title: An in situ study of bioenergetic properties of human colorectal cancer: the regulation of mitochondrial respiration and distribution of flux control among the components of ATP synthasome.
abstract: The aim of this study is to characterize the function of mitochondria and main energy fluxes in human colorectal cancer (HCC) cells. We have performed quantitative analysis of cellular respiration in post-operative tissue samples collected from 42 cancer patients. Permeabilized tumor tissue in combination with high resolution respirometry was used. Our results indicate that HCC is not a pure glycolytic tumor and the oxidative phosphorylation (OXPHOS) system may be the main provider of ATP in these tumor cells. The apparent Michaelis-Menten constant (Km) for ADP and maximal respiratory rate (Vm) values were calculated for the characterization of the affinity of mitochondria for exogenous ADP: normal colon tissue displayed low affinity (Km = 260 ± 55 μM) whereas the affinity of tumor mitochondria was significantly higher (Km = 126 ± 17 μM). But concurrently the Vm value of the tumor samples was 60-80% higher than that in control tissue. The reason for this change is related to the increased number of mitochondria. Our data suggest that in both HCC and normal intestinal cells tubulin β-II isoform probably does not play a role in the regulation of permeability of the MOM for adenine nucleotides. The mitochondrial creatine kinase energy transfer system is not functional in HCC and our experiments showed that adenylate kinase reactions could play an important role in the maintenance of energy homeostasis in colorectal carcinomas instead of creatine kinase. Immunofluorescent studies showed that hexokinase 2 (HK-2) was associated with mitochondria in HCC cells, but during carcinogenesis the total activity of HK did not change. Furthermore, only minor alterations in the expression of HK-1 and HK-2 isoforms have been observed. Metabolic Control analysis showed that the distribution of the control over electron transport chain and ATP synthasome complexes seemed to be similar in both tumor and control tissues. High flux control coefficients point to the possibility that the mitochondrial respiratory chain is reorganized in some way or assembled into large supercomplexes in both tissues.
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Andrus
authors.initials: A
authors.lastname: Kaldma
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Klepinin
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Chekulayev
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Kati
authors.initials: K
authors.lastname: Mado
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Igor
authors.initials: I
authors.lastname: Shevchuk
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Natalja
authors.initials: N
authors.lastname: Timohhina
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Kersti
authors.initials: K
authors.lastname: Tepp
authors.affiliation: Tallinn University, Tallinn, Estonia.
authors.forename: Manana
authors.initials: M
authors.lastname: Kandashvili
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Minna
authors.initials: M
authors.lastname: Varikmaa
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Andre
authors.initials: A
authors.lastname: Koit
authors.affiliation: Tallinn University of Technology, Tallinn, Estonia.
authors.forename: Margus
authors.initials: M
authors.lastname: Planken
authors.affiliation: North Estonian Regional Hospital, Tallinn, Estonia.
authors.forename: Karoliina
authors.initials: K
authors.lastname: Heck
authors.affiliation: Tallinn University of Technology, Tallinn, Estonia.
authors.forename: Laura
authors.initials: L
authors.lastname: Truu
authors.affiliation: Cancer Research Competence Center, Tallinn, Estonia.
authors.forename: Anu
authors.initials: A
authors.lastname: Planken
authors.affiliation: North Estonian Regional Hospital, Tallinn, Estonia.
authors.forename: Vahur
authors.initials: V
authors.lastname: Valvere
authors.affiliation: Cancer Research Competence Center, Tallinn, Estonia.
authors.forename: Egle
authors.initials: E
authors.lastname: Rebane
authors.affiliation: Laboratory of Bioenergetics, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia; Tallinn University, Tallinn, Estonia. Electronic address: tuuli.kaambre@kbfi.ee.
authors.forename: Tuuli
authors.initials: T
authors.lastname: Kaambre
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000263:Adenylate Kinase / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism*; D003401:Creatine / Q000378:metabolism; D004734:Energy Metabolism; D015972:Gene Expression Regulation, Neoplastic; D006593:Hexokinase / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014404:Tubulin / Q000235:genetics / Q000378:metabolism
chemical_list: D014404:Tubulin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D006593:Hexokinase; D000263:Adenylate Kinase; D003401:Creatine
keywords: Colorectal cancer; Energy metabolism; Hexokinase; Metabolic control analysis; Mitochondria; Tubulin; VDAC; Warburg effect