Biology subjects

Dahan, I.

Publications and source records attributed to Dahan, I..

2 recordsLinked to original sources

bioRxiv2022

Dexamethasone Inhibits Cytokine-Induced, DUOX2-Related VEGF-A Expression and DNA damage in Human Pancreatic Cancer Cells and Growth of Pancreatic Cancer Xenografts

Previously, we demonstrated that pro-inflammatory cytokines enhance dual oxidase 2 (DUOX2)-dependent production of reactive oxygen species by human pancreatic ductal carcinoma (PDAC) cells, and that DUOX2 expression is significantly increased in patients with early stages of PDAC. In genetically-engineered mouse models of PDAC, dexamethasone (Dex) decreases formation of pancreatic intraepithelial neoplasia (PanIn) foci as well as PDAC invasiveness. Herein, we report that Dex, in a concentration- and time-dependent fashion, inhibited pro-inflammatory cytokine (IFN-{gamma}/LPS/IL-17A/IL-4)-mediated enhancement of DUOX2 expression in BxPC-3, CFPAC-1, and AsPC-1 human PDAC cell lines, as well as DUOX2-induced DNA damage. The inhibitory effects of Dex were abolished by pre-treatment with the Dex antagonist RU-486. Examination of the human DUOX2 promoter in silico revealed a putative negative glucocorticoid receptor (GR) binding element (IRnGRE). Western analysis, using nuclear extracts from Dex-treated PDAC cells, demonstrated that Dex activated the glucocorticoid receptor in PDAC cell nuclei in the presence of certain co-repressors, such as NCoR-1/2 and histone deacetylases (HDAC1, 2, and 3). Dex produced no anti-proliferative effects on PDAC cells in vitro. However, Dex significantly decreased the growth of BxPC-3 xenografts while decreasing inflammatory and immune cell infiltration of the microenvironment, as well as the mRNA expression of DUOX2 and VEGF-A, in BxPC-3 tumors. In contrast, Dex had no effect on the growth of xenografts developed from MIA-PaCa cells that are unresponsive to pro-inflammatory cytokines in culture. In summary, these studies suggest that suppression of inflammation-related DUOX2 expression by Dex could diminish the oxidative milieu supporting PDAC growth and development.

pharmacology and toxicology↗

bioRxiv2021

HDAC9 structural variants disrupting TWIST1 transcriptional regulation lead to craniofacial and limb malformations

Structural variants (SVs) can affect protein-coding sequences as well as gene regulatory elements. However, SVs disrupting protein-coding sequences that also function as cis-regulatory elements remain largely uncharacterized. Here, we show that craniosynostosis patients with SVs containing the Histone deacetylase 9 (HDAC9) protein-coding sequence are associated with disruption of TWIST1 regulatory elements that reside within HDAC9 sequence. Based on SVs within the HDAC9-TWIST1 locus, we defined the 3 HDAC9 sequence (~500Kb) as a critical TWIST1 regulatory region, encompassing craniofacial TWIST1 enhancers and CTCF sites. Deletions of either Twist1 enhancers (eTw5-7{Delta}/{Delta}) or Ctcf site (Ctcf{Delta}/{Delta}) within the Hdac9 protein-coding sequence in mice led to decreased Twist1 expression and altered anterior\posterior limb expression patterns of Shh pathway genes. This decreased Twist1 expression results in a smaller sized and asymmetric skull and polydactyly that resembles Twist1+/- mouse phenotype. Chromatin conformation analysis revealed that the Twist1 promoter region interacts with Hdac9 sequences that encompass Twist1 enhancers and a Ctcf site and that interactions depended on the presence of both regulatory regions. Finally, a large inversion of the entire Hdac9 sequence (Hdac9INV/+) in mice that does not disrupt Hdac9 expression but repositions Twist1 regulatory elements showed decreased Twist1 expression and led to a craniosynostosis-like phenotype and polydactyly. Thus, our study elucidated essential components of TWIST1 transcriptional machinery that reside within the HDAC9 sequence, suggesting that SVs, encompassing protein-coding sequence, such as HDAC9, could lead to a phenotype that is not attributed to its protein function but rather to a disruption of the transcriptional regulation of a nearby gene, such as TWIST1.

genomics↗