Figure 6.

Multiple subsets of melanoma MPCs exhibit chemoresistance. A, treatment of parental melanoma cultures 1445 and 1118 with 500 μmol/L temozolomide or 0.5 μg/mL cisplatin (IC₉₀ doses) yields marked reduction of the p75⁺ populations and persistence of the CD34⁺ subsets. Numbers highlighted in red indicate a loss in subset percentage, whereas green indicates percentage gain compared with vehicle controls (left). B, single-cell FACS of subsets sorted directly into temozolomide- or cisplatin-spiked medium showed that some CD34⁺ and CD34⁻p75⁻ cells were capable of recovering from each chemotherapy treatment, whereas p75⁺ cells were not. Percent survival shown was normalized to untreated controls. Columns, mean (n = 3); bars, SE.