Heme oxygenase-1-mediated partial cytoprotective effect by NO on cadmium-induced cytotoxicity in C6 rat glioma cells

• Published in: Toxicology in vitro 2005-02, Vol.19 (1), p.31-39
• Main Authors: Srisook, Klaokwan, Jung, Nam-Hee, Kim, Bum-Rae, Cha, Seok-Ho, Kim, Hye-Sun, Cha, Young-Nam
• Format: Article
• Language: English
• Subjects: Animals; Brain Neoplasms - drug therapy; Brain Neoplasms - enzymology; Brain Neoplasms - pathology; C6 glioma cell; Cadmium - toxicity; Cell Line, Tumor; Cell Survival - drug effects; Cytoprotection - drug effects; Dose-Response Relationship, Drug; Enzyme Induction; Enzyme Inhibitors - pharmacology; Glioma - drug therapy; Glioma - enzymology; Glioma - pathology; Heme Oxygenase (Decyclizing) - antagonists & inhibitors; Heme Oxygenase (Decyclizing) - biosynthesis; Heme Oxygenase (Decyclizing) - genetics; Heme Oxygenase-1; Nitric Oxide - biosynthesis; Nitric Oxide Donors - pharmacology; Nitrogen Oxides; Protoporphyrins - pharmacology; Rats; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Spermine - analogs & derivatives; Spermine - pharmacology; Up-Regulation
• ISSN: 0887-2333; 1879-3177
• DOI: 10.1016/j.tiv.2004.04.012

Heme oxygenase-1 (HO-1) is a 32-kDa stress induced enzyme that degrades heme to carbon monoxide (CO) and biliverdin. By employing RT-PCR and Western blotting techniques, we have examined the HO-1 induction in C6 glioma cells that were treated with cadmium chloride (CdCl2) or spermine NONOate (SPER/NO). By employing a cell viability assay, we have also examined the cytoprotective effect of HO-1 induction against the cytotoxicity caused by toxic dose of CdCl2. In C6 glioma cells exposed to CdCl2, expression of HO-1 (mRNA and protein) was increased in a dose- and time-dependent manner. Nitric oxide (NO) generated from SPER/NO very rapidly increased HO-1 mRNA expression in the C6 glioma cells. The induction of HO-1 by SPER/NO protected the cells from toxic dose of CdCl2. The up-regulation of HO-1 mRNA expression by CdCl2 was inhibited by a pre-incubation of the cells with actinomycin D, a potent inhibitor of mRNA transcription. Upon the inhibition of elevated HO-1 mRNA expression by the use of zinc protoporphyrin IX (ZnPP), an inhibitor of HO activity, the change of HO-1 mRNA expression by ZnPP was not observed. Thus, the glial cell may respond to CdCl2 toxicity by enhancing the HO-1 expression in its effort to minimize the CdCl2-derived oxidative damage, and to survive. In the glioma cells, when the HO-1 expression was elevated by a prior incubation with SPER/NO, the cell viability against the cytotoxicity of CdCl2 was significantly increased. When the results of our experiment are taken together, we discovered that NO provided a rapid enhancement of HO-1 expression, and it provided a protective effect against CdCl2-derived oxidative injury in the C6 rat glioma cells.