title: Energy metabolism during anchorage-independence. Induction by osteopontin-c.
abstract: The detachment of epithelial cells, but not cancer cells, causes anoikis due to reduced energy production. Invasive tumor cells generate three splice variants of the metastasis gene osteopontin, the shortest of which (osteopontin-c) supports anchorage-independence. Osteopontin-c signaling upregulates three interdependent pathways of the energy metabolism. Glutathione, glutamine and glutamate support the hexose monophosphate shunt and glycolysis and can feed into the tricarboxylic acid cycle, leading to mitochondrial ATP production. Activation of the glycerol phosphate shuttle also supports the mitochondrial respiratory chain. Drawing substrates from glutamine and glycolysis, the elevated creatine may be synthesized from serine via glycine and supports the energy metabolism by increasing the formation of ATP. Metabolic probing with N-acetyl-L-cysteine, L-glutamate, or glycerol identified differential regulation of the pathway components, with mitochondrial activity being redox dependent and the creatine pathway depending on glutamine. The multiple skewed components in the cellular metabolism synergize in a flow toward two mechanisms of ATP generation, via creatine and the respiratory chain. It is consistent with a stimulation of the energy metabolism that supports anti-anoikis. Our findings imply a coalescence in cancer cells between osteopontin-a, which increases the cellular glucose levels, and osteopontin-c, which utilizes this glucose to generate energy.
authors.affiliation: University of Cincinnati Academic Health Center, Cincinnati, Ohio, United States of America.
authors.forename: Zhanquan
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio, United States of America.
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio, United States of America.
authors.forename: Tafadzwa
authors.initials: T
authors.lastname: Chihanga
authors.affiliation: Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio, United States of America.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kennedy
authors.affiliation: University of Cincinnati Academic Health Center, Cincinnati, Ohio, United States of America.
authors.forename: Georg F
authors.initials: GF
authors.lastname: Weber
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001940:Breast / Q000378:metabolism / Q000473:pathology*; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004734:Energy Metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005973:Glutamine / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006019:Glycolysis; D006801:Humans; D061986:MCF-7 Cells; D008969:Molecular Sequence Data; D009154:Mutation; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D053495:Osteopontin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics; D010545:Peroxides / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D010545:Peroxides; D020033:Protein Isoforms; D005973:Glutamine; D053495:Osteopontin; D000255:Adenosine Triphosphate; D010088:Oxidoreductases; D005990:Glycerol