The cells were maintained in RPMI-1640 medium (Invitrogen, Carlsbad, CA, USA) supplemented with 10% FBS (Gibco, Grand Island, NY, USA) and 1% Penicillin-Streptomycin (10,000 U/mL) (Invitrogen). For cell transfection, siRNAs including DNMT1 siRNA, BCAT1 siRNA, scrambled siRNA (NC siRNA), miR-124-3p mimics and its negative control (NC mimics) were supplied by Ribobio Company (Guangzhou, China) and pcDNA-BCAT1(OE-BCAT1) or pcDNA-negative (OE-NC) were constructed using pcDNA3.1(+) vector. KYSE-150 and Eca-109 cells grown in 6-well cell plates (1 × 106) were transfected with siRNA or pcDNA3.1vector using Lipofectamine 2000 (Invitrogen) according to the manufacturer’s instruction. After 6 h, the transfection solution was replaced by complete medium.
For drug treatment, KYSE-150 or Eca109 cells were treated with 5 μM 5-Azacitidine (5-Aza, Sigma-Aldrich, Saint Louis, MO, USA), which is the inhibitor of DNMT1.