Matrix metalloproteinase 11/stromelysin-3 exerts both activator and repressor functions during the hematogenous metastatic process in mice.

MMP11 expression is a poor prognosis factor in human carcinomas. Although it has been shown to favor primary tumor development, its role in metastatic processes remains unclear. We studied the hematogenous metastatic activity of C26 mouse colon cancer cells injected into the tail vain of wild-type or MMP11-deficient mice during 2 months. Using X-ray computed tomography to image metastasis development in recipient living mice, lung metastases were found to occur earlier and to grow faster in wild-type mice. Histological analyses of the lung, liver, kidney, adrenal gland, mammary gland, ovary and salivary gland, performed at the end of experiment, also showed lower numbers of metastases in wild-type mice, regardless of organ. Lung metastases showed similar Factor VIII-positive vascular networks regardless of the mouse MMP11 status. However, those found in MMP11-deficient mice also exhibited vessel-like structures that did not express Factor VIII, Lyve-1 and vimentin, and were not stained with PAS. Consequently, they did not correspond to vascular or lymphatic vessels or to vascular mimicry channels. Collectively, these results revealed significant spatio-temporal variability that is dependent on host MMP11 status. Furthermore, they point-out the paradoxical role of MMP11 in favoring the onset and growth of lung metastases but limiting lung foci number, and inhibiting the cancer cell dissemination to other organs. These data highlight the complexity of the metastatic process in which the same factor can play activator or repressor functions depending on the metastatic step.