3-methylbutanoic-acid-[(2R-3S-6S-7R)-3-[[(3-formamido-2-hydroxyphenyl)-oxomethyl]amino]-8-hexyl-2-6-dimethyl-4-9-dioxo-1-5-dioxonan-7-yl]-ester and Colonic-Neoplasms

The importance of upregulated Wnt signaling in colorectal cancers led to efforts to develop inhibitors that target β-catenin in this pathway. We now report that several "Wnt inhibitors" that allegedly target β-catenin actually function as mitochondrial proton uncouplers that independently activate AMPK and concomitantly inhibit Wnt signaling. As expected for a process in which mitochondrial uncoupling diminishes ATP production, a mitochondrial proton uncoupler, FCCP, and a glucose metabolic inhibitor, 2-DG, activated AMPK and inhibited Wnt signaling. Also consistent with these findings, a well-known "Wnt inhibitor", FH535, functioned as a proton uncoupler, and in support of this finding, the

Topics: AMP-Activated Protein Kinases; Animals; beta Catenin; Brain; Colonic Neoplasms; Energy Metabolism; Enzyme Activation; Enzyme Activators; Gene Expression Regulation, Neoplastic; Humans; Hydrocarbons, Fluorinated; Mitochondria; Oxygen Consumption; Sulfonamides; Tumor Cells, Cultured; Urea; Wnt Proteins

A known (1) and a structurally related new natural product (2), both belonging to the amorfrutin benzoic acid class, were isolated from the roots of Glycyrrhiza foetida. Compound 1 (amorfrutin B) is an efficient agonist of the nuclear peroxisome proliferator activated receptor (PPAR) gamma and of other PPAR subtypes. Compound 2 (amorfrutin C) showed comparably lower PPAR activation potential. Amorfrutin C exhibited striking antiproliferative effects for human colorectal cancer cells (HT-29 and T84), prostate cancer (PC-3), and breast cancer (MCF7) cells (IC50 values ranging from 8 to 16 μM in these cancer cell lines). Notably, amorfrutin C (2) showed less potent antiproliferative effects in primary colon cells. For HT-29 cells, compound 2 induced G0/G1 cell cycle arrest and modulated protein expression of key cell cycle modulators. Amorfrutin C further induced apoptotic events in HT-29 cells, including caspase activation, DNA fragmentation, PARP cleavage, phosphatidylserine externalization, and formation of reactive oxygen species. Mechanistic studies revealed that 2 disrupts the mitochondrial integrity by depolarization of the mitochondrial membrane (IC50 0.6 μM) and permanent opening of the mitochondrial permeability transition pore, leading to increased mitochondrial oxygen consumption and extracellular acidification. Structure-activity-relationship experiments revealed the carboxylic acid and the hydroxy group residues of 2 as fundamental structural requirements for inducing these apoptotic effects. Synergy analyses demonstrated stimulation of the death receptor signaling pathway. Taken together, amorfrutin C (2) represents a promising lead for the development of anticancer drugs.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; bcl-2-Associated X Protein; Caspases; Cell Cycle Checkpoints; Cell Proliferation; Colonic Neoplasms; Drug Screening Assays, Antitumor; Female; G1 Phase Cell Cycle Checkpoints; Glycyrrhiza; HT29 Cells; Humans; Inhibitory Concentration 50; Male; Membrane Potential, Mitochondrial; Mitochondria; Molecular Structure; Morocco; Peroxisome Proliferator-Activated Receptors; Plant Roots; Reactive Oxygen Species; Salicylates; Structure-Activity Relationship