TABLE 3.

MMPI blocks shedding or release of proteins to the conditioned mediuma

ProteinMMP-14/vectorMMPI/vehicle
RatioNo. of peptidesRatioNo. of peptides
Known MMP substrates
    Fibromodulin4.2210.582b
    Fibronectin2.8590.504
    MMP-142.6120.752
    MMP-11.8510.712
    CTGF1.5750.2212
    Tissue factor pathway inhibitor1.2320.402
    Follistatin-related protein 11.1080.337
Other bioactive molecules
    EGF-containing fibulin-like extracellular matrix protein 13.9020.251
    RNase (pancreatic)3.0520.221
    Quiescin Q62.1610.725
    Elafin1.8520.532
    RNase T21.7120.711
    CD591.6710.412
    Galectin-3-binding protein1.6120.511
    Ectonucleotide pyrophosphatase/phosphodiesterase 11.5810.542
    IGFBP-71.5470.262
    Cysteine-rich motor neuron-11.51c40.245
    Niemann-Pick disease, type C2 variant1.4220.364b
    Hypothetical protein LOC1964631.3310.571
    Iduronate 2-sulfatase1.3210.091
    TIMP-11.3230.618b
    Serine protease 231.3220.361
    Pentraxin-related protein PTX31.2630.511
    N-Acetylglucosamine-6-sulfatase1.1910.721
    Follistatin-related protein 31.1410.411
    KIAA1392/Storkhead-box 21.1410.391
    Kunitz-type protease inhibitor 11.1330.311
  • 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.