Validation of the mitotic kinesin Eg5 as a therapeutic target in leukemia using S-trityl-L-cysteine

In this study, we investigated the antiproliferative effects of S-trityl-L-cysteine (STLC) in CML K562 cell lines. We observed that the concentrations of IC50 value causing significant inhibition of cell growth with 24, 48 and 72 h treatment were 5, 10 and 1 μM, respectively, using chemosensitivity assay. STLC specifically arrested the cells’ cycle progression at S phases at 12 or 24 h and did not interfere with G2/M progression. Subsequent studies demonstrated that STLC also triggered profound G2/M arrest following the detected early stage of apoptosis. These results were consistent with other observations that the formation of monopolar spindles was accompanied by a ring of chromosomes obtained by confocal microscopy, suggesting that STLC-induced apoptosis is independent of AIF in K562 cells. These findings may be useful in identifying such STLC small-molecular inhibitors as having anti-leukemic activity before clinical trials in the future.