Snu cell lines

HNC cell lines (HN2–10) and SNU cell lines were purchased from the Korea Cell Line Bank (Seoul, Republic of Korea) and authenticated by short tandem repeat-based DNA fingerprinting and multiplex polymerase chain reaction (PCR). The cells were cultured in Eagle's minimum essential medium or Roswell Park Memorial Institute (RPMI) 1640 (Thermo Fisher Scientific, Waltham, MA, USA) with 10% fetal bovine serum at 37 °C in a humidified atmosphere containing 5% CO₂. Normal oral keratinocytes or fibroblasts were obtained from patients undergoing oral surgery and used for in vitro assays. Three cisplatin-resistant HNC cell lines (HN3-cisR, HN4-cisR, and HN9-cisR) were developed from the parental HN3, HN4, and HN9 cells, respectively, by subjecting them to continuous exposure of increasing cisplatin concentrations [30] (link). The half-maximal inhibitory concentrations (IC₅₀) of cisplatin (Sigma-Aldrich, St. Louis, MO, USA) in the parental (2.2–3.5 µM) and cisplatin-resistant (25.5–38.9 µM) HNC cells were determined using cell viability assays.