Li Ye, Zhang Xu, Yang Jian, Zhang Yi, Zhu Dongming, Zhang Lifeng, Zhu Yanbo, Li Dechun, Zhou Jian
Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.
Pancreatic Disease Research Centre, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.
Oncotarget. 2017 Jun 28;8(38):63208-63222. doi: 10.18632/oncotarget.18736. eCollection 2017 Sep 8.
Bcl-2 interacting protein 3 (BNIP3) is involved in various cellular processes and is considered a key regulator of hypoxia-induced apoptosis. In the present study, the expression of BNIP3 in pancreatic cancer tissues, the correlation with clinicopathological characteristics and prognosis and the regulation of this protein in pancreatic cancer cell lines with regard to the induction of apoptosis were investigated. BNIP3 expression was significantly lower in pancreatic cancer tissues compared with normal epithelia and was associated with tumor size, clinical stage, and lymph node metastasis. The expression of BNIP3 correlated positively to the proapoptotic protein Bax and negatively to the antiapoptotic protein Bcl-2, whereas the induction of apoptosis by BNIP3 was independent of caspase 3 and 9 activation. The restoration of BNIP3 expression in pancreatic cancer cells , caused loss of ΔΨm, increase in ROS production, and apoptosis induction. The opposite effect was observed in pancreatic cancer cells, following BNIP3 silencing by RNAi. The absence of BNIP3 expression in pancreatic cancer cells was related to gene methylation that suppressed binding of HIF-1α to the BNIP3 promoter, whereas 5-Aza-2'-deoxycytidine (Aza-dC) treatment restored BNIP3 expression and sensitized pancreatic cancer cells to BNIP3-induced apoptosis. The findings indicated that BNIP3 was significantly downregulated in pancreatic cancer resulting in reduced apoptosis induction. Silencing of BNIP3 expression was associated with methylation of the hypoxia-responsive element (HRE) site that in turn inhibited the binding of HIF-1α to the BNIP3 promoter. The data suggest that BNIP3 reactivation is a potential target for therapeutic intervention against pancreatic cancer.
Bcl-2相互作用蛋白3（BNIP3）参与多种细胞过程，被认为是缺氧诱导凋亡的关键调节因子。在本研究中，我们调查了BNIP3在胰腺癌组织中的表达、与临床病理特征及预后的相关性，以及该蛋白在胰腺癌细胞系中对凋亡诱导的调节作用。与正常上皮相比，BNIP3在胰腺癌组织中的表达显著降低，且与肿瘤大小、临床分期和淋巴结转移相关。BNIP3的表达与促凋亡蛋白Bax呈正相关，与抗凋亡蛋白Bcl-2呈负相关，而BNIP3诱导的凋亡独立于半胱天冬酶3和9的激活。胰腺癌细胞中BNIP3表达的恢复导致线粒体膜电位丧失、活性氧生成增加并诱导凋亡。在用RNAi沉默BNIP3后，在胰腺癌细胞中观察到相反的效果。胰腺癌细胞中BNIP3表达的缺失与基因甲基化有关，该甲基化抑制了HIF-1α与BNIP3启动子的结合，而5-氮杂-2'-脱氧胞苷（Aza-dC）处理可恢复BNIP3表达并使胰腺癌细胞对BNIP3诱导的凋亡敏感。研究结果表明，BNIP3在胰腺癌中显著下调，导致凋亡诱导减少。BNIP3表达的沉默与缺氧反应元件（HRE）位点的甲基化有关，这反过来又抑制了HIF-1α与BNIP3启动子的结合。数据表明，BNIP3的重新激活是胰腺癌治疗干预的潜在靶点。
