RESUMO
RNA surveillance pathways detect and degrade defective transcripts to ensure RNA fidelity. We found that disrupted nuclear RNA surveillance is oncogenic. Cyclin-dependent kinase 13 (CDK13) is mutated in melanoma, and patient-mutated CDK13 accelerates zebrafish melanoma. CDK13 mutation causes aberrant RNA stabilization. CDK13 is required for ZC3H14 phosphorylation, which is necessary and sufficient to promote nuclear RNA degradation. Mutant CDK13 fails to activate nuclear RNA surveillance, causing aberrant protein-coding transcripts to be stabilized and translated. Forced aberrant RNA expression accelerates melanoma in zebrafish. We found recurrent mutations in genes encoding nuclear RNA surveillance components in many malignancies, establishing nuclear RNA surveillance as a tumor-suppressive pathway. Activating nuclear RNA surveillance is crucial to avoid accumulation of aberrant RNAs and their ensuing consequences in development and disease.
Assuntos
Proteína Quinase CDC2 , Carcinógenos , Melanoma , Estabilidade de RNA , RNA Nuclear , Neoplasias Cutâneas , Animais , Proteína Quinase CDC2/genética , Melanoma/genética , Mutação , RNA Nuclear/genética , Neoplasias Cutâneas/genética , Peixe-Zebra , HumanosRESUMO
Development of inhibitors targeting CDK12/13 is of increasing interest as a potential therapy for cancers as these compounds inhibit transcription of DNA damage response (DDR) genes. We previously described THZ531, a covalent inhibitor with selectivity for CDK12/13. In order to elucidate structure-activity relationship (SAR), we have undertaken a medicinal chemistry campaign and established a focused library of THZ531 analogs. Among these analogs, BSJ-01-175 demonstrates exquisite selectivity, potent inhibition of RNA polymerase II phosphorylation, and downregulation of CDK12-targeted genes in cancer cells. A 3.0 Å co-crystal structure with CDK12/CycK provides a structural rational for selective targeting of Cys1039 located in a C-terminal extension from the kinase domain. With moderate pharmacokinetic properties, BSJ-01-175 exhibits efficacy against an Ewing sarcoma tumor growth in a patient-derived xenograft (PDX) mouse model following 10 mg/kg once a day, intraperitoneal administration. Taken together, BSJ-01-175 represents the first selective CDK12/13 covalent inhibitor with in vivo efficacy reported to date.
Assuntos
Anilidas/farmacologia , Proteína Quinase CDC2/antagonistas & inibidores , Quinases Ciclina-Dependentes/antagonistas & inibidores , Descoberta de Drogas , Inibidores de Proteínas Quinases/farmacologia , Pirimidinas/farmacologia , Anilidas/síntese química , Anilidas/química , Animais , Proteína Quinase CDC2/metabolismo , Células Cultivadas , Quinases Ciclina-Dependentes/metabolismo , Relação Dose-Resposta a Droga , Humanos , Masculino , Camundongos , Microssomos Hepáticos/química , Microssomos Hepáticos/metabolismo , Estrutura Molecular , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Pirimidinas/síntese química , Pirimidinas/química , Relação Estrutura-AtividadeRESUMO
Cyclin-dependent kinase 12 (CDK12) modulates transcription elongation by phosphorylating the carboxy-terminal domain of RNA polymerase II and selectively affects the expression of genes involved in the DNA damage response (DDR) and mRNA processing. Yet, the mechanisms underlying such selectivity remain unclear. Here we show that CDK12 inhibition in cancer cells lacking CDK12 mutations results in gene length-dependent elongation defects, inducing premature cleavage and polyadenylation (PCPA) and loss of expression of long (>45 kb) genes, a substantial proportion of which participate in the DDR. This early termination phenotype correlates with an increased number of intronic polyadenylation sites, a feature especially prominent among DDR genes. Phosphoproteomic analysis indicated that CDK12 directly phosphorylates pre-mRNA processing factors, including those regulating PCPA. These results support a model in which DDR genes are uniquely susceptible to CDK12 inhibition primarily due to their relatively longer lengths and lower ratios of U1 snRNP binding to intronic polyadenylation sites.
Assuntos
Quinases Ciclina-Dependentes/genética , Dano ao DNA , Reparo do DNA/genética , Linhagem Celular Tumoral , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Humanos , Modelos Moleculares , Fosforilação , Poliadenilação , Processamento Pós-Transcricional do RNA , Espectrometria de Massas em TandemRESUMO
Although poly(ADP-ribose) polymerase (PARP) inhibitors are active in homologous recombination (HR)-deficient cancers, their utility is limited by acquired resistance after restoration of HR. Here, we report that dinaciclib, an inhibitor of cyclin-dependent kinases (CDKs) 1, 2, 5, and 9, additionally has potent activity against CDK12, a transcriptional regulator of HR. In BRCA-mutated triple-negative breast cancer (TNBC) cells and patient-derived xenografts (PDXs), dinaciclib ablates restored HR and reverses PARP inhibitor resistance. Additionally, we show that de novo resistance to PARP inhibition in BRCA1-mutated cell lines and a PDX derived from a PARP-inhibitor-naive BRCA1 carrier is mediated by residual HR and is reversed by CDK12 inhibition. Finally, dinaciclib augments the degree of response in a PARP-inhibitor-sensitive model, converting tumor growth inhibition to durable regression. These results highlight the significance of HR disruption as a therapeutic strategy and support the broad use of combined CDK12 and PARP inhibition in TNBC.