The Vitamin K-Dependent Anticoagulant Factor, Protein S, Regulates Vascular Permeability.

Protein S (PROS1) is a vitamin K-dependent anticoagulant factor, which also acts as an agonist for the TYRO3, AXL, and MERTK (TAM) tyrosine kinase receptors. PROS1 is produced by the endothelium which also expresses TAM receptors, but little is known about its effects on vascular function and permeability. Transwell permeability assays as well as Western blotting and immunostaining analysis were used to monitor the possible effects of PROS1 on both endothelial cell permeability and on the phosphorylation state of specific signaling proteins.

iPSC-Derived Hereditary Breast Cancer Model Reveals the -Deleted Tumor Niche as a New Culprit in Disease Progression.

Tumor progression begins when cancer cells recruit tumor-associated stromal cells to produce a vascular niche, ultimately resulting in uncontrolled growth, invasion, and metastasis. It is poorly understood, though, how this process might be affected by deletions or mutations in the breast cancer type 1 susceptibility (BRCA1) gene in patients with a lifetime risk of developing breast and/or ovarian cancer. To model the BRCA1-deleted stroma, we first generated induced pluripotent stem cells (iPSCs) from patients carrying a germline deletion of exon 17 of the BRCA1 gene (BRCA1+/- who, based on their family histories, were at a high risk for cancer.

The downregulation of BAP1 expression by BCR-ABL reduces the stability of BRCA1 in chronic myeloid leukemia.

BCR-ABL induces an intrinsic genetic instability in chronic myeloid leukemia (CML). The protein breast cancer 1, early onset (BRCA1)-associated protein 1 (BAP1) is a deubiquitinase interacting with the DNA repair regulator BRCA1 and is frequently inactivated in many cancers. Here, we report that BAP1 mRNA and protein levels are downregulated in a BCR-ABL1-expressing hematopoietic cell line (UT-7/11).

Modeling the influence of stromal microenvironment in the selection of ENU-induced BCR-ABL1 mutants by tyrosine kinase inhibitors.

Tyrosine kinase inhibitors (TKIs) have profoundly changed the natural history of chronic myeloid leukemia (CML). However, acquired resistance to imatinib, dasatinib or nilotinib (1(st) and 2(nd) generation TKIs), due in part to BCR-ABL1 kinase mutations, has been largely described. These drugs are ineffective on the T315I gatekeeper substitution, which remains sensitive to 3(rd) generation TKI ponatinib.

STAT3 is essential for the maintenance of neurosphere-initiating tumor cells in patients with glioblastomas: a potential for targeted therapy?

Glioblastoma (GBM), the highest-grade form of gliomas, is the most frequent and the most aggressive. Recently, a subpopulation of cells with stem cells characteristics, commonly named "tumor-initiating stem cells" (TISCs) or "cancer stem cells" (CSCs) were identified in GBM. These cells were shown to be highly resistant to chemotherapeutic drugs and to ionizing radiations.

Electrotransfer of cDNA coding for a heterologous prion protein generates autoantibodies against native murine prion protein in wild-type mice.

Prion diseases (e.g., Creutzfeldt-Jakob disease in humans) are always fatal neurodegenerative disorders characterized by conversion of the ubiquitous cellular prion protein (PrP(c)) into a pathological conformer.

Curative properties of antibodies against prion protein: a comparative in vitro study of monovalent fragments and divalent antibodies.

Prion diseases, which include Creutzfeldt-Jakob disease (CJD) in humans, are a group of devastating neurodegenerative disorders for which no therapy is yet available. However, passive immunotherapy appears to be a promising therapeutic approach, given that antibodies against the cellular prion protein (PrPc) have been shown in vitro to antagonize deposition of the disease-associated prion protein (PrPSc). Nevertheless, in vivo deleterious side effects of injected anti-PrP antibodies have been reported, mainly due to their Fc fragments and divalence.

Generating antibodies against the native form of the human prion protein (hPrP) in wild-type animals: a comparison between DNA and protein immunizations.

Generation of therapeutic antibodies against human proteins is hampered by the difficulty of obtaining large quantities of correctly folded immunogens when following classic immunization procedures. Here we compared several genetic immunization protocols for their potential ability to generate high levels of antibodies against proteins expressed in their native form. We chose as a model the prion protein (PrP) because it has been demonstrated that the recognition of the native conformation of PrP is an absolute prerequisite for anti-PrP antibodies to be used as therapeutic tools for prion diseases, a group of lethal neurodegenerative disorders.

Expression and detection strategies for an scFv fragment retaining the same high affinity than Fab and whole antibody: Implications for therapeutic use in prion diseases.

Since antibodies currently constitute the most rapidly growing class of human therapeutics, the high-yield production of recombinant antibodies and antibody fragments is a real challenge. Using as model a monoclonal antibody directed against the human prion protein that we prepared previously and tested for its therapeutic value, we describe here experimental conditions allowing the production of large quantities (up to 35 mg/l of bacterial culture) of correctly refolded and totally functional single chain fragment variable (scFv). These quantities were sufficient to characterize the binding properties of this small recombinant fragment through in vitro and ex vivo approaches.

Characterization of endostatin binding to heparin and heparan sulfate by surface plasmon resonance and molecular modeling: role of divalent cations.

Endostatin (20 kDa) is a C-terminal proteolytic fragment of collagen XVIII that is localized in vascular basement membrane zones in various organs. It binds zinc, heparin/heparan sulfate, laminin, and sulfatides and inhibits angiogenesis and tumor growth. Here we determined the kinetics and affinity of the interaction of endostatin with heparin/heparan sulfate and investigated the effects of divalent cations on these interactions and on the biological activities of endostatin.

Endostatin exhibits a direct antitumor effect in addition to its antiangiogenic activity in colon cancer cells.

Endostatin has been considered a highly specific inhibitor of endothelial cell proliferation and/or migration. To explore the use of endostatin in antiangiogenic gene therapy, we generated a recombinant adenovirus, AdEndo, carrying the gene for mouse endostatin. Injection of 10(9) PFU of AdEndo resulted in a low but significant suppression (25%) of preestablished tumor growth in murine models involving murine Lewis lung carcinoma (LLC) and human breast cancer MDA-MB-231 tumors.