Human AML cells differ with respect to their expression of TNF and their sensitivity toward the BMM-derived inflammatory factor PGE2. (A) Relative expression of TNF in the indicated cell lines, as measured by quantitative real time polymerase chain reaction (P = .0009; P = .0100; P = .0489; 2-way ANOVA; Sidak test; n = 4-9). (B) Log2 expression of TNF in leukocytes of patients with AML due to various genetic aberrations, taken from the BloodSpot portal (The Cancer Genome Atlas Program). (C) Proliferation of OCIAML3 (NPM1 gene mutation [type A] and the DNMT3A R882C gene mutation; left), THP1 (MLL-AF9⁺; middle), and Kasumi (AML1-ETO⁺; right) cells exposed to PGE2 (0.1 μM for 72 hours), the inhibitor of PGE2 receptor 4 subtype E7046 (iEP4) (3 μM for 72 hours) or PGE2 and iEP4 (P = .0026, P = .0128, P = .014, and P = .038; 1-way ANOVA; Sidak test; n = 5-7). (D-E) Representative immunofluorescence images (left) and their quantification (right) of β-catenin in THP1 (D) or Kasumi (E) cells exposed to PGE2 (0.1 μM for 2 hours) or PGE2 and iEP4 (3 μM for 2 hours), stained for β-catenin (green) and DAPI (blue) (n = 4). The scale bar represents 50 μm (P = .006 and P = .040; 1-way ANOVA; Sidak test; n = 5). Four different fields from 5 individual biological replicates were imaged; each dot represents the average per replicate. (F-G) Proliferation, assessed after 72 hours, of THP1 (F) or Kasumi (G) cells plated on hMSCs, which had been pretreated with vehicle or an inhibitor of NF-κB, NF-κB inhibitor III, (iNF-κB) at a concentration of 10 μM for 24 hours.