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New knowledge relative to the role and mechanism of action of extra-cellular proteases MMPs, ADAMs and uPA

Several cellular/molecular mechanisms of protease activities, which are important as regard to tumorigenesis, have been elucidated. The uPAR associated protein uPARAP is key for the uPAR-driven internalization of collagen.

MMP14 stimulates the very potent angiogenic factor VEGF due to its cytoplasmic domain triggering an intra-cellular signalling cascade. ADAM17 is able to cleave several cellular adhesion molecules and to release active EGF.

Many experiments have been conducted and analysis performed using several animal models based on tumour induction combined with transgenic mice. The overall results, combined to data yielded by protease expression profiling in samples from tumour tissue banks, point to an important role for several proteases in cancer development.

These proteases are therefore identified as priority therapeutic targets: MMP2, MMP9, MMP13, MMP14, MMP17, ADAMTS17, ADAM10, uPA/uPAR.
On an other hand, our results have also revealed that some other proteinases could also have a negative effect on tumour growth/induction, ie MMP8, MMP11, MMP19.

These are clearly targets that must be avoided by potential therapeutic inhibitors.
Cancer is a stepwise development process and requires that some cells and tissues from the host organism fall under the control of the tumour. Knowing when (which steps) and where (cancer, stromal, vascular,immune cells?) individual proteases targets are produced is therefore of a crucial interest.

The results yielded throughout this project have allowed to pintpoint the detrimental importance of neutrophils and myofibroblast recruitment, associated with persistent MMP9 and MMP13 expression. These stromal MMPs seem to act in concert with MMP14, which is highly expressed by cancer cells. These studies strongly support the hypothesis that tumour progression from immortal to benign and malignant tumours is mediated by the step-wise induction and or over expression of different growth factors, which in turn activates MMPs on stromal cells as well as induces simultaneous MMP-expression by the tumour cells.

In the specific situation of pregnancy, it has been shown that PAI-1 and both MMP2/MMP9 are important for an adequate foeto-placental development, but also that there is a high level of redundancy inside the protease families.
On the other hand, a proteinase associated with progeria (FACE-1) has been characterized and represent a potential therapeutic target for this desease.

Informations connexes

Reported by

University of Liège
Tumour and Development Biology Laboratory, Sart-Tilman, Pathologie, CHU B-23
4000 Liege