Fig. 4

EV-packaged circBIRC6 promotes oxaliplatin resistance via activation of NHEJ-dependent DNA repair in pancreatic cancer. (A) Pathway enrichment analysis of differentially expressed mRNAs in Panc-1 cells treated with EVs from circBIRC6-overexpressing CAFs. (B-G) Panc-1 and MiaPaCa-2 cells treated with CAF-derived EVs for a week were analyzed as follows: (B-C) Imaging and quantification of oxaliplatin-induced DNA damage using a neutral comet assay. Scale bar, 200 μm. (D-E) Imaging and quantification of γH2AX-positive foci. Scale bar, 10 μm. (F-G) NHEJ-mediated DNA repair efficiency evaluated via pDR-GFP reporter assay. (H-I) Panc-1 and MiaPaCa-2 cells, post-treatment with EVs from circBIRC6-overexpressing CAFs and exposed to oxaliplatin, were allowed to recover with or without 10 µM SCR7. (H) Imaging and quantification of DNA damage using a neutral comet assay. Scale bar, 10 μm. (I) Western blot analysis of γH2AX expression. Data are expressed as mean ± SD. *p < 0.05, **p < 0.01, ***p < 0.001