The Effect of Sodium Fluoride on Cell Apoptosis
and the Mechanism of Human Lung BEAS-2B Cells In Vitro
Received: 11 October 2016 /Accepted: 10 January 2017 / Published online: 22 January 2017
Springer Science+Business Media New York 2017
Abstract Sodium fluoride (NaF) is a source of fluoride ions
used in many applications. Previous studies found that NaF
suppressed the proliferation of osteoblast MC3T3 E1 cells and
induced the apoptosis of chondrocytes. However, little is
known about the effects of NaF on human lung BEAS-2B
cells. Therefore, we investigated the mode of cell death in-
duced by NaF and its underlying molecular mechanisms.
BEAS-2B cells were treated with NaF at concentrations of
0, 0.25, 0.5, 1.0, 2.0, and 4.0 mmol/L. Cell viability decreased
and apoptotic cells significantly increased as concentrations of
NaF increased over specific periods of time. The IC
was 1.9 and 0.9 mM after 24 and 48 h, respectively. The rates
of apoptosis increased from 4.8 to 37.7% after NaF exposure.
HE staining, electron microscopy, and single cell gel electro-
phoresis revealed that morphological changes of apoptosis
increased with exposure concentrations. RT-PCR and
Western blotting were used to detect the apoptotic pathways.
The expressions of bax, caspase-3, caspase-9, p53, and the
cytoplasmic CytC of the NaF groups increased, while bcl-2
and mitochondrial CytC decreased compared with that of the
control group (P < 0.05). Further, the fluorescence intensities
of ROS in the NaF groups were higher than those in the con-
trol group, and the membrane potential of mitochondria in the
NaF group was significantly lower than that of the control
group (P < 0.05). These findings suggested that NaF induced
apoptosis in the BEAS-2B cells through mitochondria-
mediated signal pathways. Our study provides the theoretical
foundation and experimental basis for exploring the mecha-
nisms of human lung epithelial cell damage and cytotoxicity
induced by fluorine.
Keywords Sodium fluoride
Human bronchial epithelial
Reactive oxygen species
Mitochondrial membrane potential
Fluoride is an essential trace element for human and animal
health . Although fluoride within certain limits is thought to
be safe, excessive fluoride intake can cause fluorosis.
Fluorosis is an endemic disease in more than 40 countries.
In China, fluorosis is common and is found in as many as
1308 regions affecting up to 120 million people . The pri-
mary clinical symptoms of fluorosis are skeletal and dental
abnormalities. Recent studies found that acute and high-dose
exposure to fluorides can also cause respiratory system toxic-
ity , liver damage , neurological defects , reproductive
toxicity , and mental retardation .
The pathogenesis of fluorosis is complex and is not fully
understood. Studies found that excess fluoride can cause DNA
damage and trigger apoptosis and cell cycle changes [8, 9].
Fluoride inhibits the proliferation of osteoblast MC3T3 E1
cells in a time- and dose-dependent manner and induces
Jun Ying and Jie Xu are contributed equally to this work.
* Qiyu Bao
* Peizhen Li
School of Laboratory Medicine and Life Science/Institute of
Biomedical Informatics, Wenzhou Medical University,
Wenzhou 325035, China
School of Forensic Medicine, Xi’an Jiaotong University,
Xi’an 710000, China
School of Renji, Wenzhou Medical University, Wenzhou 325035,
118 Hospital of PLA, Wenzhou 325000, China
Biol Trace Elem Res (2017) 179:59–69