title: Microcystin-LR induces mitochondria-mediated apoptosis in human bronchial epithelial cells.
abstract: The present study aimed to investigate the toxicity of microcystin-LR (MC-LR) and to explore the mechanism of MC-LR-induced apoptosis in human bronchial epithelial (HBE) cells. HBE cells were treated with MC-LR (1, 10, 20, 30 and 40 µg/ml) alone or with MC-LR (0, 2.5, 5 and 10 µg/ml) and Z-VAD-FMK (0, 10, 20, 40, 60, 80, 100, 120 and 140 µM), which is a caspase inhibitor, for 24 and 48 h. Cell viability was assessed via an MTT assay and the half maximal effective concentration of MC-LR was determined. The optimal concentration of Z-VAD-FMK was established as 50 µm, which was then used in the subsequent experiments. MC-LR significantly inhibited cell viability and induced apoptosis of HBE cells in a dose-dependent manner, as detected by an Annexin V/propidium iodide assay. MC-LR induced cell apoptosis, excess reactive oxygen species production and mitochondrial membrane potential collapse, upregulated Bax expression and downregulated B-cell lymphoma-2 expression in HBE cells. Moreover, western blot analysis demonstrated that MC-LR increased the activity levels of caspase-3 and caspase-9 and induced cytochromecrelease into the cytoplasm, suggesting that MC-LR-induced apoptosis is associated with the mitochondrial pathway. Furthermore, pretreatment with Z-VAD-FMK reduced MC-LR-induced apoptosis by blocking caspase activation in HBE cells. Therefore, the results of the present study suggested that MC-LR is capable of significantly inhibiting the viability of HBE cells by inducing apoptosis in a mitochondria-dependent manner. The present study provides a foundation for further understanding the mechanism underlying the toxicity of MC-LR in the respiratory system.
authors.affiliation: College of Public Health, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Henan Science and Technology Exchange Center with Foreign Countries, Zhengzhou University, Zhengzhou, Henan 450003, P.R. China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Public Health, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Huang
authors.affiliation: College of Public Health, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China.
authors.forename: Mingfeng
authors.initials: M
authors.lastname: Yang
authors.affiliation: College of Public Health, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China.
authors.forename: Donggang
authors.initials: D
authors.lastname: Zhuang
authors.affiliation: College of Public Health, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China.
authors.forename: Xuemin
authors.initials: X
authors.lastname: Cheng
authors.affiliation: College of Public Health, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China.
authors.forename: Huizhen
authors.initials: H
authors.lastname: Zhang
authors.affiliation: College of Public Health, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Fu
keywords: apoptosis; human bronchial epithelial cell; microcystin-LR; mitochondria