Selective molecular inhibition of the HDAC6 ZnF-UBP binding domain impairs multiple myeloma cell proliferation

Histone deacetylase 6 (HDAC6) is overexpressed in multiple myeloma (MM) patients and may be involved in the acquisition of resistance to conventional treatments. Here, we propose a two-residue mutation impairing the HDAC6 ZnF-UBP domain. HDAC6 knockout and ZnF-UBP mutant RPMI 8226 MM cell lines were generated using CRISPR-Cas9. MM cells harboring this mutation showed impaired aggresome formation, cell growth and a dysregulated gene expression profile in a more pronounced manner than the HDAC6 knockout cells. To investigate the role of the HDAC6 ZnF-UBP domain in MM pathogenesis, we established two RPMI 8226 cell lines: one with a knock-out of HDAC6 (KO), and another one with a two-residue mutation in the HDAC6 ZnF-UBP domain (R1155A, Y1155A; RY) preventing its ubiquitin-binding capacity. Both cell lines were obtained by CRISPR-Cas9 edition. We then performed gene expression profiling analysis using data obtained by bulk RNA-seq of the three cell lines (RPMI 8226 WT, HDAC6 KO and HDAC6 RY).