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SIRT6 overexpression predicts high risk of metastasis and relapse in Delta16HER2-positive breast cancer [RNA-seq]

ABSTRACT: We investigate the impact of SIRT6-overexpression (SIRT6-OE) in the breast cancer mouse model Delta16HER2. After an initial delay in the tumor onset, starting form 20 weeks of age, SIRT6-OE induces a more aggressive phenotype of Delta16HER2 tumors, promoting the formation of more tumors and metastases with respect to controls. SIRT6 can regulate gene expression and chromatin integrity via deacetylation of H3K9ac. Therefore, to gain mechanistic insights, we performed H3K9ac ChIP-seq and RNA-seq on tumors from Delta16HER2/SIRT6-OE and Delta16HER2 mice, harvested at 20 weeks of age.

ORGANISM(S): Mus musculus

PROVIDER: GSE216185 | GEO | 2023/12/31

REPOSITORIES: GEO

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Project description:Purpose: The complete understanding of how genetic and epigenetic components control beta cell differentiation and function is key to the discovery of novel therapeutic approaches to prevent beta cell dysfunction and failure in the progression of type 2 diabetes. Our goal was to elucidate the role of histone deacetylase SIRT6 in beta-cell development and homeostasis. Methods: The Sirt6 endocrine progenitor cell conditional knockout (EKO) and beta-cell-specific knockout (BKO) mice were generated using the Cre-loxP system. Mice were assayed for islet morphology, glucose tolerance, glucose-stimulated insulin secretion, and susceptibility to streptozotocin. Transcriptional regulatory functions of SIRT6 in primary islets were evaluated by RNA-seq analysis. RT-qPCR and immunoblot were used to verify and investigate the gene expression changes. Chromatin occupancies of SIRT6, H3K9Ac, H3K56Ac, and active RNA Polymerase II were evaluated by chromatin immunoprecipitation. Results: Deletion of Sirt6 in pancreatic endocrine progenitor cells did not affect endocrine morphology, beta cell mass, or insulin production, but did result in glucose intolerance and defective glucose-stimulated insulin secretion in mice. Conditional deletion of Sirt6 in adult beta cells reproduced the insulin secretion defect. Loss of Sirt6 resulted in aberrant upregulation of TXNIP. SIRT6 deficiency led to increased accumulations of H3K9Ac, H3K56Ac, and active RNA polymerase II at the promoter region of Txnip. SIRT6-deficient beta cells exhibited a time-dependent increase of H3K9Ac, H3K56Ac, and TXNIP levels. Furthermore, beta-cell-specific SIRT6 deficient mice showed increased sensitivity to streptozotocin. Conclusions: Our results reveal that SIRT6 suppresses Txnip expression in beta-cells via deacetylation of histone H3 and plays a critical role in maintaining beta-cell function and viability. Agents that preserve SIRT6 activity may be beneficial for preventing the progression of type 2 diabetes.

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SIRT6 overexpression predicts high risk of metastasis and relapse in Delta16HER2-positive breast cancer [RNA-seq]

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