TW9 is a dual inhibitor of bromodomain 2 (BD2) in bromodomain-containing protein 4 (BRD4) and histone deacetylase 1 (HDAC1; IC50s = 0.074 and 0.29 μM, respectively).1It is selective for BD2 over BD1 in BRD4 (IC50= 0.72 μM) and for HDAC1 over HDAC2 (IC50= 2.5 μM). TW9 (50 nM) induces apoptosis in, and inhibits proliferation of, MIA PaCa-2 pancreatic cancer cells. It induces cell cycle arrest at the G1phase in HPAC pancreatic cancer cells when used at a concentration of 2 μM. TW9 acts synergistically with gemcitabine to reduce the viability of HPAC cells. 1.Zhang, X., Zegar, T., Weiser, T., et al.Characterization of a dual BET HDAC inhibitor for treatment of pancreatic ductal adenocarcinomaInt. J. Cancer147(10)2847-2861(2020)
Givinostat (ITF-2357) is a HDAC inhibitor with an IC50 of 198 and 157 nM for HDAC1 and HDAC3, respectively. Givinostat (ITF2357) suppresses total LPS-induced IL-1β production robustly compared with the reduction by ITF3056. At 25, 50, and 100 nM, Givinostat reduced IL-1β secretion more than 70%. Givinostat (ITF-2357) suppresses the production of IL-6 in PBMCs stimulated with TLR agonists as well as the combination of IL-12 plus IL-18. IL-6 secretion decreases to 50% at 50 nM Givinostat, but at 100 and 200 nM, there is no reduction[1]. As shown by the CCK-8 assay, Givinostat (ITF-2357) inhibits JS-1 cell proliferation in a concentration-dependent manner. Treatment with Givinostat ≥500 nM is associated with significant inhibition of JS-1 cell proliferation (P<0.01). Also, the cell inhibition rate significantly differs between the group cotreated with Givinostat ≥250 nM plus LPS and the group without LPS treatment (same Givinostat concentration) (P<0.05)[2]. Givinostat (ITF2357) at 10 mg kg is used as a positive control and, as expected, reduced serum TNFα by 60%. Strikingly, pretreatment of ITF3056 starting at 0.1 mg kg significantly reduces the circulating TNFα by nearly 90%. To achieve a significant increase in serum IL-1β production, a higher dose of LPS is injected (10 mg kg), and blood is collected after 4 h. Similarly, when pretreated with lower doses of Givinostat (ITF-2357) (1 or 5 mg kg), there is a 22% reduction for 1 mg kg and 40% for 5 mg kg[1]. [1]. Li S, et al. Specific inhibition of histone deacetylase 8 reduces gene expression and production of proinflammatory cytokines in vitro and in vivo. J Biol Chem. 2015 Jan 23;290(4):2368-78. [2]. Wang YG, et al. Givinostat inhibition of hepatic stellate cell proliferation and protein acetylation. World J Gastroenterol. 2015 Jul 21;21(27):8326-39. [3]. Leoni F, et al. The histone deacetylase inhibitor ITF2357 reduces production of pro-inflammatory cytokines in vitro and systemic inflammation in vivo. Mol Med. 2005 Jan-Dec;11(1-12):1-15.
CAY17c is an inhibitor of bromodomain-containing protein 4 (BRD4; IC50= 0.71 μM), as well as class I histone deacetylases (HDACs; IC50s = 0.046, 0.058, 0.075, and 0.167 μM for HDAC1, -2, -3, and -8, respectively) and class IIb HDACs (IC50s = 0.073 and 0.923 μM for HDAC6 and HDAC10, respectively).1It is selective for these enzymes over BRD2, -3, and -T (IC50s = >20 μM for all), as well as over HDAC4, -5, -7, -9, and -11 (IC50s = >10 μM for all). CAY17c inhibits the proliferation of HCT116, SW620, and DLD-1 colorectal cancer cells (IC50s = 0.45, 1.78, and 2.11 μM, respectively), as well as induces apoptosis and autophagy in HCT116 cells. It reduces tumor growth in an HCT116 mouse xenograft model when administered at doses of 15 and 30 mg/kg. 1.Pan, Z., Li, X., Wang, Y., et al.Discovery of thieno[2,3-d]pyrimidine-based hydroxamic acid derivatives as bromodomain-containing protein 4/histone deacetylase dual inhibitors induce autophagic cell death in colorectal carcinoma cellsJ. Med. Chem.63(7)3678-3700(2020)