TIMP-1 signaling via CD63 triggers granulopoiesis and neutrophilia in mice.

The homeostasis of neutrophil granulocytes can affect the outcome of several inflammation-associated diseases including cancer. The regulation of this homeostasis is still not completely understood. We previously found that elevated systemic levels of tissue inhibitor of metalloproteinases-1 (TIMP-1) induce an increase of neutrophils in the liver, which in turn strongly promotes liver metastasis. Here, we report that increasing systemic TIMP-1 levels were sufficient to induce neutrophilia in mice. This was not attributed to prolonged survival or direct mobilization of neutrophils. However, TIMP-1 induced enrichment of myeloid progenitors and concomitant upregulation of granulopoiesis-associated genes in the bone marrow compartment. BrdU pulse-labeling confirmed that proliferating progenitors accounted for TIMP-1-induced neutrophilia. TIMP-1 variants that dissect its protease-inhibitory from its CD63 binding function relevant for cell signaling revealed that the TIMP-1 signaling domain was necessary and sufficient to augment granulopoiesis. Consequently, ablation of the TIMP-1 receptor CD63 abolished both neutrophilia and TIMP-1-enhanced granulopoiesis in the bone marrow. Our findings reveal that elevated levels of TIMP-1 impact on neutrophil homeostasis via signaling through CD63. This may provide a link to clinical observations, where TIMP-1 correlates with high severity and bad prognosis in inflammation-associated diseases.

Tissue inhibitor of metalloproteinases (TIMP)-1 creates a premetastatic niche in the liver through SDF-1/CXCR4-dependent neutrophil recruitment in mice.

UNLABELLED: Due to its ability to inhibit prometastatic matrix metalloproteinases, tissue inhibitor of metalloproteinases (TIMP)-1 has been thought to suppress tumor metastasis. However, elevated systemic levels of TIMP-1 correlate with poor prognosis in cancer patients, suggesting a metastasis-stimulating role of TIMP-1. In colorectal cancer patients, tumor as well as plasma TIMP-1 levels were correlated with synchronous liver metastasis or distant metastasis-associated disease relapse. In mice, high systemic TIMP-1 levels increased the liver susceptibility towards metastasis by triggering the formation of a premetastatic niche. This promoted hepatic metastasis independent of origin or intrinsic metastatic potential of tumor cells. High systemic TIMP-1 led to increased hepatic SDF-1 levels, which in turn promoted recruitment of neutrophils to the liver. Both inhibition of SDF-1-mediated neutrophil recruitment and systemic depletion of neutrophils reduced TIMP-1-induced increased liver susceptibility towards metastasis. This indicates a crucial functional role of neutrophils in the TIMP-1-induced premetastatic niche. CONCLUSION: Our results identify TIMP-1 as an essential promoter of hepatic premetastatic niche formation.

A disintegrin and metalloproteinase-10 (ADAM-10) mediates DN30 antibody-induced shedding of the met surface receptor.

Met, the tyrosine kinase receptor for the hepatocyte growth factor is a prominent regulator of cancer cell invasiveness and has emerged as a promising therapeutic target. Binding of the anti-Met monoclonal antibody DN30 to its epitope induces the proteolytic cleavage of Met, thereby impairing the invasive growth of tumors. The molecular mechanism controlling this therapeutic shedding process has so far been unknown. Here, we report that A Disintegrin And Metalloproteinase (ADAM)-10, but not ADAM-17, is required for DN30-induced Met shedding. Knockdown of ADAM-10 in different tumor cell lines or abrogation of its proteolytic activity by natural or synthetic inhibitors abolished Met down-regulation on the cell surface as well as reduction of Met activation. Moreover, hepatocyte growth factor-induced tumor cell migration and invasion were impaired upon ADAM-10 knockdown. Thus, the therapeutic effect of DN30 involves ADAM-10-dependent Met shedding, linking for the first time a specific metalloprotease to target therapy against a receptor tyrosine kinase.