title: Consumption of oxygen: a mitochondrial-generated progression signal of advanced cancer.
abstract: Changes in mitochondrial genome such as mutation, deletion and depletion are common in cancer and can determine advanced phenotype of cancer; however, detailed mechanisms have not been elucidated. We observed that loss of mitochondrial genome reversibly induced overexpression and activation of proto-oncogenic Ras, especially K-Ras 4A, responsible for the activation of AKT and ERK leading to advanced phenotype of prostate and breast cancer. Ras activation was induced by the overexpression of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR), the rate-limiting enzyme of the mevalonate pathway. Hypoxia is known to induce proteasomal degradation of HMGR. Well differentiated prostate and breast cancer cells with high mitochondrial DNA content consumed a large amount of oxygen and induced hypoxia. Loss of mitochondrial genome reduced oxygen consumption and increased in oxygen concentration in the cells. The hypoxic-to-normoxic shift led to the overexpression of HMGR through inhibiting proteasomal degradation. Therefore, reduction of mitochondrial genome content induced overexpression of HMGR through hypoxic to normoxic shift and subsequently the endogenous induction of the mevalonate pathway activated Ras that mediates advanced phenotype. Reduction of mitochondrial genome content was associated with the aggressive phenotype of prostate cancer in vitro cell line model and tissue specimens in vivo. Our results elucidate a coherent mechanism that directly links the mitochondrial genome with the advanced progression of the disease.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors.forename: C C
authors.initials: CC
authors.lastname: Cook
authors.forename: A
authors.initials: A
authors.lastname: Kim
authors.forename: S
authors.initials: S
authors.lastname: Terao
authors.forename: A
authors.initials: A
authors.lastname: Gotoh
authors.forename: M
authors.initials: M
authors.lastname: Higuchi
mesh_terms: D000368:Aged; D017209:Apoptosis; D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D004272:DNA, Mitochondrial / Q000096:biosynthesis*; D018450:Disease Progression; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology / Q000235:genetics*; D009367:Neoplasm Staging; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; D006903:Hydroxymethylglutaryl CoA Reductases; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D018631:ras Proteins; D010100:Oxygen