Defining the targets of HDAC inhibitors in diffuse large B cell lymphoma

Lysine acetylation (Lys-Ac) is an abundant post-translational modification, occurring on thousands of proteins, which plays a regulatory role in all cellular processes. The sum total of Lys-Ac sites within a cell is called the 'acetylome', which is regulated by the opposing actions of acetyltransferase and histone deacetylase (HDAC) enzymes. Inhibition of HDACs in cancer cells, using small molecule HDAC inhibitors (HDACi), causes them to exit cell cycle and undergo apoptosis. However, the changes in the acetylome following HDAC inhibition have not been previously addressed in clinically relevant cancer cell lines, or patient samples. Plus, there is currently no logical rationale for which cell types are treated with HDACi. To address this, we plan to define the acetylome in diffuse large B-cell lymphoma (DLBCL) cells, an aggressive B-cell malignancy, treated with a panel of clinically relevant HDACi (e.g. Vorinostat). Experimental approach: DLBCL cells labelled with heavy/light amino acids are treated with HDACi for 6 hours, acetylated peptides are purified and then analysed by quantitative mass-spectrometry to identify relative changes in acetylation. By understanding the network of HDACi targets in cancer cells we can begin to use them in a more rational manner in the clinic.