Down regulation of PEBP4 sensitizes drug-resistant lung cancer cells

Objective To detect the relationship between expression of in lung cancer cell line A549 and the cell toxicity induced by cisplatin(DDP), and to investigate the mechanism of the effect of ectopic expression of PE-binding protein 4(PEBP4). Methods Construction of pcDNA3-PEBP4 recombinant plasmid, and then transfected into lung cancer cell A549, detection of A549 cells in each group PEBP4 expression. MTT were detected in transfected A549 cells, and after 48 h of DDP treatment, the changes of A549 cell viability in each group were detected by A549 cell apoptosis and the expression of p53 protein. We employed a luciferase reporter-gene assay to confirm PEBP4 as a target gene of miR-34a and the effect of miR-34a on the expression of PEBP4 in A549 cells was detected by Western blot. Results The expression of PEBP4 protein in pcDNA3-PEBP4 transfected group was significantly higher than that in control group and shRNA PEBP4 transfection group(P<0.01). After 48 h of DDP treatment, MTT assays indicated that A549 cell viability was significantly lower in the DDP-treated group compared with the control group(P<0.01). The viability of A549 cells in the pcDNA3-PEBP4-transfected group was lower than that in the control group(P<0.05) but higher than that in either the DDP-treated or PEBP4-shRNA-transfected groups(P<0.05). Flow cytometry detection results and Western blot detection results showed that dosing of the DDP-treated group, the apoptotic cell number and p53 protein expression level was significantly higher than the normal control group(P<0.01); pcDNA3-PEBP4 transfection group apoptosis cell number and p53 expression levels were higher than the normal control group(P<0.05), lower than that of DDP plus drug group and PEBP4 shRNA transfected group(P<0.05); and PEBP4 shRNA transfected group apoptosis and p53 expression level was significantly higher than that of normal control group(P<0.01) and DDP and medication group(P<0.05). The luciferase reporter-gene assay showed that the relative luciferase activity after transfection with a miR-34a mimic was significantly reduced compared with the control group(P<0.01). In A549 cells transfected with mimic miR-34a 48 h, the expression of PEBP4 protein was significantly decreased(P<0.01). Conclusion Overexpression of PEBP4 reduced the sensitivity of A549 cells to DDP induced cytotoxicity, which was mainly accomplished by affecting the expression of p53 protein or by the regulation of miR-34a. Key words: PE-binding protein 4, human; Lung cancer; RNA interference; Cisplatin; MiR-34a, human