The Influence of Hypo-Oxygenation or Hyper-Oxygenation on Cell Survival after Paraquat Exposure in A549 Cells

Kim, Hoon; Lee, Suk Woo; Park, Jung Soo

Abstract

PURPOSE
Paraquat (1,1'-dimethy-4,4'-bipyridinium dichloride, PQ) is a very effective and widely used herbicide that was commercially introduced in 1962. It is reduced by an electron donor such NADPH and then it transfers the electrons to molecular oxygen. As a result, the produced reactive oxygen species (ROS) are related to its cellular toxicity. However, the influence of the intracellular oxygen levels on praquat-induced oxidative cell damage has not fully been investigated.
METHODS
This experiment was conducted in vitro using the human carcinogenic aveolar basal epithelial cell line (A549 cells). The cytotoxicity was assessed by using the MTT method. The optical density was measured at 540 nm using an ELISA reader. We examined the morphological changes after drug treatment using an inverted microscope and fluorescence microscopy. The 2',7'-dichlorofluorescein diacetate (DCF-DA) assay was used to measure the intracellular ROS levels.
RESULTS
Incubation of the A549 cells in a hypo-oxygenation situation protected the A549 cells from paraquat-induced cytotoxicity according to the MTT & live/dead assay. The other hand, incubating the A549 cells in a hyper-oxygenation situation aggravated the PQ-induced cytotoxicity. We first identified that the protective effects of hypo-oxygenation on the PQ-induced cytotoxicity resulted from decreased ROS production through the DCF-DA assay.
CONCLUSION
The results of this study showed that hyperoxygenation reduced the paraquat toxicity, but hypo-oxygenation exhibits a protective effect against paraquat-induced cell death by decreasing the ROS production in A549 cells.