Clonogenic survival assay and analysis of combined drug effects

Three thousand UMSCC10A cells each well were planted in a 6-well plate and treated concurrently with different dosages of PL and APR-246. Sixteen hours later, the reagents were removed by washing the cells with 1 × PBS for three times. The cells were cultured for 14 days before fixation for clonogenic determination. Colonies with 50 or more cells were calculated. Survival rate of cells in each treatment was the ratio of value to control group. FA was calculated by “1 - survival rate”. CI was calculated with the CompuSyn software (ComboSyn, Inc. Paramus, NJ 2007).³⁹ A CI < 1.0 was considered as synergy.⁴⁰