Sterol-like drugs potentiate statin-triggered prostate cancer cell death by inhibiting SREBP2 nuclear translocation.

There is an urgent need to provide immediate and effective options for the treatment of prostate cancer (PCa) to prevent progression to lethal castration-resistant PCa (CRPC). The mevalonate (MVA) pathway is dysregulated in PCa, and statin drugs commonly prescribed for hypercholesterolemia, effectively target this pathway. Statins exhibit anti-PCa activity, however the resulting intracellular depletion of cholesterol triggers a feedback loop that restores MVA pathway activity, thus diminishing statin efficacy and contributing to resistance. To identify drugs that block this feedback response and enhance the pro-apoptotic activity of statins, we performed a high-content image-based screen of a 1508 drug library, enriched for FDA-approved compounds. Two of the validated hits, Galeterone (GAL) and Quinestrol, share the cholesterol-related tetracyclic structure, which is also evident in the FDA-approved CRPC drug Abiraterone (ABI). Molecular modeling revealed that GAL, Quinestrol and ABI not only share structural similarity with 25-hydroxy-cholesterol (25HC) but were also predicted to bind similarly to a known protein-binding site of 25HC. This suggested GAL, Quinestrol and ABI are sterol-mimetics and thereby inhibit the statin-induced feedback response. Cell-based assays demonstrated that these agents inhibit nuclear translocation of sterol-regulatory element binding protein 2 (SREBP2) and the transcription of MVA genes. Sensitivity was independent of androgen status and the Fluva-GAL combination significantly impeded CRPC tumor xenograft growth. By identifying cholesterol-mimetic drugs that inhibit SREBP2 activation upon statin treatment, we provide a potent "one-two punch" against CRPC progression and pave the way for innovative therapeutic strategies to combat additional diseases whose etiology is associated with SREBP2 dysregulation.

Alzheimer's disease as an autoimmune disorder of innate immunity endogenously modulated by tryptophan metabolites.

Introduction: Alzheimer's disease (AD) is characterized by neurotoxic immuno-inflammation concomitant with cytotoxic oligomerization of amyloid beta (Aß) and tau, culminating in concurrent, interdependent immunopathic and proteopathic pathogeneses. Methods: We performed a comprehensive series of in silico, in vitro, and in vivo studies explicitly evaluating the atomistic-molecular mechanisms of cytokine-mediated and Aß-mediated neurotoxicities in AD.  Next, 471 new chemical entities were designed and synthesized to probe the pathways identified by these molecular mechanism studies and to provide prototypic starting points in the development of small-molecule therapeutics for AD. Results: In response to various stimuli (e.g., infection, trauma, ischemia, air pollution, depression), Aß is released as an early responder immunopeptide triggering an innate immunity cascade in which Aß exhibits both immunomodulatory and antimicrobial properties (whether bacteria are present, or not), resulting in a misdirected attack upon "self" neurons, arising from analogous electronegative surface topologies between neurons and bacteria, and rendering them similarly susceptible to membrane-penetrating attack by antimicrobial peptides (AMPs) such as Aß. After this self-attack, the resulting necrotic (but not apoptotic) neuronal breakdown products diffuse to adjacent neurons eliciting further release of Aß, leading to a chronic self-perpetuating autoimmune cycle.  AD thus emerges as a brain-centric autoimmune disorder of innate immunity. Based upon the hypothesis that autoimmune processes are susceptible to endogenous regulatory processes, a subsequent comprehensive screening program of 1137 small molecules normally present in human brain identified tryptophan metabolism as a regulator of brain innate immunity and a source of potential endogenous anti-AD molecules capable of chemical modification into multi-site therapeutic modulators targeting AD's complex immunopathic-proteopathic pathogenesis. Discussion:  Conceptualizing AD as an autoimmune disease, identifying endogenous regulators of this autoimmunity, and designing small molecule drug-like analogues of these endogenous regulators represents a novel therapeutic approach for AD.

Identification of Potent Indoleamine 2,3-Dioxygenase 1 (IDO1) Inhibitors Based on a Phenylimidazole Scaffold.

Inhibition of indoleamine 2,3-dioxygenase (IDO1) is an attractive immunotherapeutic approach for the treatment of a variety of cancers. Dysregulation of this enzyme has also been implicated in other disorders including Alzheimer's disease and arthritis. Herein, we report the structure-based design of two related series of molecules: N1-substituted 5-indoleimidazoles and N1-substituted 5-phenylimidazoles. The latter (and more potent) series was accessed through an unexpected rearrangement of an imine intermediate during a Van Leusen imidazole synthesis reaction. Evidence for the binding modes for both inhibitor series is supported by computational and structure-activity relationship studies.

Searching for an endogenous anti-Alzheimer molecule: identifying small molecules in the brain that slow Alzheimer disease progression by inhibition of ß-amyloid aggregation.

BACKGROUND: Alzheimer disease is a neurodegenerative disorder that progresses with marked interindividual clinical variability. We postulate the existence of endogenous molecules within the human brain exerting an antiaggregant activity that will prevent/slow Alzheimer disease progression. METHODS: We performed in silico studies to determine if the small endogenous molecules L-phosphoserine (L-PS) and 3-hydroxyanthranilic acid (3-HAA) could bind to the target region of ß-amyloid responsible for protein misfolding. In vitro assays measured the antiaggregation effect of these molecules at varying concentrations. RESULTS: In silico studies demonstrated that L-PS and 3-HAA, both endogenous brain molecules, were capable of binding to the histidine(13)-histidine-glutamine-lysine(16) (HHQK) region of ß-amyloid involved in misfolding: these interactions were energetically favoured. The in vitro assays showed that both L-PS and 3-HAA were capable of inhibiting ß-amyloid aggregation in a dose-dependent manner, with 3-HAA being more potent than L-PS. LIMITATIONS: Studies were performed in silico and in vitro but not in vivo. CONCLUSION: We successfully identified 2 endogenous brain molecules, L-PS and 3-HAA, that were capable of binding to the region of ß-amyloid that leads to protein misfolding and neurotoxicity. Both L-PS and 3-HAA were able to inhibit ß-amyloid aggregation in varying concentrations; levels of these compounds in the brain may impact their effectiveness in slowing/preventing ß-amyloid aggregation.