TY - JOUR
T1 - NADH autofluorescence, a new metabolic biomarker for cancer stem cells
T2 - Identification of Vitamin C and CAPE as natural products targeting "stemness"
AU - Bonuccelli, Gloria
AU - De Francesco, Ernestina Marianna
AU - de Boer, Rianne
AU - Tanowitz, Herbert B.
AU - Lisanti, Michael P.
N1 - Funding Information:
Dr. Ernestina M. De Francesco was supported by an iCARE fellowship from the Associazione Italiana per la Ricerca sul Cancro (AIRC) cofunded by Marie Curie Actions. The Lisanti Laboratory is currently supported by private donations, and by funds from the Healthy Life Foundation (HLF) and the University of Salford.
PY - 2017
Y1 - 2017
N2 - 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.
AB - 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.
KW - Cancer stem-like cells
KW - Metabolic cell fractionation
KW - Metabolic heterogeneity
KW - Mitochondria
KW - NADH
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UR - http://www.scopus.com/inward/citedby.url?scp=85016393617&partnerID=8YFLogxK
U2 - 10.18632/oncotarget.15400
DO - 10.18632/oncotarget.15400
M3 - Article
AN - SCOPUS:85016393617
SN - 1949-2553
VL - 8
SP - 20667
EP - 20678
JO - Oncotarget
JF - Oncotarget
IS - 13
ER -