ABSTRACT
Proteolysis-targeting chimera (PROTAC)-mediated protein degradation is a rapidly emerging therapeutic intervention that induces the degradation of targeted proteins. Herein, we report the design and biological evaluation of a series of androgen receptor (AR) PROTAC degraders for the treatment of metastatic castration-resistant prostate cancer. Predominantly, instead of thalidomide, we utilized the TD-106 scaffold, a novel cereblon (CRBN) binder that was identified in our previous study. Our results suggest that the linker position in the TD-106 CRBN binder is critical for the efficiency of AR degradation. The compounds attached to the 6-position of TD-106 promoted better degradation of AR than those at the 5- and 7-positions. Among the synthesized AR PROTACs, the representative degrader 33c (TD-802) effectively induced AR protein degradation, with a degradation concentration 50% of 12.5 nM and a maximum degradation of 93% in LNCaP prostate cancer cells. Additionally, most AR PROTAC degraders, including TD-802, displayed good liver microsomal stability and in vivo pharmacokinetic properties. Finally, we showed that TD-802 effectively inhibited tumor growth in an in vivo xenograft study.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Antineoplastic Agents/therapeutic use , Neoplasms/drug therapy , Piperazines/therapeutic use , Proteolysis/drug effects , Receptors, Androgen/metabolism , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacokinetics , Cell Line, Tumor , Humans , Male , Mice, Inbred ICR , Mice, SCID , Microsomes, Liver/metabolism , Piperazines/chemical synthesis , Piperazines/pharmacokinetics , Receptors, Androgen/chemistry , Xenograft Model Antitumor AssaysABSTRACT
Proteolysis targeting chimeras (PROTACs) are an emerging strategy for promoting targeted protein degradation by inducing the proximity between targeted proteins and E3 ubiquitin ligases. Although successful degradation of numerous proteins by PROTACs has been demonstrated, the elements that determine the degradability of PROTAC-targeted proteins have not yet been explored. In this study, we developed von Hippel-Lindau-Cereblon (VHL-CRBN) heterodimerizing PROTACs that induce the degradation of CRBN, but not VHL. A quantitative proteomic analysis further revealed that VHL-CRBN heterodimerizing PROTACs induced the degradation of CRBN, but not the well-known immunomodulatory drug (IMiD) neo-substrates, IKAROS family zinc finger 1 (IKZF1) and -3 (IZKF3). Moreover, truncation of disordered regions of CRBN and the androgen receptor (AR) attenuated their PROTAC-induced degradation, and attachment of the disordered region to stable CRBN or AR facilitated PROTAC-induced degradation. Thus, these results suggest that the intrinsically disordered region of targeted proteins is essential for efficient proteolysis, providing a novel criterion for choosing degradable protein targets.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Proteolysis , Recombinant Fusion Proteins/metabolism , Ubiquitin-Protein Ligases/metabolism , Adaptor Proteins, Signal Transducing/genetics , HEK293 Cells , Humans , Ikaros Transcription Factor/genetics , Ikaros Transcription Factor/metabolism , Jurkat Cells , Protein Domains , Recombinant Fusion Proteins/genetics , Ubiquitin-Protein Ligases/geneticsABSTRACT
The ruthenium(II)-catalyzed C-H aminocarbonylation of N-(hetero)aryl-7-azaindoles with isocyanates is described. The excellent site selectivity at the ortho-position within the N-(hetero)aryl ring was observed to provide ortho-amidated N-(hetero)aryl-7-azaindoles under the mild reaction conditions. The resulting 7-azaindole derivatives can be readily transformed into 7-azaindoles containing carboxylic acid and alkyl amine functional groups.
