Development of an optimized activatable MMP-14 targeted SPECT imaging probe.
Matrix metalloproteinase-14 (MT1-MMP or MMP-14) is a membrane-associated protease implicated in a variety of tissue remodeling processes and a molecular hallmark of select metastatic cancers. The ability to detect MMP-14 in vivo would be useful in studying its role in pathologic processes and may potentially serve as a guide for the development of targeted molecular therapies. Four MMP-14 specific probes containing a positively charged cell penetrating peptide (CPP) d-arginine octamer (r(8)) linked with a MMP-14 peptide substrate and attenuating sequences with glutamate (8e, 4e) or glutamate-glycine (4eg and 4egg) repeating units were modeled using an AMBER force field method. The probe with 4egg attenuating sequence exhibited the highest CPP/attenuator interaction, predicting minimized cellular uptake until cleaved. The in vitro MMP-14-mediated cleavage studies using the human recombinant MMP-14 catalytic domain revealed an enhanced cleavage rate that directly correlated with the linearity of the embedded peptide substrate sequence. Successful cleavage and uptake of a technetium-99m labeled version of the optimal probe was demonstrated in MMP-14 transfected human breast cancer cells. Two-fold reduction of cellular uptake was found in the presence of a broad spectrum MMP inhibitor. The combination of computational chemistry, parallel synthesis and biochemical screening, therefore, shows promise as a set of tools for developing new radiolabeled probes that are sensitive to protease activity.
Watkins
Gregory A
GA
Center for Molecular and Functional Imaging, Department of Radiology and Biomedical Imaging, University of California, San Francisco, 185 Berry Street, Suite 350, Box 0946, San Francisco, CA 94107, United States.
Jones
Ella Fung
EF
Scott Shell
M
M
VanBrocklin
Henry F
HF
Pan
Mei-Hsiu
MH
Hanrahan
Stephen M
SM
Feng
Jin Jin
JJ
He
Jiang
J
Sounni
Nor Eddine
NE
Dill
Ken A
KA
Contag
Christopher H
CH
Coussens
Lisa M
LM
Franc
Benjamin L
BL
D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D053511:Matrix Metalloproteinase 14 / Q000032:analysis*; D008958:Models, Molecular; D013667:Technetium; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014407:Tumor Cells, Cultured
D013667:Technetium; C507086:MMP14 protein, human; D053511:Matrix Metalloproteinase 14