Non-Invasive Imaging of Cysteine Cathepsin Activity in Solid Tumors Using a 64Cu-Labeled Activity-Based Probe
Figure 2
In vitro labeling properties of imaging probes.
(A) Labeling of active cathepsins in the mouse myoblast cell line C2C12Ras, in the human breast cancer cell line MDA-MB-435, or in NIH3T3 mouse fibroblasts. Intact cells were labeled with GB123 for 1 hr followed by lysis and analysis of by SDS-PAGE and scanning of the gel for Cy5 fluorescence using a flatbed laser scanner (B) Labeling of cathepsins in C2C12/Ras and MDA-MB-435 cells. Cells were pretreated with 50 µM JPM-OEt (+) or with control DMSO (-) for 2 h and labeled by addition of 64Cu-Z-FK(DOTA)-AOMK (555 KBq, 15 µCi) for 2 h. Cells were collected, lysed and analyzed by SDS-PAGE. The labeled proteases were visulized by phosphorimaging with a Typhoon 9410 scanner. (C) NIH3T3 cells were incuabted with each probe at the indicated concentration for 1 hr followed by addition of a BODIPY-TMR-X-labeled GB111 probe. Directly labeling of target cathepsins by probes was obtained by SDS-PAGE followe by scanning of the gel using a flatbed laser scanner (Top gel). Inhibition of the same targets was observed by scanning of the gel for the BODIPY labeled probe using a Typhoon 9410 scanner (bottom gel).