Cell migration and invasion assays

Cell migration assay was performed in 24-well CIM plates (BD Biosciences, CA, USA). Briefly, 1–3 × 10⁴ cells per well were seeded in serum-free medium plus indicated drugs in the upper compartment of the CIM plates. Serum-complemented medium was added to the lower compartment of the chamber. After 24 h incubation, cells that passed through the septum were fixed with cold methanol and stained with crystal violet. The average number of migrated cells in four random microscopic fields was counted. Cell invasion assay was performed in 24-well CIM plates coated with matrigel. Other steps were identical to those of cell migration assay. VP-16 was provided by Hengrui Medicine (Jiangsu, China), ADM and CPT-11 were provided by Pfizer (New York, NY, USA). Fludarabine (HY-B0069), Bay11–7082 (HY-13453), C-176 (HY-112906), KU55933 (HY-12016) and AG490 (HY-12000) were purchased from MCE (Middlesex County, NJ, USA). GSH was purchased from Beyotime (Beijing, China).