EWS/FLI Confers Tumor Cell Synthetic Lethality to CDK12 Inhibition in Ewing Sarcoma

Many cancer types are driven by oncogenic transcription factors that have been difficult to drug. Transcriptional inhibitors, however, may offer inroads into targeting these cancers. Through chemical genomics screening, we identified that Ewing sarcoma is a disease with preferential sensitivity to THZ1, a covalent small-molecule CDK7/12/13 inhibitor. The selective CDK12/13 inhibitor, THZ531, impairs DNA damage repair in an EWS/FLI-dependent manner, supporting a synthetic lethal relationship between response to THZ1/THZ531 and EWS/FLI expression. The combination of these molecules with PARP inhibitors showed striking synergy in cell viability and DNA damage assays in vitro and in multiple models of Ewing sarcoma, including a PDX, in vivo without hematopoietic toxicity. Iniguez et al. find that inhibition of CDK12 is synthetic lethal with EWS/FLI expression. CDK12/13 inhibitors impair DNA damage repair in cells expressing EWS/FLI, and the combination of CDK12/13 and PARP inhibitors synergistically reduces tumor growth and extends survival in Ewing sarcoma mouse models

Targeting transcription regulation in cancer with a covalent CDK7 inhibitor

Tumor oncogenes include transcription factors that co-opt the general transcriptional machinery to sustain the oncogenic state1, but direct pharmacological inhibition of transcription factors has thus far proven difficult2. However, the transcriptional machinery contains various enzymatic co-factors that can be targeted for development of new therapeutic candidates3, including cyclin-dependent kinases (CDKs)4. Here we present the discovery and characterization of the first covalent CDK7 inhibitor, THZ1, which has the unprecedented ability to target a remote cysteine residue located outside of the canonical kinase domain, providing an unanticipated means of achieving selectivity for CDK7. Cancer cell line profiling indicates that a subset of cancer cell lines, including T-ALL, exhibit exceptional sensitivity to THZ1. Genome-wide analysis in Jurkat T-ALL shows that THZ1 disproportionally affects transcription of RUNX1 and suggests that sensitivity to THZ1 may be due to vulnerability conferred by the RUNX1 super-enhancer and this transcription factor’s key role in the core transcriptional regulatory circuitry of these tumor cells. Pharmacological modulation of CDK7 kinase activity may thus provide an approach to identify and treat tumor types exhibiting extreme dependencies on transcription for maintenance of the oncogenic state

Targeting transcription regulation in cancer with a covalent CDK7 inhibitor

Tumour oncogenes include transcription factors that co-opt the general transcriptional machinery to sustain the oncogenic state, but direct pharmacological inhibition of transcription factors has so far proven difficult. However, the transcriptional machinery contains various enzymatic cofactors that can be targeted for the development of new therapeutic candidates, including cyclin-dependent kinases (CDKs). Here we present the discovery and characterization of a covalent CDK7 inhibitor, THZ1, which has the unprecedented ability to target a remote cysteine residue located outside of the canonical kinase domain, providing an unanticipated means of achieving selectivity for CDK7. Cancer cell-line profiling indicates that a subset of cancer cell lines, including human T-cell acute lymphoblastic leukaemia (T-ALL), have exceptional sensitivity to THZ1. Genome-wide analysis in Jurkat T-ALL cells shows that THZ1 disproportionally affects transcription of RUNX1 and suggests that sensitivity to THZ1 may be due to vulnerability conferred by the RUNX1 super-enhancer and the key role of RUNX1 in the core transcriptional regulatory circuitry of these tumour cells. Pharmacological modulation of CDK7 kinase activity may thus provide an approach to identify and treat tumour types that are dependent on transcription for maintenance of the oncogenic state.National Institutes of Health (U.S.) (Grant HG002668)National Institutes of Health (U.S.) (Grant CA109901

Phencyclidine (PCP)-Induced Disruption in Cognitive Performance is Gender-Specific and Associated with a Reduction in Brain-Derived Neurotrophic Factor (BDNF) in Specific Regions of the Female Rat Brain

Phencyclidine (PCP), used to mimic certain aspects of schizophrenia, induces sexually dimorphic, cognitive deficits in rats. In this study, the effects of sub-chronic PCP on expression of brain-derived neurotrophic factor (BDNF), a neurotrophic factor implicated in the pathogenesis of schizophrenia, have been evaluated in male and female rats. Male and female hooded-Lister rats received vehicle or PCP (n = 8 per group; 2 mg/kg i.p. twice daily for 7 days) and were tested in the attentional set shifting task prior to being sacrificed (6 weeks post-treatment). Levels of BDNF mRNA were measured in specific brain regions using in situ hybridisation. Male rats were less sensitive to PCP-induced deficits in the extra-dimensional shift stage of the attentional set shifting task compared to female rats. Quantitative analysis of brain regions demonstrated reduced BDNF levels in the medial prefrontal cortex (p < 0.05), motor cortex (p < 0.01), orbital cortex (p < 0.01), olfactory bulb (p < 0.05), retrosplenial cortex (p < 0.001), frontal cortex (p < 0.01), parietal cortex (p < 0.01), CA1 (p < 0.05) and polymorphic layer of dentate gyrus (p < 0.05) of the hippocampus and the central (p < 0.01), lateral (p < 0.05) and basolateral (p < 0.05) regions of the amygdaloid nucleus in female PCP-treated rats compared with controls. In contrast, BDNF was significantly reduced only in the orbital cortex and central amygdaloid region of male rats (p < 0.05). Results suggest that blockade of NMDA receptors by sub-chronic PCP administration has a long-lasting down-regulatory effect on BDNF mRNA expression in the female rat brain which may underlie some of the behavioural deficits observed post PCP administration

Advancing schizophrenia drug discovery : optimizing rodent models to bridge the translational gap

Although our knowledge of the pathophysiology of schizophrenia has increased, treatments for this devastating illness remain inadequate. Here, we critically assess rodent models and behavioural end points used in schizophrenia drug discovery and discuss why these have not led to improved treatments. We provide a perspective on how new models, based on recent advances in the understanding of the genetics and neural circuitry underlying schizophrenia, can bridge the translational gap and lead to the development of more effective drugs. We conclude that previous serendipitous approaches should be replaced with rational strategies for drug discovery in integrated preclinical and clinical programmes. Validation of drug targets in disease-based models that are integrated with translationally relevant end point assessments will reduce the current attrition rate in schizophrenia drug discovery and ultimately lead to therapies that tackle the disease process

Subanaesthetic ketamine treatment alters prefrontal cortex connectivity with thalamus and ascending subcortical systems

Acute treatment with subanaesthetic doses of NMDA receptor antagonists, such as ketamine, provides a translational model with relevance to many of the symptoms of schizophrenia. Previous studies have focused specifically on the prefrontal cortex (PFC) because this region is implicated in many of the functional deficits associated with this disorder and shows reduced activity (hypofrontality) in schizophrenia patients. Chronic NMDA antagonist treatment in rodents can also induce hypofrontality, although paradoxically acute NMDA receptor antagonist administration induces metabolic hyperfrontality. In this study, we use 2-deoxyglucose imaging data in mice to characterize acute ketamine-induced alterations in regional functional connectivity, a deeper analysis of the consequences of acute NMDA receptor hypofunction. We show that acute ketamine treatment increases PFC metabolic activity while reducing metabolic activity in the dorsal reticular thalamic nucleus (dRT). This is associated with abnormal functional connectivity between the PFC and multiple thalamic nuclei, including the dRT, mediodorsal (MDthal), and anteroventral (AVthal) thalamus. In addition, we show that acute NMDA receptor blockade alters the functional connectivity of the serotonergic (dorsal raphe [DR]), noradrenergic (locus coeruleus [LC]), and cholinergic (vertical limb of the diagonal band of broca [VDB]) systems. Together with other emerging data, these findings suggest that the reticular nucleus of the thalamus, along with the diffusely projecting subcortical aminergic/cholinergic systems, represent a primary site of action for ketamine in reproducing the diverse symptoms of schizophrenia. Our results also demonstrate the added scientific insight gained by characterizing the functional connectivity of discrete brain regions from brain imaging data gained in a preclinical context