title: Impairment of mitochondrial respiration in mouse fibroblasts by oncogenic H-RAS(Q61L).
abstract: A common metabolic change in cancer is the acquisition of glycolytic phenotypes. Increased expression of glycolytic enzymes is considered as one contributing factor. The role of mitochondrial defects in acquisition of glycolytic phenotypes has been postulated but remains controversial. Here we show that functional defects in mitochondrial respiration could be induced by oncogenic H-Ras(Q61L) transformation, even though the mitochondrial contents or mass was not reduced in the transformed cells. First, mitochondrial respiration, as measured by mitochondrial oxygen consumption, was suppressed in NIH-3T3 cells transformed with H-Ras(Q61L). Second, oligomycin or rotenone did not reduce the cellular ATP levels in the H-Ras(Q61L) transformed cells, suggesting a diminished role of mitochondrial respiration in the cellular energy metabolism. Third, inhibition of glycolysis with iodoacetic acid reduced ATP levels at a much faster rate in H-Ras(Q61L) transformed cells than in the vector control cells. The reduction of cellular ATP levels was reversed by exogenously added pyruvate in the vector control cells but not in H-Ras(Q61L) transformed cells. Finally when compared to the HRas(Q61L) transformed cells, the vector control cells had increased resistance toward glucose deprivation. The increased resistance was dependent on mitochondrial oxidative phosphorylation since rotenone or oligomycin abolished the increased survival of the vector control cells under glucose deprivation. The results also suggest an inability of the H-Ras(Q61L) transformed cells to reactivate mitochondrial respiration under glucose deprivation. Taken together, the data suggest that mitochondrial respiration can be impaired during transformation of NIH-3T3 cells by oncogeneic H-Ras(Q61L).
authors.affiliation: Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine and Simmons Cooper Cancer Institute, Springfield, IL, USA.
authors.forename: Dianer
authors.initials: D
authors.lastname: Yang
authors.forename: Man-Tzu
authors.initials: MT
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: Tang
authors.forename: Yakun
authors.initials: Y
authors.lastname: Chen
authors.forename: Hongmei
authors.initials: H
authors.lastname: Jiang
authors.forename: Torrie T
authors.initials: TT
authors.lastname: Jones
authors.forename: Krishna
authors.initials: K
authors.lastname: Rao
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Brewer
authors.forename: Keshav K
authors.initials: KK
authors.lastname: Singh
authors.forename: Daotai
authors.initials: D
authors.lastname: Nie
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D002471:Cell Transformation, Neoplastic; D004579:Electron Transport / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects; D005347:Fibroblasts / Q000378:metabolism*; D011905:Genes, ras; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects; D019807:Iodoacetic Acid / Q000494:pharmacology; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D020125:Mutation, Missense; D041681:NIH 3T3 Cells / Q000378:metabolism; D009840:Oligomycins / Q000494:pharmacology; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000502:physiology*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D017354:Point Mutation; D019289:Pyruvic Acid / Q000494:pharmacology; D012402:Rotenone / Q000494:pharmacology
chemical_list: D009840:Oligomycins; D012402:Rotenone; D000968:Antimycin A; D019289:Pyruvic Acid; D000255:Adenosine Triphosphate; D015689:Oncogene Protein p21(ras); D005947:Glucose; D019807:Iodoacetic Acid