Figure 5.

Aminopeptidase inhibitors reduce sensitivity to melflufen in MM cell lines. (A) MM cell lines RPMI-8226 and MM.1S were treated with different concentrations of the aminopeptidase inhibitor tosedostat for 48 h, and cell viability was measured using PrestoBlue cell viability reagent. (B) RPMI-8226 cells or (C) MM.1S cells were pretreated with DMSO (control) or the aminopeptidase inhibitors bestatin (10 μM) or tosedostat (10 μM) for 1 h, then either left without additional treatment or treated with three different concentrations of melflufen or melphalan for 15 min, after which the medium was replaced. After 48 h, cell viability was measured using PrestoBlue cell viability reagent. Statistical significance is indicated as *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001; ****p ≤ 0.0001. DMSO: dimethyl sulfoxide