MMPI blocks shedding or release of proteins to the conditioned mediuma
| Protein | MMP-14/vector | MMPI/vehicle | ||
|---|---|---|---|---|
| Ratio | No. of peptides | Ratio | No. of peptides | |
| Known MMP substrates | ||||
| Fibromodulin | 4.22 | 1 | 0.58 | 2b |
| Fibronectin | 2.85 | 9 | 0.50 | 4 |
| MMP-14 | 2.61 | 2 | 0.75 | 2 |
| MMP-1 | 1.85 | 1 | 0.71 | 2 |
| CTGF | 1.57 | 5 | 0.22 | 12 |
| Tissue factor pathway inhibitor | 1.23 | 2 | 0.40 | 2 |
| Follistatin-related protein 1 | 1.10 | 8 | 0.33 | 7 |
| Other bioactive molecules | ||||
| EGF-containing fibulin-like extracellular matrix protein 1 | 3.90 | 2 | 0.25 | 1 |
| RNase (pancreatic) | 3.05 | 2 | 0.22 | 1 |
| Quiescin Q6 | 2.16 | 1 | 0.72 | 5 |
| Elafin | 1.85 | 2 | 0.53 | 2 |
| RNase T2 | 1.71 | 2 | 0.71 | 1 |
| CD59 | 1.67 | 1 | 0.41 | 2 |
| Galectin-3-binding protein | 1.61 | 2 | 0.51 | 1 |
| Ectonucleotide pyrophosphatase/phosphodiesterase 1 | 1.58 | 1 | 0.54 | 2 |
| IGFBP-7 | 1.54 | 7 | 0.26 | 2 |
| Cysteine-rich motor neuron-1 | 1.51c | 4 | 0.24 | 5 |
| Niemann-Pick disease, type C2 variant | 1.42 | 2 | 0.36 | 4b |
| Hypothetical protein LOC196463 | 1.33 | 1 | 0.57 | 1 |
| Iduronate 2-sulfatase | 1.32 | 1 | 0.09 | 1 |
| TIMP-1 | 1.32 | 3 | 0.61 | 8b |
| Serine protease 23 | 1.32 | 2 | 0.36 | 1 |
| Pentraxin-related protein PTX3 | 1.26 | 3 | 0.51 | 1 |
| N-Acetylglucosamine-6-sulfatase | 1.19 | 1 | 0.72 | 1 |
| Follistatin-related protein 3 | 1.14 | 1 | 0.41 | 1 |
| KIAA1392/Storkhead-box 2 | 1.14 | 1 | 0.39 | 1 |
| Kunitz-type protease inhibitor 1 | 1.13 | 3 | 0.31 | 1 |
↵a A comparison of MDA-MB-231 cells transfected with MMP-14 to those transfected with empty vector (in the absence of inhibitor) (MMP-14/vector) revealed several proteins which were increased in the medium of MMP-14-transfected cells, indicating increased shedding/release from cellular or pericellular sites that is MMP-14 dependent. A comparison of MMP-14-transfected MDA-MB-231 cells treated with MMPI or with DMSO vehicle (MMPI/vehicle) revealed proteins which were decreased in the conditioned medium, suggesting inhibition of metalloprotease-dependent shedding. The individual peptide sequences for MMP-14/vector are shown in Table S5 in the supplemental material, and those for MMP-14/vehicle are shown in Table S6 in the supplemental material. Abbreviations: CTGF, connective tissue growth factor; IGFBP, insulin-like growth factor binding protein; EGF, epidermal growth factor.
↵b Peptide numbers include those differing only by oxidation of a methionine, which were counted as two peptides, since these are identified independently of each other in the MS analysis.
↵c Peptide mapping (26) of the three peptides for this protein indicate shedding of the N-terminal domain. The most N-terminal peptide had a ratio of 3.06 compared with ratios of 1.08 and 0.40 for peptides nearer the C terminus and plasma membrane.