Lithium toxicity and expression of stress-related genes or proteins in A549 cells.
To unveil some molecular mechanisms underlying lithium toxicity, expression changes of stress-related genes or proteins were analysed in A549 cells, cultured for 3 days in presence of lithium. A dose-dependent cell-growth inhibition was found for concentrations ranging from 2 (toxicity threshold) to 12 mM (lethality threshold). cDNA arrays technology was used to analyse effects of 5 and 10 mM lithium. Among genes involved in cell cycle regulation, proliferating cell nuclear antigen (PCNA) was down-regulated and cyclin kinase inhibitor p21 (CDKN1A), up-regulated. Genes of paraoxonase 2, known to prevent LDL lipid peroxidation, and of catalase and SOD were found to be down-regulated whereas genes of cytochrome P450 (CYP2F1, CYP2E1) were up-regulated. This probably results in higher intracellular levels of reactive oxygen species and account for increased levels of lipid peroxidation commonly associated with lithium exposure. Moreover, lithium was found to down-regulate genes coding for anti-apoptotic gene BAG-1 and for most of the molecular chaperones (HSP, GRP). This might account for lithium toxicity since these proteins are critical for cell survival. At translational level, a 105 kDa protein was found to be over-expressed. This protein was recognized by the anti-GRP94, anti-KDEL and anti-phosphoserine monoclonal antibodies suggesting that, lithium could induce post-translational modifications of GRP94 phosphorylation. Using tunicamycin and thapsigargin, it was concluded that lithium effects are not related to defect in N-linked glycosylation and/or to changes in calcium homeostasis.
Allagui
M S
MS
Laboratoire de Biologie cellulaire et pollution, Faculté of Médicine-Purpan, Université Toulouse III 37, Allées Jules Guesde, 31073 Toulouse, France.
Vincent
C
C
El feki
A
A
Gaubin
Y
Y
Croute
F
F
D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008094:Lithium / Q000494:pharmacology / Q000633:toxicity; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D013312:Stress, Physiological
D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D008094:Lithium