High impact information on NSC83265

• S-trityl-L-cysteine inhibits Eg5-driven microtubule sliding velocity in a reversible fashion with an IC(50) of 500 nm [1].
• The results presented here together with the proven effect on human tumor cell line growth make S-trityl-L-cysteine a very attractive starting point for the development of more potent mitotic inhibitors [1].
• In vitro, S-trityl-L-cysteine targets the catalytic domain of Eg5 and inhibits Eg5 basal and microtubule-activated ATPase activity as well as mant-ADP release [1].
• Here we show that in cell-based assays S-trityl-L-cysteine does not prevent cell cycle progression at the S or G(2) phases but inhibits both separation of the duplicated centrosomes and bipolar spindle formation, thereby blocking cells specifically in the M phase of the cell cycle with monoastral spindles [1].
• Following removal of S-trityl-L-cysteine, mitotically arrested cells exit mitosis normally [1].

Biological context of NSC83265

• Identification of the protein binding region of S-trityl-L-cysteine, a new potent inhibitor of the mitotic kinesin Eg5 [2].
• We have used hydrogen-deuterium exchange mass spectrometry and directed mutagenesis to identify the secondary structure elements that form the binding sites of new Eg5 inhibitors, in particular for S-trityl-l-cysteine, a potent inhibitor of Eg5 activity in vitro and in cell-based assays [2].
• Subsequent cell-based assays revealed that S-trityl-L-cysteine induced mitotic arrest in HeLa cells (IC50, 700 nmol/L) with characteristic monoastral spindles [3].
• Blocking Eg5 expression with antisense oligonucleotide (Eg5-ASO) or inhibiting its activity with the small-molecule Eg5 inhibitor, S-trityl-L-cysteine induced G(2)/M cell cycle block and subsequent cell death in both Imatinib-sensitive and -resistant cells [4].

Associations of NSC83265 with other chemical compounds

• We show here that S-trityl-l-cysteine and monastrol both bind to the same region on Eg5 by induced fit in a pocket formed by helix alpha3-strand beta5 and loop L5-helix alpha2, and both inhibitors trigger similar local conformational changes within the interaction site [2].
• Among the 10 compounds tested, only SAMC, diallyl disulfide (DADS), and S-trityl-L-cysteine (trityl-cys) cause significant inhibition of cell growth with IC(50) values of 150, 56, and 0.9 micromol/L, respectively [5].

Gene context of NSC83265

• Replacement of the Tyr125-Glu145 region with the equivalent region in the Neurospora crassa conventional kinesin heavy chain prevents the inhibition of the Eg5 ATPase activity by S-trityl-l-cysteine [2].

References