title: Attenuation of both apoptotic and necrotic actions of cadmium by Bcl-2.
abstract: We examined the effects of cadmium on the bcl-2 family of proteins--bcl-2, bax, bad, and bcl-xS/L--in cadmium-induced cytotoxicity. Addition of 10 microM cadmium to cultured porcine kidney LLC-PK(1) cells caused apoptosis. Western blot analyses revealed that cadmium markedly increased endogenous bcl-2 protein (to 3-4 times the level in wild-type cells) earlier than metallothionein induction, but that the metal did not enhance the induction of bax, bad, or bcl-xS proteins. Cadmium also induced the transcript of bcl-2, with the amount of bcl-2 reaching a maximum at 1-2 hr of exposure; this increase occurred earlier than cadmium-induced increase in the protooncogene such as c-myc. A cadmium-induced increase in endogenous bcl-2 protein was also seen in rat primary thymocytes. Overexpression of the bcl-2 protein by gene transfection prevented cadmium-induced apoptosis. Following the detection of apoptosis, lactate dehydrogenase release in the culture medium (a marker of necrosis) was observed, and this release was also inhibited by overexpression of bcl-2. Electron microscopic observations also supported the fact that cadmium induced apoptotic chromatin condensation at an early stage of exposure, followed by necrotic features of the cells, both of which were also inhibited by overexpression of bcl-2 proteins. Thus, our data demonstrated that both apoptotic and necrotic actions of cadmium were attenuated by bcl-2.
authors.affiliation: Pathophysiology Research Team, National Institute for Environmental Studies, Tsukuba, Japan. ishidou@nies.go.jp
authors.forename: Masami
authors.initials: M
authors.lastname: Ishido
authors.forename: Rieko
authors.initials: R
authors.lastname: Ohtsubo
authors.forename: Tatsumi
authors.initials: T
authors.lastname: Adachi
authors.forename: Manabu
authors.initials: M
authors.lastname: Kunimoto
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002104:Cadmium / Q000009:adverse effects*; D018929:Cell Culture Techniques; D004785:Environmental Pollutants / Q000009:adverse effects*; D019254:Genes, bcl-2; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000473:pathology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008854:Microscopy, Electron; D009336:Necrosis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000494:pharmacology; D013552:Swine
chemical_list: D004785:Environmental Pollutants; D019253:Proto-Oncogene Proteins c-bcl-2; D002104:Cadmium; D007770:L-Lactate Dehydrogenase