[Silencing PBX1 expression induces apoptosis and ROS production of lung cancer cells]

Objective: To investigate the effects of pre-B lymphocytic leukemia transcription factor (PBX1) expression on the apoptosis, reactive oxygen species (ROS) content and transcriptional activation factor 3 (STAT3) signaling pathway of lung cancer cells. Methods: Real-time quantitative polymerase chain reaction was used to detect the expression level of PBX1 in lung cancer tissues and adjacent tissues. The correlation between PBX1 expression level and clinical pathological parameters of patients were analyzed. Western blot was used to detect the protein expression level of PBX1 in human lung cancer cell lines, including A549, SPC-A1, SK-MES-1 and H1299. A549 cells were transfected with blank control (blank group), negative control (NC group) or PBX1 small interfering RNA (siRNA group), respectively. The cells apoptosis and ROS content were detected by flow cytometry. The protein expression levels of PBX1, STAT3, phosphorylated STAT3 (p-STAT3), B cell lymphoma/leukemia-2 (Bcl-2) and survivin in each group were detected by western blot. Results: The expression level of PBX1 mRNA in lung cancer was (2.36±0.23), significantly higher than (1.02±0.15) in paracancerous tissues (P<0.05). The expression level of PBX1 was correlated with lung cancer differentiation, lymph node metastasis and TNM stage (P<0.05). The expression levels of PBX1 in human lung cancer cells A549, SPC-A1, SK-MES-1 and H1299 were (0.454±0.038), (0.403±0.034), (0.311±0.028) and (0.377±0.035), respectively, significantly higher than (0.041±0.007) of human normal lung cells MRC-5 (P<0.05). The expression level of PBX1 protein in A549 cells transfected with PBX1 siRNA was (0.082±0.010), significantly lower than (0.704±0.065) of the blank group (P<0.05). The apoptosis rate and ROS content of siPBX1 group were (30.78±3.64)% and (51.55±5.03), respectively, significantly higher than (3.92±0.27)% and (22.36±1.31) of blank group (P<0.05). The protein expressions of p-STAT3, Bcl-2 and survivin were (0.051±0.006), (0.202±0.018) and (0.068±0.008), respectively, significantly lower than (0.172±0.010), (0.425±0.041) and (0.196±0.021) of blank group (P<0.05). Conclusion: Inhibition of PBX1 expression can induce the apoptosis of lung cancer cell, the mechanism may be related to ROS production and down-regulation of STAT3 signal.