High mitochondrial DNA content is a key determinant of stemness, proliferation, cell migration, and cancer metastasis in vivo

Mauro-Lizcano, Marta; Di Pisa, Filippo; Larrea Murillo, Luis; Sugden, Conor J.; Sotgia, Federica; Lisanti, Michael P.

Abstract

Here, we examined the potential role of mitochondrial DNA (mtDNA) levels in conveying aggressive phenotypes in cancer cells, using two widely-used breast cell lines as model systems (MCF7[ER+] and MDA-MB-231[ER-]). These human breast cancer cell lines were fractionated into mtDNA-high and mtDNA-low cell sub-populations by flow cytometry, using SYBR Gold as a vital probe to stain mitochondrial nucleoids in living cells. Enrichment of mtDNA-high and mtDNA-low cell sub-populations was independently validated, using a specific DNA-binding mAb probe (AC-30-10), and mitochondrial-based functional assays. As predicted, mtDNA-high MCF7 cells showed significant increases in mitochondrial mass, membrane potential, and superoxide production, as well as increased mitochondrial respiration and ATP production. Moreover, mtDNA-high MCF7 cells demonstrated increases in stemness features, such as anchorage-independent growth and CD44 levels, as well as drug-resistance to Gemcitabine and Tamoxifen. Proliferation rates were also significantly increased, with a dramatic shift towards the S- and G2/M-phases of the cell cycle; this was indeed confirmed by RNA-Seq analysis. Complementary results were obtained with MDA-MB-231 cells. More specifically, mtDNA-high MDA-MB-231 cells showed increases in stemness features and ATP production, as well as rapid cell cycle progression. Moreover, mtDNA-high MDA-MB-231 cells also exhibited increases in both cell migration and invasion, suggesting a role for mtDNA in distant metastasis. To test this hypothesis more directly, a preclinical in vivo model was utilized. For this purpose, MDA-MB-231 tumour cell grafts were treated with an established mtDNA synthesis inhibitor, namely Alovudine (3’-deoxy-3’-fluorothymidine). As expected, drug-induced depletion of mtDNA led to a shift from mitochondrial to glycolytic metabolism. Interestingly, Alovudine very effectively reduced the formation of spontaneous metastases by nearly 70%, but minimally inhibited tumour growth by approximately 20%. Taken together, these data suggest that high mtDNA content is a key driver of stemness, proliferation, and migration, as well as cancer cell metastasis.

Citation

Mauro-Lizcano, M., Di Pisa, F., Larrea Murillo, L., Sugden, C. J., Sotgia, F., & Lisanti, M. P. (in press). High mitochondrial DNA content is a key determinant of stemness, proliferation, cell migration, and cancer metastasis in vivo. Cell Death and Disease, 15(10), Article 745. https://doi.org/10.1038/s41419-024-07103-9

• Journal Article Type: Article
• Acceptance Date: Sep 23, 2024
• Online Publication Date: Oct 11, 2024
• Deposit Date: Oct 24, 2024
• Publicly Available Date: Oct 24, 2024
• Journal: Cell Death and Disease
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 15
• Issue: 10
• Article Number: 745
• DOI: https://doi.org/10.1038/s41419-024-07103-9