Published online before print January 25, 2002, 10.1148/radiol.2223010812
(Radiology 2002;222:814.)
A more recent version of this article appeared on March 1, 2002
Imaging of Differential Protease Expression in Breast Cancers for Detection of Aggressive Tumor Phenotypes1
Christoph Bremer, MD,
Ching-Hsuan Tung, PhD,
Alex Bogdanov, Jr, PhD and
Ralph Weissleder, MD, PhD
1 From the Center for Molecular Imaging Research, Massachusetts General Hospital and Harvard Medical School, Boston. Received April 19, 2001; revision requested May 25; revision received June 22; accepted July 16. Supported in part by NIH NOI-C0M065, P50-CA86355-01, and a Dana Farber grant. C.B. supported by the Deutsche Forschungsgemeinschaft. Address correspondence to C.B., Department of Clinical Radiology, University of Muenster, Albert-Schweitzer-Strasse 33, D-48129 Muenster, Germany (e-mail: bremerc@umi-muenster.de).

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Figure 1. Cathepsin-B expression revealed by Western blot analysis of cell lysates (top: gel, bottom: density profiles) is 1.7-fold higher in highly invasive DU4475 cells compared with BT20 cells (A = 1.7 x B).
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Figure 2. Photomicrograph of cathepsin-B expression in DU4475 (A) and BT20 (B) tumors. (Original magnification, x40.) Inserts show controls without primary antibody. Cathepsin-B expression is revealed as a blue precipitate of the alkaline phosphatase-labeled secondary antibody. Note the strong cathepsin-B expression in the highly invasive DU4475 tumor (A) compared with the well differentiated adenocarcinoma (B).
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Figure 3. NIRF imaging 24 hours after intravenous injection of the cathepsin-B-sensitive autoquenched probe in a representative animal. A, light image; B, raw NIRF image; and C, color encoded NIRF signal (arbitrary units of NIRF intensity) superimposed on light image. The highly invasive breast adenocarcinoma (DU4475) was implanted on the right of the chest and the well differentiated adenocarcinoma (BT20) on the left. Note the higher fluorescent signal depicted on the highly invasive breast lesion (B, C).
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Figure 4. Bar graph shows in vivo NIRF signal in the tumors. Note the significantly higher signal intensity (SI) for the highly invasive breast cancer (DU4475) compared with the less aggressive lesion (BT20) (*, P < .01). AU = arbitrary units.
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Figure 5. NIRF microscopy of unstained frozen tumor sections. (Original magnification, x40.) The cathepsin-B-generated fluorescence signal is higher in the highly invasive DU4475 tumor (A) compared with the well differentiated BT20 adenocarcinoma (B).
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Copyright © 2002 by the Radiological Society of North America.