RESUMO
The response to poly(ADP-ribose) polymerase inhibitors (PARPi) is dictated by homologous recombination (HR) DNA repair and the abundance of lesions that trap PARP enzymes. It remains unclear, however, if the established role of PARP in promoting chromatin accessibility impacts viability in these settings. Using a CRISPR-based screen, we identified the PAR-binding chromatin remodeller ALC1/CHD1L as a key determinant of PARPi toxicity in HR-deficient cells. ALC1 loss reduced viability of breast cancer gene (BRCA)-mutant cells and enhanced sensitivity to PARPi by up to 250-fold, while overcoming several resistance mechanisms. ALC1 deficiency reduced chromatin accessibility concomitant with a decrease in the association of base damage repair factors. This resulted in an accumulation of replication-associated DNA damage, increased PARP trapping and a reliance on HR. These findings establish PAR-dependent chromatin remodelling as a mechanistically distinct aspect of PARPi responses and therapeutic target in HR-deficient cancers.
Assuntos
Cromatina/metabolismo , DNA Helicases/metabolismo , Proteínas de Ligação a DNA/metabolismo , Recombinação Homóloga/genética , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Proteína BRCA1/genética , Proteína BRCA2/genética , Sistemas CRISPR-Cas/genética , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Montagem e Desmontagem da Cromatina/efeitos dos fármacos , Aberrações Cromossômicas , DNA Helicases/química , Reparo do DNA/efeitos dos fármacos , Proteínas de Ligação a DNA/química , Epistasia Genética/efeitos dos fármacos , Instabilidade Genômica , Proteínas de Fluorescência Verde/metabolismo , Recombinação Homóloga/efeitos dos fármacos , Humanos , Metanossulfonato de Metila , Mutação/genética , Ftalazinas/farmacologia , Piperazinas/farmacologia , Poli Adenosina Difosfato Ribose/metabolismo , Poli(ADP-Ribose) Polimerases/metabolismo , Domínios ProteicosRESUMO
Despite optimal chemotherapy, radiotherapy (RT), and/or surgery, non-small-cell lung carcinoma (NSCLC) remains the leading cause of cancer-related death in the US and worldwide. Thoracic RT, a mainstay in the treatment of locally advanced NSCLC, is often restricted in efficacy by a therapeutic index limited by sensitivity of tissues surrounding the malignancy. Therefore, radiosensitizers that can improve the therapeutic index are a vital unmet need. Inhibition of the NF-κB pathway is a proposed mechanism of radiosensitization. Here we demonstrate that inhibition of the canonical NF-κB pathway by dimethylaminoparthenolide (DMAPT) radiosensitizes NSCLC by blocking DNA double-strand break (DSB) repair. NF-κB inhibition results in significant impairment of both homologous recombination (HR) and non-homologous end joining (NHEJ), as well as reductions in ionizing radiation (IR)-induced DNA repair biomarkers. NF-κB inhibition by DMAPT shows preclinical potential for further investigation as a NSCLC radiosensitizer.
RESUMO
Knowledge of the effectiveness of multimodal analgesic treatments to manage children's postoperative pain during hospital stays is limited. Our retrospective chart review of a convenience sample of 200 pediatric surgical patients' pain experiences during the first 24 hours after laparoscopic appendectomy demonstrates the benefits of a multimodal analgesic approach. We found that pediatric patients who received perioperative IV ketorolac in addition to opioids reported statistically significantly lower mean pain intensity (n = 134, mean [M] = 2.9, standard deviation [SD] = 1.7) during the first 24 hours after surgery when compared with the pain intensity of patients who did not receive perioperative IV ketorolac (n = 66, M = 3.7, SD = 1.7, t = 3.14, P = .002). Patients who received perioperative IV ketorolac (M = 0.94, SD = 0.71) also received significantly fewer morphine equivalents of postoperative opioids during the first 24 hours after surgery than those who did not (M = 1.21, SD = 0.78, t = 2.41, P = .02). We will use data from these patients to introduce the potential for a personalized medicine approach to postoperative pain.
Assuntos
Analgésicos/uso terapêutico , Apendicectomia/métodos , Laparoscopia/métodos , Dor Pós-Operatória/tratamento farmacológico , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Auditoria Médica , Estudos RetrospectivosRESUMO
BACKGROUND: Risk of normal tissue toxicity limits the amount of thoracic radiation therapy (RT) that can be routinely prescribed to treat non-small cell lung cancer (NSCLC). An early biomarker of response to thoracic RT may provide a way to predict eventual toxicities-such as radiation pneumonitis-during treatment, thereby enabling dose adjustment before the symptomatic onset of late effects. MicroRNAs (miRNAs) were studied as potential serological biomarkers for thoracic RT. As a first step, we sought to identify miRNAs that correlate with delivered dose and standard dosimetric factors. METHODS: We performed miRNA profiling of plasma samples obtained from five patients with Stage IIIA NSCLC at five dose-points each during radical thoracic RT. Candidate miRNAs were then assessed in samples from a separate cohort of 21 NSCLC patients receiving radical thoracic RT. To identify a cellular source of circulating miRNAs, we quantified in vitro miRNA expression intracellularly and within secreted exosomes in five NSCLC and stromal cell lines. RESULTS: miRNA profiling of the discovery cohort identified ten circulating miRNAs that correlated with delivered RT dose as well as other dosimetric parameters such as lung V20. In the validation cohort, miR-29a-3p and miR-150-5p were reproducibly shown to decrease with increasing radiation dose. Expression of miR-29a-3p and miR-150-5p in secreted exosomes decreased with radiation. This was concomitant with an increase in intracellular levels, suggesting that exosomal export of these miRNAs may be downregulated in both NSCLC and stromal cells in response to radiation. CONCLUSIONS: miR-29a-3p and miR-150-5p were identified as circulating biomarkers that correlated with delivered RT dose. miR-150 has been reported to decrease in the circulation of mammals exposed to radiation while miR-29a has been associated with fibrosis in the human heart, lungs, and kidneys. One may therefore hypothesize that outlier levels of circulating miR-29a-3p and miR-150-5p may eventually help predict unexpected responses to radiation therapy, such as toxicity.