Figure 1.

B-ALL cells show increased susceptibility to conventional chemotherapy after PKC inhibition in the mesenchymal support. (A) Cell viability of primary B-ALL cells after PKC inhibition and treatment with MTX. As control, B-ALL cells without treatment (NT) were included. MSC were treated with HKPS, the commercial inhibitor ENZA, or the controls for 2 h, as indicated. B-ALL cells, pre-treated 6 h with 6.25 µM of MTX, were co-cultured for additional 72 h on MSC. Co-cultures were collected after trypsinization and the cell viability was assessed by flow cytometry on the leukemic cell population through the double staining with the reactive LIVE/DEAD Aqua and the anti-CD19 antibody. A representative experiment is shown. (B) Quantification of the B-ALL cell population double positive for CD19 and LIVE/DEAD Aqua as described in A. (C) Quantification of the viability of the B-ALL cells after inhibition of PKC in MSC with HKPS, HK (40 µM), ENZA (20 µM), or the vehicle (0.4% DMSO) and co-culturing for 72 h with B-ALL cells pre-treated with VNC (500 nM). (D) Simultaneous effect of DEXA and HKPS on B-ALL cells viability. Leukemic cells were pre-treated for 6 h with DEXA (250 nM), HKPS (40 µM), or both, and then they were co-cultured for 24 h with non-treated MSC (CO-CULTURE (MSC NT)); also, co-cultures were established and then cells were treated with the combination of HKPS and DEXA (CO-CULTURE TREATED); as controls, B-ALL cells without support were employed (B-ALL ALONE, upper panel). Cell viability was assessed by flow cytometry. A representative experiment is shown. (E) Percentages of B-ALL cells viability in the conditions indicated above. Data are expressed as mean ± SEM (p values: Non-parametric one-way ANOVA. * p < 0.05. ** p < 0.01. *** p < 0.001) from two independent experiments.