Zhang B, Xu J, Li C, Shi S, Ji S, Xu W, Liu J, Jin K, Liang D, Liang C, Liu L, Liu C, Qin Y, Yu X
Department of Oncology, Shanghai Medical College, Fudan University; Pancreatic Cancer Institute, Fudan University, 270 DongAn Road, Shanghai 200032, China.
Department of Pancreatic and Hepatobiliary Surgery, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University; Pancreatic Cancer Institute, Fudan University, 270 DongAn Road, Shanghai 200032, China.
Curr Mol Med. 2016;16(4):404-11. doi: 10.2174/1566524016666160316154150.
MBD1 (Methyl-CpG Binding Domain Protein 1) is highly expressed in pancreatic cancer. Nrf2 (NF-E2 p45-related factor 2) and the 'antioxidant response element' (ARE)-driven genes that NRF2 controls are frequently upregulated in pancreatic cancer and correlate with poor survival. Keap1 (Kelch-like ECH-associated protein 1) is a dominant negative regulator of NRF2 and is reported to be epigenetically regulated by promoter methylation. However, the role of MBD1 with antioxidant response and its association with KEAP1 has never been reported before and remains unclear.
We investigated the role of MBD1 in antioxidant response and its regulatory function in KEAP1 transcription in pancreatic cancer cells.
MBD1 was silenced to examine its role in antioxidant response. To explore the underlying mechanism, transcriptional and protein levels of KEAP1 was examined. The correlation between MBD1 and KEAP1 was confirmed in pancreatic cancer tissue samples by using immunohistochemistry (IHC). Dualluciferase reporter assay and Chromatin immunoprecipitation (ChIP) were used to elucidate he mechanism of MBD1 in KEAP1 transcriptional control. Moreover, co-immunoprecipitation (CoIP) assay was performed to uncover the regulatory role of MBD1 in KEAP1 transcription through its association with c-myc.
MBD1 silencing decreased antioxidant response and the related ARE target genes through epigenetic regulation of KEAP1. MBD1 negatively correlated with KEAP1 in pancreatic cancer tissue samples. Moreover, c-myc was a MBD1 interaction partner in KEAP1 epigenetic regulation.
MBD1 can induce antioxidant response in pancreatic cancer through down-regulation of KEAP1. c-myc plays a key role in MBD1 mediated epigenetic silencing of KEAP1.
MBD1（甲基化CpG结合域蛋白1）在胰腺癌中高表达。Nrf2（NF-E2 p45相关因子2）以及NRF2调控的“抗氧化反应元件”（ARE）驱动基因在胰腺癌中常上调，且与生存率低相关。Keap1（kelch样ECH相关蛋白1）是Nrf2的显性负调节因子，据报道其受启动子甲基化的表观遗传调控。然而，MBD1在抗氧化反应中的作用及其与Keap1的关系此前从未被报道，仍不清楚。
我们研究了MBD1在抗氧化反应中的作用及其对胰腺癌细胞中Keap1转录的调控功能。
使MBD1沉默以检测其在抗氧化反应中的作用。为探究潜在机制，检测了Keap1的转录和蛋白水平。通过免疫组织化学（IHC）在胰腺癌组织样本中证实MBD1与Keap1之间的相关性。采用双荧光素酶报告基因检测和染色质免疫沉淀（ChIP）来阐明MBD1在Keap1转录调控中的机制。此外进行了免疫共沉淀（CoIP）检测，以揭示MBD1通过与c-myc结合在Keap1转录中的调控作用。
MBD1沉默通过对Keap1的表观遗传调控降低了抗氧化反应及相关ARE靶基因。在胰腺癌组织样本中，MBD1与Keap1呈负相关。此外，c-myc是MBD1在Keap1表观遗传调控中的相互作用伙伴。
MBD1可通过下调Keap1诱导胰腺癌中的抗氧化反应。c-myc在MBD1介导的Keap1表观遗传沉默中起关键作用。
