RESUMEN
AZD0156 is a potent and selective, bioavailable inhibitor of ataxia-telangiectasia mutated (ATM) protein, a signaling kinase involved in the DNA damage response. We present preclinical data demonstrating abrogation of irradiation-induced ATM signaling by low doses of AZD0156, as measured by phosphorylation of ATM substrates. AZD0156 is a strong radiosensitizer in vitro, and using a lung xenograft model, we show that systemic delivery of AZD0156 enhances the tumor growth inhibitory effects of radiation treatment in vivo Because ATM deficiency contributes to PARP inhibitor sensitivity, preclinically, we evaluated the effect of combining AZD0156 with the PARP inhibitor olaparib. Using ATM isogenic FaDu cells, we demonstrate that AZD0156 impedes the repair of olaparib-induced DNA damage, resulting in elevated DNA double-strand break signaling, cell-cycle arrest, and apoptosis. Preclinically, AZD0156 potentiated the effects of olaparib across a panel of lung, gastric, and breast cancer cell lines in vitro, and improved the efficacy of olaparib in two patient-derived triple-negative breast cancer xenograft models. AZD0156 is currently being evaluated in phase I studies (NCT02588105).
Asunto(s)
Proteínas de la Ataxia Telangiectasia Mutada/uso terapéutico , Ftalazinas/uso terapéutico , Piperazinas/uso terapéutico , Piridinas/uso terapéutico , Quinolinas/uso terapéutico , Fármacos Sensibilizantes a Radiaciones/uso terapéutico , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Neoplasias de la Mama Triple Negativas/radioterapia , Animales , Proteínas de la Ataxia Telangiectasia Mutada/farmacología , Línea Celular Tumoral , Humanos , Masculino , Ratones , Ratones Desnudos , Ftalazinas/farmacología , Piperazinas/farmacología , Piridinas/farmacología , Quinolinas/farmacología , Fármacos Sensibilizantes a Radiaciones/farmacología , Neoplasias de la Mama Triple Negativas/patologíaRESUMEN
Physical and chemical agents that induce DNA double-strand breaks (DSBs) are among the most potent mutagens. The mammalian cell response to DSB comprises a highly co-ordinated, yet complex network of proteins that have been categorized as sensors, signal transducers, mediators and effectors of damage and repair. While this provides an accessible classification system, review of the literature indicates that many proteins satisfy the criteria of more than one category, pointing towards a series of highly co-operative pathways with overlapping function. In summary, the MRE11-NBS1-RAD50 complex is necessary for achieving optimal activation of ataxia-telangiectasia-mutated (ATM) kinase, which catalyses a phosphorylation-mediated signal transduction cascade. Among the subset of proteins phosphorylated by ATM are histone H2AX (H2AX), mediator of damage checkpoint protein 1, nibrin (NBS1), P53-binding protein 1 and breast cancer protein 1, all of which subsequently redistribute into DSB-containing sub-nuclear compartments. Post-translational modification of DSB responding proteins achieves a rapid and reversible change in protein behaviour and mediates damage-specific interactions, hence imparting a high degree of vigilance to the cell. This review highlights events fundamental in maintaining genetic integrity with emphasis on early stages of the DSB response.
Asunto(s)
Roturas del ADN de Doble Cadena , Proteínas de Unión al ADN/metabolismo , Ácido Anhídrido Hidrolasas , Animales , Proteínas de la Ataxia Telangiectasia Mutada , Proteínas de Ciclo Celular/metabolismo , Enzimas Reparadoras del ADN , Histonas/metabolismo , Humanos , Proteína Homóloga de MRE11 , Proteínas Nucleares/metabolismo , Fosfopéptidos , Proteínas Serina-Treonina Quinasas , Estructura Terciaria de Proteína , Telómero/enzimología , Proteínas Supresoras de TumorRESUMEN
Inhibition of ataxia-telangiectasia mutated (ATM) during radiotherapy of glioblastoma multiforme (GBM) may improve tumor control by short-circuiting the response to radiation-induced DNA damage. A major impediment for clinical implementation is that current inhibitors have limited central nervous system (CNS) bioavailability; thus, the goal was to identify ATM inhibitors (ATMi) with improved CNS penetration. Drug screens and refinement of lead compounds identified AZ31 and AZ32. The compounds were then tested in vivo for efficacy and impact on tumor and healthy brain. Both AZ31 and AZ32 blocked the DNA damage response and radiosensitized GBM cells in vitro AZ32, with enhanced blood-brain barrier (BBB) penetration, was highly efficient in vivo as radiosensitizer in syngeneic and human, orthotopic mouse glioma model compared with AZ31. Furthermore, human glioma cell lines expressing mutant p53 or having checkpoint-defective mutations were particularly sensitive to ATMi radiosensitization. The mechanism for this p53 effect involves a propensity to undergo mitotic catastrophe relative to cells with wild-type p53. In vivo, apoptosis was >6-fold higher in tumor relative to healthy brain after exposure to AZ32 and low-dose radiation. AZ32 is the first ATMi with oral bioavailability shown to radiosensitize glioma and improve survival in orthotopic mouse models. These findings support the development of a clinical-grade, BBB-penetrating ATMi for the treatment of GBM. Importantly, because many GBMs have defective p53 signaling, the use of an ATMi concurrent with standard radiotherapy is expected to be cancer-specific, increase the therapeutic ratio, and maintain full therapeutic effect at lower radiation doses. Mol Cancer Ther; 17(8); 1637-47. ©2018 AACR.
Asunto(s)
Barrera Hematoencefálica/metabolismo , Glioma/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/uso terapéutico , Fármacos Sensibilizantes a Radiaciones/uso terapéutico , Administración Oral , Animales , Proteínas de la Ataxia Telangiectasia Mutada/antagonistas & inhibidores , Línea Celular Tumoral , Humanos , Ratones , Ratones Desnudos , Inhibidores de Proteínas Quinasas/farmacología , Fármacos Sensibilizantes a Radiaciones/farmacologíaRESUMEN
Although DNA damage proteins are infrequently regulated at the transcriptional level, RAD52 mRNA levels appear to be significantly induced in human cells following methyl methanesulphonate (MMS) and Etoposide treatment. Studies have so far been limited to biochemical analysis of cellular extracts and we aimed to extend this observation to whole cells. To address this, we have developed a series of molecular beacon (MB) probes that fluoresce upon hybridising with RAD52 mRNA sequence. MB's are synthetic hairpin probes, which generate a significant fluorescent signal only upon hybridising complementary nucleotide. Three MB's are described herein, which display differential sensitivity, specificity and stability. In particular, the suitability of a texas red-labelled DNA MB (TR-MB), a dual-labelled (FAM-TAMRA) fluorescence resonance energy transfer-capable DNA MB (FRET-MB) and a FAM-labelled MB of 2'-O-methylated RNA backbone (FAM-MB) was investigated. We conclude that FAM-MB is most suitable for intracellular applications, and demonstrate a positive correlation between MB fluorescence intensity, RAD52 gene expression and both gamma ionising radiation and MMS concentration in human TK6 cells. RAD52 contribution to DNA repair has been ascribed to its role in homologous recombination (HR) and therefore we propose FAM-MB could be a potential tool for discriminating between substrates of HR and non-homologous end joining (NHEJ).