DNA methylation and histone acetylation are major epigenetic modifications in 
gene silencing. In our previous research, we found that the methylated 
oligonucleotide (SurKex) complementary to a region of promoter of survivin could 
induce DNA methylation in a site-specific manner leading to survivin silencing. 
Here, we further studied the role of histone acetylation in survivin silencing 
and the relationship between histone acetylation and DNA methylation. First we 
observed the levels of histone H4 and H4K16 acetylation that were decreased 
after SurKex treatment by using the chromatin immunoprecipitation (ChIP) assay. 
Next, we investigated the roles of histone acetylation and DNA methylation in 
survivin silencing after blockade of histone deacetylation with Trichostatin A 
(TSA). We assessed survivin mRNA expression by RT-PCR, measured survivin 
promoter methylation by bisulfite sequencing and examined the level of histone 
acetylation by the ChIP assay. The results showed that histone deacetylation 
blocked by TSA reversed the effects of SurKex on inhibiting the expression of 
survivin mRNA, inducing a site-specific methylation on survivin promoter and 
decreasing the level of histone acetylation. Finally, we examined the role of 
histone acetylation in the expression of DNA methyltransferase 1 (DNMT1) mRNA. 
The results showed that histone deacetylation blocked by TSA reversed the 
increasing effect of histone deacetylation on the expression of survivin mRNA. 
This study suggests that histone deacetylation guides SurKex-induced DNA 
methylation in survivin silencing possibly through increasing the expression of 
DNMT1 mRNA.