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The matrix metalloproteinases (MMP) are a group of zinc dependent enzymes (endopeptidases) which degrade varying components of the extracellular matrix in both normal and diseased tissue. Some of the functions are summarized in the table below.

Embryogenesis and development Controlled proteolytic activity and extracellular matrix remodelling occurs during implantation and normal embryonic development
Acute wound healing

MMP1 and MMP10 are expressed by basal keratinocytes at the migrating wound front

MMP3 is expressed by distinct group of keratinocytes behind this migrating front

Cancer and metastasis

MMP7 may play a role in tumor progression and has been demonstrated in cancers of the colon, pancreas, transitional cell carcinomas of the kidney, and small cell carcinomas of the lung

MMP may contribute to tumor growth by facilitating development of angiogenesis allowing extravasation of tumor cells-may involve MMP1, 2, 9, and MT1-MMP with serine proteases

Cutaneous tumors

In basal cell carcinoma, MMP1, 2, 9, 11 protein and mRNA have been demonstrated in stromal cells adjacent to the tumor

Invasive squamous cell carcinomas are associated with expression of MMP 1 and 10


J Biol Chem 1999;274:21056-21062

Melanoma has been associated with MMP-2 with expression associated with the degree of cellular atypia-also highly invasive melanoma cell lines produce significantly lower amounts of TIMP-2 than do lesser invasive ones, suggesting more proteolytic activity in the invasive cells

Chronic wounds MMP 1 and 3 are in higher levels
Bullous diseases Bullous pemphigoid shows distinct expression profile with MMP9 mRNA limited to eosinophils and capable of cleaving the extracellular portion of the 180 kd BP autoantigen
Noninfectious granulomatous disease Sarcoidosis, granuloma annulare, and necrobiosis lipoidica show similar profile of MMP9 and 12
MMP2 localized to stromal fibroblasts
Photodamage Increased MMP1,3,7,9, and 12 have been found in sun-exposed skin
Contact hypersensitivity MMP 3 necessary for initiation of the response and MMP 9 required to clear the eruption

The families of MMP are continually being catalogued. The following compilation is the most recent classification.

1 Collagenase 1, interstitial collagenase
2 Gelatinase A, 72kD gelatinase
Stromelysin 1
Matrilysin, PUMP
8 Collagenase 2, neutropil collagenase
9 Gelatinase B, 92kD gelatinase
10 Stromelysin 2
11 Stromelysin 3
12 Macrophage metalloelastase
13 Collagenase 3
14 MT1-MMP
15 MT2-MMP
16 MT3-MMP
17 MT4-MMP
18 Collagenase 4
19 No other name
20 Enamelysin
23 No other name

MPPs are not constitutively expressed. The activity of MMP is regulated by the following:

Gene expression via cytokines, growth factors, and cell-cell and cell-matrix interactions
Activation of the proenzyme or zymogen form
Natural inhibitors including tissue metalloproteinase inhibitors (TIMPs)

There is a tightly regulated balance between these enzymes and inhibitors. Disease processes result when this balance goes awry. Recently synthetic inhibitors are in clinical trials as possible anti-cancer agents.

750 kd protein  
16.5 kd protein  
Marimastat (BP-2516) Synthetic inhibitor
Currently in trial as an anti-angiogenic agent
Primomastat (AG3340) Synthetic inhibitor
Specific inhibitor of MMP2, 13, and MT-MMP

Adv Dermatol 2000;16:185-208
Henry JB. Clinical Diagnosis and Management by Laboratory Methods. Twentieth Edition. WB Saunders. 2001.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 5th Edition. McGraw-Hill. 1999.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.

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Last Updated 1/5/2004

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