The Mechanism Of Arsenic Trioxide And STI571 Inducing Apoptosis Of K562 Cells Alone Or In Combination

Objective: To investigate the mechanism of Arsenic Trioxide (ATO) and STI571 inducing apoptosis of K562 cells which express P210bcr/abl and whether the two drugs have synergistic effect.Methods: Apoptosis was analyzed by cell proliferation, cell viability, morphological changes, colony formation, DNA-PI staining. Transcriptional levels of BC!-XL and bcr/abl were assayed by semiquantitative reverse transcriptase ploymerase chain reaction. Elisa kits were also used to analyze cytosolic cytochrome C and Caspase-3.Results: The growth of K562 cells which were treated by 2.5μ mol/L ATO and 0.5μmol/L STI571 for 2 days could be inhibited, and cells could be induced to apoptosis. Apoptotic morphology can be seen. ATO and STI571 both could make K562 cells arrest in G2/M phase, and the number of cells in G1 phase and S phase decreases significantly. These effects were all dose-time-dependent. In apoptosis process, Caspase-3 was activated and there was a cytosolic accumulation of cytochrome C. And STI571 can reduce the transcriptional level of Bcl-XL and bcr/abl, while ATO can only reduce the mRNA level of Bcl-XL. And the two drugs have synergetic activation.Conclusion: (1) ATO and STI571 could both inhibit the growth of K562 cells, and the effects were dose-time-dependent. (2) That ATO and STI571 could both induce K562 cells to apoptosis and make them arrestin G2/M phase is the main mechanism of the inhibition effect. (3) The signal pathway mediated by the cytosolic translocation of mitochondria cytochrome C is one of the mechanisms that ATO and STI571 induce apoptosis, and Caspase-3 is activated during the apoptosis. (4) We first prove the finding of Porosnicu, that ATO and STI571 can downregulate the pathogenesis fusion gene of CML-bcr/abl and the anti-apoptotic gene Bcl-XL.