1.Structural insights into HDAC6 tubulin deacetylation and its selective inhibition.
Miyake Y;Keusch JJ;Wang L;Saito M;Hess D;Wang X;Melancon BJ;Helquist P;Gut H;Matthias P Nat Chem Biol. 2016 Sep;12(9):748-54. doi: 10.1038/nchembio.2140. Epub 2016 Jul 25.
We report crystal structures of zebrafish histone deacetylase 6 (HDAC6) catalytic domains in tandem or as single domains in complex with the (R) and (S) enantiomers of trichostatin A (TSA) or with the HDAC6-specific inhibitor nexturastat A. The tandem domains formed, together with the inter-domain linker, an ellipsoid-shaped complex with pseudo-twofold symmetry. We identified important active site differences between both catalytic domains and revealed the binding mode of HDAC6 selective inhibitors. HDAC inhibition assays with (R)- and (S)-TSA showed that (R)-TSA was a broad-range inhibitor, whereas (S)-TSA had moderate selectivity for HDAC6. We identified a uniquely positioned α-helix and a flexible tryptophan residue in the loop joining α-helices H20 to H21 as critical for deacetylation of the physiologic substrate tubulin. Using single-molecule measurements and biochemical assays we demonstrated that HDAC6 catalytic domain 2 deacetylated α-tubulin lysine 40 in the lumen of microtubules, but that its preferred substrate was unpolymerized tubulin.
2.Synthesis and Pharmacological Evaluation of Selective Histone Deacetylase 6 Inhibitors in Melanoma Models.
Tavares MT;Shen S;Knox T;Hadley M;Kutil Z;Bařinka C;Villagra A;Kozikowski AP ACS Med Chem Lett. 2017 Sep 5;8(10):1031-1036. doi: 10.1021/acsmedchemlett.7b00223. eCollection 2017 Oct 12.
Only a handful of therapies offer significant improvement in the overall survival in cases of melanoma, a cancer whose incidence has continued to rise in the past 30 years. In our effort to identify potent and isoform-selective histone deacetylase (HDAC) inhibitors as a therapeutic approach to melanoma, a series of new HDAC6 inhibitors based on the nexturastat A scaffold were prepared. The new analogues ;4d;, ;4e;, and ;7b; bearing added hydrophilic substituents, so as to establish additional hydrogen bonding on the rim of the HDAC6 catalytic pocket, exhibit improved potency against HDAC6 and retain selectivity over HDAC1. Compound ;4d; exhibits antiproliferative effects on several types of melanoma and lymphoma cells. Further studies indicates that ;4d; selectively increases acetylated tubulin levels ;in vitro; and elicits an immune response through down-regulating cytokine IL-10. A preliminary ;in vivo; efficacy study indicates that ;4d; possesses improved capability to inhibit melanoma tumor growth and that this effect is based on the regulation of inflammatory and immune responses.
