Anti-mitochondrial therapy in human breast cancer multi-cellular spheroids

• Published in: Biochimica et biophysica acta Vol. 1833; no. 3; pp. 541 - 551
• Main Authors: Mandujano-Tinoco, Edna Ayerim, Gallardo-Pérez, Juan Carlos, Marín-Hernández, Alvaro, Moreno-Sánchez, Rafael, Rodríguez-Enríquez, Sara
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2013
• Subjects: Anti-mitochondrial therapy; Antineoplastic Agents - pharmacology; Blotting, Western; Breast - drug effects; Breast - metabolism; Breast cancer cell; Breast Neoplasms - drug therapy; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Cell Proliferation; Copper - metabolism; Energy Metabolism - drug effects; Female; Glycolysis; Glycolysis - drug effects; Humans; Immunoenzyme Techniques; Mitochondria - drug effects; Mitochondria - metabolism; Mitochondrial Degradation - drug effects; Mitochondrial Proteins - metabolism; Multi-cellular tumor spheroids; Oligomycins - pharmacology; Organometallic Compounds - pharmacology; Oxidative phosphorylation; Oxidative Phosphorylation - drug effects; Proteome - analysis; Spheroids, Cellular - drug effects; Spheroids, Cellular - metabolism; Spheroids, Cellular - pathology; Uncoupling Agents - pharmacology; HK; LC3B; HIF-1α; 2OG; PRL; COXIV; LDH; PDH; SDH; Multi-cellular tumor spheroids; Atg7; Anti-mitochondrial therapy; QS; GLUT; PGC-1α; 2OGDH; MCTS; Oxidative phosphorylation; Glycolysis; Bnip 3; GA-K; Breast cancer cell; ND1; LAMP; MCT-1
• ISSN: 0167-4889; 0006-3002; 1879-2596
• DOI: 10.1016/j.bbamcr.2012.11.013

During multi-cellular tumor spheroid growth, oxygen and nutrient gradients develop inducing specific genetic and metabolic changes in the proliferative and quiescent cellular layers. An integral analysis of proteomics, metabolomics, kinetomics and fluxomics revealed that both proliferative- (PRL) and quiescent-enriched (QS) cellular layers of mature breast tumor MCF-7 multi-cellular spheroids maintained similar glycolytic rates (3–5nmol/min/106 cells), correlating with similar GLUT1, GLUT3, PFK-1, and HKII contents, and HK and LDH activities. Enhanced glycolytic fluxes in both cell layer fractions also correlated with higher HIF-1α content, compared to MCF-7 monolayer cultures. On the contrary, the contents of the mitochondrial proteins GA-K, ND1, COXIV, PDH-E1α, 2-OGDH, SDH and F1-ATP synthase (20 times) and the oxidative phosphorylation (OxPhos) flux (2-times) were higher in PRL vs. QS. Enhanced mitochondrial metabolism in the PRL layers correlated with an increase in the oncogenes h-Ras and c-Myc, and transcription factors p32 and PGC-1α, which are involved in the OxPhos activation. On the other hand, the lower mitochondrial function in QS was associated with an increase in Beclin, LC3B, Bnip3 and LAMP protein levels, indicating active mitophagy and lysosome biosynthesis processes. Although a substantial increase in glycolysis was developed, OxPhos was the predominant ATP supplier in both QS and PRL layers. Therefore, targeted anti-mitochondrial therapy by using oligomycin (IC50=11nM), Casiopeina II-gly (IC50=40nM) or Mitoves (IC50=7nM) was effective to arrest MCF-7 spheroid growth without apparent effect on normal epithelial breast tissue at similar doses; canonical anti-neoplastic drugs such as cisplatin and tamoxifen were significantly less potent. [Display omitted] ► Proliferative and quiescent breast cancer micro-regions depend on mitochondrial ATP. ► Anti-mitochondrial therapy at nanomolar doses arrests breast tumor spheroid growth. ► Glycolysis and chemotherapy inhibitors do not affect breast tumor spheroid growth. ► Anti-mitochondrial therapy does not modify energy metabolism of normal breast spheroids. ► Anti-mitochondrial drugs prevent, and revert, breast tumor spheroid growth.