[Monitoring early toxicity of heavy metals including Hg using a HSE-SEAP reporter gene].
OBJECTIVE
To develop a cellular assay based on heat shock signal pathway and secreted alkaline phosphatase (SEAP) reporter gene for investigating/predicting the early toxicity of heavy metals on HeLa cells in Chinese traditional medicine (TCM).


METHODS
The pHSE-SEAP plasmid was transfected into HeLa cells to build a HSE-SEAP-HeLa cell model. For validation of the model, the transfected cells were treated by either heating at 42 degrees C for 1 h or incubated with 5 mol x L(-1) CdCl2 for 4 h. Then the cells were covered in complete DMEM culture medium for 48 h and the activity of SEAP (reflecting the cellular level of heat shock protein) in cultural supernatants was measured; meanwhile, cell viability was determined by MTT assays. In addition, the cells were treated by four mercury compounds, HgCl2, merthilate sodium, HgS and cinnabar at the sub-lethal concentrations (determined by MTT assays). Then the heat shock response was detected likewise.


RESULTS
Significant level of secreted alkaline phosphatase (SEAP) was found in pHSE-SEAP transfected HeLa cells treated either by heating (42 degrees C) or incubating with CdCl2. The heat shock protein was induced by CdCl2 before decrease of cell viability was observed. All four mercury compounds induced heat shock response in both time and concentration-dependant manner. However, there were big differences among the mercury compounds, suggesting potential differences for early-stage toxicity in vivo.


CONCLUSIONS
The pHSE-SEAP transfected HeLa cells respond effectively to heat shock and metal stresses, and therefore provide a practical and repeatable assay for investigating/predicting the early toxicity of heavy metals and mineral-containing drugs in TCM.
Yu
Zhan-Jiang
ZJ
School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100083, China.
Yang
Qin
Q
Yang
Xiao-Da
XD
Wang
Kui
K
D000469:Alkaline Phosphatase / Q000096:biosynthesis / Q000235:genetics*; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D017930:Genes, Reporter; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D008627:Mercuric Chloride / Q000008:administration & dosage / Q000633:toxicity; D017669:Mercury Compounds / Q000008:administration & dosage / Q000633:toxicity*; D019216:Metals, Heavy / Q000008:administration & dosage / Q000633:toxicity*; D010957:Plasmids; D020218:Response Elements / Q000235:genetics; D013995:Time; D014162:Transfection
D006360:Heat-Shock Proteins; D017669:Mercury Compounds; D019216:Metals, Heavy; D008627:Mercuric Chloride; D000469:Alkaline Phosphatase; C034211:cinnabar