4.5. Cytotoxicity Assay and Colony Formation Assay

The MTS assay (Promega, Beijing, China) was used to determine the IC50s of enzalutamide, docetaxel, and cisplatin (Selleck, Shanghai, China) in LNcap, PC3, and DU145. Briefly, cells were seeded in 96-well plates with gradated concentrations of the therapeutic drugs, and then the 96-well plates were incubated at 37 °C for 48 h. The absorbance at 492 nm was measured by using a microplate reader (TECAN Spark 10 M, Shanghai, China). A total of 1000 cells/well were seeded in 6-well plates, and clones were harvested after 14 days of culture. Then, the colonies were fixed with 4% paraformaldehyde and then stained with 0.2% crystal violet. The number of clones was counted for statistical analysis.