Figure 2.

MMP activity differs significantly between the HaCaT-A-5RT3 tumors at differential angiogenic and invasive stages. (A) Assessment of MMP activity in vivo by FMT-μCT imaging reveals significant differences in intratumoral concentrations of activated MMPSense 750 FAST between s.c. advanced (n = 5), i.d. intermediate (n = 5), and s.c. early (n = 7) tumors. Highest concentrations are recorded for s.c. advanced tumors at the highly angiogenic and invasive stage, whereas lowest concentrations are found in s.c. early tumors at the onset of angiogenesis and invasion. (B) Quantification of in situ zymography of MMP activity on tumor sections confirms the in vivo data. (C) Representative FMT/μCT fusion images of tumor-bearing mice (transverse plane) show the fluorescent signals of activated MMPSense 750 FAST in s.c. early, i.d., and s.c. advanced tumors (tumors indicated by a white arrow). The additional fluorescent signals found in the intestine region can occur from hepatobiliary excretion of the probe through the intestine. (D) Representative images of in situ zymography of MMP activity (green) [counterstained with collagen IV (red) and DAPI (blue)] of an s.c. early-stage tumor at the onset of angiogenesis and invasion, an i.d. tumor at the intermediate angiogenic and invasion stage, and an s.c. advanced, highly angiogenic, and invasive tumor. (E) Representative H&E staining of the different HaCaT-ras A-5RT3 tumors. Bar, 200 μm. Data are presented as means ± SD (*P < .05, ** P < .01, and ***P < .001).