The metalloproteinase matrilysin is preferentially expressed by epithelial cells in a tissue-restricted pattern in the mouse

Enhanced expression of matrilysin, collagenase, and stromelysin-1 in gastrointestinal ulcers

Programmed expression of several matrix metalloproteinases is an important feature of cutaneous wound healing. To study whether this also applies to gastrointestinal ulcer healing, we used in situ hybridization with 35S-labeled probes to localize sites of collagenase, stromelysin-1, and matrilysin expression in 26 samples representing peptic ulcers, Crohn's disease, and ulcerative colitis. In contrast to skin wounds, collagenase mRNA was not detected in the surface epithelium bordering gastrointestinal ulcer areas. However, together with stromelysin-1 mRNA, it was abundantly expressed by the granulation tissue in all types of ulcers. Signal for matrilysin mRNA and protein was detected in the mucosal epithelium bordering the ulcerations but never in the ulcer stroma. The gut basement membrane was disrupted under the matrilysin-producing epithelial cells as assessed by immunostaining for laminin. Tissue inhibitor of metalloproteinases (TIMP-1) mRNA never co-localized with matrilysin-positive mucosal epithelial cells. These data indicate that matrilysin plays a significant role in epithelial remodelling occurring in gastrointestinal ulcerations whereas collagenase and stromelysin-1 are involved in the reparative processes in the ulcer bed.

Contributions of tumor and stromal matrix metalloproteinases to tumor progression, invasion and metastasis

The malignant progression of tumors is driven by the expression of oncogenes and loss of expression of tumor suppressor genes; factors that are intrinsic to cancer cells. The phenotypic changes brought about by the gain or loss of expression of oncogenes and tumor suppressor genes lead to the acquisition of malignant traits, namely, the ability to invade into and grow in ectopic tissue environments. Recently, however, focus in cancer research has widened from the cancer cell to include the surrounding tumor stroma as an integral player in the process of tumor progression. One of the areas in cancer research contributing to this enhanced appreciation of stromal involvement in tumor progression and metastasis is that of matrix metalloproteinases (MMPs). This review provides an overview of the characteristics of MMPs and discusses their role in the progression and metastasis of tumors. Initially, attention will focus on the regulation of MMPs in tumor cells but will switch to discourse on stromal expression of MMPs in tumors and speculation on the functional consequences of stromal expression of MMPs.

Matrix metalloproteinases are expressed during ductal and alveolar mammary morphogenesis, and misregulation of stromelysin-1 in transgenic mice induces unscheduled alveolar development

The matrix-degrading metalloproteinases stromelysin-1, stromelysin-3, and gelatinase A are expressed during ductal branching morphogenesis of the murine mammary gland. Stromelysin-1 expression in particular correlates with ductal elongation, and in situ hybridization and three-dimensional reconstruction studies revealed that stromelysin-1 mRNA was concentrated in stromal fibroblasts along the length of advancing ducts. Transgenic mice expressing an activated form of stromelysin-1 under the control of the MMTV promoter/enhancer exhibited inappropriate alveolar development in virgin females. Ultrastructural analysis demonstrated that the basement membrane underlying epithelial and myoepithelial cells was amorphous and discontinuous compared with the highly ordered basal lamina in control mammary glands. Transgenic mammary glands had at least a twofold increase in the number of cells/unit area and a 1.4-fold increase in the percent of cycling cells by 13 wk of age compared with nontransgenic littermates. In addition, transgenic glands expressed beta-casein mRNA, but not protein, and resembled the proliferative and differentiated state of an animal between 8 and 10 days pregnant. An analysis of metalloproteinase expression in the glands of normal pregnant females demonstrated that the same matrix metalloproteinase family members, including stromelysin-1, were expressed in connective tissue cells surrounding epithelial clusters during the time of lobuloalveolar development. These results suggest that metalloproteinases may assist in remodeling ECM during normal ductal and alveolar branching morphogenesis, and that disruption of the basement membrane by an activated metalloproteinase can affect basic cellular processes of proliferation and differentiation.