Heterotopic endochondrial ossification with mixed tumor formation in C3(1)/Tag transgenic mice is associated with elevated TGF-beta1 and BMP-2 expression. (1/39)

Transgenic mice which express the simian virus 40 large T-antigen (Tag) under the regulatory control of the hormone responsive rat C3(1) gene develop unusual lesions of heterotopic bone growth associated with mixed tumor formation arising from eccrine sweat glands found only in the foot pads of mice, ischiocavernosus muscle adjacent to bulbourethral glands and occasionally the salivary and mammary glands. These lesions are very similar to mixed tumors arising in several types of human cancers. Based upon electron microscopic examination and immunocytochemical analyses of cellular differentiation markers, the mixed proliferative lesions in this transgenic mouse model begin with the Tag-induced proliferation of epithelial and myoepithelial cells. The proliferation of these two types of cells results in hyperplasia and adenomatous transformation of the epithelial component, whereas the proliferating myoepithelial cells undergo metaplasia to form chondrocytes which deposit extracellular matrix, including collagen fibers. Cartilage develops focally between areas of epithelial proliferation and subsequently ossifies through a process of endochondrial bone formation. The metaplasia of myoepithelial cells to chondrocytes appears to require the inductive interaction of factors produced by the closely associated proliferating epithelial cells, including members of the TGF-beta superfamily. We demonstrate that TGF-beta1 protein accumulates in the extracellular matrix of the lesions, whereas RNA in situ hybridization reveals that BMP-2, another strong inducer of heterotopic bone formation, is overexpressed by the proliferating epithelial cells during the development of ectopic bone. The formation of sarcomatous tumors within the mixed tumors appears to be androgen-dependent and more frequent in mice lacking a normal allele of p53. This process of cartilage and bone induction may mimic epithelial-mesenchymal interactions which occur during embryonic bone formation. These transgenic mice may provide new insights into the processes of ectopic endochondrial bone formation associated with mixed tumor formation and serve as a useful model for human heterotopic bone disease.  (+info)

The C3(1)/SV40 T-antigen transgenic mouse model of mammary cancer: ductal epithelial cell targeting with multistage progression to carcinoma. (2/39)

The 5' flanking region of the C3(1) component of the rat prostate steroid binding protein (PSBP) has been used to successfully target the expression of the SV40 large T-antigen (Tag) to the epithelium of both the mammary and prostate glands resulting in models of mammary and prostate cancers which histologically resemble the human diseases. Atypia of the mammary ductal epithelium develops at about 8 weeks of age, progressing to mammary intraepithelial neoplasia (resembling human ductal carcinoma in situ [DCIS]) at about 12 weeks of age with the development of invasive carcinomas at about 16 weeks of age in 100% of female mice. The carcinomas share features to what has been classified in human breast cancer as infiltrating ductal carcinomas. All FVB/N female mice carrying the transgene develop mammary cancer with about a 15% incidence of lung metastases. Approximately 10% of older male mice develop anaplastic mammary carcinomas. Unlike many other transgenic models in which hormones and pregnancy are used to induce a mammary phenotype, C3(1)/Tag mice develop mammary tumors in the mammary epithelium of virgin animals without hormone supplementation or pregnancy. Although mammary tumor development appears hormone-responsive at early stages, invasive carcinomas are hormone-independent, which corresponds to the loss of estrogen receptor-alpha expression during tumor progression. Molecular and biologic factors related to mammary tumor progression can be studied in this model since lesions evolve over a predictable time course. Genomic alterations have been identified during tumor progression, including an amplification of the distal portion of chromosome 6 containing ki-ras and loss of heterozygosity (LOH) in other chromosomal regions. We have demonstrated that stage specific alterations in the expression of genes which are critical regulators of the cell cycle and apoptosis are functionally important in vivo. C3(1)/Tag mice appear useful for testing particular therapies since growth of the mammary tumors can be reduced using chemopreventive agents, cytokines, and an anti-angiogenesis agent.  (+info)

The phosphatidylethanolamine-binding protein is the prototype of a novel family of serine protease inhibitors. (3/39)

Serine proteases are involved in many processes in the nervous system and specific inhibitors tightly control their proteolytic activity. Thrombin is thought to play a role in tissue development and homeostasis. To date, protease nexin-1 is the only known endogenous protease inhibitor that specifically interferes with thrombotic activity and is expressed in the brain. In this study, we report the detection of a novel thrombin inhibitory activity in the brain of protease nexin-1(-/-) mice. Purification and subsequent analysis by tandem mass spectrometry identified this protein as the phosphatidylethanolamine-binding protein (PEBP). We demonstrate that PEBP exerts inhibitory activity against several serine proteases including thrombin, neuropsin, and chymotrypsin, whereas trypsin, tissue type plasminogen activator, and elastase are not affected. Since PEBP does not share significant homology with other serine protease inhibitors, our results define it as the prototype of a novel class of serine protease inhibitors. PEBP immunoreactivity is found on the surface of Rat-1 fibroblast cells and although its sequence contains no secretion signal, PEBP-H(6) can be purified from the conditioned medium upon recombinant expression.  (+info)

Raf kinase inhibitor protein interacts with NF-kappaB-inducing kinase and TAK1 and inhibits NF-kappaB activation. (4/39)

The Raf kinase inhibitor protein (RKIP) acts as a negative regulator of the mitogen-activated protein (MAP) kinase (MAPK) cascade initiated by Raf-1. RKIP inhibits the phosphorylation of MAP/extracellular signal-regulated kinase 1 (MEK1) by Raf-1 by disrupting the interaction between these two kinases. We show here that RKIP also antagonizes the signal transduction pathways that mediate the activation of the transcription factor nuclear factor kappa B (NF-kappaB) in response to stimulation with tumor necrosis factor alpha (TNF-alpha) or interleukin 1 beta. Modulation of RKIP expression levels affected NF-kappaB signaling independent of the MAPK pathway. Genetic epistasis analysis involving the ectopic expression of kinases acting in the NF-kappaB pathway indicated that RKIP acts upstream of the kinase complex that mediates the phosphorylation and inactivation of the inhibitor of NF-kappaB (IkappaB). In vitro kinase assays showed that RKIP antagonizes the activation of the IkappaB kinase (IKK) activity elicited by TNF-alpha. RKIP physically interacted with four kinases of the NF-kappaB activation pathway, NF-kappaB-inducing kinase, transforming growth factor beta-activated kinase 1, IKKalpha, and IKKbeta. This mode of action bears striking similarities to the interactions of RKIP with Raf-1 and MEK1 in the MAPK pathway. Emerging data from diverse organisms suggest that RKIP and RKIP-related proteins represent a new and evolutionarily highly conserved family of protein kinase regulators. Since the MAPK and NF-kappaB pathways have physiologically distinct roles, the function of RKIP may be, in part, to coordinate the regulation of these pathways.  (+info)

The combined effects of vinclozolin and procymidone do not deviate from expected additivity in vitro and in vivo. (5/39)

The combination effects of the well-known antiandrogenic fungicides, vinclozolin and procymidone, were tested both in vitro and in vivo. In vitro both vinclozolin and procymidone significantly inhibited the binding of agonist to the androgen receptor with the concentration that resulted in 50% inhibition (IC(50)) values of 0.1 and 0.6 micro M, respectively. By applying the isobole method, the effect of combining the two pesticides in vitro was found to be additive. In castrated testosterone-treated rats the administration of vinclozolin starting at 10 mg/kg led to a decrease in organ weight of all tested reproductive organs. The levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were increased significantly with doses of 100 mg/kg vinclozolin and above. Expression of the androgen-responsive gene, TRPM-2, was increased starting at 100 mg/kg vinclozolin. For procymidone, reproductive organ weights were diminished at 10 mg/kg and LH was increased at a concentration of 25 mg/kg and above, compared to the testosterone-treated controls. FSH was significantly increased only at 25 mg/kg procymidone. The studied gene expressions were changed by 100 mg/kg procymidone. Dosing the animals with a combination of a 1:1 mixture of vinclozolin and procymidone resulted in a weight reduction in the reproductive organs and an increase of serum LH and FSH as early as with 10 mg/kg combined dose. The relative expressions of TRPM-2 and PBP C3 were changed compared to controls at 100 mg/kg. The level of 5-HT in the rat brain was increased after a dose of 10 mg/kg. Using the isobole method, comparisons of the observed and predicted effects assuming additivity on reproductive organ weights, hormone levels, and gene expression showed agreement and thus the combination effects are suggested to be additive in vivo as well as in vitro.  (+info)

Raf kinase inhibitory protein regulates aurora B kinase and the spindle checkpoint. (6/39)

Raf kinase inhibitory protein (RKIP or PEBP) is an inhibitor of the Raf/MEK/MAP kinase signaling cascade and a suppressor of cancer metastasis. We now show that RKIP associates with centrosomes and kinetochores and regulates the spindle checkpoint in mammalian cells. RKIP depletion causes decreases in the mitotic index, the number of metaphase cells, and traversal times from nuclear envelope breakdown to anaphase, and an override of mitotic checkpoints induced by spindle poisons. Raf-1 depletion or MEK inhibition reverses the reduction in the mitotic index, whereas hyperactivation of Raf mimics the RKIP-depletion phenotype. Finally, RKIP depletion or Raf hyperactivation reduces kinetochore localization and kinase activity of Aurora B, a regulator of the spindle checkpoint. These results indicate that RKIP regulates Aurora B kinase and the spindle checkpoint via the Raf-1/MEK/ERK cascade and demonstrate that small changes in the MAP kinase (MAPK) pathway can profoundly impact the fidelity of the cell cycle.  (+info)

Spontaneous and prostatic steroid binding protein peptide-induced autoimmune prostatitis in the nonobese diabetic mouse. (7/39)

Chronic nonbacterial prostatitis is a poorly defined syndrome of putative autoimmune origin. To further understand its pathogenesis, we have analyzed autoimmune prostatitis in the NOD mouse, a strain genetically prone to develop different organ-specific autoimmune diseases. Spontaneous development of autoimmune prostatitis in the NOD male, defined by lymphomonuclear cell infiltration in the prostate gland, is well-established by approximately 20 wk of age and is stably maintained afterward. Disease development is indistinguishable in NOD and NOR mice, but is markedly delayed in IFN-gamma-deficient NOD mice. A T cell response to the prostate-specific autoantigen prostatic steroid-binding protein (PSBP) can be detected in NOD males before development of prostate infiltration, indicating lack of tolerance to this self Ag. The intraprostatic inflammatory infiltrate is characterized by Th1-type CD4(+) T cells, which are able to transfer autoimmune prostatitis into NOD.SCID recipients. We characterize here experimental autoimmune prostatitis, detected by intraprostatic infiltrate and PSBP-specific T cell responses, induced in 6- to 8-wk-old NOD males by immunization with synthetic peptides corresponding to the C1 subunit of PSBP. Three PSBP peptides induce in NOD mice vigorous T and B cell responses, paralleled by a marked lymphomononuclear cell infiltration in the prostate. Two of these peptides, PSBP(21-40) and PSBP(61-80), correspond to immunodominant self epitopes naturally processed in NOD mice after immunization with PSBP, whereas peptide PSBP(91-111) represents a cryptic epitope. These model systems address pathogenetic mechanisms in autoimmune prostatitis and will facilitate testing and mechanistic analysis of therapeutic approaches in this condition.  (+info)

Identification of rat prostatic secreted proteins using mass spectrometric analysis and androgen-dependent mRNA expression. (8/39)

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