Fig. 2. SoNar-low B-ALL cells prefer using oxidative phosphorylation as the main energy source.

(A to C) FACS-purified SoNar-high and low B-ALL cells were evaluated for the ratio of SoNar fluorescence by confocal microscopy (A). Quantitative data in (A) as determined by either flow cytometric analysis (B) (n = 3) or confocal microscopy (C) (n = 3) are shown. Scale bar, 10 μm. (D to G) SoNar fluorescence ratios were measured in SoNar-high and low B-ALL cells upon treatment with oxamate, pyruvate, rotenone, and AOA. (H to J) ATP levels (H) and mitochondrial membrane potential (I) in SoNar-high and low B-ALL cells were measured by bioluminescence assay and TMRM staining (n = 3). MFI, mean fluorescence intensity. (K and L) OCRs (K) and extracellular acidification rates (ECAR) (L) were measured in SoNar-high and low B-ALL cells (n = 3). 2-DG, 2-deoxyglucose. mpH, mili potential of hydrogen. (M and N) basal respiration, ATP turnover, and maximum respiration in OCR (OCR_bas, OCR_ATP, and max resp, respectively) (K) as well as glycolysis and glycolysis capacity in ECAR (L) were analyzed (n = 3). (O) Mitochondrial DNA (mtDNA) copies were detected in SoNar-high and low B-ALL cells (n = 3). (P) Extracellular lactate levels in SoNar-high and SoNar-low B-ALL cells (n = 3). (Q) The intermediate metabolites derived from glycolysis and TCA cycle were determined in SoNar-high and SoNar-low B-ALL cells after in vitro labeling with ¹³C-labeled glucose (n = 5). (R) ¹³C-labeled glucose was used for the in vivo labeling in SoNar B-ALL cells, followed by the measurement of intermediate metabolites derived from glycolysis and TCA cycle in SoNar-high and low leukemia cells (n = 3). Data are represented as means ± SEM. Student’s two-tailed unpaired t test (B, C, H, J, and O) and two-way ANOVA with Sidak’s multiple comparison test (M, N, P, Q, and R) were used for the comparison of statistical significance. *P < 0.05, **P < 0.01, and ***P < 0.001.