Electrochemical detection of the human cancer biomarker ‘autocrine motility factor-phosphoglucose isomerase’ based on a biosensor formed with a monosaccharidic inhibitor

Abstract Human intracellular glycolytic enzyme phosphoglucose isomerase (hPGI) plays the role of autocrine motility factor (AMF) once secreted in the extracellular medium. AMF is a cytokine that stimulates tumor cell motility in vitro and metastases development in vivo. High blood levels of the protein have been reported to be closely related to metastases formation. Since it is secreted by a large variety of tumors, AMF is considered as a validated cancer biomarker. In this work, we report a specific and sensitive electrochemical biosensor designed for the detection and quantification of AMF which is a cancer biomarker present in urine and/or blood of cancer patients. Overexpression and purification of the human protein were performed as well as the synthesis of the inhibitor N-(5-phosphate- d -arabinoyl)-2-amino ethanamine that selectively interacts with the protein. Affinity of the inhibitor for the protein was first evaluated by molecular docking and then by measuring its binding affinity (IC50 = 0.95 µM). The biosensor was constructed by covalent attachment of the synthesized inhibitor bearing an amine function in terminal position to a transducer which is formed with polypyrrole bearing the redox dendrimer PAMAM G2. Protein interactions were quantified by amperometric measurement in a range of 1 pM to 1 µM in HEPES buffer. The biosensor demonstrated a detection limit of 43 fM in phosphate buffer (PBS) and high selectivity for AMF when compared with non-specific D-glucose-6-phosphate dehydrogenase (G6PDH) protein. Detection of AMF in spiked human plasma was performed to demonstrate the efficiency of such system in real sample.