[Effects of specific siRNA targeting at bcr-abl fusion gene and its combination with p27 gene clone on chronic myeloid leukemia cell line K562]

Abstract

This study was purposed to explore the effect of specific small interfering RNA targeting at bcr-abl fusion gene and its combination with p27 gene clone on the proliferation, cell cycle and apoptosis of chronic myeloid leukemia (CML) cell line K562. CML cell line K562 was used as the study object. A 21nt siRNA targeting at the fusion site of b3:a2 mRNA in bcr-abl fusion gene was designed, synthesized and transfected into the K562 cells as RNA interference group. Northern blot was used to detect the bcr-abl fusion gene, Western blot was used to detect the expression of P210 protein and apoptosis-related protein BCL-xL after the transfection. Meanwhile, p27 gene was amplified from peripheral blood mononuclear cells by RT-PCR, and was confirmed to be correct by sequencing, then p27-pcDNA3.1 vector was constructed and transfected into K562 cell line by Lipofectin. After being selected with G418, p27-pcDNA3.1-K562 cell clone stably expressing p27 was isolated. P27 protein was identified by Western blot. Finally, siRNA and p27 gene clone were together applied to K562 cells, the cell survival rate was tested by MTT. The cell cycle and the apoptosis were tested by flow cytometry. The result showed that in contrast with the control group, the expression level of bcr-abl fusion gene was much lower in siRNA group, about 18.4% of K562 cells in siRNA group were apoptotic at 24 hours after siRNA transfection, and the expression of apoptosis-associated protein BCL-xL was greatly down-regulated. The expression of P27 protein could be detected by Western blot in p27-pcDNA3.1-K562 cells. The strong inhibition of cell proliferation was observed in p27-pcDNA3.1-K562 cells, as compared with control K562 cells. The count of p27-pcDNA3.1-K562 cells in G(0)/G(1) phase increased apparently, but that in S phase declined greatly. Cell cycle was arrested in G(0)/G(1) phase. After the combination of p27-pcDNA3.1-K562 cells with specific siRNA, the percentage of apoptosis obviously increased and cell survival rate significantly declined. It is concluded that the specific siRNA distinctly inhibits the expression of bcr-abl fusion gene, and can induce K562 cell apoptosis. The combination of specific siRNA with P27 gene clone displays a synergy of inhibition and pro-apoptosis effects to K562 cells.