Page 149 - Haematologica April 2020

MSC-induced SP phenotype leads to chemoresistance
AB
D
E
F
C
Figure 3. Circulating leukemia blasts acquire a Side Population (SP) phenotype in contact with mesenchymal stromal cells (MSC) from healthy donors (HD) or acute myeloid leukemia (AML) patients through α4 integrin interaction. (A) Cytograms illustrating the gating strategy of AML blasts for cytometry analysis (top left) and SP visualization before co-culture (top right) and after a 3-day culture without (bottom left) or with (bottom right) HD MSC. (B) Percentage of SP AML blasts before and after a 3-day co-culture on MSC (either from HD or AML patients) (P<0.001, n=27, Wilcoxon test). (C) Percentage of SP AML blasts after co-culture with HD MSC (P<10-4, n=8-33) or AML patients (P<10-4, n=8-35). (D) Cytograms showing SP phenotype observed on AML blasts from MSC adherent (left) or supernatant fractions (SN, middle) and in transwell experiments (right) after a 3-day co-culture with HD MSC. (E) Percentage of SP blasts in the three experimental conditions. (F and G) Percentage of SP AML blasts after co-culture or not with HD MSC and after inhibition of β1 (n=18) and α4 (n=7) integrins (P=0.04) or CD44 (n=18) (F) and their downstream signaling pathways (G) using dasatinib, LY294002, CAS2859863 and LY209031, inhibiting Src (P=0.002, n=9), AKT (P=0.003, n=9), STAT5 (P=0.009, n=9), and GSK3 pathways (P=0.01, n=6), respectively. *P<0.05; **P<0.01; ***P<0.001.
haematologica | 2020; 105(4)
991
G