ABSTRACT
We report the analysis of CPI-613, the first member of a large set of analogs of lipoic acid (lipoate) we have investigated as potential anticancer agents. CPI-613 strongly disrupts mitochondrial metabolism, with selectivity for tumor cells in culture. This mitochondrial disruption includes activation of the well-characterized, lipoate-responsive regulatory phosphorylation of the E1α pyruvate dehydrogenase (PDH) subunit. This phosphorylation inactivates flux of glycolysis-derived carbon through this enzyme complex and implicates the PDH regulatory kinases (PDKs) as a possible drug target. Supporting this hypothesis, RNAi knockdown of the PDK protein levels substantially attenuates CPI-613 cancer cell killing. In both cell culture and in vivo tumor environments, the observed strong mitochondrial metabolic disruption is expected to significantly compromise cell survival. Consistent with this prediction, CPI-613 disruption of tumor mitochondrial metabolism is followed by efficient commitment to cell death by multiple, apparently redundant pathways, including apoptosis, in all tested cancer cell lines. Further, CPI-613 shows strong antitumor activity in vivo against human non-small cell lung and pancreatic cancers in xenograft models with low side-effect toxicity.
Subject(s)
Antineoplastic Agents/pharmacology , Caprylates/pharmacology , Mitochondria/enzymology , Neoplasms/drug therapy , Oxidative Phosphorylation/drug effects , Pyruvate Dehydrogenase Complex/metabolism , Sulfides/pharmacology , Thioctic Acid/pharmacology , Animals , Antineoplastic Agents/chemistry , Antioxidants/pharmacology , Caprylates/chemistry , Cell Line, Tumor , Drug Screening Assays, Antitumor , Gene Knockdown Techniques , Humans , Mice , Neoplasm Transplantation , Neoplasms/enzymology , Neoplasms/genetics , Oxidation-Reduction/drug effects , Pyruvate Dehydrogenase Complex/genetics , Sulfides/chemistry , Thioctic Acid/chemistry , Transplantation, HeterologousABSTRACT
Isotope-edited IR of proteins has generated considerable interest. Double labeling with 13C and 18O with high levels of isotopic enrichment is required for residue-specific resolution. Current methods for the preparation of doubly labeled amino acids give modest 18O enrichment, limiting the utility of the approach. We report a simple and economical method for preparing 13C,18O-doubly labeled N-(9-fluorenylmethoxycarbonyl)amino acids with high levels of enrichment for residues that do not require acid-labile side-chain protecting groups.
