Cadmium induces apoptosis in human embryonic kidney (HEK) 293 cells by caspase-dependent and -independent pathways acting on mitochondria.
Cadmium (Cd) is a well-known toxic compound for the kidney in vivo and in vitro. It has been demonstrated to induce nephrotoxicity via in part by apoptotic cell death, but the precise mechanism is still unclear. Therefore, we have studied the effects of Cd on HEK 293 cells and investigated the mechanisms of Cd-induced apoptosis. Studies of morphology and oligonucleosomal DNA fragmentation demonstrated that 30-60 microM Cd induced apoptosis as early as 6-9h with strong effects on MTT activity, whereas 120 microM Cd revealed mainly necrosis, and the result of flow cytometry confirmed it. A concomitant time-dependent decrease of mitochondrial transmembrane potential (DeltaPsi(m)) and Bcl-2 expression was observed, subsequently, release of cytochrome c (Cyt c) and activation of caspase-3 were detected, suggesting a caspase-dependent pathway. Meanwhile, mitochondrial AIF was released to cytoplasm and nucleus, suggesting a caspase-independent pathway. Furthermore, when cells were transfected with pcDNA3/Bcl-2 before exposed to CdCl(2), alleviated apoptosis was assessed by part of the apoptotic features in this study. Taken together, our results showed that CdCl(2) caused time- and dose-dependent apoptosis or even necrosis in HEK 293 cells depending on the exposure conditions. The apoptotic events may involve mitochondrial disruption including both caspase-dependent and -independent pathways.
Mao
Wei-Ping
WP
Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 122 Ninghai Road, Nanjing 210097, Jiangsu Province, People's Republic of China. maoweiping@njnu.edu.cn
Ye
Ji-Lin
JL
Guan
Zheng-Bing
ZB
Zhao
Jie-Ming
JM
Zhang
Chao
C
Zhang
Na-Na
NN
Jiang
Ping
P
Tian
Ting
T
D017209:Apoptosis / Q000187:drug effects*; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D019256:Cadmium Chloride / Q000633:toxicity*; D053148:Caspase 3 / Q000096:biosynthesis*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000633:toxicity; D005562:Formazans / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000502:physiology; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013778:Tetrazolium Salts / Q000378:metabolism
D051033:Apoptosis Inducing Factor; D004785:Environmental Pollutants; D005562:Formazans; D019253:Proto-Oncogene Proteins c-bcl-2; D013778:Tetrazolium Salts; C079782:MTT formazan; D045304:Cytochromes c; D053148:Caspase 3; D019256:Cadmium Chloride