Matrix metalloproteinase-13 refines pathological staging of precancerous colorectal lesions

An exact classification of precancerous stages of colorectal polyps might improve therapy and patients´ outcome. Here we investigate the association between grade of dysplasia and Matrix metalloproteinase-13 (MMP-13) expression in 137 biopsies from patients with cancerous and non-cancerous colorectal adenomas. A reproducible staining procedure for histologic MMP-13 analysis in routinely fixed colorectal biopsy specimens has been established. A newly adopted immunoreactive scoring system for MMP-13 was demonstrated as reliable readout. The strength of the association between pathologic stage and immunoreactive MMP-13 scoring emphasizes its eligibility for diagnosis in precancerous colorectal lesions

Helicobacter pylori CagA protein targets the c-Met receptor and enhances the motogenic response

Infection with the human microbial pathogen Helicobacter pylori is assumed to lead to invasive gastric cancer. We find that H. pylori activates the hepatocyte growth factor/scatter factor receptor c-Met, which is involved in invasive growth of tumor cells. The H. pylori effector protein CagA intracellularly targets the c-Met receptor and promotes cellular processes leading to a forceful motogenic response. CagA could represent a bacterial adaptor protein that associates with phospholipase Cγ but not Grb2-associated binder 1 or growth factor receptor–bound protein 2. The H. pylori–induced motogenic response is suppressed and blocked by the inhibition of PLCγ and of MAPK, respectively. Thus, upon translocation, CagA modulates cellular functions by deregulating c-Met receptor signaling. The activation of the motogenic response in H. pylori–infected epithelial cells suggests that CagA could be involved in tumor progression

Hepatitis B virus surface proteins accelerate cholestatic injury and tumor progression in Abcb4-knockout mice

Understanding of the pathophysiology of cholestasis associated carcinogenesis could challenge the development of new personalized therapeutic approaches and thus improve prognosis. Simultaneous damage might aggravate hepatic injury, induce chronic liver disease and even promote carcinogenesis. We aimed to study the effect of Hepatitis B virus surface protein (HBsAg) on cholestatic liver disease and associated carcinogenesis in a mouse model combining both impairments. Hybrids of Abcb4-/- and HBsAg transgenic mice were bred on fibrosis susceptible background BALB/c. Liver injury, serum bile acid concentration, hepatic fibrosis, and carcinogenesis were enhanced by the combination of simultaneous damage in line with activation of c-Jun N-terminal kinase (JNK), proto-oncogene c-Jun, and Signal transducer and activator of transcription 3 (STAT3). Activation of Protein Kinase RNA-like Endoplasmic Reticulum Kinase (PERK) and Eukaryotic translation initiation factor 2A (eIF2a) indicated unfolded protein response (UPR) in HBsAg-expressing mice and even in Abcb4-/- without HBsAg-expression. CONCLUSION: Cholestasis-induced STAT3- and JNK-pathways may predispose HBsAg-associated tumorigenesis. Since STAT3- and JNK-activation are well characterized critical regulators for tumor promotion, the potentiation of their activation in hybrids suggests an additive mechanism enhancing tumor incidence

Bim and Bmf synergize to induce apoptosis in Neisseria gonorrhoeae infection

Abstract: Bcl-2 family proteins including the pro-apoptotic BH3-only proteins are central regulators of apoptotic cell death. Here we show by a focused siRNA miniscreen that the synergistic action of the BH3-only proteins Bim and Bmf is required for apoptosis induced by infection with Neisseria gonorrhoeae (Ngo). While Bim and Bmf were associated with the cytoskeleton of healthy cells, they both were released upon Ngo infection. Loss of Bim and Bmf from the cytoskeleton fraction required the activation of Jun-N-terminal kinase-1 (JNK-1), which in turn depended on Rac-1. Depletion and inhibition of Rac-1, JNK-1, Bim, or Bmf prevented the activation of Bak and Bax and the subsequent activation of caspases. Apoptosis could be reconstituted in Bim-depleted and Bmf-depleted cells by additional silencing of antiapoptotic Mcl-1 and Bcl-XL, respectively. Our data indicate a synergistic role for both cytoskeletal-associated BH3-only proteins, Bim, and Bmf, in an apoptotic pathway leading to the clearance of Ngo-infected cells. Author Summary: A variety of physiological death signals, as well as pathological insults, trigger apoptosis, a genetically programmed form of cell death. Pathogens often induce host cell apoptosis to establish a successful infection. Neisseria gonorrhoeae (Ngo), the etiological agent of the sexually transmitted disease gonorrhoea, is a highly adapted obligate human-specific pathogen and has been shown to induce apoptosis in infected cells. Here we unveil the molecular mechanisms leading to apoptosis of infected cells. We show that Ngo-mediated apoptosis requires a special subset of proapoptotic proteins from the group of BH3-only proteins. BH3-only proteins act as stress sensors to translate toxic environmental signals to the initiation of apoptosis. In a siRNA-based miniscreen, we found Bim and Bmf, BH3-only proteins associated with the cytoskeleton, necessary to induce host cell apoptosis upon infection. Bim and Bmf inactivated different inhibitors of apoptosis and thereby induced cell death in response to infection. Our data unveil a novel pathway of infection-induced apoptosis that enhances our understanding of the mechanism by which BH3-only proteins control apoptotic cell death

Tyrosine-Phosphorylated Caveolin-1 Blocks Bacterial Uptake by Inducing Vav2-RhoA-Mediated Cytoskeletal Rearrangements

During the early stages of infection, Neisseria gonorrhoeae triggers a phosphotyrosine-dependent Cav1-Vav2-RhoA signaling cascade that promotes the pathogen's extracellular state

Helicobacter pylori type IV secretion, host cell signalling and vaccine development.

Helicobacter pylori is a bacterial pathogen specialised to colonise and persist the gastric mucosa and to cause severe gastroduodenal disease. A major disease-associated bacterial component is a type IV secretion system (TFSS) encoded by the cytotoxin-associated genes pathogenicity island (cagPAI). Among the multiple responses in H. pylori-infected epithelial cells, the induction of proinflammatory cytokines and chemokines, cell spreading and motility associated with the "hum mingbird" phenotype appear strictly dependent on the functional transporter complex in the cagPAI. H. pylori is also capable of occasionally entering epithelial cells and manipulates the host immune system for immune evasion. Attached bacteria actively translocate the CagA protein into epithelial cells by a TFSS-dependent process and translocated CagA undergoes tyrosine phosphorylation in the carboxy terminal EPIYA sequence repeat motif (Y-972) by kinases of the Src family. Furthermore, we have identified a novel TFSS in H. pylori involved in horizontal DNA-transfer. Host cell signalling events and cellular phenotypes provoked by the cagPAI, the investigation of mechanisms related to gastric cancer as well as the development of a Salmonella based live recombinant vaccine are in the focus of additional departmental activities

Genomic Methylation Inhibits Expression of Hepatitis B Virus Envelope Protein in Transgenic Mice: A Non-Infectious Mouse Model to Study Silencing of HBV Surface Antigen Genes.

The Hepatitis B virus genome persists in the nucleus of virus infected hepatocytes where it serves as template for viral mRNA synthesis. Epigenetic modifications, including methylation of the CpG islands contribute to the regulation of viral gene expression. The present study investigates the effects of spontaneous age dependent loss of hepatitis B surface protein- (HBs) expression due to HBV-genome specific methylation as well as its proximate positive effects in HBs transgenic mice.Liver and serum of HBs transgenic mice aged 5-33 weeks were analyzed by Western blot, immunohistochemistry, serum analysis, PCR, and qRT-PCR.From the third month of age hepatic loss of HBs was observed in 20% of transgenic mice. The size of HBs-free area and the relative number of animals with these effects increased with age and struck about 55% of animals aged 33 weeks. Loss of HBs-expression was strongly correlated with amelioration of serum parameters ALT and AST. In addition lower HBs-expression went on with decreased ER-stress. The loss of surface protein expression started on transcriptional level and appeared to be regulated epigenetically by DNA methylation. The amount of the HBs-expression correlated negatively with methylation of HBV DNA in the mouse genome.Our data suggest that methylation of specific CpG sites controls gene expression even in HBs-transgenic mice with truncated HBV genome. More important, the loss of HBs expression and intracellular aggregation ameliorated cell stress and liver integrity. Thus, targeted modulation of HBs expression may offer new therapeutic approaches. Furthermore, HBs-transgenic mice depict a non-infectious mouse model to study one possible mechanism of HBs gene silencing by hypermethylation

Loss of HBs expression ameliorated liver injury.

<p>(A) Immunohistochemical staining of HBs demonstrated the appearance of hepatic areas without transgene expression in distinct mice beginning with the age of 12 weeks. At the same age, mice with HBs expression in single hepatocytes and mice with expression of HBs in every hepatocyte were observed. Representative micrographs are shown. Scale bars in left and right panels: 160μm, magnification x200. Scale bar 320 μm in the medium panel: magnification x100. (B) The observed loss of HBs expression is age-dependent. The relative number of mice exhibiting areas without HBs expression increased with higher age of the mice. Bars indicate the relative number (%) of animals with unchanged HBs expression in all hepatocytes. (C) Quantitative analysis of HBs expression in liver tissue assessed by ELISA. *<i>P</i> < 0.05. (D) Amelioration of liver serum parameters correlates significantly with loss of HBs expression. *<i>P</i> < 0.05. (E) Correlation of AP and HBs. r² = 0.864, P < 0.001. (F) H&E staining indicates ground glass hepatocytes and enhanced numbers of inflammatory cells in the „high”and „medium”group. Scale bars 80 μm, magnification x400. Arrowheads: inflammatory infiltrates, arrows: ground-glass-hepatocytes. Sirius Red staining indicates fibrillary collagen. Scale bars 160μm, magnification x200.</p