The role of tNOX in Benzo[a]pyrene-induced migration.

• Main Authors: Huei-Yu Chen, 陳惠郁
• Other Authors: Pin-Ju Chueh
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/17957339342741023023

碩士 === 國立中興大學 === 生物醫學研究所 === 105 === Benzo[a]pyrene which is a family member of polycyclic aromatic hydrocarbon (PAHs), is known as an environmental pollutant. Previous studies have reported that Benzo[a]pyrene plays a role in carcinogenicity via converting to benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE). Furthermore, in Benzo[a]pyrene–induced cell migration, Benzo[a]pyrene up-regulates sirtuin 1 (SIRT1) protein expression level, causing the activation of the TNF-α/β-catenin axis by deacetylating acetyl-β-catenin. SIRT1 as a NAD+-dependent deacetylase, which acts as a deacetylase for both histone and non-histone proteins and affects many cellular responses. A tumor-associated NADH oxidase (tNOX) expresses in a wide array of tumor cell lines that catalyzes oxidation of NADH into NAD+. Our previous studies have shown that tNOX involves in regulating several cell functions, including cell migration. Morever, tNOX-knockdown cells are associated with SIRT1 downregulation that is important in multiple cellular functions like cell migration and the epithelial-mesenchymal transition. Thus, it is interesting to study wether Benzo[a]pyrene affects cell migration is through tNOX and SIRT1. In this study, we demonstrated that, in HCT116 cells, Benzo[a]pyrene induced up-regulation of tNOX, in turn increased the intracellular NAD+/NADH ratio and enhanced the deacetylase activity of SIRT1. Subsequently, we confirmed that enhanced SIRT1 activity acted to deacetylate -catenin, a transcription factor that moved into cell nucleus, and increased the expression level of migration-associated proteins, such as MMP-9 and MMP-2, leading to increased cell migration. Moreover, we found that the up-regulation of tNOX reduced the expression of p53, leading to down-regulation of miR-34a. Ultimately, the attenuation of miR-34a induced the up-regulation of SIRT1. Together, our results demonstrate that Benzo[a]pyrene enhances tNOX activity, and that the tNOX-modulates NAD+-SIRT1-β-catenin acetylation axis is essential for Benzo[a]pyrene-induced cell migration.