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MECHANISM OF ACTION AND REGULATION OF MEMBRANE SERINE PROTEASE PROSTASIN IN THE PROSTATE AND PROSTATE CANCER
Title
MECHANISM OF ACTION AND REGULATION OF MEMBRANE SERINE PROTEASE PROSTASIN IN THE PROSTATE AND PROSTATE CANCER.
Creator
Chen, Mengqian, Chai, Karl, University of Central Florida
Abstract / Description
The glycosylphosphatidylinositol (GPI)-anchored serine protease prostasin (PRSS8) is expressed at the apical membrane surface of epithelial cells and acts as a suppressor of tumor invasion when re-expressed in highly invasive human prostate and breast cancer cell lines. To better understand the molecular mechanisms underlying the anti-invasion phenotype associated with prostasin re-expression in prostate cancer cells, we expressed wild-type human prostasin or a serine active-site mutant...
Show moreThe glycosylphosphatidylinositol (GPI)-anchored serine protease prostasin (PRSS8) is expressed at the apical membrane surface of epithelial cells and acts as a suppressor of tumor invasion when re-expressed in highly invasive human prostate and breast cancer cell lines. To better understand the molecular mechanisms underlying the anti-invasion phenotype associated with prostasin re-expression in prostate cancer cells, we expressed wild-type human prostasin or a serine active-site mutant prostasin in the PC-3 human prostate carcinoma cells. Molecular changes were measured at the mRNA and the protein levels. The expression of several invasion-promoting molecules is regulated by prostasin re-expression, mediated by a protein-level down-regulation of the epidermal growth factor receptor (EGFR). As a result, the cellular response to EGF was reduced as shown by the down-regulation of EGF-stimulated Erk1/2 phosphorylation. The expression of Slug, urokinase-type plasminogen activator (uPA), urokinase-type plasminogen activator receptor (uPAR), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and granulocyte-macrophage colony stimulating factor (GM-CSF) was also down-regulated by prostasin re-expression in the PC-3 cells. Co-expression of prostasin and its activating protease matriptase with EGFR in FT-293 cells induces an apparent proteolytic cleavage of the EGFR in the extracellular domain at two specific sites, generating two N-terminally truncated EGFR fragments, named EGFR135 and EGFR110. The EGFR110 is constitutively tyrosine-phosphorylated, and in its presence the phosphorylation of downstream signaling molecules including Erk1/2 and Akt is increased under serum-free conditions. Neither EGFR135 nor EGFR110 is responsive to EGF stimulation. Deletions of the EGFR extracellular domain (ECD) were generated to map the matriptase-prostasin cleavage sites. Two candidate sites were localized to regions AA1-273 and AA273-410. These data support a mechanism of action for the matriptase-prostasin epithelial extracellular serine protease activation cascade by proteolytically modulating the EGF-EGFR signaling. Prostasin gene expression is down-regulated in high-grade and hormone-refractory prostate cancers. We investigated the mechanisms by which androgens regulate prostasin expression in the prostate and prostate cancer. We treated the LNCaP human prostate cancer cells with dihydrotestosterone (DHT) and measured the mRNA expression of prostasin and potential transcription regulators of prostasin predicted by interrogation of the prostasin gene promoter sequence. Prostasin mRNA expression in the LNCaP cells was not responsive to DHT treatment. DHT marginally up-regulated mRNA expression of SREBP-1c, SREBP-2, and SNAIL, but not SREBP-1a, while dramatically increased SLUG mRNA expression, in a dose-dependent manner. Co-transfection of a prostasin promoter-reporter and SREBP cDNA in HEK-293 cells resulted in stimulation of the promoter activity at ~2 fold by SREBP-1c, and up to 6 fold by SREBP-2; while co-transfection with SNAIL or SLUG cDNA resulted in repression of the promoter activity to 43% or 59%, respectively. Co-transfection of the SLUG cDNA negated SREBP-2 s stimulation of the prostasin promoter in a dose-dependent manner. Transfection of an SREBP-2 cDNA in HEK-293 and DU-145 cells resulted in up-regulation of the endogenously expressed prostasin while transfection of a SLUG cDNA in the LNCaP cells repressed prostasin expression. Multiple SREBP-2 binding sites, known as sterol regulatory elements (SRE s), were identified at positions -897, -538, +8, +71, and +98 (named SRE-897, SRE-538, SRE+8, SRE+71, and SRE+98) in the human prostasin gene promoter. Mutagenesis of the five SRE s was carried out to evaluate their roles in SREBP-2 up-regulation of prostasin. SRE+98, a novel functional sterol regulatory element was found to be the major site for the stimulatory response of prostasin gene expression to SREBP-2. CONCLUSIONS: Prostasin regulates the expression of several invasion-promoting molecules in prostate cancer cells by down-modulating the EGF-EGFR signaling pathway. Active prostasin induces proteolytic cleavage in the EGFR ECD at two specific sites. One of the N-terminally truncated EGFR, the EGFR110 is auto-phosphorylated along with increased phosphorylation of downstream signaling molecules. The effect of the androgen DHT on prostasin expression in prostate cells is mediated via SREBP s, which stimulate the promoter, and Slug, which represses the promoter. Slug is up-regulated by DHT and EGF, providing a molecular mechanism by which epithelial cell-specific genes are silenced during prostate cancer development and progression.
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Date Issued
2007
Identifier
CFE0001782, ucf:47257
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001782
PROSTASIN IS EXPRESSED IN BENIGN PROSTATIC HYPERPLASIA AND REGULATES CELL PROLIFERATION AND INVASION VIA INOS, ICAM-1, AND CYCLIN D1
Title
PROSTASIN IS EXPRESSED IN BENIGN PROSTATIC HYPERPLASIA AND REGULATES CELL PROLIFERATION AND INVASION VIA INOS, ICAM-1, AND CYCLIN D1.
Creator
Hatfield, Meghan, Chai, Karl, University of Central Florida
Abstract / Description
ABSTRACT Prostasin is expressed in normal prostate epithelial cells but down-regulated in prostate cancers, while prostasin re-expression in invasive prostate cancer cells reduced invasion. We examined prostasin expression and function in benign prostatic hyperplasia (BPH). We evaluated prostasin expression in 12 BPH specimens by immunohistochemistry, and evaluated the impact of prostasin silencing by siRNA on the expression of the inducible nitric oxide synthase (iNOS), intercellular...
Show moreABSTRACT Prostasin is expressed in normal prostate epithelial cells but down-regulated in prostate cancers, while prostasin re-expression in invasive prostate cancer cells reduced invasion. We examined prostasin expression and function in benign prostatic hyperplasia (BPH). We evaluated prostasin expression in 12 BPH specimens by immunohistochemistry, and evaluated the impact of prostasin silencing by siRNA on the expression of the inducible nitric oxide synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), and cyclin D1, as well as on cell proliferation and invasion, using the BPH-1 human prostate epithelial cell line model. Prostasin expression was localized in the glands of BPH tissues by immunohistochemistry, in either the tall columnar-shaped or the flattened epithelial cells. We silenced prostasin expression by >50% at both the mRNA and protein levels using siRNA in the BPH-1 human prostate epithelial cell line, and this silencing of prostasin expression was associated with an induction of iNOS and ICAM-1 expression and a down-regulation of cyclin D1 expression. The protein expression of EGFR, a putative prostasin substrate, was not affected by prostasin silencing in this cell line. The prostasin-silenced cells displayed a reduced cell proliferation rate and reduced invasiveness, cell behaviors regulated by cyclin D1, iNOS, and ICAM-1 in the BPH-1 cells. We believe that this down-regulation of cyclin D1 is due to prostasin's augmentative effect on iNOS. We also believe that the decrease in cell motility is due to an increase in iNOS and ICAM-1 as well as a decrease in cyclin D1, since all of these molecules can play a role in cell motility. In conclusion, Prostasin is somehow involved in the regulation of inflammatory gene expression (iNOS and ICAM-1) in prostate epithelial cells, as well as cyclin D1 expression, cell proliferation and invasion, involving molecular mechanisms different than those in the prostate cancer cells. These studies suggest that prostasin is a player in the glandular components of benign prostatic hyperplasia.
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Date Issued
2008
Identifier
CFE0002190, ucf:47895
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002190
Antimicrobial Peptide Resistance and Immunomodulation by HIV-1 gp41
Title
Antimicrobial Peptide Resistance and Immunomodulation by HIV-1 gp41.
Creator
Wood, Matthew, Cole, Alexander, Chai, Karl, Teter, Kenneth, Parkinson, Christopher, University of Central Florida
Abstract / Description
Fusion inhibitors are a class of antiretroviral drugs used to prevent entry of HIV into host cells. Many of the fusion inhibitors being developed, including the drug enfuvirtide (ENF), are peptides designed to mimic, and thereby competitively inhibit, the viral fusion protein gp41. An exception to this is a class of cyclic, cationic, antimicrobial peptides known as ?-defensins, which are produced by many non-human primates and exhibit broad-spectrum antiviral and antibacterial activity....
Show moreFusion inhibitors are a class of antiretroviral drugs used to prevent entry of HIV into host cells. Many of the fusion inhibitors being developed, including the drug enfuvirtide (ENF), are peptides designed to mimic, and thereby competitively inhibit, the viral fusion protein gp41. An exception to this is a class of cyclic, cationic, antimicrobial peptides known as ?-defensins, which are produced by many non-human primates and exhibit broad-spectrum antiviral and antibacterial activity. Currently, the ?-defensin analog RC-101 is being developed as a microbicide to prevent sexual transmission of HIV-1. Understanding potential RC-101 resistance, and how resistance to other fusion inhibitors affects RC-101 susceptibility, is critical for future development.Partial drug resistance due to genetic variability within HIV-1 presents a major hurdle in microbicide development. Drug-resistance mutations, whether naturally occurring or resulting from selection during treatment, often apply to many drugs in a particular class. Combining different drug classes into a single microbicide should provide greater protection against the growing variability observed in HIV. Our work has identified the beneficial effects of combining the fusion inhibitor RC-101 and the RT inhibitor CSIC to prevent transmission of clinically isolated and drug-resistant HIV-1.Several aspects of HIV-1 virulence and pathogenesis are mediated by the envelope protein gp41. Additionally, peptides derived from the gp41 ectodomain have been shown to induce chemotaxis in monocytes and neutrophils. While this chemotactic activity has been characterized, it is not known how these peptides could be produced under biological conditions. Our findings demonstrate that the epithelial serine protease matriptase efficiently cleaves the gp41 HR1 region at conserved residues into a chemotactic peptide.Here, we present evidence that advances our understanding of resistance to peptide entry inhibitors, reveals a potential benefit to combining specific drugs in an antiviral microbicide, and identifies a pathway by which HIV-1 may generate peptides to exploit host immunity. This work thereby facilitates improved methods in countering drug resistance and the development of new antiviral approaches to prevent HIV-1 transmission. Additionally, we have revealed basic mechanistic evidence that shed light on our current understanding of HIV-1 infection. Specifically, our focus on gp41 provides much needed insight into its role in membrane fusion, drug susceptibility, and modification of host responses.
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Date Issued
2014
Identifier
CFE0005560, ucf:50286
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005560