TY - JOUR T1 - Changes in Fluoride Sensitivity During <em>In Vitro</em> Senescence of Normal Human Oral Cells JF - Anticancer Research JO - Anticancer Res SP - 2085 LP - 2090 VL - 25 IS - 3B AU - RIE SATOH AU - KAORI KISHINO AU - SUFI REZA MD. MORSHED AU - FUMITOSHI TAKAYAMA AU - SUMIKO OTSUKI AU - FUMIKA SUZUKI AU - KEN HASHIMOTO AU - HIROTAKA KIKUCHI AU - HIROFUMI NISHIKAWA AU - TOSHIKAZU YASUI AU - HIROSHI SAKAGAMI Y1 - 2005/05/01 UR - http://ar.iiarjournals.org/content/25/3B/2085.abstract N2 - We have previously reported that sodium fluoride (NaF) showed slightly higher cytotoxicity against human oral tumor cell lines than normal human oral cells. Possible changes in the NaF sensitivity of three normal human oral cell types (gingival fibroblast HGF, pulp cell HPC, periodontal ligament fibroblast HPLF) during in vitro ageing were investigated in the present study. When these cells were subcultured at 1:4 split ratio every week, their saturation density declined with increasing population doubling level (PDL), and they ceased to divide when they reached 20 PDL. Mitochondrial function, evaluated by MTT stainability per cell basis, was elevated at the terminal phase. NaF dose-dependently reduced the viable cell number, but did not show any beneficial (growth promoting) effect (so-called “hormesis”) at lower concentrations. NaF produced large DNA fragments, without induction of internucleosomal DNA fragmentation, possibly due to weak activation of caspases -3, -8 and -9. Higher concentrations of NaF were required to reduce the number of viable senescent cells than younger cells, indicating that cells become resistant to cytotoxicity of NaF with in vitro ageing. Copyright© 2005 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved ER -