ABSTRACT
Lactate exchange between glycolytic and oxidative cancer cells is proposed to optimize tumor growth. Blocking lactate uptake through monocarboxylate transporter 1 (MCT1) represents an attractive therapeutic strategy but may stimulate glucose consumption by oxidative cancer cells. We report here that inhibition of mitochondrial pyruvate carrier (MPC) activity fulfils the tasks of blocking lactate use while preventing glucose oxidative metabolism. Using in vitro 13C-glucose and in vivo hyperpolarized 13C-pyruvate, we identify 7ACC2 as a potent inhibitor of mitochondrial pyruvate transport which consecutively blocks extracellular lactate uptake by promoting intracellular pyruvate accumulation. Also, while in spheroids MCT1 inhibition leads to cytostatic effects, MPC activity inhibition induces cytotoxic effects together with glycolysis stimulation and uncompensated inhibition of mitochondrial respiration. Hypoxia reduction obtained with 7ACC2 is further shown to sensitize tumor xenografts to radiotherapy. This study positions MPC as a control point for lactate metabolism and expands on the anticancer potential of MPC inhibition.
Subject(s)
Lactic Acid/pharmacokinetics , Mitochondria/metabolism , Monocarboxylic Acid Transporters/genetics , Monocarboxylic Acid Transporters/physiology , Pyruvic Acid/metabolism , Symporters/genetics , Symporters/physiology , Animals , Antineoplastic Agents/pharmacology , Biological Transport , Cell Line, Tumor , Female , Gene Silencing , Glucose/chemistry , Glycolysis/drug effects , Humans , Ion Transport/drug effects , Lactic Acid/chemistry , MCF-7 Cells , Male , Mice , Mice, Inbred C57BL , Muscle Proteins/genetics , Muscle Proteins/physiology , Neoplasm Transplantation , Oxygen/chemistry , RNA, Small Interfering/metabolism , Radiation-Sensitizing Agents/pharmacology , Rats , Thiophenes/chemistry , Uracil/analogs & derivatives , Uracil/chemistry , Xenopus laevisABSTRACT
Transient receptor potential (TRP) cation channel subfamily M member 3 (TRPM3), a member of the TRP channel superfamily, was recently identified as a nociceptor channel in the somatosensory system, where it is involved in the detection of noxious heat; however, owing to the lack of potent and selective agonists, little is known about other potential physiological consequences of the opening of TRPM3. Here we identify and characterize a synthetic TRPM3 activator, CIM0216, whose potency and apparent affinity greatly exceeds that of the canonical TRPM3 agonist, pregnenolone sulfate (PS). In particular, a single application of CIM0216 causes opening of both the central calcium-conducting pore and the alternative cation permeation pathway in a membrane-delimited manner. CIM0216 evoked robust calcium influx in TRPM3-expressing somatosensory neurons, and intradermal injection of the compound induced a TRPM3-dependent nocifensive behavior. Moreover, CIM0216 elicited the release of the peptides calcitonin gene-related peptide (CGRP) from sensory nerve terminals and insulin from isolated pancreatic islets in a TRPM3-dependent manner. These experiments identify CIM0216 as a powerful tool for use in investigating the physiological roles of TRPM3, and indicate that TRPM3 activation in sensory nerve endings can contribute to neurogenic inflammation.
Subject(s)
Neuropeptides/metabolism , Quinolines/pharmacology , TRPM Cation Channels/metabolism , Animals , Calcium/metabolism , Cell Membrane Permeability/drug effects , HEK293 Cells , Hot Temperature , Humans , Insulin/metabolism , Insulin Secretion , Insulin-Secreting Cells/drug effects , Insulin-Secreting Cells/metabolism , Ion Channel Gating/drug effects , Ligands , Mice, Inbred C57BL , Nerve Endings/drug effects , Nerve Endings/metabolism , Nociception/drug effects , Pain/pathology , Pain/physiopathology , Pregnenolone/pharmacology , Quinolines/chemistry , Sensory Receptor Cells/drug effects , Sensory Receptor Cells/metabolism , TRPM Cation Channels/agonists , TransfectionABSTRACT
The development of a novel, chemoselective, and catalytic deprotection methodology that proceeds under mild and neutral conditions is described, and its mechanism of action is analyzed in some detail. The scope, limitations, and advantages of this protocol are discussed. Selected applications in synthesis are also highlighted.