San Martín, A , Ceballo, S., Ruminot, I., Lerchundi, R., Frommer, W.B. & Barros, L.F. 

Biophysic and Molecular Physiology, Center for Scientific Studies

Abstract:

Lactate is a metabolic marker of cancer. In cancer cells mitochondrial function is impaired and most energy is produced via glycolysis, resulting in highly increased production and release of lactate, a phenomenon known as the Warburg effect. Current methods to measure cancer cell metabolism rely on estimation of oxygen consumption in cell populations with limited temporal resolution. In order to measure lactate in single cells with temporal resolution of seconds, we engineered a genetically-encoded Forster Resonance Energy Transfer (FRET)-based Lactate nanosensor designed on the bacterial transcription factor LldR. The sensor, termed Laconic, quantified lactate between 1 μM to 10 mM, spanning physiological and pathological concentrations. Used in combination with ad hoc transporter-block protocols, Laconic allowed for the first time singlecell estimation of two important metabolic parameters: the rate of cellular lactate production and the rate of mitochondrial metabolism. The ratio between lactate production and mitochondrial metabolism, which we have termed Warburg index, was identified as a very sensitive parameter of anomalous metabolism in cancer cells. We envisage that the lactate sensor and associated protocols may be amenable for high-throughput format, for example for cancer drug discovery (PCT/US12/33639).