Characterization of MOLT-4 Cell Line Derivatives

The human T-cell leukemia MOLT-4 cell line bearing wild-type p53 [17 (link),18 (link)] was established and gifted from Dr. Jun Minowada (Roswell Park Memorial Institute, Buffalo, NY, USA), and their derivative transformed cell lines (KD-1 (p53-knockdown by p53-targeting shRNA), Nega (negative control of the shRNA), and KD-1/R-p53-1 (p53-revertant of KD-1)) were established as described in our previous reports [19 (link),20 (link)]. They were cultured in RPMI 1640 medium (Wako, Osaka, Japan). The human hepatoblastoma cell line Hep G2 cells [21 (link)] purchased from ATCC (HB-8065) were cultured in DMEM/F12 medium (Wako). The media were supplemented with 10% fetal bovine serum (FBS) (Gibco, CA, USA) and antibiotics (Nacalai Tesque, Kyoto, Japan) including 100 U/mL penicillin and 0.1 mg/mL streptomycin. They were maintained at 37 °C in a humidified atmosphere with 5% CO₂ and irradiated using an X-ray generator (MBR-1520R-3, Hitachi, Tokyo, Japan) under a tube voltage of 150 kV, a tube current of 20 mA, and a dose rate of approximately 1.6 Gy/min. Dosimetry was carried out with a 0.3 cc N31003 ionization chamber (PTW Freiburg, Freiburg, Germany).