The absence of Il6 in MSCs impairs the OXPHOS status in AML cells. (A) Overall survival analysis of patients with AML with high (n = 65) and low expression (n = 65) of IL-6R from the TCGA database. (B) Gene set enrichment analysis of the high OXPHOS gene signature in patients with AML with high and low IL-6R expression from the TCGA database. (C) Measurement of mitochondrial respiration in AML cells isolated from Il6^fl/fl and Il6_Prrx1^–/– AML mice using a Seahorse Bioscience XF analyzer (n = 3). (D) Calculation of basal respiration, maximal respiration, and mitochondrial ATP production based on measurements shown in panel C (n = 3). (E-G) FCM analysis of mitochondrial mass (E), membrane potential (F), and mtROS levels (G) in AML cells isolated from Il6^fl/fl and Il6_Prrx1^–/– AML mice (n = 5). (H) Colony formation assay of AML cells isolated from Il6^fl/fl and Il6_Prrx1^–/– AML mice (n = 3; scale bar, 100 μm). (I) FCM analysis of LSC frequency, defined as YFP⁺ c-KIT⁺ cells, in the BM of Il6^fl/fl and Il6_Prrx1^–/– mice (n = 5). (J) Kaplan-Meier survival curves of secondary recipient mice transplanted with 2 × 10⁵ AML cells derived from primary Il6^fl/fl or Il6_Prrx1^–/– AML mice (n = 5). Data are presented as mean ± SD. Log-rank (Mantel-Cox) test was used for survival study comparisons (panels A,J). Differences were analyzed using 2-way ANOVA with Sidak multiple comparisons test (panel D) or 2-tailed unpaired t test (panels E-I). ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001. ATP, adenosine triphosphate; Basal, basal respiration; FDRq, false discovery rate q-value; Max, maximal respiration; MFI, mean fluorescence intensity; NES, normalized enrichment score; OCR, oxygen consumption rate.