FEN1 and head and neck squamous cell carcinoma: For example, in head and neck squamous cell carcinoma, miR-205-5p down-regulates BRCA1 expression, inhibits DDR, promotes cell growth and tumor metastasis [11]; in osteosarcoma cells and cervical cancer cells, miR-22 inhibits the DDR process by targeting MDC1, Increase cell radiotherapy tolerance; in glioblastoma, miR-1193 directly targets YY1AP1 (YY1-associated protein 1), thereby inhibiting FEN1 (Flap endonuclease 1), leading to the accumulation of DNA double-strand breaks, thereby increasing Genomic instability [12].