Crotonaldehyde induces oxidative stress and caspase-dependent apoptosis in human bronchial epithelial cells

Crotonaldehyde is a widespread environmental pollutant and lipid peroxidation product. Crotonaldehyde is a risk factor for many diseases (e.g., chronic pulmonary inflammation). However, its toxicity and its mechanism of action have not been thoroughly investigated. The purpose of this study is to investigate crotonaldehyde-induced oxidative stress and mechanism of cell death in BEAS-2B cells. Crotonaldehyde caused decreases of intracellular reduced glutathione levels and increases of reactive oxygen species in a dose-dependent manner. Crotonaldehyde induced cell death by apoptosis, and gradually transitioned to necrosis at high dose of crotonaldehyde, as demonstrated by Annexin V-FITC/PI staining and cell morphology analysis. Crotonaldehyde-induced ATP decline observed in the study might partially account for the switch from apoptosis to necrosis. Mitochondria membrane potential, cytochrome c release, caspase-9, and caspase-3/7 activity were investigated, and the results suggest that crotonaldehyde-induced apoptosis was activated in a caspase-dependent way. Collectively, these results demonstrate crotonaldehyde induces cell oxidative stress and caspase-dependent apoptosis.