No abstract

Balanced expression of proteases and their inhibitors is one prerequisite of tissue homeostasis. Metastatic spread of tumor cells through the organism depends on proteolytic activity and is the death determinant for cancer patients. Paradoxically, increased expression of tissue inhibitor of metalloproteinases-1 (TIMP-1), a natural inhibitor of several endometalloproteinases, including matrix metalloproteinases and a disintegrin and metalloproteinase-10 (ADAM-10), in cancer patients is negatively correlated with their survival, although TIMP-1 itself inhibits invasion of some tumor cells. Here, we show that elevated stromal expression of TIMP-1 promotes liver metastasis in two independent tumor models by inducing the hepatocyte growth factor (HGF) signaling pathway and expression of several metastasis-associated genes, including HGF and HGF-activating proteases, in the liver. We also found in an in vitro assay that suppression of ADAM-10 is in principle able to prevent shedding of cMet, which may be one explanation for the increase of cell-associated HGF receptor cMet in livers with elevated TIMP-1. Similar TIMP-1-associated changes in gene expression were detected in livers of patients with metastatic colorectal cancer. The newly identified role of TIMP-1 to create a prometastatic niche may also explain the TIMP-1 paradoxon. [Cancer Res 2007;67(18):8615-23]

Histamine is a major mast cell mediator of immunoneural signalling in the gut and mast cells play a role in the pathophysiology of functional and inflammatory bowel diseases. Histamine receptors are therefore promising drug targets to treat gut disorders. We aimed to study the so far unknown effect of histamine on neural activity in the human enteric nervous system (ENS) and to identify the pharmacology of histamine response. We used fast imaging techniques in combination with the potentiometric dye di-8-ANEPPS to monitor directly membrane potential changes and thereby neuronal excitability in the human submucous plexus from surgical specimens of 110 patients (2137 neurones, 273 ganglia). Local microejection of histamine resulted in action potential discharge in 37% of neurones. This excitatory effect was mimicked by the H 1 agonist HTMT-dimaleat, H 2 agonist dimaprit, H 3 agonist (

Quantitative changes of enteric glia (EGC) have been implicated in gastrointestinal disorders. To facilitate future studies of EGC in human pathology, we aimed to characterize thoroughly glial markers in the human enteric nervous system (ENS) and to compare EGC in man and guinea pig. Whole-mount preparations of the enteric nerve plexuses from human and guinea pig ileum and colon were labeled with antibodies against S100b, glial fibrillary acidic protein (GFAP), and p75NGFR and the transcription factors Sox8/9/10 and neuronally counterstained. Abundant immunoreactivity (IR) for S100b, GFAP, p75NGFR, and Sox8/9/10 was detected in EGC of all studied regions. Although the cytoplasmatic staining pattern of most markers did not permit glial quantification, the nuclear localization of Sox8/9/10-IR allowed to identify and count all EGC individually. In both man and guinea pig, myenteric ganglia were larger and contained more EGC and neurons than submucous ganglia. Furthermore, there were more EGC in the human than in the guinea pig myenteric plexus (MP), glial density was consistently higher in the human ENS, and the glia index (glia:neuron ratio) ranged from 1.3 to 1.9 and from 5.9 to 7.0 in the human submucous plexus (SMP) and MP, respectively, whereas, in guinea pig, the glia index was 0.8-1.0 in the SMP and 1.7 in the MP. The glia index was the most robust quantitative descriptor within one species. This is a comprehensive set of quantitative EGC measures in man and guinea pig that provides a basis for pathological assessment of glial proliferation and/or degeneration in the diseased gut.

The specific spatiotemporal role of the matrix metalloproteinase 2 (MMP-2) and MMP-9 (gelatinase) during metastasis is still under debate. Host cells have been described as major contributors to these MMPs during metastasis. Here, we show strong overexpression of MMP-2 and MMP-9 by tumor cells of clinical liver specimen of recurrent metachronous metastases, leading us to address the importance of tumor cell -derived MMP-2 or MMP-9 during liver metastasis. Thus far, distinction of their roles was impossible due to lack of inhibitors which can act exclusively on tumor cells or distinguish MMP-2 from MMP-9. We therefore used short hairpin RNA interference technology in the well-established syngeneic L-CI.5s lymphoma model, in which we could analyze the time course of experimental liver colonization (arrest/invasion of single tumor cells, outgrowth, and invasion within the parenchyma) in immunocompetent mice and correlate these steps with MMP-2 or MMP-9 expression levels. In parental tumor cells, MMP-9 expression closely correlated with the invasive phases of liver colonization, whereas MMP-2 expression remained unaltered. Specific knockdown of MMP-9 revealed a close correlation between invasion-dependent events and tumor cell -derived MMP-9 expression. In contrast, knockdown of MMP-2 did not significantly alter the metastatic potential of the cells but led to a marked inhibition of metastatic foci growth. These findings explain the efficacy of gelatinase-specific synthetic inhibitors on invasion and growth of tumor cells and attribute distinct functions of MMP-2 and MMP-9 to aspects of liver metastasis. (Mol Cancer Res 2008;6(3):341 -51)