Figure 1

Impact of YB-1 overexpression on oxaliplatin resistance in SW480 cells. A) Survival assay of SW480 cells treated for 24, 48, or 72 hours with the indicated concentrations of oxaliplatin. Live cells were then counted with a hemacytometer by the trypan blue exclusion technique. Experiments were performed in duplicate. Bars represent SEM. B) Survival assays of SW480 cells transfected with either wild type YB-1 or an expression empty vector. Six hours after the transfections, cells were treated with one or two μM of oxaliplatin for 24 or 48 hours. Live cells were then counted with a hemacytometer by the trypan blue exclusion technique. Experiments were performed in duplicate. Bars represent SEM. C) Example of Western blots showing endogenous YB-1 expression in control transfected cells (6 hours after transfection) and in nontransfected SW480 cells. The histogram below the Western blots represents the YB-1 signal over β-actin signal. D) Clonogenic assays with SW480 cells transfected either with wild type YB-1 or an empty expression vector. Transfected cells were treated (6 hours after transfection) with the indicated concentrations of oxaliplatin for 18 hours and then plated in 90-mm petri dishes with fresh media without drugs for 10 days. Survival fraction represents the number of colonies after treatment divided by the number of colonies without treatment (in %). Results represent the mean ± SEM of duplicate experiments. E) Example of Western blots showing YB-1 expression in transfected cells (6 hours after transfection). Bands were revealed using an ECL plus kit after less than a five second exposition. The histogram below the Western blots represents the YB-1 signal over β-actin signal.