miR-665 mimic increases the radiosensitivity of CRC cells by targeting NOTCH1. LOVO and SW480 cells were introduced with miRNA NC, miR-665 mimic, miR-665 mimic + pc-NC, or miR-665 mimic + pc-NOTCH1 and then treated with 6 Gy irradiation. Cell viability (a), apoptosis (b), colony number (c), migration and invasion (d and e), and migratory rate (f) were detected using CCK-8 assay, flow cytometry, colony formation assay, transwell, and scratch assay, respectively. Data are shown as mean ± SD, n = 3. *P < 0.05.