| Summary: | Introduction
There is evidence that cigarette smoking participates in disease
progression through endothelial apoptosis. Bcl-2 family proteins are essential and
critical regulators of apoptosis. We explored whether Bcl-2 plays a role in cigarette
smoke extract induced (CSE-induced) endothelial apoptosis. Furthermore, given
the involvement of epigenetics in apoptosis and Bcl-2 expression, we hypothesized
that CSE-induced apoptosis might be caused by gene methylation.
Methods
Human umbilical vascular endothelial cells (HUVECs) were treated with
CSE, CSE plus 5-aza-2’-deoxycytidine (AZA, an inhibitor of DNA methylation), or
AZA and phosphate-buffered saline (PBS). Endothelial apoptosis was determined
by Annexin-V and propidium iodide staining. The expression levels of Bcl-2, Bax,
and cytochrome C (cyt C) were assessed by immunoblotting and RT-PCR. The
methylation status of the Bcl-2 promoter was observed by bisulfite sequencing
PCR (BSP).
Results
The apoptotic index of endothelial cells in the CSE-treated group increased.
Decreased expression of Bcl-2 and high methylation of the Bcl-2 promoter were
observed after CSE treatment. AZA alleviated the endothelial apoptosis caused by
CSE. AZA treatment also increased Bcl-2 expression along with decreased Bcl-2
promoter methylation.
Conclusions
Inhibiting DNA methylation alleviates CSE-induced endothelial
apoptosis and Bcl-2 promoter methylation. Bcl-2 promoter methylation might be
involved in CES-induced endothelial apoptosis.
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