Int J Oral Biol.  2010 Jun;35(2):51-60.

Mechanism Underlying NaF-Induced Apoptosis in Human Oral Squamous Cell Carcinoma

• Hur YJ
• Kim DK
• Lee SE
• Kim IR
• Jeong NY
• Kim JY
• Park BS

Abstract

Few studies have evaluated the apoptosis-inducing efficacy of NaF on cancer cells in vitro but there has been no previous investigation of the apoptotic effects of NaF on human oral squamous cell carcinoma cells. In this study, we have investigated the mechanisms underlying the apoptotic response to NaF treatment in the YD9 human squamous cell carcinoma cell line. The viability of YD9 cells and their growth inhibition were assessed by MTT and clonogenic assays, respectively. Hoechst staining, DNA electrophoresis and TUNEL staining were conducted to detect apoptosis. YD9 cells were treated with NaF, and western blotting, immunocytochemistry, confocal microscopy, FACScan flow cytometry, and MMP and proteasome activity assays were performed sequentially. The NaF treatment resulted in a time- and dose-dependent decrease in YD9 cell viability, a dose-dependent inhibition of cell growth, and the induction of apoptotic cell death. The apoptotic response of these cells was manifested by nuclear condensation, DNA fragmentation, the reduction of MMP and proteasome activity, a decreased DNA content, the release of cytochrome c into the cytosol, the translocation of AIF and DFF40 (CAD) into the nucleus, a significant shift of the Bax/Bcl-2 ratio, and the activation of caspase-9, caspase-3, PARP, Lamin A/C and DFF45 (ICAD). Furthermore, NaF treatment resulted in the downregulation of G1 cell cyclerelated proteins, and upregulation of p53 and the Cdk inhibitor p27KIP1. Taken collectively, our present findings demonstrate that NaF strongly inhibits YD9 cell proliferation by modulating the expression of G1 cell cycle-related proteins and inducing apoptosis via mitochondrial and caspase pathways.

Keyword

NaF (sodium fluoride); apoptosis; YD9 human oral squamous cell carcinoma cell line; cell cycle-related proteins

MeSH Terms

Apoptosis
Blotting, Western
Carcinoma, Squamous Cell
Caspase 3
Caspase 9
Cell Death
Cell Line
Cell Proliferation
Cell Survival
Cytochromes c
Cytosol
DNA
DNA Fragmentation
Down-Regulation
Electrophoresis
Flow Cytometry
Humans
Immunohistochemistry
In Situ Nick-End Labeling
Microscopy, Confocal
Proteasome Endopeptidase Complex
Proteins
Up-Regulation
Caspase 3
Caspase 9
Cytochromes c
DNA
Proteasome Endopeptidase Complex
Proteins