Clonogenic survival assays

Clonogenic survival assays were conducted as described previously [53]. Briefly, 1 × 10²⁻⁵ cells were seeded in 6‐well plates containing 6 mL of 1.6% W/V methylcellulose‐containing DMEM/F12 medium (Gibco) with various concentrations of DNA‐damaging agents: etoposide (0, 100, 200, and 300 nm) (Sigma‐Aldrich, St. Louis, MO, USA), camptothecin (0, 15, 30, and 45 nm) (Sigma‐Aldrich), cisplatin (0, 0.5, 1, 1.5, and 2 µm) (Sigma‐Aldrich), and olaparib (0, 0.5, 1, 1.5, and 2 µm) (Selleckchem, Houston, TX, USA). For UV‐C sensitivity assay, cells were seeded as described above and exposed to various doses of UV‐C (0, 3, 6, and 9 J·m⁻²) using a HL‐2000 HybridLinker™ hybridization oven and cross‐linker (Thermo Fisher Scientific, Waltham, MA, USA), and then, 6 mL of 1.6% W/V methylcellulose‐containing DMEM/F12 medium was added. Surviving colonies were counted within 10–14 days. The percentage of survival was calculated by normalizing to a number of surviving colonies of untreated cells.