The Study of Detoxification Mechanism in MousePulmonary Stem/Progenitor Cells for Paraquat Intoxication

• Main Authors: Chia-Yuan Tang, 湯佳元
• Other Authors: Fu-Chuo Peng
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/61750319663025277041

碩士 === 國立臺灣大學 === 毒理學研究所 === 99 === Paraquat (PQ) is one of the most widely used herbicides in the world, and it is the well-known pneumotoxicant. Paraquat accumulates mainly in the lungs through polyamine uptake system and undergoes a process of redox-cycling, which leads to reactive oxygen species (ROS) production at the expense of NADPH. We have set a primary culture of mouse pulmonary stem/progenitor cells (mPSCs) which includes epithelial colony cells and surrounding stroma cells in theculture system. However, the toxicity of cellular response to PQ in mPSCs was not elucidated. According to our previous data, we found stroma cells were more sensitive to PQ than epithelial colony cells. This difference between two cells may be explained by the expression of ABCB1 transporter. Hence, the aim of this study is to investigate the role of ABCB1 in PQ-induced cell death in mPSCs. First, we examined and compared cell viability of PQ on mPSCs and three lung cell lines, such as BEAS-2B, A549 and MLE-15 cells. By MTT assay, it showed mPSCs were more resistant to PQ among these cells. Then, we evaluated the relationship between ABCB1 transporter and mPSC PQ’s cell viability. The results indicared that ABCB1 was mainly expressed on the membrane of epithelial colony cells, and inhibition of ABCB1 transporter by verapamil caused more intracellular ROS production when administrated with paraquat, which leaded to lower cell viability. Our previous study also showed FasL expression was increased in response to paraquat-induced cell apoptosis in mPSCs. Therefore, we investigated whether the FasL was located in epithelial colony cells or stroma cells. The results showed that FasL was expressed in the surrounding stroma cells but not epithelial colony cells. The expression of Fas and FasL in stroma cells was increased in a time-dependent manner. To verify whether Fas/FasL pathway was activated in stroma cells, the expression of pro-caspase 8 and pro-caspase 3 was investigated. It indicated that the extrinsic apoptotic pathway was activated despite the induction of ABCB1 mRNA expression in stroma cells. Taken together, the current study showed that ROS was involved in PQ-induced mPCSs cell death, and ABCB1 may export PQ out of cells and attenuated the PQ toxicity. Furthemore, FasL might play an important in induction of extrinsic apoptotic pathway.