Antibody-based targeting of FGFR3 in bladder carcinoma and t(4;14)-positive multiple myeloma in mice

Overexpression of FGF receptor 3 (FGFR3) is implicated in the development of t(4;14)-positive multiple myeloma. While FGFR3 is frequently overexpressed and/or activated through mutations in bladder cancer, the functional importance of FGFR3 and its potential as a specific therapeutic target in this disease have not been elucidated in vivo. scientist report that inducible knockdown of FGFR3 in human bladder carcinoma cells arrested cell-cycle progression in culture and markedly attenuated tumor progression in xenografted mice. Further,they developed a unique antibody (R3Mab) that inhibited not only WT FGFR3,but also various mutants of the receptor, including disulfide-linked cysteine mutants. Biochemical analysis and 2.1-A resolution crystallography revealed that R3Mab bound to a specific FGFR3 epitope that simultaneously blocked ligand binding, prevented receptor dimerization, induced substantial conformational changes in the receptor. R3Mab exerted potent antitumor activity against bladder carcinoma and t(4;14)-positive multiple myeloma xenografts in mice by antagonizing FGFR3 signaling and eliciting antibody-dependent cell-mediated cytotoxicity (ADCC). These studies provide in vivo evidence demonstrating an oncogenic role of FGFR3 in bladder cancer and support antibody-based targeting of FGFR3 in hematologic and epithelial cancers driven by WT or mutantFGFR3

Inhibition of HIV entry by carbohydrate-binding proteins

Carbohydrate-binding proteins (CBP) can be isolated from a variety of species, including procaryotes (i.e. cyanobacteria), sea corals, algae, plants, invertebrates and vertebrates. A number of them, in particular those CBP that show specific recognition for mannose (Man) and N-acetylglucosamine (GlcNAc) are endowed with a remarkable anti-HIV activity in cell culture. The smallest CBP occur as monomeric peptides with a molecular weight of not, vert, similar8.5 kDa. Many others are functionally dimers, trimers or tetramers, and their molecular weight can sometimes largely exceed 50 kDa. CBP can contain 2 to up to 12 carbohydrate-binding sites per single molecule, depending on the nature of the lectin and its oligomerization state. CBP qualify as potential anti-HIV microbicide drugs because they not only inhibit infection of cells by cell-free virus (in some cases in the lower nano- or even subnanomolar range) but they can also efficiently prevent virus transmission from virus-infected cells to uninfected T-lymphocytes. Their most likely mechanism of antiviral action is the interruption of virus entry (i.e. fusion) into its target cell. CBP presumably act by direct binding to the glycans that are abundantly present on the HIV-1 gp120 envelope. They may cross-link several glycans during virus/cell interaction and/or freeze the conformation of gp120 consequently preventing further interaction with the coreceptor. Several CBP were shown to have a high genetic barrier since multiple (≥5) glycan deletions in the HIV envelope are necessary to provoke a moderate level of drug resistance. CBP are the prototypes of conceptionally novel chemotherapeutics with a unique mechanism of antiviral action, drug resistance profile and an intrinsic capacity to trigger a specific immune response against HIV strains after glycan deletions on their envelope occur in an attempt to escape CBP drug pressure

Inhibition of HIV infectivity by a natural human isolate of Lactobacillus jensenii engineered to express functional two-domain CD4

The predominant mode of HIV transmission worldwide is via heterosexual contact, with the cervico-vaginal mucosa being the main portal of entry in women. The cervico-vaginal mucosa is naturally colonized with commensal bacteria, primarily lactobacilli. To address the urgent need for female-controlled approaches to block the heterosexual transmission of HIV, scientists natural human vaginal isolates of Lactobacillus jensenii to secrete two-domain CD4 (2D CD4) proteins. The secreted 2D CD4 recognized a conformation-dependent anti-CD4 antibody and bound HIV type 1 (HIV-1) gp120, suggesting that the expressed proteins adopted a native conformation. Single-cycle infection assays using HIV-1_HxB2 carrying a luciferase reporter gene demonstrated that Lactobacillus-derived 2D CD4 inhibited HIV-1 entry into target cells in a dose-dependent manner. Importantly, coincubation of the engineered bacteria with recombinant HIV-1_HxB2 reporter virus led to a significant decrease in virus infectivity of HeLa cells expressing CD4–CXCR4–CCR5. Engineered lactobacilli also caused modest, but statistically significant, decrease in infectivity of a primary isolate, HIV-1_JR-FL. This represents an important first step toward the development of engineered commensal bacteria within the vaginal microflora to inhibit heterosexual transmission of HIV

http://www.pnas.org/content/100/20/11672.full.pdf+html

Effects of recombinant soluble CD4 (rCD4) on HIV-1 infection of monocyte/macrophages

The human immunodeficiency virus (HIV) binds to its cellular receptor, CD4. This binding is mediated by the viral surface glycoprotein gpl20, thus initiating viral infection at the cellular level. This process may also be partly responsible for the cytopathic properties of HIV. Regardless of the strain variations encountered within HIV and the differences between HIV-1 and HIV-2, CD4 binding is an essential part of the infectious process. Interruption of the binding process may be a means of altering infection. A soluble, cell-free form of the extracellular part of the CD4 molecule, known as rCD4, was previously shown to bind with HIV in a manner similar to the natural molecule. The bound rCD4 appeared, in earlier studies, to inhibit HIV infection of lymphoid cells. This study examines the effects of rCD4 on acute HIV infection of human pulmonary macrophages (PAM) and monocytes (monocytic U937 cells), and evaluates its ability to interfere with the possible transfer of infection to target lymphocytes. (Monocytes and lymphocytes are types of white blood cells.) The potential of the success of these effects is in the treatment of HIV infections such as AIDS. The rCD4 was capable of preventing infection of PAM cells at concentrations greater than or equal to 1 microgram per milliliter. The same concentration inhibited the transmission of HIV-1 to peripheral blood mononuclear leucocytes (PMNL) cultured together with chronically infected PAM in the absence of cell contact. With cell contact, rCD4 concentrations of 10 micrograms per milliliter produced substantial inhibition; transfer was completely blocked at higher concentrations. The potential value of rCD4 as a tool in the antiretrovirus efforts requires further study