Fig. 4

Murine bone marrow stromal cells nullify the effect of the combination RBA on MOLM-13 cells, but ascorbic acid restores it. A PI exclusion assay showing cell death of MOLM-13 leukemic cells treated with 10nM RA, 2.25nM Btz, and 500nm ATO (RBA) for 72 h, in mono-culture (blue) or co-culture (red) with primary BMSCs and MS-5 stromal cell line, (left and right panel respectively, one-way ANOVA). B Cell death (left) and cell proliferation (right) of MOLM-13 cells (upper panels) and MS-5 cells (lower panels) treated in co-culture with RBA and 4.5mM ascorbic acid (ASC), for 72 h (one-way ANOVA). MOLM-13 cells, treated in mono-culture, are shown as control (blue bars). C MOLM-13 cells were treated in co-culture with MS-5 cells as in (B), and ROS levels were measured after 72 h. D HMOX, BiP, sXBP1, and CHOP mRNA expression levels of MOLM-13 cells, treated for 24 h as in (B) (one-way ANOVA). E MOLM-13 and MS-5 cells were treated with the combination RBA and ASC as in (B) in co-culture. After 24 h, the conditioned medium (CM) was collected and used to treat MOLM-13 cells in mono-culture. The graph shows cell death of MOLM-13 cells treated for 48 h with CM (one-way ANOVA). F MS-5 cells were treated in co-culture with MOLM-13 for 72 h, then analyzed for Nrf-2 expression by confocal microscopy. The histogram reports the quantification of Nrf-2 mean fluorescence intensity (n = 8 fields ± S.E.M., one-way ANOVA). G ROS measurement in MS-5 cells from the co-culture by flow cytometry (one-way ANOVA). H Assessment of BiP and sXBP1 mRNA expression levels in MS-5 cells from the co-culture, 24 h after treatment (one-way ANOVA)