The Relevance of the Mitochondrial H+-ATP Synthase in Cancer Biology

Cancer cells depend on metabolic changes to cover the increased energy and metabolite demands that sustain proliferation. The enhanced rate of aerobic glycolysis and the activation of other metabolic pathways provide the energy and building blocks that support cell division. These changes occurred in response to the partial silencing of the bioenergetic function of mitochondria, specifically of the H+-ATP synthase, which is the engine that produces most of the ATP that sustains cellular activities in normal differentiated aerobic cells. Changes in the bioenergetic phenotype of carcinomas can be assessed by the determination of the expression of the catalytic subunit of the H+-ATP synthase (β-F1-ATPase) relative to the expression of the enzyme of glycolysis glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The β-F1-ATPase/GAPDH ratio provides a bioenergetic signature of the tumor with clinical relevance as a molecular marker of the prognosis of different cancer patients as well as of the tumor response to chemotherapy. Energy metabolism of cancer cells has become an attractive target for cancer therapy because it is a common phenotypic trait of most carcinomas. In addition, silencing of the H+-ATP synthase in most prevalent carcinomas is also exerted at the activity level by overexpression of the ATPase inhibitory factor 1 (IF1), a protein that contributes to metabolic rewiring and the signaling of cell death-resistant phenotypes in cancer cells.