Effect of adenovirus-mediated interleukin 24 on glioma cells and its mechanism

Objective To investigate the effect of adenovirus-mediated interleukin 24 (Ad-IL-24) on proliferation and apoptosis of glioma cells and its mechanism. Methods We set up Ad-IL-24 group, Ad-GFP group and PBS group. The expression of IL-24 in each group was detected by real-time quantitative PCR (qRT-PCR) and Western blot, and the proliferation activity of 3 groups of U251 cells was detected by MTT assay. Apoptosis of U251 cells was detected by flow cytometry. The expression of Survivin and Bax in U251 cells was detected by qRT-PCR. Results (1) In group PBS and group Ad-GFP, U251 cells adhered well and grew well. The number of adherent growth in group Ad-IL-24 was significantly reduced and the infection efficiency in group Ad-IL-24 and Ad-GFP was above 95%. (2) The results of qRT-PCR and Western blot showed that the expression levels of IL-24 in PBS group and Ad-GFP group were significantly lower than those in Ad-IL-24 group (all P<0.05). (3) U251 cells infected with 100 MOI Ad-IL-24 for 48 h significantly inhibited the growth of U251 cells and the inhibitory effect was significantly higher than that in PBS and Ad-GFP groups (both P<0.05) and presented certain time dependence (P<0.05). (4) The U251 cells were infected with 100 MOI Ad-IL-24 for 48 h. Flow cytometry results showed that the rate of cell apoptosis in Ad-IL-24 group was 39.2%±4.2%, which was significantly higher than that of PBS group and Ad-GFP group (2.5%±1.0% and 4.9%±2.3%, respectively, both P<0.05). (5) The expression level of Survivin in Ad-IL-24 group was significantly lower than that in PBS group and Ad-GFP group (both P<0.05). The expression level of Bax was significantly higher in Ad-IL-24 group than in PBS group and Ad-GFP group (both P<0.05). Conclusions Ad-IL-24 expression could significantly inhibit the growth of U251 cells and induce apoptosis. It is speculated that the mechanism of action may be down-regulating the expression of apoptosis-inhibiting gene Survivin and up-regulating the expression of apoptosis-promoting gene Bax. Key words: Glioma; Cell proliferation; Apoptosis; Interleukin-24; Survivin; Bax