BCL(X)L and BCL2 increase the metabolic fitness of breast cancer cells: a single-cell imaging study

• Published in: Cell death and differentiation 2021-05, Vol.28 (5), p.1512-1531
• Main Authors: Lucantoni, Federico, Salvucci, Manuela, Düssmann, Heiko, Lindner, Andreas U., Lambrechts, Diether, Prehn, Jochen H. M.
• Format: Article
• Language: English
• Subjects: 13/109; 13/31; 13/89; 14; 14/19; 14/33; 45/91; 631/67/2327; 692/699/67/2327; 82/1; 96; Apoptosis; ATP synthase; bcl-X Protein - metabolism; Biochemistry; Bioenergetics; Biomedical and Life Sciences; Breast cancer; Breast Neoplasms - diagnostic imaging; Breast Neoplasms - genetics; Cell Biology; Cell Cycle Analysis; Cell death; Female; Fluorescence resonance energy transfer; Humans; Life Sciences; Membrane permeability; Metabolism; Mitochondria; NAD; Oligomycin; Protonmotive force; Single-Cell Analysis - methods; Stem Cells; Tumor cells; Tumor microenvironment
• ISSN: 1350-9047; 1476-5403
• DOI: 10.1038/s41418-020-00683-x

The BCL2 family of proteins regulate apoptosis by controlling mitochondrial outer membrane permeability. However, the effects on mitochondrial structure and bioenergetics have also been reported. Here we comprehensively characterized the effects of BCL2 and BCL(X)L on cellular energetics in MCF7 breast cancer cells using time-lapse confocal single-cell imaging and mitochondrial and cytosolic FRET reporters. We found that BCL2 and BCL(X)L increase the metabolic robustness of MCF7 cells, and that this was associated with increased mitochondrial NAD(P)H and ATP levels. Experiments with the F 1 F 0 synthase inhibitor oligomycin demonstrated that BCL2 and in particular BCL(X)L, while not affecting ATP synthase activity, more efficiently coupled the mitochondrial proton motive force with ATP production. This metabolic advantage was associated with an increased resistance to nutrient deprivation and enhanced clonogenic survival in response to metabolic stress, in the absence of profound effects on cell death. Our data suggest that a primary function of BCL(X)L and BCL2 overexpression in tumor cells is to increase their resistance to metabolic stress in the tumor microenvironment, independent of cell death signaling.