ABSTRACT
It has long been understood that dilute samples of chiral molecules such as rarefied gases should exhibit Rayleigh optical activity. We extend the existing theory by accounting for molecular dynamics and correlations, thus obtaining a more general theory of Rayleigh-Brillouin optical activity applicable to dense samples such as neat liquids.
ABSTRACT
RAS is a major anticancer drug target which requires membrane localization to activate downstream signal transduction. The direct inhibition of RAS has proven to be challenging. Here, we present a novel strategy for targeting RAS by stabilizing its interaction with the prenyl-binding protein PDE6D and disrupting its localization. Using rationally designed RAS point mutations, we were able to stabilize the RAS:PDE6D complex by increasing the affinity of RAS for PDE6D, which resulted in the redirection of RAS to the cytoplasm and the primary cilium and inhibition of oncogenic RAS/ERK signaling. We developed an SPR fragment screening and identified fragments that bind at the KRAS:PDE6D interface, as shown through cocrystal structures. Finally, we show that the stoichiometric ratios of KRAS:PDE6D vary in different cell lines, suggesting that the impact of this strategy might be cell-type-dependent. This study forms the foundation from which a potential anticancer small-molecule RAS:PDE6D complex stabilizer could be developed.
Subject(s)
Cyclic Nucleotide Phosphodiesterases, Type 6/metabolism , Peptides/pharmacology , Protein Binding/drug effects , Proto-Oncogene Proteins p21(ras)/antagonists & inhibitors , Proto-Oncogene Proteins p21(ras)/analysis , Signal Transduction/drug effects , Cell Line, Tumor , Cell Membrane/metabolism , Humans , Proto-Oncogene Proteins p21(ras)/metabolismABSTRACT
Glioblastoma (GBM) is an aggressive and incurable primary brain tumor that causes severe neurologic, cognitive, and psychologic symptoms. Symptoms are caused and exacerbated by the infiltrative properties of GBM cells, which enable them to pervade the healthy brain and disrupt normal function. Recent research has indicated that although radiotherapy (RT) remains the most effective component of multimodality therapy for patients with GBM, it can provoke a more infiltrative phenotype in GBM cells that survive treatment. Here, we demonstrate an essential role of the actin-myosin regulatory kinase myotonic dystrophy kinase-related CDC42-binding kinase (MRCK) in mediating the proinvasive effects of radiation. MRCK-mediated invasion occurred via downstream signaling to effector molecules MYPT1 and MLC2. MRCK was activated by clinically relevant doses per fraction of radiation, and this activation was concomitant with an increase in GBM cell motility and invasion. Furthermore, ablation of MRCK activity either by RNAi or by inhibition with the novel small-molecule inhibitor BDP-9066 prevented radiation-driven increases in motility both in vitro and in a clinically relevant orthotopic xenograft model of GBM. Crucially, treatment with BDP-9066 in combination with RT significantly increased survival in this model and markedly reduced infiltration of the contralateral cerebral hemisphere.Significance: An effective new strategy for the treatment of glioblastoma uses a novel, anti-invasive chemotherapeutic to prevent infiltration of the normal brain by glioblastoma cells.Cancer Res; 78(22); 6509-22. ©2018 AACR.
Subject(s)
Brain Neoplasms/drug therapy , Brain Neoplasms/metabolism , Glioblastoma/drug therapy , Glioblastoma/metabolism , Myotonin-Protein Kinase/antagonists & inhibitors , Actins/chemistry , Animals , Antineoplastic Agents/pharmacology , Brain Neoplasms/radiotherapy , Cardiac Myosins/metabolism , Cell Line, Tumor , Cell Movement , Female , Glioblastoma/radiotherapy , Humans , Mice , Mice, Nude , Microscopy, Fluorescence , Myosin Light Chains/metabolism , Myosin-Light-Chain Phosphatase/metabolism , Myosins/chemistry , Neoplasm Invasiveness , Phenotype , RNA Interference , RNA, Small Interfering/metabolismABSTRACT
The myotonic dystrophy-related Cdc42-binding kinases MRCKα and MRCKß contribute to the regulation of actin-myosin cytoskeleton organization and dynamics, acting in concert with the Rho-associated coiled-coil kinases ROCK1 and ROCK2. The absence of highly potent and selective MRCK inhibitors has resulted in relatively little knowledge of the potential roles of these kinases in cancer. Here, we report the discovery of the azaindole compounds BDP8900 and BDP9066 as potent and selective MRCK inhibitors that reduce substrate phosphorylation, leading to morphologic changes in cancer cells along with inhibition of their motility and invasive character. In over 750 human cancer cell lines tested, BDP8900 and BDP9066 displayed consistent antiproliferative effects with greatest activity in hematologic cancer cells. Mass spectrometry identified MRCKα S1003 as an autophosphorylation site, enabling development of a phosphorylation-sensitive antibody tool to report on MRCKα status in tumor specimens. In a two-stage chemical carcinogenesis model of murine squamous cell carcinoma, topical treatments reduced MRCKα S1003 autophosphorylation and skin papilloma outgrowth. In parallel work, we validated a phospho-selective antibody with the capability to monitor drug pharmacodynamics. Taken together, our findings establish an important oncogenic role for MRCK in cancer, and they offer an initial preclinical proof of concept for MRCK inhibition as a valid therapeutic strategy.Significance: The development of selective small-molecule inhibitors of the Cdc42-binding MRCK kinases reveals their essential roles in cancer cell viability, migration, and invasive character. Cancer Res; 78(8); 2096-114. ©2018 AACR.
Subject(s)
Antineoplastic Agents/therapeutic use , Carcinoma, Squamous Cell/drug therapy , Drug Discovery , Myotonin-Protein Kinase/antagonists & inhibitors , Protein Kinase Inhibitors/therapeutic use , Pyridines/therapeutic use , Pyrimidines/therapeutic use , Pyrroles/therapeutic use , Skin Neoplasms/drug therapy , Animals , Antineoplastic Agents/pharmacology , Carcinoma, Squamous Cell/enzymology , Cell Line, Tumor , Disease Models, Animal , HEK293 Cells , Humans , Mice , Mice, Nude , Phosphorylation , Protein Kinase Inhibitors/pharmacology , Pyridines/pharmacology , Pyrimidines/pharmacology , Pyrroles/pharmacology , Skin Neoplasms/enzymology , Xenograft Model Antitumor AssaysABSTRACT
We present a correction to parts of Fig. 5, Fig. 6 and Fig. 7, relating to the Purcell factors and Lamb shifts, due to an incorrect renormalization used in our custom Fortran code. The resulting corrections to some of the Q-factors are large, but do not affect the conclusions of the original manuscript.
ABSTRACT
We analyze the enhancement of the rates of both the emission and the far field radiation for dipoles placed in the gap between a metallic nanorod, or nanosphere, and a metallic substrate. For wavelengths between 150 nm and 650 nm, the response of the gapped nanostructures considered in this work is dominated by few principal modes of the nanoparticle, which include self-consistently the effect of the substrate. For wavelengths shorter than 370 nm, the far field radiative enhancements of aluminum nanostructures are significantly higher than those for gold or silver. With aluminum, bright mode resonances are tunable over tens or hundreds of nanometers by changing the size of the nanoparticle and have far field radiative enhancements of up to three orders of magnitude. These results provide a road map to label-free detection of many emitters too weakly fluorescent for present approaches.
ABSTRACT
We determine how to alter the properties of the quantum vacuum at ultraviolet wavelengths to simultaneously enhance the spontaneous transition rates and the far field detection rate of quantum emitters. We find the response of several complex nanostructures in the 200 - 400 nm range, where many organic molecules have fluorescent responses, using an analytic decomposition of the electromagnetic response in terms of continuous spectra of plane waves and discrete sets of modes. Coupling a nanorod with an aluminum substrate gives decay rates up to 2.7 × 103 times larger than the decay rate in vacuum and enhancements of 824 for the far field emission into the entire upper semi-space and of 2.04 × 103 for emission within a cone with a 60° semi-angle. This effect is due to both an enhancement of the field at the emitter's position and a reshaping of the radiation patterns near mode resonances and cannot be obtained by replacing the aluminum substrate with a second nanoparticle or with a fused silica substrate. These large decay rates and far field enhancement factors will be very useful in the detection of fluorescence signals, as these resonances can be shifted by changing the dimensions of the nanorod. Moreover, these nanostructures have potential for nano-lasing because the Q factors of these resonances can reach 107.9, higher than the Q factors observed in nano-lasers.
ABSTRACT
We model a scheme for the coherent control of light waves and currents in metallic nanospheres which applies independently of the nonlinear multiphoton processes at the origin of waves and currents. Using exact mathematical formulae, we calculate numerically with a custom fortran code the effect of an external control field which enable us to change the radiation pattern and suppress radiative losses or to reduce absorption, enabling the particle to behave as a perfect scatterer or as a perfect absorber. Data are provided in tabular, comma delimited value format and illustrate narrow features in the response of the particles that result in high sensitivity to small variations in the local environment, including subwavelength spatial shifts.
ABSTRACT
We propose a scheme for the coherent control of light waves and currents in metallic nanospheres which applies independently of the nonlinear multiphoton processes at the origin of waves and currents. We derive conditions on the external control field which enable us to change the radiation pattern and suppress radiative losses or to reduce absorption, enabling the particle to behave as a perfect scatterer or as a perfect absorber. The control introduces narrow features in the response of the particles that result in high sensitivity to small variations in the local environment, including subwavelength spatial shifts.
ABSTRACT
BACKGROUND: The myotonic dystrophy kinase-related CDC42-binding kinases MRCKα and MRCKß regulate actin-myosin contractility and have been implicated in cancer metastasis. Along with the related ROCK1 and ROCK2 kinases, the MRCK proteins initiate signalling events that lead to contractile force generation which powers cancer cell motility and invasion. A potential strategy for cancer therapy is to reduce metastasis by blocking MRCK activity, either alone or in combination with ROCK inhibition. However, to date no potent small molecule inhibitors have been developed with selectivity towards MRCK. RESULTS: Screening a kinase-focused small molecule chemical library resulted in the identification of compounds with inhibitory activity towards MRCK. Medicinal chemistry combined with in vitro enzyme profiling led to the discovery of 4-chloro-1-(4-piperidyl)-N-[5-(2-pyridyl)-1H-pyrazol-4-yl]pyrazole-3-carboxamide (BDP00005290; abbreviated as BDP5290) as a potent MRCK inhibitor. X-ray crystallography of the MRCKß kinase domain in complex with BDP5290 revealed how this ligand interacts with the nucleotide binding pocket. BDP5290 demonstrated marked selectivity for MRCKß over ROCK1 or ROCK2 for inhibition of myosin II light chain (MLC) phosphorylation in cells. While BDP5290 was able to block MLC phosphorylation at both cytoplasmic actin stress fibres and peripheral cortical actin bundles, the ROCK selective inhibitor Y27632 primarily reduced MLC phosphorylation on stress fibres. BDP5290 was also more effective at reducing MDA-MB-231 breast cancer cell invasion through Matrigel than Y27632. Finally, the ability of human SCC12 squamous cell carcinoma cells to invade a three-dimensional collagen matrix was strongly inhibited by 2 µM BDP5290 but not the identical concentration of Y27632, despite equivalent inhibition of MLC phosphorylation. CONCLUSIONS: BDP5290 is a potent MRCK inhibitor with activity in cells, resulting in reduced MLC phosphorylation, cell motility and tumour cell invasion. The discovery of this compound will enable further investigations into the biological activities of MRCK proteins and their contributions to cancer progression.
Subject(s)
Antineoplastic Agents/pharmacology , Myotonin-Protein Kinase/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , Pyrazoles/pharmacology , Pyridines/pharmacology , Amides/pharmacology , Cell Line, Tumor , Cell Movement/drug effects , Humans , Myotonin-Protein Kinase/metabolism , Neoplasm Invasiveness , rho-Associated Kinases/antagonists & inhibitors , rho-Associated Kinases/metabolismABSTRACT
Systematic optimisation of a poorly soluble lead series of isoxazole-3-carboxamides was conducted. Substitution of the 4-position with specific polar functionality afforded the requisite balance of potency, solubility and physicochemical properties. Compound 21a was found to be efficacious in the rat Capsaicin Hargreaves assay following oral administration.
Subject(s)
Cyclohexanols/chemistry , Isoxazoles/chemistry , TRPV Cation Channels/antagonists & inhibitors , Administration, Oral , Amides/chemistry , Amides/pharmacokinetics , Amides/therapeutic use , Animals , Capsaicin/toxicity , Cyclohexanols/pharmacokinetics , Cyclohexanols/therapeutic use , Disease Models, Animal , Drug Evaluation, Preclinical , Humans , Hyperalgesia/chemically induced , Hyperalgesia/drug therapy , Isoxazoles/pharmacokinetics , Isoxazoles/therapeutic use , Microsomes, Liver/metabolism , Rats , Structure-Activity Relationship , TRPV Cation Channels/metabolismABSTRACT
Optimization of a water soluble, moderately potent lead series of isoxazole-3-carboxamides was conducted, affording a compound with the requisite balance of potency, solubility and physicochemical properties for in vivo use. Compound 8e was demonstrated to be efficacious in a rat model of inflammatory pain, following oral administration.
Subject(s)
Isoxazoles/chemistry , TRPV Cation Channels/antagonists & inhibitors , Administration, Oral , Amides/chemical synthesis , Amides/chemistry , Amides/therapeutic use , Animals , Disease Models, Animal , Humans , Isoxazoles/chemical synthesis , Isoxazoles/therapeutic use , Pain/drug therapy , Rats , TRPV Cation Channels/metabolismABSTRACT
We report an expansion of the structure-activity relationship (SAR) of a novel series of indole-3-heterocyclic CB1 receptor agonists. Starting from the potent but poorly soluble lead, 1, a rational approach was taken in order to balance solubility, hERG activity and potency while retaining the desired long duration of action within the mouse tail flick test. This led to the discovery of compound 38 which successfully progressed into clinical development.
Subject(s)
Heterocyclic Compounds/chemistry , Indoles/chemistry , Receptor, Cannabinoid, CB1/agonists , Thiazoles/chemistry , Animals , Cytochrome P-450 Enzyme System/metabolism , Dogs , Drug Design , Drug Evaluation, Preclinical , Heterocyclic Compounds/chemical synthesis , Heterocyclic Compounds/pharmacokinetics , Mice , Rats , Rats, Wistar , Receptor, Cannabinoid, CB1/metabolism , Structure-Activity Relationship , Thiazoles/chemical synthesis , Thiazoles/pharmacokineticsABSTRACT
Novel 3-(1H-indol-3-yl)-1,2,4-oxadiazoles and -thiadiazoles were synthesized and found to be potent CB1 cannabinoid receptor agonists. The oral bioavailability of these compounds could be dramatically improved by optimization studies of the side chains attached to the indole and oxadiazole cores, leading to identification of a CB1 receptor agonist with good oral activity in a range of preclinical models of antinociception and antihyperalgesia.
Subject(s)
Heterocyclic Compounds/pharmacokinetics , Receptor, Cannabinoid, CB1/agonists , Administration, Oral , Animals , Biological Availability , Drug Discovery , Heterocyclic Compounds/administration & dosage , RatsABSTRACT
Optimisation of a screening hit incorporating both TRPV1 activity and solubility was conducted. Substitution of the isoxazole-3-carboxamide with the bespoke 1S, 3R-3-aminocyclohexanol motif afforded the requisite balance of potency and solubility. Compounds 32 and 40 were found to have antihyperalgesic effects in the rat CFA Hg assay and induce a mechanism based hyperthermia.
Subject(s)
Amides/chemistry , Antihypertensive Agents/chemistry , Cyclohexanols/chemistry , Isoxazoles/chemistry , TRPV Cation Channels/antagonists & inhibitors , Amides/chemical synthesis , Amides/pharmacokinetics , Animals , Antihypertensive Agents/chemical synthesis , Antihypertensive Agents/pharmacokinetics , Cyclohexanols/chemical synthesis , Cyclohexanols/pharmacokinetics , Hyperthermia, Induced , Isoxazoles/chemical synthesis , Isoxazoles/pharmacokinetics , Rats , Rats, Wistar , Structure-Activity Relationship , TRPV Cation Channels/metabolismABSTRACT
Novel indole-3-heterocycles were designed and synthesized and found to be potent CB1 receptor agonists. Starting from a microsomally unstable lead 1, a bioisostere approach replacing a piperazine amide was undertaken. This was found to be a good strategy for improving stability both in vitro and in vivo. This led to the discovery of 24, which had an increased duration of action in the mouse tail flick test in comparison to the lead 1.
Subject(s)
Heterocyclic Compounds/chemistry , Indoles/chemistry , Receptor, Cannabinoid, CB1/agonists , Thiadiazoles/chemistry , Animals , Drug Design , Heterocyclic Compounds/chemical synthesis , Heterocyclic Compounds/pharmacokinetics , Indoles/chemical synthesis , Indoles/pharmacokinetics , Mice , Microsomes/metabolism , Models, Molecular , Receptor, Cannabinoid, CB1/metabolism , Structure-Activity Relationship , Thiadiazoles/chemical synthesis , Thiadiazoles/pharmacokineticsABSTRACT
A knowledge based approach has been adopted to identify novel NOP receptor agonists with simplified hydrophobes. Substitution of the benzimidazol-2-one piperidine motif with a range of hydrophobic groups and pharmacophore guided bio-isosteric replacement of the benzimidazol-2-one moiety was explored. Compound 51 was found to be a high affinity, potent NOP receptor agonist with reduced affinity for the hERG channel.