β-arrestin 1 facilitates acetylation of IL-6 gene promoter to affect proliferation and apoptosis of non-small cell lung cancer cells / 肿瘤

ABSTRACT

Objective: To investigate the effects of β-arrestin 1 (ARRB1) on apoptosis and proliferation of non-small cell lung cancer (NSCLC) cells, and to explore the underlying molecular mechanism. Methods: In NSCLC cell lines A549 and H1650, the expression of ARRB1 was knocked down by transfection of siRNA or over-expressed by transfection of Flag-ARRB1 recombinant plasmids, which was verified by real-time fluorescent quantitative PCR and Western blotting. The effects of down-regulating and up-regulating ARRB1 expression on the transcription and secretion of interleukin-6 (IL-6) were detected by real-time fluorescent quantitative PCR and ELISA method, respectively. The interaction between ARRB1 and p300 was detected by protein immunocoprecipitation. The recruitment of p300 and the acetylation of histone in IL-6 promoter region after ARRB1 knock-down or overexpression were detected by chromatin immunocoprecipitation. The proliferation and apoptosis of ARRB1 silencing A549 cells were detected by CCK-8 assay and FCM, respectively. The expression and activation of IL-6/signal transducer and activator of transcription 3 (STAT3) signaling pathway-related molecules in ARRB1 silencing or overexpression NSCLC cells were investigated by Western blotting. Results: In ARRB1-silenced or overexpressed NSCLC cell lines A549 and H1650, ARRB1 enhanced the transcription and production of IL-6 (all P < 0.05). The interaction of ARRB1 and p300 was confirmed by forward and reverse immunocoprecipitation. After ARRB1 knockdown or overexpression, it was found that ARRB1 enhanced the recruitment of p300 in IL-6 promoter region (both P < 0.01) and increased the acetylating of IL-6 promoter (both P < 0.05). Moreover, ARRB1 could facilitate the growth (P < 0.01) and apoptosis inhibition of NSCLC cells. ARRB1 could promote the phosphorylation of STAT3 and the expressions of c-Myc and Bcl-2 proteins. Conclusion: In NSCLC cells, ARRB1 interacts with p300, facilitates the recruitment of p300 to IL-6 promoter, and up-regulates the acetylation of histone H3 and H4 in IL-6 promoter, leading to transcriptional activation of IL-6. So that ARRB1 positively regulates the activation of IL-6/STAT3 signaling through promoting the phosphorylation of STAT3 and the expressions of c-Myc and Bcl-2 proteins, contributing to the growth and anti-apoptosis of NSCLC cells.