Studies on the Mechanism of Regulation in EMT marker Vimentin in H1299：The Role of Aryl Hydrocarbon receptor

• Main Authors: Yu-Hsuan Yang, 楊于萱
• Other Authors: 康照洲
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/48277033977105077208

碩士 === 國立臺灣大學 === 毒理學研究所 === 100 === Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor. It will translocate into nucleus and may directly linked to transcriptional activation of target genes in response to ligands, polycyclic aromatic hydrocarbon (PAH). Epithelial - mesenchymal transition (EMT) is a process in which epithelial cells lose its intercellular adhesion during critical phases such as embryonic development and tumor progression. Previous studies have shown that EMT will be induced by ligand-activated AhR through activating a transcription factor of EMT. However, in our study, the non-activated AhR could decrease EMT in H1299 cell, and the detailed mechanism is still unknown. In this study, we found that the level of AhR expression in different lung cancer cells was correlated with their invasive potential. H1299 cell, which expressed AhR in low basal level, showed a high expression level in vimentin, an EMT marker, and showed a higher invasive ability (compared with A549, lung epithelial cell with high-level AhR expression and lower invasive ability). When AhR overexpression in H1299, not only the expression of vimentin was reduced, but the invasive cell was suppressed. Although the vimentin protein level was changed in AhR overexpressed cell, whereas the mRNA level was remained unaffected. We also found the overexpressed AhR protein was stayed in cytosol, and without transcriptional activity until the stimulation of B[a]P, suggested the anti-EMT function of AhR was independent of their transactivational activity. Moreover, non-activated AhR reduced the protein expression level of GTPase exchange factor (GEF), Rac1, and without change in their mRNA level. However, treatment of Rac1 inhibitor NSC23766 did not reverse the decrease in vimentin, and the phospho- vimentin still increased, suggested that overexpressed-AhR regulate vimentin through Rac1-independent pathway. Moreover, we found that the protein-protein interaction between AhR and Rac1, Ubiquitin, vimentin, phospho-vimentin was increased in AhR-overexpressed H1299 cell.