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Paradoxical Role of AT-rich Interactive Domain 1A in Restraining Pancreatic Carcinogenesis.

ABSTRACT: Background & Aims: ARID1A is postulated to be a tumor suppressor gene owing to loss-of-function mutations in human pancreatic ductal adenocarcinomas (PDAC). However, its role in pancreatic pathogenesis is not clear despite recent studies using genetically engineered mouse (GEM) models. We aimed at further understanding of its direct functional role in PDAC, using a combination of GEM model and PDAC cell lines. Methods: Pancreas-specific mutant Arid1a-driven GEM model (Ptf1a-Cre; KrasG12D; Arid1af/f or "KAC") was generated by crossing Ptf1a-Cre; KrasG12D ("KC") mice with Arid1af/f mice and characterized histologically with timed necropsies. Arid1a was also deleted using CRISPR-Cas9 system in established human and murine PDAC cell lines to study the immediate effects of Arid1a loss in isogenic models. Cell lines with or without Arid1a expression were developed from respective autochthonous PDAC GEM models, compared functionally using various culture assays, and subjected to RNA-sequencing for comparative gene expression analysis. DNA damage repair was analyzed in cultured cells using immunofluorescence and COMET assay. Results: Retention of Arid1a is critical for early progression of mutant Kras-driven pre-malignant lesions into PDAC, as evident by lower Ki-67 and higher apoptosis staining in "KAC" as compared to "KC" mice. Enforced deletion of Arid1a in established PDAC cell lines caused suppression of cellular growth and migration, accompanied by compromised DNA damage repair. Despite early development of relatively indolent cystic precursor lesions called intraductal papillary mucinous neoplasms (IPMNs), a subset of "KAC" mice developed aggressive PDAC in later ages. PDAC cells obtained from older autochthonous "KAC" mice revealed various compensatory ("escaper") mechanisms to overcome the growth suppressive effects of Arid1a loss. Conclusions: Arid1a is an essential survival gene whose loss impairs cellular growth, and thus, its expression is critical during early stages of pancreatic tumorigenesis in mouse models. In tumors that arise in the setting of ARID1A loss, a multitude of "escaper" mechanisms drive progression.

SUBMITTER: Ferri-Borgogno S

PROVIDER: S-EPMC7564752 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Paradoxical Role of AT-rich Interactive Domain 1A in Restraining Pancreatic Carcinogenesis.

Ferri-Borgogno Sammy S Barui Sugata S McGee Amberly M AM Griffiths Tamara T Singh Pankaj K PK Piett Cortt G CG Ghosh Bidyut B Bhattacharyya Sanchari S Singhi Aatur A Pradhan Kith K Verma Amit A Nagel Zac Z Maitra Anirban A Gupta Sonal S

Cancers 20200921 9

Background & Aims: ARID1A is postulated to be a tumor suppressor gene owing to loss-of-function mutations in human pancreatic ductal adenocarcinomas (PDAC). However, its role in pancreatic pathogenesis is not clear despite recent studies using genetically engineered mouse (GEM) models. We aimed at further understanding of its direct functional role in PDAC, using a combination of GEM model and PDAC cell lines. Methods: Pancreas-specific mutant Arid1a-driven GEM model (Ptf ...[more]

PMID: 32967217

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Project description:Background - One of the causal mechanisms underlying neurodevelopmental disorders (NDDs) is chromatin modification, and the genes that regulate chromatin. AT-Rich Interactive Domain 1B (ARID1B), a chromatin modifier, has been shown to be reduced in autism spectrum disorder (ASD) and to affect rare and inherited genetic variation in a broad set of NDDs. Methods - A novel preclinical mouse model of Arid1b deficiency was created and validated to characterize and define neuroanatomical, behavioural and tran¬scriptional phenotypes. Neuroanatomy was assessed ex vivo in adult animals and in vivo longitudinally from birth to adulthood. Behavioural testing was also performed throughout development and tested all aspects of motor, learning, sociability, repetitive behaviours, seizure susceptibility and general milestones delays. Results – We validated decreased Arid1b mRNA and protein in Arid1b+/- mice, with signatures of increased axonal and synaptic gene expression and decreased transcriptional regulator and RNA processing expression in adult Arid1b+/- cerebellum. During neonatal development, Arid1b+/- mice exhibited robust impairments in ultrasonic vocalizations (USVs) and metrics of developmental growth. In addition, a striking sex dependence was observed throughout development; males had an early emergence of this neuroanatomical phenotype at postnatal day 7, whereas females had a delayed emergence around postnatal day 40. Behaviourally, as adults, Arid1b+/- mice showed low motor skills in open field exploration and normal three chambered approach. Arid1b+/- mice had learning and memory deficits in novel object recognition but not in visual discrimination and reversal touchscreen tasks. Social interactions in the male-female social dyad with USVs revealed social deficits on some but not all parameters. No repetitive behaviours were observed. Brains of adult Arid1b+/- mice had a smaller cerebellum and a larger hippocampus and corpus callosum. These results stand in contrast to previously reported data highlighting losses in corpus callosum volume in mice. Limitations – The behaviour and neuroimaging analyses were done on separate cohorts of mice, which did not allow a direct correlation between the imaging and behavioural findings, and the transcriptomic analyses was exploratory, with no validation of altered expression beyond Arid1b. Conclusions – This study represents a full validation and investigation of a novel model of Arid1b+/- haploinsufficiency throughout development and highlights the importance of examining both sexes throughout development in NDDs.

Dataset Information

Paradoxical Role of AT-rich Interactive Domain 1A in Restraining Pancreatic Carcinogenesis.

Publications

Paradoxical Role of AT-rich Interactive Domain 1A in Restraining Pancreatic Carcinogenesis.

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