A soluble form of the urokinase plasminogen activator receptor (suPAR) can bind to hematopoietic cells

The receptor for urokinase plasminogen activator (uPAR; CD87) is a 50‐ to 65‐kDa glycosylphosphatidylinositol (GPI)‐anchored glycoprotein expressed by leukocytes and tumor cells where it facilitates uPA‐dependent, plasmin‐mediated pericellular proteolysis during cellular invasion. Because uPAR is inducibly shed into culture supernatants and human body fluids, we tested the hypothesis that soluble uPAR (suPAR) can bind to the plasma membrane of hematopoietic cells where it might modulate their invasive phenotype. As measured by flow cytometry, recombinant biotinylated‐suPAR (B‐suPAR) bound in a specific fashion to THP‐1 leukemia cells and blood PMNs and monocytes (but not to lymphocytes). B‐suPAR also demonstrated specific binding to a variety of leukemic lines, including cells that are positive or negative for membrane uPAR expression. Binding of B‐suPAR to THP‐1 cells was enhanced four‐ to sevenfold by 24‐h exposure of cells to PMA or by coincubation with uPA ligand (but not its isolated catalytic and binding fragments). Conversely, binding of B‐suPAR to PMNs was unaffected by brief exposure to fMLP, and was inhibited by coincubation with uPA. B‐suPAR binding to PMA‐differentiated THP‐1 cells in the presence of uPA was further enhanced by acid washing (removing endogenous uPA) but was partially inhibited by treatment of cells with trypsin. Pretreatment of PMA‐differentiated THP‐1 cells and unstimulated PMNs with soluble sugars, calcium chelators, and antibodies specific for integrins or extracellular matrix proteins failed to consistently block the binding of B‐suPAR. Whereas the binding of suPAR did not measurably affect cell‐associated plasmin activation, suPAR did competitively inhibit the binding of exogenous uPA to membrane‐associated uPAR. These observations support the hypothesis that suPAR can bind specifically to trypsin‐sensitive receptors expressed by certain normal and neoplastic hematopoietic cells where its binding is variably influenced by uPA ligand. J. Leukoc. Biol. 64: 203–213; 1998.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142227/1/jlb0203.pd

Association of calmodulin inhibition, erythrocyte membrane stabilization and pharmacological effects of drugs

The present study was designed to determine whether there is an association of drug-induced inhibition of calmodulin functions, drug-induced membrane stabilization (protection against osmotic lysis), and pharmacological effects of drugs. First, data on drugs which have been studied for both calmodulin inhibition and membrane antihemolysis were collected from the literature and an association of the two properties was established. Second, ten additional drugs were selected for study of all three properties. Four drugs, with known antihemolytic effects, were studied for calmodulin inhibition. One drug, which was a known calmodulin inhibitor, was studied for antihemolysis. Our results show that membrane-stabilizing drugs are usually calmodulin inhibitors, and vice versa; that drugs in certain therapeutic classes inhibit calmodulin-activated functions and protect against osmotic lysis; and finally, that there is a significant correlation (P < 0.01) in terms of potency between these two actions of drugs. Data from the literature which bear on these mechanisms of drug actions suggest that the interactions between drugs and calmodulin, and drugs and the membrane, appear to be hydrophobic in nature. At this point, we do not know whether there is some causal relationship between calmodulin inhibition and the antihemolytic effect of drugs, or whether the two are simply a result of hydrophobic properties of drugs. Similarly, the roles of calmodulin inhibition and/or membrane antihemolysis in producing therapeutic efficacy are unknown.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23808/1/0000046.pd

Genetic Studies on the Behavior of the B3 Chromosome in Tb-3a, and the Use of a-B Translocations in Mutation Studies, in Maize

87 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1963.Abstract not available.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Serum Antibodies to Huntingtin Interacting Protein-1: A New Blood Test for Prostate Cancer

International audienceHuntingtin-interacting protein 1 (HIP1) is frequently overexpressed in prostate cancer. HIP1 is a clathrin-binding protein involved in growth factor receptor trafficking that transforms fibroblasts by prolonging the half-life of growth factor receptors. In addition to human cancers, HIP1 is also overexpressed in prostate tumors from the transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse model. Here we provide evidence that HIP1 plays an important role in mouse tumor development, as tumor formation in the TRAMP mice was impaired in the Hip1null/null background. In addition, we report that autoantibodies to HIP1 developed in the sera of TRAMP mice with prostate cancer as well as in the sera from human prostate cancer patients. This led to the development of an anti-HIP1 serum test in humans that had a similar sensitivity and specificity to the anti-alpha-methylacyl CoA racemase (AMACR) and prostate-specific antigen tests for prostate cancer and when combined with the anti-AMACR test yielded a specificity of 97%. These data suggest that HIP1 plays a functional role in tumorigenesis and that a positive HIP1 autoantibody test may be an important serum marker of prostate cancer

Huntingtin-interacting protein 1 is overexpressed in prostate and colon cancer and is critical for cellular survival

Huntingtin-interacting protein 1 (HIP1) is a cofactor in clathrin-mediated vesicle trafficking. It was first implicated in cancer biology as part of a chromosomal translocation in leukemia. Here we report that HIP1 is expressed in prostate and colon tumor cells, but not in corresponding benign epithelia. The relationship between HIP1 expression in primary prostate cancer and clinical outcomes was evaluated with tissue microarrays. HIP1 expression was significantly associated with prostate cancer progression and metastasis. Conversely, primary prostate cancers lacking HIP1 expression consistently showed no progression after radical prostatectomy. In addition, the expression of HIP1 was elevated in prostate tumors from the transgenic mouse model of prostate cancer (TRAMP). At the molecular level, expression of a dominant negative mutant of HIP1 led to caspase-9–dependent apoptosis, suggesting that HIP1 is a cellular survival factor. Thus, HIP1 may play a role in tumorigenesis by allowing the survival of precancerous or cancerous cells. HIP1 might accomplish this via regulation of clathrin-mediated trafficking, a fundamental cellular pathway that has not previously been associated with tumorigenesis. HIP1 represents a putative prognostic factor for prostate cancer and a potential therapy target in prostate as well as colon cancers

Immunologic Detection of the Cellular Receptor for Urokinase Plasminogen Activator

The cellular receptor for urokinase plasminogen activator (uPA-R) is a monomeric phosphatidylinositol-linked glycoprotein (gp40-65) that may contribute to the invasive capacity of tumor and inflammatory cells by focusing the activity of urokinase (uPA) in converting plasminogen to plasmin, a serine protease capable of degrading extracellular matrix proteins. The further characterization of uPA-R has been facilitated by our recent development of a monoclonal antibody, anti-Mo3f, specific for uPA-R. This mAb bound to uPA-R expressed by phorbol myristate acetate-stimulated U-937 cells and by NIH-3T3 cells permanently transfected with uPA-R cDNA. In competitive binding assays, anti-Mo3f inhibited the binding of fluorescein-conjugated uPA ligand to uPA-R expressed by U-937 cells and uPA-R transfectants; conversely, preexposure of cells to saturating quantities of exogenous uPA partially blocked the subsequent binding of anti-Mo3f mAb to uPA-R. Anti-Mo3f mAb was employed as the capture reagent in an ELISA for the quantitation of soluble forms of uPA-R (derived from U-937 cells and recombinant uPA-R) which had a sensitivity of approximately 4-12 ng/ml. Anti-Mo3f mAb was also applied as a serologic probe for the detection of uPA-R expressed by human tumor tissues. By immunoperoxidase staining, anti-Mo3f demonstrated positive tumor cell staining in 4 of 16 breast and 7 of 31 prostate carcinomas in formalin-fixed, paraffin-embedded specimens. These data indicate that the anti-M03f mAb detects an epitope proximate to or within the ligand binding domain (domain 1) of uPA-R and may be useful as a tool for the serologic detection of uPA-R in soluble form or associated with human tumors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31653/1/0000587.pd