Zhou Jiahui, Huang Zunnan, Wang Ziyou, Liu Shumin, Grandien Alf, Ernberg Ingemar, He Zhiwei, Zhang Xiangning
Department of Pathophysiology and China-America Cancer Research Institute, Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Dongguan Scientific Research Center, Guangdong Medical University, Dongguan, Guangdong, China.
Center for Haematology and Regenerative Medicine, Karolinska Institutet, Stockholm, Sweden.
Oncotarget. 2017 Jul 4;8(27):43853-43865. doi: 10.18632/oncotarget.14126.
A putative tumor suppressor BLU mapped on the chromosomal 3p21 region, is frequently lost in human tumors including nasopharyngeal carcinoma (NPC). To explore the underlying mechanism of tumor suppression by BLU, its potential to promote apoptosis induced by TRAIL, an effector molecule elaborated by natural killer-T (NKT) cells was investigated. BLU was re-expressed in NPC-derived HNE1 cells by recombinant adenoviral infection and the cells were challenged with recombinant TRAIL. The growth inhibition of BLU was assayed and apoptosis was examined by flow cytometry-based tetramethylrhodamine ethyl ester (TMRE) and annexin V staining, cleavage of pro-caspase-8 and poly ADP ribose polymerase (PARP). The modulation of NF-κB pathway by BLU was evaluated by the reporter activity and estimation of the level of the molecules involved such as IKKalpha, p65 NF-κB, as well as NF-κB induced anti-apoptotic factors cFLIPL and cIAP2. The expression of BLU exerted in vitro and in vivo growth inhibitory effect and promoted TRAIL-induced apoptosis. This phenomenon was validated by FACS-based assays of mitochondrial membrane potential (BLU vs. Vector 87.8% ± 7.7% and 72.1%±6.7% at 6h exposure to TRAIL) and phosphatidylserine turnover (BLU vs. vector: 28.7%±2.9% and 22.6%±2.5%), as well as, enhanced caspapse-8 cleavage. Similar with the findings that BLU promotes chemotherapeutic agent-induced apoptosis, it also augmented death receptor-induced pathway through NF-κB pathway inhibition. In conclusion, BLU suppressed tumor formation by strengthening the antitumor immunity.
一种假定的肿瘤抑制因子BLU定位于染色体3p21区域，在包括鼻咽癌（NPC）在内的人类肿瘤中经常缺失。为了探究BLU抑制肿瘤的潜在机制，研究了其促进由自然杀伤T（NKT）细胞产生的效应分子TRAIL诱导的细胞凋亡的潜力。通过重组腺病毒感染在源自NPC的HNE1细胞中重新表达BLU，并使用重组TRAIL对细胞进行刺激。通过基于流式细胞术的四甲基罗丹明乙酯（TMRE）和膜联蛋白V染色、前半胱天冬酶-8和聚ADP核糖聚合酶（PARP）的裂解来测定BLU的生长抑制作用并检测细胞凋亡。通过报告基因活性以及对诸如IKKα、p65 NF-κB等相关分子水平的评估，以及对NF-κB诱导的抗凋亡因子cFLIPL和cIAP2的评估，来评价BLU对NF-κB途径的调节作用。BLU的表达在体外和体内均发挥生长抑制作用，并促进TRAIL诱导的细胞凋亡。通过基于流式细胞术的线粒体膜电位测定（在暴露于TRAIL 6小时时，BLU组与载体组分别为87.8%±7.7%和72.1%±6.7%）和磷脂酰丝氨酸翻转测定（BLU组与载体组分别为28.7%±2.9%和22.6%±2.5%），以及增强的半胱天冬酶-8裂解，验证了这一现象。与BLU促进化疗药物诱导的细胞凋亡的研究结果相似，它还通过抑制NF-κB途径增强死亡受体诱导的途径。总之，BLU通过增强抗肿瘤免疫来抑制肿瘤形成。
