Mitochondrial carriers as new molecular targets for cancer treatement

The flux of a variety of metabolites, nucleotides and coenzymes across the inner membrane of mitochondria is catalysed by a nuclear-coded superfamily of secondary transport proteins called mitochondrial carriers (MCs) [1]. The importance of MCs is demonstrated by their wide distribution in all eukaryotes, their role in numerous metabolic pathways and cell functions with different tissuespecific expression patterns, and the identification of several diseases caused by alterations of their genes [2]. Until now, 22 MC subfamilies have been functionally characterized, mainly by transport assays upon heterologous gene expression, purification and reconstitution into liposomes [1]. In particular two well characterized MC subfamilies are known to play a crucial role in activating the mitochondrial apoptotic pathway, the first is the subfamily of the ADP/ATP carriers and the second is the subfamily of the citrate carrier. ADP/ATP carriers catalyze the efflux of ATP from the mitochondrial matrix in exchange for cytosolic ADP and their specific inhibition can lead the permeability transition pore opening in case of oxidative stress [3]. Citrate carrier catalyses the efflux of citrate from the mitochondrial matrix in exchange for cytosolic malate and plays a key role in inflammation [4,5]. Our data together with literature data let us suppose that these two MC subfamilies are promising molecular targets for cancer treatment. In particular basing on our knowledge of MC structure, translocation mechanism and substrate specificity [6] we are evaluating neuroendocrine cancer cell resistance to old MC inhibitors and we are screening chemical libraries to develop new specific drugs to be used for viability assays.