FIG. 3.

Targeting CD34⁺CD38⁻ CML cells while sparing normal counterparts by fenretinide. (A) Apoptosis rate of CD34⁺CD38⁻ and CD34⁺CD38⁺ CML cells under the indicated drug exposure for 48 h in SFM. Compared with the untreated control, fenretinide alone and the co-treatment markedly induced apoptosis of CD34⁺CD38⁻ and CD34⁺CD38⁺ CML cells, especially the CD34⁺CD38⁻ cells. CD34⁺ cells were stained with CD34-PE, CD38-APC, AnnexinV-FITC, and 7-AAD, and then tested by flow cytometry analysis. (B) The proportion of CD34⁺CD38⁻ cells under the indicated drug exposure. Compared with untreated control, fenretinide alone and the co-treatment markedly decreased the proportion of CD34⁺CD38⁻ CML cells. (C) Representative flow cytometry dot plots showing the effects of fenretinide and imatinib on CD34⁺CD38⁻ CML cells. The bottom panels show the apoptosis rate of CD34⁺CD38⁻ CML cells linked to the top panels. Numbers on the top panels indicate the proportions of CD34⁺CD38⁻ CML cells after 48 h of drug exposure, and numbers on the bottom panels represent the apoptosis rates. (D) Apoptosis rate of normal CD34⁺CD38⁻ and CD34⁺CD38⁺ cells induced by the indicated drug treatments. The CD34⁺ cells were derived from three normal donors. No significant difference was observed for each pair-wise comparison. (E) Flow cytometry dot plots showing Ki-67 expression of CD34⁺ cells population. Proportions of quiescent cells under the indicated drug exposure are lacking expression of Ki-67, as normalized by isotype. Compared with untreated control, fenretinide greatly increased the proportion of Ki-67⁺ cells. Error bar represents SEM. *p<0.05, **p<0.01, respectively denote the statistically significant level of difference between the drug treatments and the untreated control. 7-AAD, 7-aminoactinomycin; SFM, serum-free medium.