Despite advances in surgery and adjuvant therapy, brain tumours represent one of the leading causes of cancer-related mortality and morbidity in both adults and children. Gliomas constitute about 60% of all cerebral tumours, showing varying degrees of malignancy. They are difficult to treat due to dismal prognosis and limited therapeutics. Metabolomics is the untargeted and targeted analyses of endogenous and exogenous small molecules, which characterizes the phenotype of an individual. This emerging “omics” science provides functional readouts of cellular activity that contribute greatly to the understanding of cancer biology including brain tumour biology. Metabolites are highly informative as a direct signature of biochemical activity; therefore, metabolite profiling has become a promising approach for clinical diagnostics and prognostics. The metabolic alterations are well-recognized as one of the key hallmarks in monitoring disease progression, therapy and revealing new molecular targets for effective therapeutic intervention. Taking advantage of the latest high-throughput analytical technologies, i.e. nuclear magnetic resonance spectroscopy and mass spectrometry, metabolomics is now a promising field for precision medicine and drug discovery. In the present report, we review the application of metabolomics and in vivo metabolic profiling in the context of adult gliomas and paediatric brain tumours. Analytical platforms such as high-resolution nuclear magnetic resonance, in vivo magnetic resonance spectroscopic imaging and high- and low-resolution mass spectrometry are discussed. Moreover, the relevance of metabolic studies in the development of new therapeutic strategies for treatment of gliomas are reviewed.

Extensive studies in prostate cancer and other malignancies have revealed thatl-methionine (l-Met) and its metabolites play a critical role in tumorigenesis. Preclinical and clinical studies have demonstrated that systemic restriction of seruml-Met, either via partial dietary restriction or with bacteriall-Met–degrading enzymes exerts potent antitumor effects. However, administration of bacteriall-Met–degrading enzymes has not proven practical for human therapy because of problems with immunogenicity. As the human genome does not encodel-Met–degrading enzymes, we engineered the human cystathionine-γ-lyase (hMGL-4.0) to catalyze the selective degradation ofl-Met. At therapeutically relevant dosing, hMGL-4.0 reduces seruml-Met levels to >75% for >72 h and significantly inhibits the growth of multiple prostate cancer allografts/xenografts without weight loss or toxicity. We demonstrate that in vitro, hMGL-4.0 causes tumor cell death, associated with increased reactive oxygen species, S-adenosyl-methionine depletion, global hypomethylation, induction of autophagy, and robust poly(ADP-ribose) polymerase (PARP) cleavage indicative of DNA damage and apoptosis.

Exploiting metabolic vulnerabilities of cancer cells with nontoxic, plant derived compounds constitutes a novel strategy for both chemoprevention and treatment. A high‐throughput screening approach was used to evaluate a library of natural products to determine the most synergistic combination in precursor‐B cell acute lymphoblast leukemia. Dimethylaminoparthenolide and shikonin effectively inhibited proliferation resulting in cell death in primary and immortalized leukemia cells, while having negligible effects on normal cells. Dimethylaminoparthenolide and shikonin have been shown separately to inhibit cell survival and proliferative signaling and activate tumor suppressors and proapoptotic pathways. Untargeted metabolomics and metabolic flux analysis with stable isotopically labeled glucose and glutamine exhibited a global shift in metabolism following treatment. Pathway analysis indicated significant differences in amino acid, antioxidant, tricarboxylic acid cycle, and nucleotide metabolism. Together, dimethylaminoparthenolide and shikonin reduced the shunting of glycolytic intermediates into the pentose phosphate pathway for biosynthetic purposes. Similarly, the incorporation of glutamine and glutamine‐derived metabolites into purine and pyrimidine synthesis was inhibited by the combination of dimethylaminoparthenolide and shikonin, effectively impeding biosynthetic pathways critical for leukemia cell survival. This approach demonstrates that a synergistic pair of compounds with malignant cell specificity can effectively target metabolic pathways crucial to leukemia cell proliferation and induce apoptosis.

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