Myeloid cell-synthesized coagulation factor X dampens antitumor immunity.

Immune evasion in the tumor microenvironment (TME) is a crucial barrier for effective cancer therapy, and plasticity of innate immune cells may contribute to failures of targeted immunotherapies. Here, we show that rivaroxaban, a direct inhibitor of activated coagulation factor X (FX), promotes antitumor immunity by enhancing infiltration of dendritic cells and cytotoxic T cells at the tumor site. Profiling FX expression in the TME identifies monocytes and macrophages as crucial sources of extravascular FX.

Novel Paraoxonase 2-Dependent Mechanism Mediating the Biological Effects of the Pseudomonas aeruginosa Quorum-Sensing Molecule N-(3-Oxo-Dodecanoyl)-L-Homoserine Lactone.

Pseudomonas aeruginosa produces N-(3-oxo-dodecanoyl)-L-homoserine lactone (3OC12), a crucial signaling molecule that elicits diverse biological responses in host cells thought to subvert immune defenses. The mechanism mediating many of these responses remains unknown. The intracellular lactonase paraoxonase 2 (PON2) hydrolyzes and inactivates 3OC12 and is therefore considered a component of host cells that attenuates 3OC12-mediated responses.

Paraoxonases-2 and -3 Are Important Defense Enzymes against Pseudomonas aeruginosa Virulence Factors due to Their Anti-Oxidative and Anti-Inflammatory Properties.

The pathogen Pseudomonas aeruginosa causes serious damage in immunocompromised patients by secretion of various virulence factors, among them the quorum sensing N-(3-oxododecanoyl)-L-homoserine lactone (3OC12) and the redox-active pyocyanin (PCN). Paraoxonase-2 (PON2) may protect against P. aeruginosa infections, as it efficiently inactivates 3OC12 and diminishes PCN-induced oxidative stress.

PON3 is upregulated in cancer tissues and protects against mitochondrial superoxide-mediated cell death.

To achieve malignancy, cancer cells convert numerous signaling pathways, with evasion from cell death being a characteristic hallmark. The cell death machinery represents an anti-cancer target demanding constant identification of tumor-specific signaling molecules. Control of mitochondrial radical formation, particularly superoxide interconnects cell death signals with appropriate mechanistic execution.

Beyond reduction of atherosclerosis: PON2 provides apoptosis resistance and stabilizes tumor cells.

Major contributors to atherosclerosis are oxidative damage and endoplasmic reticulum (ER) stress-induced apoptosis; both of which can be diminished by the anti-oxidative protein paraoxonase-2 (PON2). ER stress is also relevant to cancer and associated with anti-cancer treatment resistance. Hence, we addressed, for the first time, whether PON2 contributes to tumorigenesis and apoptotic escape.

One enzyme, two functions: PON2 prevents mitochondrial superoxide formation and apoptosis independent from its lactonase activity.

The human enzyme paraoxonase-2 (PON2) has two functions, an enzymatic lactonase activity and the reduction of intracellular oxidative stress. As a lactonase, it dominantly hydrolyzes bacterial signaling molecule 3OC12 and may contribute to the defense against pathogenic Pseudomonas aeruginosa. By its anti-oxidative effect, PON2 reduces cellular oxidative damage and influences redox signaling, which promotes cell survival.

Paraoxonase 2 is down-regulated by the Pseudomonas aeruginosa quorumsensing signal N-(3-oxododecanoyl)-L-homoserine lactone and attenuates oxidative stress induced by pyocyanin.

Two virulence factors produced by Pseudomonas aeruginosa are pyocyanin and N-(3-oxododecanoyl)-L-homoserine lactone (3OC12). Pyocyanin damages host cells by generating ROS (reactive oxygen species). 3OC12 is a quorum-sensing signalling molecule which regulates bacterial gene expression and modulates host immune responses.

Protective effect of paraoxonase-2 against endoplasmic reticulum stress-induced apoptosis is lost upon disturbance of calcium homoeostasis.

PON2 (paraoxonase-2) is a ubiquitously expressed antioxidative protein which is largely found in the ER (endoplasmic reticulum). Addressing the cytoprotective functions of PON2, we observed that PON2 overexpression provided significant resistance to ER-stress-induced caspase 3 activation when the ER stress was induced by interference with protein modification (by tunicamycin or dithiothreitol), but not when ER stress was induced by disturbance of Ca(2+) homoeostasis (by thapsigargin or A23187). When analysing the underlying molecular events, we found an activation of the PON2 promoter in response to all tested ER-stress-inducing stimuli.

Paraoxonase-2 reduces oxidative stress in vascular cells and decreases endoplasmic reticulum stress-induced caspase activation.

Background: In the vascular system, elevated levels of reactive oxygen species (ROS) produce oxidative stress and predispose to the development of atherosclerosis. Therefore, it is important to understand the systems producing and those scavenging vascular ROS. Here, we analyzed the ROS-reducing capability of paraoxonase-2 (PON2) in different vascular cells and its involvement in the endoplasmic reticulum stress pathway known as the unfolded protein response.

Fibroblast growth factors are required for efficient tumor angiogenesis.

Although the function of vascular endothelial growth factor in the induction of tumor angiogenesis is well understood, the role of a second group of angiogenic factors, the fibroblast growth factors (FGFs), remains elusive. We used a recombinant adenovirus expressing soluble FGF receptor (AdsFGFR) to interfere with FGF function in tumor angiogenesis. AdsFGFR repressed endothelial cell proliferation in vitro and inhibited tumor angiogenesis in an ex vivo bioassay, in which endothelial cells were cocultured with angiogenic tumor biopsies in a collagen gel.

Reduced expression of neural cell adhesion molecule induces metastatic dissemination of pancreatic beta tumor cells.

As in the development of many human cancers, in a transgenic mouse model of beta-cell carcinogenesis (Rip1Tag2), expression of neural cell adhesion molecule (NCAM) changes from the 120-kDa isoform in normal tissue to the 140/180-kDa isoforms in tumors. NCAM-deficient RiplTag2 mice, generated by crossing Rip1Tag2 mice with NCAM knockout mice, develop metastases, a tumor stage that is not seen in normal Rip1Tag2 mice. In contrast, overexpression of NCAM 120 in NCAM-deficient Rip1Tag2 mice prevents tumor metastasis.

Two Li-Fraumeni syndrome families with novel germline p53 mutations: loss of the wild-type p53 allele in only 50% of tumours.

We describe two Li-Fraumeni syndrome families. Family A was remarkable for two early childhood cases of adrenocortical tumours, family B for a high incidence of many characteristic cancers, including a childhood case of choroid plexus tumour. Using direct sequencing, we analysed exons 5-9 of the p53 gene in constitutional DNA of individuals from both families and found two novel germline mutations in exon 5.

A causal role for E-cadherin in the transition from adenoma to carcinoma.

Development of malignant tumours is in part characterized by the ability of a tumour cell to overcome cell-cell adhesion and to invade surrounding tissue. E-cadherin is the main adhesion molecule of epithelia, and it has been implicated in carcinogenesis because it is frequently lost in human epithelial cancers. Re-establishing the functional cadherin complex in tumour cell lines results in a reversion from an invasive to a benign epithelial phenotype.

Chromosomal distribution of the hamster intracisternal A-particle (IAP) retrotransposons.

The retrotransposon-like elements of the intracisternal A-particle (IAP) sequences occur in about 900 copies per haploid hamster cell genome. By applying the fluorescent in situ hybridization (FISH) technique and four different, cloned segments of the IAP element as hybridization probes, these elements were found to be distributed in specific patterns over many of the 44 hamster chromosomes. The hybridization patterns were very similar regardless of whether all four probes or only the IAPI probe carrying the long terminal repeat (LTR) region were used.

Chromosomal insertion of foreign (adenovirus type 12, plasmid, or bacteriophage lambda) DNA is associated with enhanced methylation of cellular DNA segments.

Insertion of foreign DNA into an established mammalian genome can extensively alter the patterns of cellular DNA methylation. Adenovirus type 12 (Ad12)-transformed hamster cells, Ad12-induced hamster tumor cells, or hamster cells carrying integrated DNA of bacteriophage lambda were used as model systems. DNA methylation levels were examined by cleaving cellular DNA with Hpa II, Msp I, or Hha I, followed by Southern blot hybridization with 32P-labeled, randomly selected cellular DNA probes.

On the insertion of foreign DNA into mammalian genomes: mechanism and consequences.

We have studied the integration of adenovirus type 12 (Ad12) DNA in transformed and hamster tumor cells over many years. Upon infection of hamster cells with Ad12, viral DNA has been found in association with hamster chromosomes, possibly in part integrated into the host genome. Ad12 DNA integration is not sequence specific.

A radiation hybrid map of human chromosome 18.

A human x Chinese hamster (CH) somatic cell hybrid subclone deficient in HPRT and containing only human chromosome 18 was irradiated with 7000 rad and fused to a thymidine kinase deficient CH cell line. Radiation-rescued hybrid cell lines, selected in HAT medium, were analyzed for human DNA with human interspersed-repeat sequence primers. Size and number of human chromosome fragments retained in a subset of hybrids were determined by FISH.

Mutation screening of complete fibrillin-1 coding sequence: report of five new mutations, including two in 8-cysteine domains.

Marfan syndrome (MFS) is an autosomal dominantly inherited connective tissue disorder characterized by cardiovascular, ocular and skeletal manifestations. Previously, mutations in the fibrillin-1 gene on chromosome 15 (FBN1) have been reported to cause MFS. We have now screened 44 probands with MFS or related phenotypes for alterations in the entire fibrillin coding sequence (9.