Journal
CELL CYCLE
Volume 10, Issue 15, Pages 2504-2520Publisher
TAYLOR & FRANCIS INC
DOI: 10.4161/cc.10.15.16585
Keywords
tumor stroma; microenvironment; hydrogen peroxide; aerobic glycolysis; mitochondrial oxidative phosphorylation; glucose uptake; oxidative stress; reactive oxygen species (ROS); cancer associated fibroblasts; PET imaging; the field effect; caveolin-1
Categories
Funding
- NIH/NCI [R01-CA-080250, R01-CA-098779, R01-CA-120876, R01-AR-055660, R01-CA-70896, R01-CA-75503, R01-CA-86072, R01-CA-107382]
- Susan G. Komen Breast Cancer Foundation
- W.W. Smith Charitable Trust
- Breast Cancer Alliance (BCA)
- American Cancer Society (ACS)
- Margaret Q. Landenberger Research Foundation
- Dr. Ralph and Marian C. Falk Medical Research Trust
- NIH/NCI Cancer Center [P30-CA-56036]
- Pennsylvania Department of Health
- Breakthrough Breast Cancer in the UK
- European Research Council
Ask authors/readers for more resources
Previously, we proposed that cancer cells behave as metabolic parasites, as they use targeted oxidative stress as a weapon to extract recycled nutrients from adjacent stromal cells. Oxidative stress in cancer-associated fibroblasts triggers autophagy and mitophagy, resulting in compartmentalized cellular catabolism, loss of mitochondrial function, and the onset of aerobic glycolysis, in the tumor stroma. As such, cancer-associated fibroblasts produce high-energy nutrients (such as lactate and ketones) that fuel mitochondrial biogenesis and oxidative metabolism in cancer cells. We have termed this new energy-transfer mechanism the Reverse Warburg Effect. To further test the validity of this hypothesis, here we used an in vitro MCF7-fibroblast co-culture system and quantitatively measured a variety of metabolic parameters by FACS analysis (analogous to laser-capture micro-dissection). Mitochondrial activity, glucose uptake and ROS production were measured with highly-sensitive fluorescent probes (MitoTracker, NBD-2-deoxy-glucose and DCF-DA). Interestingly, using this approach, we directly show that cancer cells initially secrete hydrogen peroxide that then triggers oxidative stress in neighboring fibroblasts. Thus, oxidative stress is contagious (spreads like a virus) and is propagated laterally and vectorially from cancer cells to adjacent fibroblasts. Experimentally, we show that oxidative stress in cancer-associated fibroblasts quantitatively reduces mitochondrial activity and increases glucose uptake, as the fibroblasts become more dependent on aerobic glycolysis. Conversely, co-cultured cancer cells show significant increases in mitochondrial activity and corresponding reductions in both glucose uptake and GLUT1 expression. Pretreatment of co-cultures with extracellular catalase (an anti-oxidant enzyme that detoxifies hydrogen peroxide) blocks the onset of oxidative stress and potently induces the death of cancer cells, likely via starvation. Given that cancer-associated fibroblasts show the largest increases in glucose uptake, we suggest that PET imaging of human tumors, with Fluoro-2-deoxy-D-glucose (F-2-DG), may be specifically detecting the tumor stroma, rather than epithelial cancer cells.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available