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

Objective: To acquire a deep understanding of the possible mechanisms of realgar in the treatment of acute promyelocytic leukemia (APL). Method: All- trans retinoic acid (ATRA) resistant APL cell line MR 2 was used as in vitro model. The effect of realgar on MR 2 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. Result: The viability and growth of MR 2 cell were inhibited after the treatment, to some extent, in a dose and time dependent manner. After being treated with realgar, MR 2 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-G 1 cells were observed by flow cytometry, as well as AnnexinⅤ FITC +/PI -cells. DNA ladder could be found by DNA gel electrophoresis. Conclusion: Realgar can induce apoptosis of ATRA resistant APL cell line MR 2 , Which shows the therapeutic effect of realgar on APL may be different from that of ATRA.