ABSTRACT
Castration-resistant prostate cancers (CRPCs) lose sensitivity to androgen-deprivation therapies but frequently remain dependent on oncogenic transcription driven by the androgen receptor (AR) and its splice variants. To discover modulators of AR-variant activity, we used a lysate-based small-molecule microarray assay and identified KI-ARv-03 as an AR-variant complex binder that reduces AR-driven transcription and proliferation in prostate cancer cells. We deduced KI-ARv-03 to be a potent, selective inhibitor of CDK9, an important cofactor for AR, MYC, and other oncogenic transcription factors. Further optimization resulted in KB-0742, an orally bioavailable, selective CDK9 inhibitor with potent anti-tumor activity in CRPC models. In 22Rv1 cells, KB-0742 rapidly downregulates nascent transcription, preferentially depleting short half-life transcripts and AR-driven oncogenic programs. In vivo, oral administration of KB-0742 significantly reduced tumor growth in CRPC, supporting CDK9 inhibition as a promising therapeutic strategy to target AR dependence in CRPC.
Subject(s)
Androgen Receptor Antagonists/pharmacology , Cyclin-Dependent Kinase 9/antagonists & inhibitors , Prostatic Neoplasms, Castration-Resistant/drug therapy , Protein Kinase Inhibitors/pharmacology , Receptors, Androgen/genetics , Transcription, Genetic/drug effects , Androgen Receptor Antagonists/therapeutic use , Animals , Cell Line, Tumor , Cyclin-Dependent Kinase 9/genetics , Gene Expression Regulation, Neoplastic/drug effects , Male , Mice , Mice, Inbred BALB C , Models, Molecular , Prostatic Neoplasms, Castration-Resistant/genetics , Protein Kinase Inhibitors/therapeutic useABSTRACT
The transcription factor Max is a basic-helix-loop-helix leucine zipper (bHLHLZ) protein that forms homodimers or interacts with other bHLHLZ proteins, including Myc and Mxd proteins. Among this dynamic network of interactions, the Myc/Max heterodimer has crucial roles in regulating normal cellular processes, but its transcriptional activity is deregulated in a majority of human cancers. Despite this significance, the arsenal of high-quality chemical probes to interrogate these proteins remains limited. We used small molecule microarrays to identify compounds that bind Max in a mechanistically unbiased manner. We discovered the asymmetric polycyclic lactam, KI-MS2-008, which stabilizes the Max homodimer while reducing Myc protein and Myc-regulated transcript levels. KI-MS2-008 also decreases viable cancer cell growth in a Myc-dependent manner and suppresses tumor growth in vivo. This approach demonstrates the feasibility of modulating Max with small molecules and supports altering Max dimerization as an alternative approach to targeting Myc.
Subject(s)
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Lactams/pharmacology , Polycyclic Compounds/pharmacology , Proto-Oncogene Proteins c-myc/genetics , Repressor Proteins/metabolism , Small Molecule Libraries/pharmacology , Transcription, Genetic/drug effects , Animals , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/chemistry , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics , Cell Line , Dimerization , Disease Models, Animal , Humans , Lactams/chemical synthesis , Lactams/therapeutic use , Male , Mice , Mice, Inbred NOD , Mice, SCID , Neoplasms/drug therapy , Polycyclic Compounds/chemical synthesis , Polycyclic Compounds/therapeutic use , Promoter Regions, Genetic , Protein Binding , Proto-Oncogene Proteins c-myc/metabolism , Rats , Repressor Proteins/chemistry , Repressor Proteins/genetics , Small Molecule Libraries/therapeutic use , Ultraviolet RaysABSTRACT
Catch and release DNA decoys (CRDDs) are a new class of non-natural DNA probes that capture and dissociate from DNA-binding proteins using a light trigger. Photolytic cleavage of non-natural nucleobases in the CRDD yields abasic sites and truncation products that lower the affinity of the CRDD for its protein target. Herein, we demonstrate the ability of the first-generation CRDD to bind and release NF-κB proteins. This platform technology should be applicable to other DNA-binding proteins by modification of the target sequence.
Subject(s)
DNA Probes/chemistry , Deoxyribonucleotides/chemistry , Indoles/chemistry , NF-kappa B/chemistry , Electrophoretic Mobility Shift Assay , Protein Binding , Ultraviolet RaysSubject(s)
Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Guanosine Monophosphate/metabolism , Ligases/antagonists & inhibitors , Ligases/metabolism , Ribonucleotides/chemistry , Ribonucleotides/pharmacology , Catalytic Domain , Enzyme Inhibitors/metabolism , Escherichia coli/enzymology , Ligases/chemistry , Models, Molecular , Ribonucleotides/metabolism , Stereoisomerism , XanthineABSTRACT
A series of structurally simplified cryptocaryone analogues were synthesized by a facile Pd-catalyzed acetoxylation of alkyne-tethered cyclohexadienones and evaluated as inhibitors of NF-κB signaling. Compounds 10 and 11 were found to possess low micromolar inhibitory properties towards induced NF-κB activity by blocking p50/p65 nuclear protein through a covalent inhibition mechanism. Both compounds were able to inhibit NF-κB-induced IL-8 expression and exhibited antiproliferative activity against two model cancer cell lines. These analogues constitute a promising new scaffold for the development of novel NF-κB inhibitors and anticancer agents.