Identification of a novel GR-ARID1a-P53BP1 protein complex involved in DNA damage repair and cell cycle regulation

Clinical outcome and molecular landscape of patients with ARID1A-loss gastric cancer

Chromatin remodelers are commonly altered in human cancer. The mutation of AT-rich interactive domain 1A (ARID1A) in gastric cancer (GC), a component of the SWI/SNF chromatin remodeling complex, was proven associated with treatment response in our previous study. However, ARID1A loss of function was caused not only by mutations but also copy number deletions. The clinicopathologic, genomic, and immunophenotypic correlates of ARID1A loss is largely uncharacterized in GC. Here, 819 patients with clinicopathological information and sequencing data or formalin-fixed paraffin-embedded tissues from four cohorts, Zhongshan Hospital (ZSHS) cohort (n = 375), The Cancer Genome Atlas (TCGA) cohort (n = 371), Samsung Medical Center (SMC) cohort (n = 53), and ZSHS immunotherapy cohort (n = 20), were enrolled. ARID1A loss was defined by genome sequencing or deficient ARID1A expression by immunohistochemistry. We found that ARID1A mutation and copy number deletion were enriched in GC with microsatellite instability (MSI) and chromosomal-instability (CIN), respectively. In the TCGA and ZSHS cohorts, only CIN GC with ARID1A loss could benefit from fluorouracil-based adjuvant chemotherapy. In the SMC and ZSHS immunotherapy cohorts, ARID1A loss exhibited a tendency of superior responsiveness and indicated favorable overall survival after anti-PD-1 immunotherapy. ARID1A-loss tumors demonstrated elevated mutation burden, neoantigen load, and interferon gamma pathway activation. Moreover, in CIN GC, ARID1A loss was correlated with higher homologous recombination deficiency. ARID1A loss defines a distinct subtype of GC characterized by high levels of genome instability, neoantigen formation, and immune activation. These tumors show sensitivity to both chemotherapy and anti-PD-1 immunotherapy. This study provides valuable insights for precision treatment strategies in GC.

Phase-shifting the circadian glucocorticoid profile induces disordered feeding behaviour by dysregulating hypothalamic neuropeptide gene expression

Here we demonstrate, in rodents, how the timing of feeding behaviour becomes disordered when circulating glucocorticoid rhythms are dissociated from lighting cues; a phenomenon most commonly associated with shift-work and transmeridian travel 'jetlag'. Adrenalectomized rats are infused with physiological patterns of corticosterone modelled on the endogenous adrenal secretory profile, either in-phase or out-of-phase with lighting cues. For the in-phase group, food intake is significantly greater during the rats' active period compared to their inactive period; a feeding pattern similar to adrenal-intact control rats. In contrast, the feeding pattern of the out-of-phase group is significantly dysregulated. Consistent with a direct hypothalamic modulation of feeding behaviour, this altered timing is accompanied by dysregulated timing of anorexigenic and orexigenic neuropeptide gene expression. For Neuropeptide Y (Npy), we report a glucocorticoid-dependent direct transcriptional regulation mechanism mediated by the glucocorticoid receptor (GR). Taken together, our data highlight the adverse behavioural outcomes that can arise when two circadian systems have anti-phasic cues, in this case impacting on the glucocorticoid-regulation of a process as fundamental to health as feeding behaviour. Our findings further highlight the need for development of rational approaches in the prevention of metabolic dysfunction in circadian-disrupting activities such as transmeridian travel and shift-work.