成人歯肉由来線維芽細胞のＤＮＡ合成とタンパク質合成におよぼすカドミウムとフッ素の影響

Abstract

Cadmium (Cd) and fluoride (F) affect the metabolism of hard tissues, but their effect on human beings is not yet known. The purpose of this study was to investigate the effect of Cd and/or F on DNA and protein syntheses of human cultured cells. Four human gingival fibroblast primary cultures (GF-5, 6, 12 and 13 cells) and two human malignant cell lines (HeLa S3cells and KU-2 cells) were used. All cells were grown in Eagle's minimum essential medium supplemented with 10% fetal calf serum. After 24hr incubation, cells were cultured in media containing CdCl2 and/or NaF in order to study their growth, DNA and protein synthesis, and intracellular Cd level. The growth and DNA synthesis of cells were inhibited by 2.0mM NaF or 10-4mM CdCl2. The incorporation of 14C-leucine in cells was increased by 0.5mM NaF or 10-5mM-10-4mM CdCl2. The enhancement of incorporation of 14C-leucine was greater in cells exposed to NaF plus CdCl2 than in cells exposed to CdCl2 alone. Increased incorporation of 35S-cysteine in cells was observed with 10-5mM-10-4mM CdCl2 or NaF plus CdCl2. However, F had no effect on the incorporation of 35S-cysteine. Gel filtration was performed with Sephadex G75. 35S peak was found in an metallothionein (MT) fraction. The intracellular Cd level was lower in gingival fibroblasts than in malignant cells. These results indicate that Cd induced the synthesis of MT in both human gingival fibroblasts and malignant cells. It also seems that F has the ability to stimulate the inducement of MT synthesis by Cd.