Strategy for tumor selective disruption of androgen receptor function in the spectrum of prostate cancer

Purpose: Testosterone suppression in prostate cancer (PC) is limited by serious side effects and resistance via restoration of androgen receptor (AR) functionality. ELK1 is required for ARdependent growth in various hormone-dependent and castration resistant PC models. The amino terminal domain of AR docks at two sites on ELK1 to co-activate essential growth genes. This study explores the ability of small molecules to disrupt the ELK1-AR interaction in the spectrum of PC, inhibiting AR activity in a manner that would predict functional tumor selectivity. Experimental design: Small molecule drug discovery and extensive biological characterization of a lead compound. Results: We have discovered a lead molecule (KCI807) that selectively disrupts ELK1-dependent promoter activation by wild-type and variant ARs without interfering with ELK1 activation by ERK. KCI807 has an obligatory flavone scaffold and functional hydroxyl groups on C5 and C3'. KCI807 binds to AR, blocking ELK1 binding, and selectively blocks recruitment of AR to chromatin by ELK1. KCI807 primarily affects a subset of AR target growth genes selectively suppressing AR-dependent growth of PC cell lines with a better inhibitory profile than enzalutamide. KCI807 also inhibits in vivo growth of castration/enzalutamide-resistant cell line-derived and patient-derived tumor xenografts. In the rodent model, KCI807 has a plasma half-life of 6h and maintenance of its antitumor effect is limited by self-induced metabolism at its 3'-hydroxyl. Conclusions: The results offer a mechanism-based therapeutic paradigm for disrupting the AR growth-promoting axis in the spectrum of prostate tumors while reducing global suppression of testosterone actions. KCI807 offers a good lead molecule for drug development

Development of high-affinity nanobodies specific for NaV1.4 and NaV1.5 voltage-gated sodium channel isoforms

Voltage-gated sodium channels, NaVs, are responsible for the rapid rise of action potentials in excitable tissues. NaV channel mutations have been implicated in several human genetic diseases, such as hypokalemic periodic paralysis, myotonia, and long-QT and Brugada syndromes. Here, we generated high-affinity anti-NaV nanobodies (Nbs), Nb17 and Nb82, that recognize the NaV1.4 (skeletal muscle) and NaV1.5 (cardiac muscle) channel isoforms. These Nbs were raised in llama (Lama glama) and selected from a phage display library for high affinity to the C-terminal (CT) region of NaV1.4. The Nbs were expressed in Escherichia coli, purified, and bio-physically characterized. Development of high-affinity Nbs specifically targeting a given human NaV isoform has been challenging because they usually show undesired cross-reactivity for different NaV isoforms. Our results show, however, that Nb17 and Nb82 recognize the CTNaV1.4 or CTNaV1.5 over other CTNav isoforms. Kinetic experiments by biolayer interferometry determined that Nb17 and Nb82 bind to the CTNaV1.4 and CTNaV1.5 with high affinity (KD ~ 40-60 nM). In addition, as proof of concept, we show that Nb82 could detect NaV1.4 and NaV1.5 channels in mammalian cells and tissues by Western blot. Furthermore, human embryonic kidney cells expressing holo NaV1.5 channels demonstrated a robust FRET-binding efficiency for Nb17 and Nb82. Our work lays the foundation for developing Nbs as anti-NaV reagents to capture NaVs from cell lysates and as molecular visualization agents for NaVs.Fil: Srinivasan, Lakshmi. University Johns Hopkins; Estados UnidosFil: Alzogaray, Vanina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Selvakumar, Dakshnamurthy. Fortébio; Estados UnidosFil: Nathan, Sara. University Johns Hopkins; Estados UnidosFil: Yoder, Jesse B.. University Johns Hopkins; Estados UnidosFil: Wright, Katharine M.. University Johns Hopkins; Estados UnidosFil: Klinke, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Nwafor, Justin N.. University Johns Hopkins; Estados UnidosFil: Labanda, María Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Goldbaum, Fernando Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Schön, Arne. University Johns Hopkins; Estados UnidosFil: Freire, Ernesto. University Johns Hopkins; Estados UnidosFil: Tomaselli, Gordon F.. University Johns Hopkins; Estados UnidosFil: Amzel, León Mario. University Johns Hopkins; Estados UnidosFil: Ben-Johny, Manu. Columbia University; Estados UnidosFil: Gabelli, Sandra. University Johns Hopkins; Estados Unido

Inhibition of Fungal β-1,3-Glucan Synthase and Cell Growth by HM-1 Killer Toxin Single-Chain Anti-Idiotypic Antibodies

Single-chain variable-fragment (scFv) anti-idiotypic antibodies of an HM-1 killer toxin (HM-1) from the yeast Williopsis saturnus var. mrakii IFO 0895 have been produced by recombinant DNA technology from the splenic lymphocytes of mice immunized by idiotypic vaccination with a neutralizing monoclonal antibody (nMAb-KT). The fungicidal activity of scFv anti-idiotypic antibodies against the isolates of four Candida species was assessed by MIC analysis. scFv antibodies were fungicidal at concentrations of 1.56 to 12.5 μg/ml in vitro against four Candida species. The scFv antibodies exerted a strong candidacidal activity in vitro, with 50% inhibitory concentration (IC(50)) values ranging from 7.3 × 10(−8) to 16.0 × 10(−8) M, and were neutralized by adsorption with nMAb-KT. Furthermore, all scFv antibodies effectively inhibited fungal β-1,3-glucan synthase activity in vitro, with IC(50) values ranging from 2.0 × 10(−8) to 22.7 × 10(−8) M, values which almost coincide with the values that are inhibitory to the growth of fungal cells. Binding assays showed that the scFv antibodies specifically bind to nMAb-KT, and this binding pattern was confirmed by surface plasmon resonance analysis. The binding ability was further demonstrated by the competition observed between scFv antibodies and HM-1 to bind nMAb-KT. To the best of our knowledge, this is the first study to show that an antifungal anti-idiotypic antibody, in the form of recombinant scFv, potentially inhibits β-1,3-glucan synthase activity