3.6 | DSG reduced the genomic DNA methylation levels,
and re-activated the expression of TSGs, resulting in cell cycle arrest
and cellular senescence of PCa cells.
It has been reported that UHRF1 depletion reduced the genomic DNA
methylation levels, and re-activated the expression of TSGs, resulting
in cell cycle arrest and cellular senescence (Yang, et al., 2017, Kong,
et al., 2019a). We validated whether DSG made the same effect on PCa
cells. We treated cells with DSG for 5 days, and assessed the genomic
DNA methylation levels using DNA dot blotting. As expected, DSG
decreased the genomic DNA methylation levels (Fig. 6a). Recent emerging
evidences have suggested that DNA hypomethylation might re-activate the
expression of TSGs (Zhang&Xu, 2017). We next examined the impact of DSG
on the expression levels of TSGs. The data showed that DSG increased the
mRNA levels of such TSGs as p16 , p21 and LXN (Fig.
6b). As we knew that p16 and p21 were important cell cycle inhibitor and
biomarkers of cellular senescence (Scott, et al., 2017, Chen, et al.,
2014, Sharma, et al., 2020). We further examined the influences of DSG
on cell cycle and cell senescence. As expected, DSG induced cell cycle
arrest in S phase, and induced cell senescence (Fig. 6c-d). These
results indicated that DSG, by inducing the protein degradation of
UHRF1, reduced the genomic DNA methylation levels and re-activated the
expression of TSGs, resulting in cell cycle arrest, and inducing
cellular senescence of PCa cells.