Cathepsin G Induces Cell Aggregation of Human Breast Cancer MCF-7 Cells via a 2-Step Mechanism: Catalytic Site-Independent Binding to the Cell Surface and Enzymatic Activity-Dependent Induction of the Cell Aggregation
Figure 2
The MCF-7 cell aggregation-inducing activity of CG is inhibited by serine protease inhibitors. CG was simultaneously added to the medium with the serine protease inhibitor chymostatin (16.5 M) (a) or Suc-Val-Pro-PheP-(OPh)2 (10 M) (b). PMSF-treated CG was added to MCF-7 cells (c). The aggregation index is shown in the left panels of Figures 2(a), 2(b), and 2(c). The results are shown as mean SD . When the bars are not shown, they are smaller than the size of the symbols. The inhibitory effect of the serine protease inhibitors on the enzymatic activity of CG is also shown (right panels). The enzymatic activity of CG was analyzed by measuring the release rate of 4-nitroanilide following the addition of CG (667 nM, right panels of (a) and (b)) and the inhibitors (16.5 M chymostatin, right panel of (a); 10 M Suc-Val-Pro-PheP-(OPh)2, right panel of (b)) to N-succinyl Ala-Ala-Pro-Phe p-nitroanilide (1.1 mg/mL) in 0.1 M HEPES buffer (pH 7.5) containing 0.5 M NaCl and 10% dimethyl sulfoxide at 25°C. The released p-nitroanilide was detected by measuring the absorbance at 405 nm. In the right panel of (c), the effect of 417 nM intact or PMSF-treated CG was measured. The data of the enzymatic activity are indicated as single-point values.
