Using Histone Deacetylase Inhibitors to Analyze the Relevance of HDACs for Translation.

Gene expression is regulated in part through the reversible acetylation of histones, by the action of histone acetyltransferases (HAT) and histone deacetylases (HDAC). HAT activity results in the addition of acetyl groups on the lysine residues of histone tails leading to decondensation of the chromatin, and increased gene transcription in general, whereas HDACs remove these acetyl groups, thus leading to an overall suppression of gene transcription. Recent evidence has elucidated that histones are not the only components of the proteome that are targeted by HATs and HDACs. A large number of nonhistone proteins undergo posttranslational acetylation. They include proteins involved in mRNA stability, protein localization and degradation, as well as protein-protein and protein-DNA interactions. In recent years, numerous studies have discovered increased HDAC expression and/or activity in numerous disease states, including cancer, where the upregulation of HDAC family members leads to dysregulation of genes and proteins involved in cell proliferation, cell cycle regulation, and apoptosis. These observations have pushed HDAC inhibitors (HDACi) to the forefront of therapeutic development of oncological conditions. HDACi, such as Vorinostat (Suberoylanilide hydroxamic acid (SAHA)), affect cancer cells in part by suppressing the translation of key proteins linked to tumorigenesis, such as cyclin D1 and hypoxia inducible factor 1 alpha (HIF-1α). Herein we describe methodologies to analyze the impact of the HDACi Vorinostat on HIF-1α translational regulation and downstream effectors.