AF1q 通过 NF-κB 上调 BAD 表达增强 γ 射线诱导的人鳞状细胞癌 A431 细胞凋亡。

AF1q enhancement of gamma irradiation-induced apoptosis by up-regulation of BAD expression via NF-kappaB in human squamous carcinoma A431 cells.

机构信息

Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, PR China.

出版信息

Oncol Rep. 2010 Aug;24(2):547-54.

PMID:20596645

Abstract

BAD (BCL-2 antagonist of cell death) is a pro-apoptotic BCL-2 family protein that plays a critical role in the regulation of apoptotic response. This study presents direct evidence that AF1q increased the radiation-induced apoptosis through up-regulation of BAD in human squamous carcinoma A431 cells and the key transcription factor involved is NF-kappaB. The minimal promoter sequence of BAD was identified; the activity was increased in AF1q stable transfectants and decreased upon AF1q siRNA transfection. The NF-kappaB consensus binding sequence is detected on BAD promoter. Inactivation of NF-kappaB by NF-kappaB inhibitor Bay 11-7082 or NF-kappaB p65 siRNA suppressed the expression and promoter activity of BAD; the suppression is more obvious in AF1q stable transfectants which also have an elevated NF-kappaB level. Mutation of putative NF-kappaB motif decreased the BAD promoter activity. The binding of NF-kappaB to the BAD promoter was confirmed by chromatin-immunoprecipitation. These findings indicate that AF1q up-regulation of BAD is through its effect on NF-kappaB and this may hint of its oncogenic mechanism in cancer.

摘要

BAD（BCL-2 凋亡蛋白家族拮抗物）是一种促凋亡的 BCL-2 家族蛋白，在调节凋亡反应中起着关键作用。本研究直接证明，AF1q 通过上调人鳞状癌细胞 A431 中的 BAD 增加了辐射诱导的细胞凋亡，而涉及的关键转录因子是 NF-κB。鉴定了 BAD 的最小启动子序列；在 AF1q 稳定转染子中活性增加，而在 AF1q siRNA 转染后活性降低。BAD 启动子上检测到 NF-κB 共有结合序列。NF-κB 抑制剂 Bay 11-7082 或 NF-κB p65 siRNA 失活 NF-κB 抑制了 BAD 的表达和启动子活性；在 AF1q 稳定转染子中抑制更为明显，因为这些细胞也具有升高的 NF-κB 水平。突变潜在的 NF-κB 模体降低了 BAD 启动子活性。染色质免疫沉淀证实了 NF-κB 与 BAD 启动子的结合。这些发现表明，AF1q 上调 BAD 是通过其对 NF-κB 的作用实现的，这可能暗示了其在癌症中的致癌机制。