vascular type of the tumor (stroma vessel type; SV and tumor vessel type; TV). In the case of TV-type tumors (renal cell carcinoma and hepatocellular carcinoma), inhibiting VEGFR2 improved intratumoral distribution, while no effect was found in the case of SV-type tumors (colorectal cancer). Moreover, through a comparison of the intratumoral distribution of LPs with a variety of physical properties (100nm vs 400nm, neutral vs negative vs positive), VEGFR2 inhibition was found to alter the tumor microenvironment, including heparan sulfate proteoglycans (HSPGs). In addition, the results regarding the effect of the size of nanoparticles indicated that VEGFR2 inhibition improved the penetration of nanoparticles through the vessel wall, but not via permeability, suggesting the involvement of an unknown mechanism. Our findings suggest that a combination of anti-angiogenic therapy and delivery via the EPR effect would be useful in certain cases, and that altering the tumor microenvironment by VEGFR2 blockade has a drastic effect on the intratumoral distribution of nanoparticles.
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Japan.
authors.forename: Shoshiro
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Japan.
authors.forename: Akari
authors.initials: A
authors.lastname: Kato
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sakurai
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Hada
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Japan. Electronic address: harasima@pharm.hokudai.ac.jp.
authors.forename: Hideyoshi
authors.initials: H
authors.lastname: Harashima
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000493:pharmacokinetics; D002199:Capillary Permeability; D002292:Carcinoma, Renal Cell / Q000098:blood supply / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000098:blood supply / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D008081:Liposomes; D008297:Male; D008807:Mice, Inbred BALB C; D008813:Mice, Inbred ICR; D008819:Mice, Nude; D053758:Nanoparticles; D009842:Oligopeptides / Q000737:chemistry*; D010316:Particle Size; D010880:Piperidines / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D034741:RNA, Small Interfering / Q000235:genetics; D059016:Tumor Microenvironment; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors* / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D008055:Lipids; D008081:Liposomes; D009842:Oligopeptides; D010880:Piperidines; D034741:RNA, Small Interfering; C580570:YSK05; D011092:Polyethylene Glycols; C047981:arginyl-glycyl-aspartic acid; D040301:Vascular Endothelial Growth Factor Receptor-2
keywords: Intratumoral distribution; Liposome; Tumor microenvironment; Tumor vasculature; siRNA