Stable Isotope Tracing Uncovers Reduced gamma/beta-ATP Turnover and Metabolic Flux Through Mitochondrial-Linked Phosphotransfer Circuits in Aggressive Breast Cancer Cells

Changes in dynamics of ATP gamma- and beta-phosphoryl turnover and metabolic flux through phosphotransfer pathways in cancer cells are still unknown. Using O-18 phosphometabolite tagging technology, we have discovered phosphotransfer dynamics in three breast cancer cell lines: MCF7 (non-aggressive), MDA-MB-231 (aggressive), and MCF10A (control). Contrary to high intracellular ATP levels, the O-18 labeling method revealed a decreased gamma- and beta-ATP turnover in both breast cancer cells, compared to control. Lower beta-ATP[O-18] turnover indicates decreased adenylate kinase (AK) flux. Aggressive cancer cells had also reduced fluxes through hexokinase (HK) G-6-P[O-18], creatine kinase (CK) [CrP[O-18], and mitochondrial G-3-P[O-18] substrate shuttle. Decreased CK metabolic flux was linked to the downregulation of mitochondrial MTCK1A in breast cancer cells. Despite the decreased overall phosphoryl flux, overexpression of HK2, AK2, and AK6 isoforms within cell compartments could promote aggressive breast cancer growth.