Effect of PML(NLS^-) Gene Mediated by Recobinant Adenovirus Vector on Emodin-induced Apoptosis of HL-60 Cells

Objective To determine the effect and mechanism of action of PML(NLS^-) gene on emodin-induced apoptosis of human HL-60 cells. Methods HL-60 cells were infected with recombinant adenovirus Ad-PML(NLS^-) and Ad-KZ, respectively. The PML(NLS^-) gene was detected by Real-time PCR(RT-PCR) and Western blot. The proliferation level of the HL-60 cells was determined by MTT method. The HL-60 cells were treated with 60 μmol/L emodin for 72 h and then analyzed by flow cytometry for their cell cycle and apoptosis rate. The transcription levels of apoptosis-related BCL-2, BAX and C-MYC genes were determined by RT-PCR. The translation levels of those genes were determined by Western blot. Results Compared with normal controls and the HL-60 cells infected with Ad-KZ, the mRNA and protein expression levels of PML(NLS^-) gene increased significantly in the HL-60 cells infected with Ad-PML(NLS^-). Increased proliferation levels of the Ad-PML(NLS^-) infected HL-60 cells were observed in those treated with 60 μmol/L emodin, which showed decreased percentage of cells at G₁ phase, increased percentage of cells at S phase, and decreased emodin-induced apoptosis. The levels of mRNA transcription and protein expression of BAX gene decreased, while those of BCL-2 and C-MYC genes increased significantly. Conclusion The over-expression of PML(NLS^-) gene might promote the proliferation and arrest the apoptosis of HL-60 cells by up-regulating the expressions of BCL-2 and C-MYC genes and down-regulating the expression of BAX gene.