title: Induction of stress response and differential expression of 70 kDa stress proteins by sodium fluoride in HeLa and rat brain tumor 9L cells.
abstract: We herein demonstrate that sodium fluoride (NaF) acts as a stress response inducer on HeLa and 9L rat brain tumor cells. NaF is only slightly cytotoxic, and inhibitory to Ser/Thr-phosphatases but not to Tyr-phosphatases in both cell lines. After treatment with 5 mM NaF for 2 h, the phosphorylation levels of vimentin and an alkali-resistant 65-kDa phosphoprotein were enhanced, a common phenomenon detected in cells under a variety of stress conditions. Under an identical treatment protocol, in which the cells were treated with 5 mM NaF for 2 h and then allowed to recover under normal growing conditions for up to 12 h, NaF differentially induced the cytoplasmic/nuclear heat-shock protein70s (including both the inducible and the constitutively expressed members of this protein family) in HeLa cells and the endoplasmic reticulum residing heat-shock protein70 (the glucose-regulated protein with an apparent molecular weight of 78 kDa) in 9L cells. Electrophoretic mobility shift assays (EMSA) using probes containing well-characterized regulatory elements revealed the activation of the heat-shock factor in HeLa but not in 9L cells; this is in good agreement with the stress protein induction pattern. Additional differential induction of binding activities toward EMSA probes individually containing NF-KB, AP-2, and CRE-like elements were detected in NaF-treated cells. The possible involvement of these binding sites as well as the corresponding factors in the stress response are discussed.
authors.affiliation: Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.
authors.forename: T J
authors.initials: TJ
authors.lastname: Cheng
authors.forename: T M
authors.initials: TM
authors.lastname: Chen
authors.forename: C H
authors.initials: CH
authors.lastname: Chen
authors.forename: Y K
authors.initials: YK
authors.lastname: Lai
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis / Q000187:drug effects; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000187:drug effects*; D006801:Humans; D010749:Phosphoprotein Phosphatases / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011506:Proteins / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D012969:Sodium Fluoride / Q000494:pharmacology*; D014157:Transcription Factors / Q000187:drug effects / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D011506:Proteins; D014157:Transcription Factors; D012969:Sodium Fluoride; D010749:Phosphoprotein Phosphatases