TABLE 5.
Candidate metalloprotease substrates identified in conditioned medium of MMP-14-transfected MDA-MB-231 cells that show reduced shedding in the presence of the MMPIa
| Candidate substrate | MMPI/vehicle ratio | No. of peptides |
|---|---|---|
| Progranulin | 0.07 | 1 |
| EGF-containing fibulin-like extracellular matrix protein 1 | 0.25 | 1 |
| IGFBP-7 | 0.26 | 3 |
| Proprotein convertase subtilisin/kexin type 9 | 0.28 | 1 |
| Cyr61 | 0.29 | 10 |
| Serine protease 23 | 0.36 | 1 |
| Niemann-Pick disease, type C2 variant | 0.36 | 4b |
| KIAA1392/Storkhead-box 2 | 0.39 | 1 |
| IGFBP-4 | 0.40 | 6 |
| Kunitz-type proteinase inhibitor 2 | 0.44 | 1 |
| KIAA0230/peroxidasin homolog | 0.45 | 5 |
| Beta-2-microglobulin | 0.47 | 1 |
| Dickkopf-1 | 0.48 | 3 |
| Extracellular matrix protein 1 | 0.50 | 6b |
| Pentraxin-related protein PTX3 | 0.51 | 1 |
| Galectin-3-binding protein | 0.51 | 1 |
| Elafin | 0.53 | 2 |
| Thrombospondin-1 | 0.54 | 2 |
| Cathepsin A | 0.55 | 1 |
| Cathepsin B | 0.57 | 3 |
| Legumain | 0.59 | 3 |
| Lupus La protein | 0.59 | 1 |
| Peptidyl-prolyl cis-trans isomerase B | 0.64 | 1 |
| Macrophage migration inhibitory factor | 0.67 | 1 |
| Peptidyl-prolyl cis-trans isomerase A | 0.68 | 4b |
| Gamma enolase | 0.68 | 3 |
| DJ-1 | 0.69 | 3 |
| Macrophage capping protein | 0.70 | 1 |
| Quiescin Q6 | 0.72 | 5 |
| Stanniocalcin-1 | 0.75 | 3 |
MDA-MB-231 breast cancer cells transfected with MMP-14 were treated with the MMPI prinomastat or with DMSO vehicle under serum-free conditions for 48 h. Proteins in each conditioned medium were labeled with ICAT reagents (heavy or light), pooled, and digested with trypsin. The biotin-tagged tryptic peptides were separated by multidimensional LC and analyzed by MS-MS. Values shown are averaged abundance ratios from three separate experiments (MMPI/vehicle) for peptides detailed in Table S8 in the supplemental material. Peptides were identified at a ≥99% confidence level, unless otherwise noted in Tables S1 and S8 in the supplemental material. Abbreviations: IGFBP, insulin-like growth factor binding protein.
Peptide numbers include those differing only by the oxidation of a methionine, which were counted as two peptides, since they were identified independently in the MS analysis.