[Role of WAVE1 in drug resistance of K562/A02 leukemia cells].
ABSTRACT To investigate if WAVE1 is involved in mult drug-resistance (MDR) of human leukemia cell line K562/A02.
The level of WAVE1 in K562 and K562/A02 cells was assayed by Western blot and RT-PCR; K562 cells and K562/A02 cells were transient transfected with pEFBOS-WAVE1 reconstructed plasmid or specifically siRNA to WAVE1. 50% inhibition concentration (IC50) of doxorubicin on K562/A02 was determined by WST-8 assay. Hoechst33258 staining was used to examine cell morphological changes and to calculate percentage of apoptotic nuclei. The mRNA level of mdrl was assayed by RT-PCR. The Bcl-2 protein was assayed by Western blot.
1. The WAVE1 expression at mRNA and protein level in K562/A02 cells was increased by about 70% and 63% respectively as compared with that in K562 cells. 2. Overexpression of WAVE1 in K562 cells by transient transfection significantly increased the resistance to doxorubicin, and increased IC50 from (0.05 +/- 0.00) microg/ml to (2.99 +/- 0.12) microg/ml, and at 1 microg/ml or 5 microg/ml of doxorubicin treatment, cell apoptotic nuclei rate was decreased by 30% or 35% respectively. 3. Suppression of WAVE1 in K562/A02 cells by siRNA resulted in a reversal of MDR to doxorubicin, and decreased IC50 from (4.29 +/- 0.15) microg/ml to (1.85 +/- 0.07) microg/ml, and at 1 microg/ml or 5 microg/ml of doxorubicin treatment, cell apoptotic nuclei rate was increased by 24% or 21% respectively. 4. Overexpression of WAVE1 in K562 cells significantly increased the mdrl mRNA and the Bcl-2 protein, and suppression of WAVE1 in K562/A02 cells by siRNA decreased the mRNA and the protein.
WAVE1 involves in the MDR mechanisms in K562/A02 leukemia cells through regulation the level of mdrl and Bcl-2.
[show abstract] [hide abstract]
ABSTRACT: Bcl-2 proteins are over-expressed in many tumors and are critically important for cell survival. Their anti-apoptotic activities are determined by intracellular localization and post-translational modifications (such as phosphorylation). Here, we showed that WAVE1, a member of the Wiskott-Aldrich syndrome protein family, was over-expressed in blood cancer cell lines, and functioned as a negative regulator of apoptosis. Further enhanced expression of WAVE1 by gene transfection rendered leukemia cells more resistant to anti-cancer drug-induced apoptosis; whereas suppression of WAVE1 expression by RNA interference restored leukemia cells' sensitivity to anti-drug-induced apoptosis. WAVE1 was found to be associated with mitochondrial Bcl-2, and its depletion led to mitochondrial release of Bcl-2, and phosphorylation of ASK1/JNK and Bcl-2. Furthermore, depletion of WAVE1 expression increased anti-cancer drug-induced production of reactive oxygen species in leukemia cells. Taken together, these results suggest WAVE1 as a novel regulator of apoptosis, and potential drug target for therapeutic intervention of leukemia.Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 11/2009; 24(1):177-86. · 8.30 Impact Factor