[Figure: see text]

• MeSH
• Asparaginase therapeutic use   MeSH
• Biosynthetic Pathways MeSH
• Leukemia * drug therapy   MeSH
• Humans MeSH
• Antineoplastic Agents * pharmacology   therapeutic use   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Asparaginase MeSH
• Antineoplastic Agents * MeSH

Childhood T-cell acute lymphoblastic leukemia (T-ALL) still remains a therapeutic challenge due to relapses which are resistant to further treatment. L-asparaginase (ASNase) is a key therapy component in pediatric T-ALL and lower sensitivity of leukemia cells to this drug negatively influences overall treatment efficacy and outcome. PTEN protein deletion and/or activation of the PI3K/Akt signaling pathway leading to altered cell growth and metabolism are emerging as a common feature in T-ALL. We herein investigated the relationship amongst PTEN deletion, ASNase sensitivity and glucose metabolism in T-ALL cells. First, we found significant differences in the sensitivity to ASNase amongst T-ALL cell lines. While cell lines more sensitive to ASNase were PTEN wild type (WT) and had no detectable level of phosphorylated Akt (P-Akt), cell lines less sensitive to ASNase were PTEN-null with high P-Akt levels. Pharmacological inhibition of Akt in the PTEN-null cells rendered them more sensitive to ASNase and lowered their glycolytic function which then resembled PTEN WT cells. In primary T-ALL cells, although P-Akt level was not dependent exclusively on PTEN expression, their sensitivity to ASNase could also be increased by pharmacological inhibition of Akt. In summary, we highlight a promising therapeutic option for T-ALL patients with aberrant PTEN/PI3K/Akt signaling.

• MeSH
• Asparaginase * pharmacology   therapeutic use   MeSH
• Child MeSH
• Phosphatidylinositol 3-Kinases * genetics   metabolism   MeSH
• PTEN Phosphohydrolase * genetics   metabolism   MeSH
• Humans MeSH
• Precursor T-Cell Lymphoblastic Leukemia-Lymphoma * drug therapy   genetics   metabolism   MeSH
• Proto-Oncogene Proteins c-akt metabolism   MeSH
• Signal Transduction MeSH
• T-Lymphocytes metabolism   MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Asparaginase * MeSH
• PTEN Phosphohydrolase * MeSH
• Proto-Oncogene Proteins c-akt MeSH
• PTEN protein, human MeSH Browser

BACKGROUND: Effectiveness of L-asparaginase administration in acute lymphoblastic leukemia treatment is mirrored in the overall outcome of patients. Generally, leukemia patients differ in their sensitivity to L-asparaginase; however, the mechanism underlying their inter-individual differences is still not fully understood. We have previously shown that L-asparaginase rewires the biosynthetic and bioenergetic pathways of leukemia cells to activate both anti-leukemic and pro-survival processes. Herein, we investigated the relationship between the metabolic profile of leukemia cells and their sensitivity to currently used cytostatic drugs. METHODS: Altogether, 19 leukemia cell lines, primary leukemia cells from 26 patients and 2 healthy controls were used. Glycolytic function and mitochondrial respiration were measured using Seahorse Bioanalyzer. Sensitivity to cytostatics was measured using MTS assay and/or absolute count and flow cytometry. Mitochondrial membrane potential was determined as TMRE fluorescence. RESULTS: Using cell lines and primary patient samples we characterized the basal metabolic state of cells derived from different leukemia subtypes and assessed their sensitivity to cytostatic drugs. We found that leukemia cells cluster into distinct groups according to their metabolic profile. Lymphoid leukemia cell lines and patients sensitive to L-asparaginase clustered into the low glycolytic cluster. While lymphoid leukemia cells with lower sensitivity to L-asparaginase together with resistant normal mononuclear blood cells gathered into the high glycolytic cluster. Furthermore, we observed a correlation of specific metabolic parameters with the sensitivity to L-asparaginase. Greater ATP-linked respiration and lower basal mitochondrial membrane potential in cells significantly correlated with higher sensitivity to L-asparaginase. No such correlation was found in the other cytostatic drugs tested by us. CONCLUSIONS: These data support that cell metabolism plays a prominent role in the treatment effect of L-asparaginase. Based on these findings, leukemia patients with lower sensitivity to L-asparaginase with no specific genetic characterization could be identified by their metabolic profile.

• Keywords
• L-asparaginase, cancer metabolism, fatty acid oxidation, glycolysis, leukemia, mitochondrial membrane potential, mitochondrial respiration, resistance,
• MeSH
• Precursor Cell Lymphoblastic Leukemia-Lymphoma blood   drug therapy   pathology   MeSH
• Asparaginase pharmacology   therapeutic use   MeSH
• Biosynthetic Pathways drug effects   MeSH
• Drug Resistance, Neoplasm MeSH
• Child MeSH
• Glycolysis drug effects   MeSH
• Infant MeSH
• Bone Marrow pathology   MeSH
• Humans MeSH
• Membrane Potential, Mitochondrial drug effects   MeSH
• Metabolome drug effects   MeSH
• Mitochondria drug effects   metabolism   MeSH
• Adolescent MeSH
• Young Adult MeSH
• Cell Line, Tumor MeSH
• Oxidative Phosphorylation drug effects   MeSH
• Child, Preschool MeSH
• Antineoplastic Agents pharmacology   therapeutic use   MeSH
• Treatment Outcome MeSH
• Check Tag
• Child MeSH
• Infant MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Child, Preschool MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Asparaginase MeSH
• Antineoplastic Agents MeSH

Cytochrome c oxidase (COX) is regulated through tissue-, development- or environment-controlled expression of subunit isoforms. The COX4 subunit is thought to optimize respiratory chain function according to oxygen-controlled expression of its isoforms COX4i1 and COX4i2. However, biochemical mechanisms of regulation by the two variants are only partly understood. We created an HEK293-based knock-out cellular model devoid of both isoforms (COX4i1/2 KO). Subsequent knock-in of COX4i1 or COX4i2 generated cells with exclusive expression of respective isoform. Both isoforms complemented the respiratory defect of COX4i1/2 KO. The content, composition, and incorporation of COX into supercomplexes were comparable in COX4i1- and COX4i2-expressing cells. Also, COX activity, cytochrome c affinity, and respiratory rates were undistinguishable in cells expressing either isoform. Analysis of energy metabolism and the redox state in intact cells uncovered modestly increased preference for mitochondrial ATP production, consistent with the increased NADH pool oxidation and lower ROS in COX4i2-expressing cells in normoxia. Most remarkable changes were uncovered in COX oxygen kinetics. The p50 (partial pressure of oxygen at half-maximal respiration) was increased twofold in COX4i2 versus COX4i1 cells, indicating decreased oxygen affinity of the COX4i2-containing enzyme. Our finding supports the key role of the COX4i2-containing enzyme in hypoxia-sensing pathways of energy metabolism.

• Keywords
• mitochondria, OXPHOS, respiratory chain, cytochrome c oxidase, COX, COX4 isoforms, COX4i2, oxygen affinity, p50, oxygen sensing,
• MeSH
• Cytochromes c metabolism   MeSH
• HEK293 Cells MeSH
• Oxygen metabolism   MeSH
• Humans MeSH
• Protein Isoforms metabolism   MeSH
• Gene Expression Regulation, Enzymologic physiology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cytochromes c MeSH
• Oxygen MeSH
• Protein Isoforms MeSH

Abnormalities in cancer metabolism represent potential targets for cancer therapy. We have recently identified a natural compound Quambalarine B (QB), which inhibits proliferation of several leukemic cell lines followed by cell death. We have predicted ubiquinone binding sites of mitochondrial respiratory complexes as potential molecular targets of QB in leukemia cells. Hence, we tracked the effect of QB on leukemia metabolism by applying several omics and biochemical techniques. We have confirmed the inhibition of respiratory complexes by QB and found an increase in the intracellular AMP levels together with respiratory substrates. Inhibition of mitochondrial respiration by QB triggered reprogramming of leukemic cell metabolism involving disproportions in glycolytic flux, inhibition of proteins O-glycosylation, stimulation of glycine synthesis pathway, and pyruvate kinase activity, followed by an increase in pyruvate and a decrease in lactate levels. Inhibition of mitochondrial complex I by QB suppressed folate metabolism as determined by a decrease in formate production. We have also observed an increase in cellular levels of several amino acids except for aspartate, indicating the dependence of Jurkat (T-ALL) cells on aspartate synthesis. These results indicate blockade of mitochondrial complex I and II activity by QB and reduction in aspartate and folate metabolism as therapeutic targets in T-ALL cells. Anti-cancer activity of QB was also confirmed during in vivo studies, suggesting the therapeutic potential of this natural compound.

• Keywords
• leukemia, metabolism, mitochondria, naphthoquinones, therapy,
• Publication type
• Journal Article MeSH