Chaetocin, a natural thiodioxopiperazine product from Chaetomium species, is a lysine-specific histone methyltransferase inhibitor, which reduces the histone methyltransferase effects of SUV39H1 with IC50 value of 0.8 μM.
SUV39H1 is a histone methyltransferase that can methylate Lys-9 of histone H3 and plays an important role in many processes including repression of MYOD1-stimulated differentiation, regulation of the cell cycle and celll differentiation, and regulation of telomere length.
Chaetocin was found to have apoptotic effects on some cancer cells. In patient CD138+ myeloma cells, chaetocin has the potent antimyeloma activity which is attributable to reactive oxygen species (ROS) induction imposed by inhibition of the redox enzyme thioredoxin reductase [1].  Chaetocin reduced the methylation of H3K9 and H3K27 in HL-60 and KG-1a cells [2].
The component has also been used in animal models to study the role of SUV39H1. This component exhibits anti-proliferative activity and anti-cancer effect in a mouse myeloma xenografts model [3].
References:
1.Isham CR, Tibodeau JD, Jin W, Xu R, Timm MM, Bible KC. Chaetocin: a promising new antimyeloma agent with in vitro and in vivo activity mediated via imposition of oxidative stress. Blood 2007,109:2579-2588.
2.Lai YS, Chen JY, Tsai HJ, Chen TY, Hung WC. The SUV39H1 inhibitor chaetocin induces differentiation and shows synergistic cytotoxicity with other epigenetic drugs in acute myeloid leukemia cells. Blood Cancer J 2015,5:e313.
3.Isham CR, Tibodeau JD, Bossou AR, Merchan JR, Bible KC. The anticancer effects of chaetocin are independent of programmed cell death and hypoxia, and are associated with inhibition of endothelial cell proliferation. Br J Cancer 2012,106:314-323.