Research Paper Volume 13, Issue 12 pp 15833—15874

The lack of functional DNMT2/TRDMT1 gene modulates cancer cell responses during drug-induced senescence

DNMT2/TRDMT1 gene knockout-mediated DNA damage (A) and chromosomal damage (B) in U-251 MG glioblastoma cells treated with DOX or ETOPO. (A) DNA double-strands breaks (DSBs) as tail DNA (%) were assessed using neutral comet assay. Representative microphotographs are shown, objective 10x, DNA staining (green). Bars indicate SD, n = 3, ***p a posteriori test), ###p a posteriori test). (B) Micronuclei (MN) formation was assayed using Hoechst 33342 staining and scored as % (a red arrowhead). Box and whisker plots are shown, n = 3, ***p **p a posteriori test), ###p #p a posteriori test). CTR, control conditions; DOX, doxorubicin treatment; ETOPO, etoposide treatment; AZA, azacytidine treatment; MIX, azacytidine post-treatment; C-NIC, control cells with unmodified levels of DNMT2/TRDMT1 containing control plasmid; D-NIC, cells with DNMT2/TRDMT1 gene knockout containing dedicated DNMT2 double nickase plasmid.

Figure 4. DNMT2/TRDMT1 gene knockout-mediated DNA damage (A) and chromosomal damage (B) in U-251 MG glioblastoma cells treated with DOX or ETOPO. (A) DNA double-strands breaks (DSBs) as tail DNA (%) were assessed using neutral comet assay. Representative microphotographs are shown, objective 10x, DNA staining (green). Bars indicate SD, n = 3, ***p < 0.001 compared to CTR (ANOVA and Dunnett’s a posteriori test), ###p < 0.001 compared to C-NIC cells at the same culture conditions (ANOVA and Tukey’s a posteriori test). (B) Micronuclei (MN) formation was assayed using Hoechst 33342 staining and scored as % (a red arrowhead). Box and whisker plots are shown, n = 3, ***p < 0.001, **p < 0.01 compared to CTR (ANOVA and Dunnett’s a posteriori test), ###p < 0.001, #p < 0.05 compared to C-NIC cells at the same culture conditions (ANOVA and Tukey’s a posteriori test). CTR, control conditions; DOX, doxorubicin treatment; ETOPO, etoposide treatment; AZA, azacytidine treatment; MIX, azacytidine post-treatment; C-NIC, control cells with unmodified levels of DNMT2/TRDMT1 containing control plasmid; D-NIC, cells with DNMT2/TRDMT1 gene knockout containing dedicated DNMT2 double nickase plasmid.