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.