Antisense oligonucleotide targeting p53 increased apoptosis of MCF-7 cells induced by ionizing radiation

To investigate the effect of antisense compounds (AS) targeting human p53 mRNA on radiosensitivity of MCF-7 cells.

Western blotting and RTPCR were used to analyze the protein content and mRNA level. Additionally, cell proliferation, cell cycle and cell apoptosis were all analyzed in irradiated or sham-irradiated cells.

Among the five antisense compounds (AS), AS3 was identified to efficiently inhibit p53 mRNA level and protein content. Interestingly, AS3 transfer has little effect on cell proliferation in DU-145 cells (mutant p53) after ionizing radiation (IR). In contrast, a marked increase of cell apoptosis and growth inhibition were observed in MCF-7 cells (wild-type p53), suggesting that AS3 can increase radiosensitivity of MCF-7 cells. Additionally, it was also observed that the transfection of AS3 decreased the fraction of G1 phase cells, and increased the proportion of S phase cells compared to untreated cells 24 h after IR in MCF-7 cell lines.

AS3 transfection increases MCF-7 cell apoptosis induced by 5 Gy-radiation, and this mechanism may be closely associated with abrogation of G1 phase arrest.