[In vitro study on realgar induced apoptosis of all-trans acid resistant acute promeylocytic leukemia cell line (MR2)].

To acquire a deep understanding of the possible mechanisms of realgar in the treatment of acute promyelocytic leukemia (APL).All-trans retinoic acid (ATRA) resistant APL cell line MR2 was used as in vitro model. The effect of realgar on MR2 cell was observed by watching cell viability, cell growth, and by using Methy thiazolyl tetrazolium (MTT) assay, cell morphology, DNA gel electrophoresis and flow cytometry assay.The viability and growth of MR2 cell were inhibited after the treatment, to some extent, in a dose and time dependent manner. After being treated with realgar, MR2 cell presented morphologically some features of apoptotic cells such as intact cell membrane, chromatin condensation and nuclear fragmentation, and apoptotic body could be found by electron microscopy as well. Sub-G1 cells were observed by flow cytometry, as well as Annexin V FITC+/PI-cells. DNA ladder could be found by DNA gel electrophoresis.Realgar can induce apoptosis of ATRA resistant APL cell line MR2, Which shows the therapeutic effect of realgar on APL may be different from that of ATRA.