Dissecting tumor metabolic heterogeneity : Telomerase and large cell size metabolically define a sub-population of stem-like, mitochondrial-rich, cancer cells

Lamb, R; Ozsvari, B; Bonuccelli, G; Smith, D; Pestell, R; Martinez-Outschoorn, U; Clarke, R; Sotgia, Federica; Lisanti, MP

Abstract

Tumor cell metabolic heterogeneity is thought to contribute to tumor recurrence, distant metastasis and chemo-resistance in cancer patients, driving poor clinical outcome. To better understand tumor metabolic heterogeneity, here we used the MCF7 breast cancer line as a model system to metabolically fractionate a cancer cell population. First, MCF7 cells were stably transfected with an hTERT-promoter construct driving GFP expression, as a surrogate marker of telomerase transcriptional activity. To enrich for immortal stem-like cancer cells, MCF7 cells expressing the highest levels of GFP (top 5%) were then isolated by FACS analysis. Notably, hTERT-GFP(+) MCF7 cells were significantly more efficient at forming mammospheres (i.e., stem cell activity) and showed increased mitochondrial mass and mitochondrial functional activity, all relative to hTERT-GFP(-) cells. Unbiased proteomics analysis of hTERT-GFP(+) MCF7 cells directly demonstrated the over-expression of 33 key mitochondrial proteins, 17 glycolytic enzymes, 34 ribosome-related proteins and 17 EMT markers, consistent with an anabolic cancer stem-like phenotype. Interestingly, MT-CO2 (cytochrome c oxidase subunit 2; Complex IV) expression was increased by >20-fold. As MT-CO2 is encoded by mt-DNA, this finding is indicative of increased mitochondrial biogenesis in hTERT-GFP(+) MCF7 cells. Importantly, most of these candidate biomarkers were transcriptionally over-expressed in human breast cancer epithelial cells in vivo. Similar results were obtained using cell size (forward/side scatter) to fractionate MCF7 cells. Larger stem-like cells also showed increased hTERT-GFP levels, as well as increased mitochondrial mass and function. Thus, this simple and rapid approach for the enrichment of immortal anabolic stem-like cancer cells will allow us and others to develop new prognostic biomarkers and novel anti-cancer therapies, by specifically and selectively targeting this metabolic sub-population of aggressive cancer cells. Based on our proteomics and functional analysis, FDA-approved inhibitors of protein synthesis and/or mitochondrial biogenesis, may represent novel treatment options for targeting these anabolic stem-like cancer cells.

Citation

Lamb, R., Ozsvari, B., Bonuccelli, G., Smith, D., Pestell, R., Martinez-Outschoorn, U., …Lisanti, M. (2015). Dissecting tumor metabolic heterogeneity : Telomerase and large cell size metabolically define a sub-population of stem-like, mitochondrial-rich, cancer cells. Oncotarget, 6(26), 21892-21905. https://doi.org/10.18632/oncotarget.5260

• Journal Article Type: Article
• Acceptance Date: Jul 13, 2015
• Publication Date: Aug 27, 2015
• Deposit Date: Jun 29, 2016
• Publicly Available Date: Jun 29, 2016
• Journal: Oncotarget
• Electronic ISSN: 1949-2553
• Publisher: Impact Journals
• Volume: 6
• Issue: 26
• Pages: 21892-21905
• DOI: https://doi.org/10.18632/oncotarget.5260
• Publisher URL: http://dx.doi.org/10.18632/oncotarget.5260
• Related Public URLs: http://www.impactjournals.com/oncotarget/index.php?journal=oncotarget
• Additional Information: Funders : Funder not known