In vivo optical imaging of MMP2 immuno protein antibody: tumor uptake is associated with MMP2 activity.

Kranthi Marella Panth,Rianne Biemans,Marcel Weber,Mario Losen,Natasja G Lieuwes,Philippe Lambin,Ala Yaromina,Twan Van Den Beucken,Ludwig J Dubois

doi:10.1038/srep22198

Kranthi Marella Panth, Rianne Biemans + Show 7 more

Open Access

https://doi.org/10.1038/srep22198

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Abstract

Matrix metalloproteinase-2 (MMP2) is important in tumorigenesis, angiogenesis and tumor invasion. In this study, we investigated if the Cy5-tagged small immuno protein targeting the catalytic domain of human MMP2 (aMMP2-SIP) detects MMP2 in tumors non-invasively. For this purpose, we generated MMP2 expressing (empty vector EV) and knock-down (KD) HT1080, U373 and U87 cells, which were injected subcutaneously in the lateral flank of NMRI-nu mice. Optical imaging (Optix MX2) performed at 0.5, 2, 4, 8, 24 and 48 hour post injection (h.p.i.) of Cy5 tagged aMMP2-SIP, indicated significantly lower tumor to background ratios at both 24 (P = 0.0090) and 48 h.p.i. (P < 0.0001) for the U87 MMP2-KD compared to control tumors. No differences were found for HT1080 and U373 models. U87 MMP2-KD tumors had significantly lower MMP2 activity (P < 0.0001) than EV tumors as determined by gelatin zymography in tumor sections and lysates, while no differences were observed between EV and MMP2-KD in HT1080 and U373. In line with these data, only U87 MMP2-KD tumors had a reduced tumor growth compared to control tumors (P = 0.0053). aMMP2-SIP uptake correlates with MMP2 activity and might therefore be a potential non-invasive imaging biomarker for the evaluation of MMP2 activity in tumors.

Highlights

Imaging can aid in detecting aggressive tumors, might serve as a surrogate marker of invasion or as biomarker for patient selection in matrix metalloproteinases (MMPs) inhibitors trials
MMP2 mRNA (Fig. 1c), protein expression (Fig. 1d,e) and activity (Fig. 1f,g) was significantly reduced in all knock-down cell lines compared to empty vector (EV) bearing controls
Since aMMP2-Small immuno protein (SIP) did not correlate with MMP2 expression levels, we investigated if aMMP2-SIP uptake could be affected by tumor microenvironmental factors like hypoxia, vasculature or perfused vessels (Supplementary Fig. 2 and supplementary Fig. 3a)

Summary

Introduction

Imaging can aid in detecting aggressive tumors, might serve as a surrogate marker of invasion or as biomarker for patient selection in MMP inhibitors trials. Imaging strategies using whole IgG antibodies are limited due to slow antibody clearance from blood[24,25]. To circumvent this disadvantage small antibody fragments (minibodies) have been generated by antibody engineering techniques to have superior clearing rates without losing binding characteristics[24,25,26]. ScFv fragments have very fast clearance rates from blood due to small size which is desirable for imaging, but on the other hand, only a small amount of the antibody reaches the tumor[27]. An antibody selectively targeting catalytic domain of human MMP2 in small immuno protein (aMMP2-SIP) format has been developed for imaging purposes[29,30]. We have evaluated aMMP2-SIP uptake using MMP2 knock-down models, as negative control in different tumor types with varying MMP2 expression and activity

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Conclusion