Induction of G(2)/M phase arrest and apoptosis by a new synthetic anticancer agent, DW2282, in promyelocytic leukemia (HL-60) cells

We studied the effect of DW2282-, {(S)-(+)-4-phenyl-1-[N-(4-aminobeazoyl)-i ndoline-5-sulfonyl-4,5-dihydro-2-imidazolone]-hydrochloride}, a newly devel oped anti-cancer agent, on cell proliferation, cell cycle progression, and induction of apoptosis in human promyelocytic leukemia (HL-60) cells. DW228 2, a diarylsulfonylurea compound, was cytotoxic to HL-60 cells, with an IC5 0 of 1.0 mug/mL. Treatment with DW2282 fragmented DNA in a concentration- a nd time-dependent manner, suggesting that these cells underwent apoptosis. Flow cytometric analysis further confirmed that DW2282-treated HL-60 cells were hypodiploid, in terms of DNA content, and were arrested at the G(2)/M phase. The cell cycle arrest was reversible upon the removal of DW2282. HL- 60 cells also underwent distinct morphological changes in response to DW228 2 treatment, including the appearance of elongated cells with conical tails and other apoptotic characteristics. G(2)/M phase cell cycle arrest was ac companied by a decrease in the levels of cdc2, a protein that plays a criti cal role for progression through the G(2)/M phase. Treatment of HL-60 cells with DW2282 was also associated with decreased levels of the anti-apoptoti c protein Bcl-2, activation of caspase-3, and proteolytic cleavage of poly( ADP-ribose) polymerase. Taken together, these results demonstrate that DW22 82 dramatically suppressed HL-60 cell growth by inducing apoptosis after G( 2)/M phase arrest. These findings are consistent with the possibility that G(2)/M phase arrest was mediated by the down-regulation of cdc2 levels in H L-60 cells. The data also suggest that DW2282 triggered apoptosis by decrea sing Bcl-2 levels and activating caspase-3 protease. These results provide important new information towards understanding the mechanisms by which DW2 282 and other diarylsulfonylureas mediate their therapeutic effects. (C) 20 01 Elsevier Science Inc. All rights reserved.