Androgen receptor (AR)-dependent transcription is a major driver of prostate tumor cell proliferation. Consequently, it is the target of several antitumor chemotherapeutic agents, including the AR antagonist MDV3100/enzalutamide. Recent studies have shown that a single AR mutation (F876L) converts MDV3100 action from an antagonist to an agonist. Here we describe the generation of a novel class of selective androgen receptor degraders (SARDs) to address this resistance mechanism. Molecules containing hydrophobic degrons linked to small-molecule AR ligands induce AR degradation, reduce expression of AR target genes and inhibit proliferation in androgen-dependent prostate cancer cell lines. These results suggest that selective AR degradation may be an effective therapeutic prostate tumor strategy in the context of AR mutations that confer resistance to second-generation AR antagonists.

New HyTs are a knockout: we previously reported that labeling HaloTag proteins with low molecular weight hydrophobic tags (HyTs) leads to targeted degradation of HaloTag fusion proteins. In this report, we employed a chemical approach to extend this hydrophobic tagging methodology to highly stabilized proteins by synthesizing and evaluating a library of HyTs, which led to the identification of HyT36.

By design: Novel small-molecule inhibitors of the interaction between the von Hippel–Lindau ligase (VHL) and its molecular target HIF1α, a transcription factor involved in oxygen sensing, have been developed and studied. The most potent inhibitor binds with an IC50 value of 0.9 μM and is thus the first sub-micromolar inhibitor of the VHL–HIF1α interaction. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

E3 ubiquitin ligases, which bind protein targets, leading to their ubiquitination and subsequent degradation, are attractive drug targets due to their exquisite substrate specificity. However, the development of small-molecule inhibitors has proven extraordinarily challenging as modulation of E3 ligase activities requires the targeting of protein-protein interactions. Using rational design, we have generated the first small molecule targeting the von Hippel-Lindau protein (VHL), the substrate recognition subunit of an E3 ligase, and an important target in cancer, chronic anemia, and ischemia. We have also obtained the crystal structure of VHL bound to our most potent inhibitor, confirming that the compound mimics the binding mode of the transcription factor HIF-1α, a substrate of VHL. These results have the potential to guide future development of improved lead compounds as therapeutics for the treatment of chronic anemia and ischemia.

Inhibitoren per Design: Niedermolekulare Inhibitoren der Wechselwirkung zwischen der von-Hippel-Lindau-Ligase (VHL) und ihrem molekularen Substrat HIF1α wurden entwickelt und untersucht. Der affinste Inhibitor bindet mit einem IC50-Wert von 0.9 μM und ist somit der erste submikromolare Inhibitor der Wechselwirkung zwischen VHL und HIF1α. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The acid sphingomyelinase is an emerging drug target, especially for inflammatory lung diseases. Presently, there are no directly-acting potent inhibitors available for cell-based studies. The potent inhibitor phosphatidylinositol-3,5-bisphosphate (PtdIns3,5P2) is not only unsuited for cell culture studies, but also does not provide hints for further structural improvements. In the SAR study described here, we replaced the inositolphosphate moiety by a carbohydrate derivative and the phosphatidic acid residue by an alkylsulfone ester. The resulting compound is more active than its parent compound and offers new means for further structural modification.

Auf der Suche nach einem Ziel: Die Überlagerung von verzweigten Gerüstbäumen für Naturstoffe und synthetische Verbindungen mit bekannter biologischer Aktivität (siehe Schema) ist eine neue Strategie zur Identifizierung vielversprechender Zielproteine für Substanzbibliotheken, deren Strukturen sich von Naturstoffen ableiten. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Heat shock protein 70 (Hsp70) is an evolutionarily highly conserved molecular chaperone that promotes the survival of stressed cells by inhibiting lysosomal membrane permeabilization, a hallmark of stress-induced cell death. Clues to its molecular mechanism of action may lay in the recently reported stress- and cancer-associated translocation of a small portion of Hsp70 to the lysosomal compartment. Here we show that Hsp70 stabilizes lysosomes by binding to an endolysosomal anionic phospholipid bis(monoacylglycero)phosphate (BMP), an essential co-factor for lysosomal sphingomyelin metabolism. In acidic environments Hsp70 binds with high affinity and specificity to BMP, thereby facilitating the BMP binding and activity of acid sphingomyelinase (ASM). The inhibition of the Hsp70-BMP interaction by BMP antibodies or a point mutation in Hsp70 (Trp90Phe), as well as the pharmacological and genetic inhibition of ASM, effectively revert the Hsp70-mediated stabilization of lysosomes. Notably, the reduced ASM activity in cells from patients with Niemann-Pick disease (NPD) A and B-severe lysosomal storage disorders caused by mutations in the sphingomyelin phosphodiesterase 1 gene (SMPD1) encoding for ASM-is also associated with a marked decrease in lysosomal stability, and this phenotype can be effectively corrected by treatment with recombinant Hsp70. Taken together, these data open exciting possibilities for the development of new treatments for lysosomal storage disorders and cancer with compounds that enter the lysosomal lumen by the endocytic delivery pathway.

More than mending bones: A simple geminal aminobisphosphonate (see picture) is the most potent selective inhibitor of the acid sphingomyelinase known to date. It can be synthesized in a one-step procedure and inhibits cell death in vitro. Since the acid sphingomyelinase is a putative drug target for inflammatory lung diseases, bisphosphonates may find application in the treatment of pulmonary diseases. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Nicht nur gegen Osteoporose? Ein einfaches geminales Aminobisphosphonat (siehe Bild) ist der bisher potenteste und selektivste Inhibitor der sauren Sphingomyelinase. Die Verbindung kann in einer Stufe synthetisiert werden und inhibiert den Zelltod in vitro. Weil die saure Sphingomyelinase ein potenzieller Angriffspunkt für Wirkstoffe bei der Behandlung entzündlicher Lungenerkrankungen ist, könnten die Bisphosphonate neue Therapiemöglichkeiten eröffnen. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.