Cell proliferation assay

Cell Counting Kit-8 (CCK-8; Dojindo, Kumamoto, Japan) was used to detect the effect of JQ1 on cell proliferation according to the manufacturer’s instructions. Briefly, the human normal epithelial cells were seeded in 96-well plates at a density of 5000 cells/well. ACC-LM and ACC-83 cells were seeded in 96-well plates at a density of 3000 cells/well. These cells were maintained with various concentrations of JQ1, respectively. After cultured for 1–4 days, 10 μl of CCK-8 solution was added to each well, and the plates were incubated for 3 h at 37 °C. The optical density (OD) levels were measured at 450 nm using the SPECTROstar Nano microplate reader (BMG Labtech Inc., Ortenberg, Germany).