title: NADH autofluorescence, a new metabolic biomarker for cancer stem cells: Identification of Vitamin C and CAPE as natural products targeting "stemness".
abstract: Here, we assembled a broad molecular "tool-kit" to interrogate the role of metabolic heterogeneity in the propagation of cancer stem-like cells (CSCs). First, we subjected MCF7 cells to "metabolic fractionation" by flow cytometry, using fluorescent mitochondrial probes to detect PCG1α activity, as well ROS and hydrogen-peroxide (H2O2) production; NADH levels were also monitored by auto-fluorescence. Then, the various cell populations were functionally assessed for "stem cell activity", using the mammosphere assay (3D-spheroids). Our results indicate that a sub-population of MCF7 cells, with increased PGC1α activity, high mitochondrial ROS/H2O2 production and high NADH levels, all form mammospheres with a higher efficiency. Thus, it appears that mitochondrial oxidative stress and the anti-oxidant response both contribute to the promotion of mitochondrial biogenesis and oxidative metabolism in CSCs. Further validation was provided by using specific inhibitors to target metabolic processes (the NAD+ salvage pathway, glycolysis, mitochondrial protein synthesis and OXPHOS), significantly reducing CSC propagation. As a consequence, we have now identified a variety of clinically-approved drugs (stiripentol), natural products (caffeic acid phenyl ester (CAPE), ascorbic acid, silibinin) and experimental pharmaceuticals (actinonin, FK866, 2-DG), that can be used to effectively inhibit CSC activity. We discuss the use of CAPE (derived from honey-bee propolis) and Vitamin C, as potential natural therapeutic modalities. In this context, Vitamin C was ~10 times more potent than 2-DG for the targeting of CSCs. Similarly, stiripentol was between 50 to 100 times more potent than 2-DG.
authors.affiliation: The Paterson Building, University of Manchester, Withington, M20 4BX, United Kingdom.
authors.forename: Gloria
authors.initials: G
authors.lastname: Bonuccelli
authors.affiliation: The Paterson Building, University of Manchester, Withington, M20 4BX, United Kingdom.|Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, 87036, Italy.
authors.forename: Ernestina Marianna
authors.initials: EM
authors.lastname: De Francesco
authors.affiliation: The Paterson Building, University of Manchester, Withington, M20 4BX, United Kingdom.
authors.forename: Rianne
authors.initials: R
authors.lastname: de Boer
authors.affiliation: Departments of Pathology and Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
authors.forename: Herbert B
authors.initials: HB
authors.lastname: Tanowitz
authors.affiliation: Translational Medicine, School of Environment and Life Sciences, Biomedical Research Centre, University of Salford, Greater Manchester, M5 4WT, United Kingdom.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Lisanti
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000378:metabolism; D002109:Caffeic Acids / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D004148:Dioxolanes / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D061986:MCF-7 Cells; D009243:NAD / Q000032:analysis* / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism*; D061848:Optical Imaging; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D002109:Caffeic Acids; D004148:Dioxolanes; D009243:NAD; C055494:caffeic acid phenethyl ester; D010626:Phenylethyl Alcohol; D001205:Ascorbic Acid; C021092:stiripentol
keywords: NADH; cancer stem-like cells; metabolic cell fractionation; metabolic heterogeneity; mitochondria