Nowsheen, Somaira

Metastatic castration-resistant prostate cancer (mCRPC) progresses aggressively and resists existing therapies. Although poly(ADP-ribose) polymerase inhibitors (PARPis) benefit a subset of patients with mCRPC and BRCA1/2 deficiencies, therapeutic options remain limited for those without such mutations. Here, we uncover a critical role for the ATM-TRMT10A-BRCA1 signaling axis in regulating homologous recombination (HR) repair and PARPi sensitivity. We demonstrate that ATM phosphorylates TRMT10A at serine-28 after DNA damage, promoting BRCA1 recruitment and efficient HR repair. TRMT10A deletion disrupts HR repair, sensitizing cells to PARPis. Moreover, TRMT10A is up-regulated in mCRPC through stabilization by USP10. Targeting USP10 with spautin-1 induces TRMT10A degradation and enhances tumor sensitivity to PARPis in cell-derived xenografts and patient-derived xenograft models. These findings identify TRMT10A as a therapeutic vulnerability in mCRPC and demonstrate that combined inhibition of PARP and USP10 offers a promising synthetic lethal strategy for a broader group of patients lacking classical BRCA mutations.

AbstractBackgroundFew large studies have assessed spironolactone treatment of adult female acne.ObjectivesTo explore the role of spironolactone in the treatment of adult female acne.MethodsWe performed a retrospective case series assessing the efficacy of spironolactone treatment of a cohort of women evaluated at Mayo Clinic in Rochester, Minnesota, from 2007 through 2017.ResultsIn total, 395 patients (median age, 32 years) received a median spironolactone dose of 100 mg daily. Approximately two‐thirds of patients (66.1%) had a complete response; 85.1% had a complete response or a partial response greater than 50%. Median times to initial response and maximum response were 3 and 5 months. Efficacy was observed across all severity subtypes of acne, including those with papulopustular and nodulocystic acne. Patients received long‐term treatment with spironolactone (median duration, 13 months) and had few adverse effects.ConclusionsSpironolactone is a safe and effective treatment of acne for women.

Abstract PARP inhibitors (PARPi) are potentially effective therapeutic agents capable of inducing synthetic lethality in tumors with deficiencies in homologous recombination (HR)-mediated DNA repair such as those carrying BRCA1 mutations. However, BRCA mutations are rare, the majority of tumors are proficient in HR repair, and thus most tumors are resistant to PARPi. Previously, we observed that ionizing radiation (IR) initiates cytoplasmic translocation of BRCA1 leading to suppression of HR-mediated DNA repair and induction of synthetic PARPi lethality in wild-type BRCA1 and HR-proficient tumor cells. The tumor suppressor p53 was identified as a key factor that regulates DNA damage–induced BRCA1 cytoplasmic sequestration following IR. However, the role of p53 in IR-induced PARPi sensitization remains unclear. This study elucidates the role of p53 in IR-induced PARPi cytotoxicity in HR-proficient cancer cells and suggests p53 status may help define a patient population that might benefit from this treatment strategy. Sensitization to PARPi following IR was determined in vitro and in vivo utilizing human breast and glioma tumor cells carrying wild-type BRCA1 and p53, and in associated cells in which p53 function was modified by knockdown or mutation. In breast and glioma cells with proficient HR repair, IR-induced BRCA1 cytoplasmic sequestration, HR repair inhibition, and subsequent PARPi sensitization in vitro and in vivo was dependent upon functional p53. Implications: Implications: p53 status determines PARP inhibitor sensitization by ionizing radiation in multiple BRCA1 and HR-proficient tumor types and may predict which patients are most likely to benefit from combination therapy. Mol Cancer Res; 16(7); 1092–102. ©2018 AACR.