NS3694 (Synonyms: Apoptosis Inhibitor II)

IC50: approximately 50 μM for cytochrome c-induced caspase activation in HeLa cell cytosolic extracts

NS3694 inhibits apoptosome formation and caspase activation.

The release of mitochondrial proapoptotic proteins into the cytosol is a critical event in apoptosis signaling, resulting in the activation of caspases. Once in the cytosol, cytochrome c triggers the formation of a caspase-activating protein complex called the apoptosome, while Smac/Diablo and Omi/htra2 antagonize the caspase inhibitory effect.

In vitro: Previous study found that NS3694, and its two analogs (NS1764 and NS1784) were well-tolerated by MCF-7S1 breast cancer cells at concentrations up to 100, 50, and 25 μM, respectively. Moreove, all three compounds could not inhibit recombinant caspase 9 and caspase 3 at concentrations ranging from 25 to 100 μM. In addition, NS3694 was able to inhibit the co-immunoprecipitation of caspase 9 and Apaf-1 from HeLa cell cytosol stimulated by cytochrome c and dATP. NS3694 could also inhibit the formation of the active 700-kDa apoptosome complex, but had no effect on TNF-induced caspase-independent death of WEHI-S cells. NS3694 did not inhibit FasL-induced caspase activation or death in type I cells neither [1].

In vivo: Up to now, there is no animal in vivo study reported.

Clinical trial: So far, no clinical study has been conducted.

Reference:
[1] Lademann, U. ,Cain, K.,Gyrd-Hansen, M., et al. Diarylurea compounds inhibit caspase activation by preventing the formation of the active 700-kilodalton apoptosome complex. Mol.Cell Biol. 23(21), 7829-7837 (2003).