NADH autofluorescence, a new metabolic biomarker for cancer stem cells : identification of Vitamin C and CAPE as natural products targeting “stemness”

Bonuccelli, G; De Francesco, E; de Boer, R; Tanowitz, H; Lisanti, MP

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.

Citation

Bonuccelli, G., De Francesco, E., de Boer, R., Tanowitz, H., & Lisanti, M. (2017). NADH autofluorescence, a new metabolic biomarker for cancer stem cells : identification of Vitamin C and CAPE as natural products targeting “stemness”. Oncotarget, 2017(8), 20667-20678. https://doi.org/10.18632/oncotarget.15400

• Journal Article Type: Article
• Acceptance Date: Jan 25, 2017
• Publication Date: Feb 16, 2017
• Deposit Date: Mar 31, 2017
• Publicly Available Date: Mar 31, 2017
• Journal: Oncotarget
• Publisher: Impact Journals
• Volume: 2017
• Issue: 8
• Pages: 20667-20678
• DOI: https://doi.org/10.18632/oncotarget.15400
• Publisher URL: http://dx.doi.org/10.18632/oncotarget.15400
• Related Public URLs: http://www.impactjournals.com/oncotarget/index.php?journal=oncotarget