Relationship between the As2O3 Induced Expression of NF-κB and Drug Resistance in K562/ADR Cells.

Abstract Summery: Anti-apoptosis is one of drug resistance mechanisms in leukemic cells. It was found in our early study that As2O3 can induce apoptosis of K562 cells, and this effect involve the degradation of IκB-αand consequently the activation of NF-κB. The relationship between drug resistance of leukemic cells and the expression of both IκB-αand NF-κB associated with apoptosis induced by arsenic trioxide(As2O3) was studied in K562 and K562/ADR cells. Methods: Apoptosis was induced in K562 and K562/ADR cells cultured with As2O3 in different concentrations. Western blot was used to analyze the expression of NF-κB in nuclear and IκB-α in cytoplasm of these cells. Apoptosis and degradation of IκB-αprotein were also observed by flow cytometry. Results: The suppressive effect of As2O3 on proliferation of K562/ADR was lower than that in K562 cell, IC50 values were 19.07μmol/L and 5.26μmol/L, respectively. After exposure to As2O3, the ratio of apoptosis cells increased with the concentration of As2O3 in K562 cells, from(13.25±1.83)% to (50.56±8.62)% with variation of As2O3 from 1μmol/L to 4μmol/L(P<0.05). The ratio of apoptosis cells in K562/ADR cultured with 4μmol/L As2O3 was significantly lower than that in K562 cells, (8.00±1.47)% vs. (50.56±8.62)%, (P<0.05). The level of IκB-α in K562 cytoplasm was down-regulated from (88.07±0.99)% to (49.21±0.95)%, (P<0.01) after As2O3 stimulation, while NF-κB in nuclear was up-regulated, that was not found in K562/ADR cells. Conclusion: As2O3 could induce apoptosis of K562 cells, associated with the degradation of IκB-αand the activation of NF-κB. There were resistance to As2O3 induced apoptosis and an abnormal regulation of NF-κB expression by As2O3 in K562/ADR cells.