An imaging technique that tracks a common cancer biomarker offers promise for diagnosing and monitoring cancers linked to mutations in metabolic genes. The compound 2-hydroxyglutarate (2-HG) is a biomarker of various cancers linked to mutations in IDH genes, which are central to metabolism. Kayvan Keshari at the Memorial Sloan Kettering Cancer Center in New York City and his colleagues found that 2-HG is rapidly produced from the amino acid glutamine in human cells with some such mutations. Using a type of magnetic resonance imaging and an isotopically labelled form of glutamine, the authors were able to measure production of this biomarker non-invasively in mice. They also found that inhibiting one gene that is mutated in these cancers reduced the production of 2-HG by about 40%. This could lead to new ways of diagnosing and monitoring these tumours, say the authors.
MicroRNAs in blood samples have been identified as an important class of biomarkers, which can reflect physiological changes from cancer to brain dysfunction. In this report we identify concordant increases in levels of expression of miR-34a in brain and two components of mouse blood samples, peripheral blood mononuclear cells (PBMCs) and plasma, from 2 day old neonates through young adulthood and mid-life to old age at 25 months. Levels of this microRNA's prime target, silent information regulator 1 (SIRT1), in brain and the two blood-derived specimens decrease with age inversely to miR-34a, starting as early as 4 months old, when appreciable tissue aging has not yet begun. Our results suggest that: 1. Increased miR-34a and the reciprocal decrease of its target, SIRT1, in blood specimens are the accessible biomarkers for age-dependent changes in brain; and 2. these changes are predictors of impending decline in brain function, as early as in young adult mice.