The histone deacetylase inhibitor Entinostat enhances polymer‐mediated transgene expression in cancer cell lines

Abstract

Eukaryotic cells maintain an immense amount of genetic information by tightly wrapping their DNA around positively charged histones. While this strategy allows human cells to maintain more than 25,000 genes, histone binding can also block gene expression. Consequently, cells express histone acetyl transferases (HATs) to acetylate histone lysines and release DNA for transcription. Conversely, histone deacetylases (HDACs) are employed for restoring the positive charge on the histones, thereby silencing gene expression by increasing histone-DNA binding. It has previously been shown that histones bind and silence viral DNA, while hyperacetylation of histones via HDAC inhibition restores viral gene expression. In this study, we demonstrate that treatment with Entinostat, an HDAC inhibitor, enhances transgene (luciferase) expression by up to 25-fold in human prostate and murine bladder cancer cell lines when used with cationic polymers for plasmid DNA delivery. Entinostat treatment altered cell cycle progression, resulting in a significant increase in the fraction of cells present in the G0/G1 phase at low micromolar concentrations. While this moderate G0/G1 arrest disappeared at higher concentrations, a modest increase in the fraction of apoptotic cells and a decrease in cell proliferation were observed, consistent with the known anticancer effects of the drug. DNase accessibility studies revealed no significant change in plasmid transcriptional availability with Entinostat treatment. However, quantitative PCR studies indicated that Entinostat treatment, at the optimal dose for enhancing transgene expression, led to an increase in the amount of plasmid present in the nucleus in two cancer cell lines. Taken together, our results show that Entinostat enhances polymer-mediated transgene expression and can be useful in applications related to transient protein expression in mammalian cells.

Dysregulation of Sirtuin 2 (SIRT2) and histone H3K18 acetylation pathways associates with adverse prostate cancer outcomes

“…Compacted nucleosomes block gene expression by sequestering the nucleotide sequences necessary for transcription factor binding and RNA polymerase recruitment [ 22 ]. Histone acetyl transferases (HATs) and histone deacetylases (HDACs) dictate the presence of acetyl marks [ 23 , 24 ], which regulate the openness of chromatin. Thus, the processes for adding and removing these marks have become putative targets for cancer therapy.…”

Histone acetyltransferase general control non‐repressed protein 5 (GCN5) affects the fatty acid composition of Arabidopsis thaliana seeds by acetylating fatty acid desaturase3 (FAD3)

“…For example, Gong et al (2002) reported that DNA methylation could mediate the silencing of exogenous promoters (Gong et al, 2002). Recently, Elmer et al (2015) provided an example of histone acetylation-regulated transgene expression (Elmer et al, 2015). In this study, we found that the expression levels of FAD3 in the 35S::FAD3/gcn5 transgenic lines were lower than those in the 35S::FAD3/Ws, which resulted in differing ALA/LA ratios in the 35S::FAD3/gcn5 and 35S::FAD3/Ws plants.…”

Enhancement of Transgene Expression by NF-Y and CTCF

“…12,13 Many DNMT inhibitors such as 5-Aza-2'-deoxycytidine and zebularine have been used to prevent methylation of DNA. 14,15 Several inhibitors of histone deacetylases (HDACs) have also been shown to increase transgene expression, including Entinostat (a HDAC 1/3 inhibitor) 16 , Tubacin (HDAC6i) 17 , Trichostatin A (HDAC6i) [18][19][20] , and Vorinostat (pan-HDACi) [21][22][23] . However, it is important to note that some of these HDAC inhibitors enhance transgene expression by influencing cytoplasmic transport instead of directly influencing histone modifications.…”