Fig. 4

circCDYL2 enhances RAD51 translation to promote DNA homologous recombination repair in nasopharyngeal carcinoma. A. Polysome profiling demonstrated that circCDYL2 enhances RAD51 mRNA expression on polysomes in NPC cells after overexpression or knockdown of circCDYL2. B. Flow cytometry showed that RAD51 could partially reverse the effect of circCDYL2 on homologous recombination repair in DR-GFP U2OS cells after simultaneous overexpression of circCDYL2 combined with knockdown of RAD51 or knockdown of circCDYL2 with overexpression of RAD51, respectively. Each group was co-transfected with the HA-Isce1 overexpression plasmid. C. Clonogenic assays showed that RAD51 partially reversed the effect of circCDYL2 on HNE2 cells survival post-irradiation. Cells were exposed to 0, 2, 4, 6, and 8 Gy X-ray irradiation, respectively after simultaneous overexpression of circCDYL2 combined with knockdown of RAD51 or knockdown of circCDYL2 with overexpression of RAD51. D. Immunofluorescence showed that RAD51 could partially reverse the regulation of γ-H2AX radiation-induced foci (IRIF) by circCDYL2 in HNE2 cells These cells were irradiated with 6 Gy X-rays for 6 hours after simultaneous overexpression of circCDYL2 combined with knockdown of RAD51 or knockdown of circCDYL2 with overexpression of RAD51. Scale bar = 10 μm. E. Western blotting demonstrated that RAD51 could partially reverse the regulation of γ-H2AX expression levels by circCDYL2 in HNE2 cells. Knockdown of circCDYL2, overexpression of RAD51, and simultaneous knockdown of circCDYL2 with overexpression of RAD51 in HNE2 cells, respectively. These cells were irradiated with 6 Gy X-rays for 0, 2, 6, 12, or 24 hours, respectively. F. Comet assays showed that RAD51 mediated the effect of circCDYL2 on DNA damage repair in HNE2 cells after simultaneous overexpression of circCDYL2 combined with knockdown of RAD51 or knockdown of circCDYL2 with overexpression of RAD51, respectively. These cells were irradiated with 6 Gy X-rays, and c Scale bar = 20 μm. Data were represented as mean ± SD. ns, not significant; *, p < 0.05; **, p < 0.01; ***, p < 0.001