The plasma lipidome in acute myeloid leukemia at diagnosis in relation to clinical disease features

Abstract

Background: Early studies established that certain lipids were lower in acute myeloid leukemia (AML) cells than normal leukocytes. Because lipids are now known to play an important role in cell signaling and regulation of homeostasis, and are often perturbed in malignancies, we undertook a comprehensive lipidomic survey of plasma from AML patients at time of diagnosis and also healthy blood donors.

Methods: Plasma lipid profiles were measured using three mass spectrometry platforms in 20 AML patients and 20 healthy blood donors. Data were collected on total cholesterol and fatty acids, fatty acid amides, glycerolipids, phospholipids, sphingolipids, cholesterol esters, coenzyme Q10 and eicosanoids.

Results: We observed a depletion of plasma total fatty acids and cholesterol, but an increase in certain free fatty acids with the observed decline in sphingolipids, phosphocholines, triglycerides and cholesterol esters probably driven by enhanced fatty acid oxidation in AML cells. Arachidonic acid and precursors were elevated in AML, particularly in patients with high bone marrow (BM) or peripheral blasts and unfavorable prognostic risk. PGF2α was also elevated, in patients with low BM or peripheral blasts and with a favorable prognostic risk. A broad panoply of lipid classes is altered in AML plasma, pointing to disturbances of several lipid metabolic interconversions, in particular in relation to blast cell counts and prognostic risk.

Conclusions: These data indicate potential roles played by lipids in AML heterogeneity and disease outcome.

General significance: Enhanced catabolism of several lipid classes increases prognostic risk while plasma PGF2α may be a marker for reduced prognostic risk in AML.

Keywords: 12-HEPE, 12-hydroxy-5Z,8Z,10E,14Z,17Z-eicosapentaenoic acid; 12-LOX, 12-lipoxygenase; 2HG, (R)-2-hydroxyglutarate; 2OG, 2-oxoglutarate; 8,9-DHET, 8,9-dihydroxy-5Z,11Z,14Z-eicosatrienoic acid; AA, arachidonic acid; ALL, acute lymphoblastic leukemia; AML, acute myeloid leukemia; Acute myeloid leukemia; Blast cell number; CE, cholesterol ester; CML, chronic myelogenous leukemia; CPT1a, carnitine palmitate transferase 1a; Cer, ceramide; CoQ10, coenzyme Q10; DG, diacylglycerol; DGLA, dihomo-γ-linoleic acid; DIC, disseminated intravascular coagulation; EPA, eicosapentaenoic acid (20:5;5Z,8Z,11Z,14Z,17Z); ESI-, electrospray ionization negative mode; ESI +,  electrospray ionization positive mode; Eicosanoids; FAA, fatty acid amide; FAB, French-American-British classification; FAME, fatty acid methyl ester; FAO, fatty acid oxidation; FLC-QqLIT-MS, fast liquid chromatography-quadrupole linear ion-trap mass spectrometry; Fatty acids; GCMS, gas chromatography–mass spectrometry; LPC, lysophosphatidylcholine; LPE, lysophosphatidylethanolamine; Lipidomics; MG, monoacylglycerol; MRM, multiple reactions monitoring; MUFA, monounsaturated fatty acid; OPLS-DA, orthogonal PLS-DA; PC, phosphatidylcholine; PCA, principal components analysis; PE, phosphatidylethanolamine; PGE2, prostaglandin E2; PGF1α, prostaglandin 1α; PGF2α, prostaglandin F2α; PGH2, prostaglandin H2; PLS-DA, projection to latent structures-discriminant analysis; POEA, palmitoleoyl ethanolamide; PUFA, polyunsaturated fatty acid; Prognostic risk; SCD1, stearoyl CoA desaturase 1; SM, sphingomyelin; TG, triacylglycerol (triglyceride); TxA2, thromboxane A2; TxB2, thromboxane B2; UPLC-ESI-QTOFMS, ultraperformance liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry; mPGES-1, microsomal prostaglandin E synthase-1.

Graphical abstract

Fig. 1

Multivariate data analysis for GCMS lipidomics in AML and control plasmas. A, Unsupervised PCA scores plot. Red and green symbols represent AML and control plasma samples, respectively. B, Supervised PLS-DA. Red and green symbols represent AML and control plasma samples, respectively. C, Validation of the PLS-DA model using the leave-one-out procedure whereby one-seventh of the data is removed, randomized, returned, and the PLS-DA model rebuilt. One hundred such permutations were used. R2 is the correlation (purple symbols) and Q2 is the predictability (orange symbols). The data are not over-fitted because the permuted values for R2 and Q2 fall below 0.3 and zero, respectively, and therefore the PLS-DA model is valid. D, Orthogonal PLS-DA loadings S-plot showing lipid molecules that are upregulated (upper right quadrant) and downregulated in AML plasma (lower left quadrant). 1 = 18:2n-6, 2 = cholesterol, 3 = 18:0, 4 = 20:4n-6, 5 = 20:3n-6, 6 = 20:2n-6, 7 = 20:5n-3.

Fig. 2

Univariate data analysis for GCMS lipidomics in AML and control plasmas. Red and green symbols represent AML and control plasma samples, respectively. Vertical dotted lines are median values, with the same color code. p-Values derive from the Mann-Whitney U test. Values are relative concentrations (peak area/internal standard peak area) measured by GCMS. A, palmitic acid (16:0); B, stearic acid (18:0); C, oleic acid (18:1n-9); D, linoleic acid (18:2n-6); E, eicosadienoic acid (20:2n-6); F, eicosatrienoic acid (20:3n-6); G, arachidonic acid (20:4n-6); H, eicosapentaenoic acid (20:5n-3); I, lignoceric acid (24:0); J, cholesterol.

Fig. 3

Lipid metabolic pathways significantly altered in relation to bone marrow (BM) blasts at diagnosis. Blue bars = plasma metabolite level in controls, orange bars = plasma metabolite level in AML patients with intermediate (5–65%) BM blasts, red bars = plasma metabolite level in AML patients with high (> 80%) BM blasts. Error bars represent SD. For distribution of BM blasts see S3A. * means p < 0.05; ** means p < 0.01; *** means p < 0.001 for differences from controls. # means p < 0.05 for differences from intermediate BM blasts. Enzymes involved are 1, fatty acid elongase; 2, Δ⁵-desaturase; 3, COX-1 and COX-2; 4, PGE synthase; 5, carbonyl reductase 1; 6, 15-hydroxyprostaglandin dehydrogenase; 7, prostacyclin synthase; 8, spontaneous reaction; 9, spontaneous reaction; 10, prostaglandin D synthase; 11, spontaneous reaction; 12, 5-lipoxygenase; 13, arachidonic acid 11-oxidoreductase; 14, 15-lipoxygenase.

Fig. 4

Lipid metabolic pathways significantly altered in relation to peripheral blasts at diagnosis. Blue bars = plasma metabolite level in controls, orange bars = plasma metabolite level in AML patients with intermediate (≤ 10%) peripheral blasts, red bars = plasma metabolite level in AML patients with high (> 10%) peripheral blasts. Error bars represent SD. For distribution of BM blasts see Supplemental Fig. 5A. * means p < 0.05; ** means p < 0.01; *** means p < 0.001 for differences from controls. For key to enzymes, see Fig. 3.

Fig. 5

Lipid metabolic pathways significantly altered in relation to risk stratification at diagnosis. Blue bars = plasma metabolite level in controls; green, orange and red bars = good, intermediate and bad risk, respectively. Error bars represent SD. * means p < 0.05; ** means p < 0.01; *** means p < 0.001 for differences from controls. # means p < 0.05 for differences from good risk patients. For key to enzymes, see Fig. 3.

Fig. 6

The AML lipidomic landscape. Ten lipid pools are shown. ↑ means lipid upregulated in AML plasma relative to control plasma. ↑↑↑ means lipid massively upregulated in AML plasma, not detected in control plasma. ↓ means lipid downregulated in AML plasma. ↓↓↓ means lipid massively downregulated in AML plasma or not detected in AML plasma. For lipid names see text.