title: In vivo imaging of membrane type-1 matrix metalloproteinase with a novel activatable near-infrared fluorescence probe.
abstract: Membrane type-1 matrix metalloproteinase (MT1-MMP) is a protease activating MMP-2 that mediates cleavage of extracellular matrix components and plays pivotal roles in tumor migration, invasion and metastasis. Because in vivo noninvasive imaging of MT1-MMP would be useful for tumor diagnosis, we developed a novel near-infrared (NIR) fluorescence probe that can be activated following interaction with MT1-MMP in vivo. MT1-hIC7L is an activatable fluorescence probe comprised of anti-MT1-MMP monoclonal antibodies conjugated to self-assembling polymer micelles that encapsulate NIR dyes (IC7-1, λem : 858 nm) at concentrations sufficient to cause fluorescence self-quenching. In aqueous buffer, MT1-hIC7L fluorescence was suppressed to background levels and increased approximately 35.5-fold in the presence of detergent. Cellular uptake experiments revealed that in MT1-MMP positive C6 glioma cells, MT1-hIC7L showed significantly higher fluorescence that increased with time as compared to hIC7L, a negative control probe lacking the anti-MT1-MMP monoclonal antibody. In MT1-MMP negative MCF-7 breast adenocarcinoma cells, both MT1-hIC7L and hIC7L showed no obvious fluorescence. In addition, the fluorescence intensity of C6 cells treated with MT1-hIC7L was suppressed by pre-treatment with an MT1-MMP endocytosis inhibitor (P < 0.05). In vivo optical imaging using probes intravenously administered to tumor-bearing mice showed that MT1-hIC7L specifically visualized C6 tumors (tumor-to-background ratios: 3.8 ± 0.3 [MT1-hIC7L] vs 3.1 ± 0.2 [hIC7L] 48 h after administration, P < 0.05), while the probes showed similarly low fluorescence in MCF-7 tumors. Together, these results show that MT1-hIC7L would be a potential activatable NIR probe for specifically detecting MT1-MMP-expressing tumors.
authors.affiliation: Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Central Institute of Isotope Science, Hokkaido University, Sapporo, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Takashi
authors.initials: T
authors.lastname: Temma
authors.forename: Isao
authors.initials: I
authors.lastname: Hara
authors.forename: Akira
authors.initials: A
authors.lastname: Makino
authors.forename: Naoya
authors.initials: N
authors.lastname: Kondo
authors.forename: Ei-Ichi
authors.initials: E
authors.lastname: Ozeki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ono
authors.forename: Hideo
authors.initials: H
authors.lastname: Saji
mesh_terms: D000818:Animals; D005453:Fluorescence; D064593:Heterografts; D053511:Matrix Metalloproteinase 14 / Q000032:analysis*; D051379:Mice; D009369:Neoplasms / Q000175:diagnosis / Q000378:metabolism*; D061848:Optical Imaging / Q000379:methods*; D051381:Rats; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D053511:Matrix Metalloproteinase 14
keywords: Activatable probe; membrane type-1 matrix metalloproteinase; molecular imaging; near-infrared; optical