metabolic oxidative stress and cancer douglas r. spitz, phd free radical and radiation biology...
TRANSCRIPT
Metabolic Oxidative Stress and Cancer
Douglas R. Spitz, PhD
Free Radical and Radiation Biology ProgramDepartment of Radiation Oncology
Holden Comprehensive Cancer CenterThe University of Iowa, Iowa City, IA
What is life?
“An electron, given off easily, has a high energy level, while an orbital which tends to take up an electron, has a low energy level. The transmitted electron thus goes from a high to a low level, and releases the energy which corresponds to the difference of the two levels. It is this energy which drives life.”Albert Szent-Györgyi, Electronic Biology and Cancer, Marcel Dekker Inc. 1976
In essence, Szent-Györgyi was one of the first scientists to recognize that all of the forces necessary for the maintenance of living systems derive from the ability of complex higher order biological structures to extract, store, and move electrons.
Chemiosmotic model. In this simple representation of the chemiosmotic theory applied to mitochondria, electrons from NADH and other oxidizable substrates pass through a chain of carriers arranged asymmetrically in the inner membrane. Electron flow is accompanied by proton transfer across the membrane, producing both a chemical gradient (pH) and an electrical gradient (). The inner mitrochondrial membrane is impermeable to protons; protons can reenter the matrix only through proton specific channels (F0). The proton-motive force that drives protons back into the matrix provides the energy for ATP synthesis, catalyzed by the F1 complex associated with F0.
Why do we breath oxygen? The Chemiosmotic HypothesisWhy is it potentially harmful?
Lehninger; Principles in Biochemistry 3 rd Edition
Ahmad IM, Aykin-Burns N, Sim JE, Walsh SA, Higashikubo R, Buettner GR, Venkataraman S, Mackey MA, Flanagan S, Oberley LW, and Spitz DR: Mitochondrial O2
- and H2O2 mediate glucose deprivation-induced
cytotoxicity and oxidative stress in human cancer cells. J. Biol. Chem. 2005; 280(6):4254-4263.
O2
O2
O2
Cyt c1FMN
Fe S
e-
Cyt c
Myxothiazol
Antimycin A
Complex IV
NADH
NAD+
Complex I
Complex III
Fe S
Cyt bH
Cyt bL
Rotenone
Q
Q
O2FAD Fe S
e-
Complex II
Succinate
Fumarate
O2
O2
QH2
QH2
Intermembrane space
Matrix
QH2
e-Q
Q
Q
What is the relationship between metabolic and genetic processes necessary for life?
Spitz DR, Azzam EI, Li JJ, and Gius D: Metabolic oxidation/reduction reactions and cellular responses to ionizing radiation: a unifying concept in stress response biology. Cancer and Metastasis Reviews 2004; 23:311–322.
Antioxidants
DNA Repair →
The Circle of Life and The Circle of Death
ReplicationDifferentiation
Cell DivisionDifferentiated Cell Functions
Cell CycleDifferentiationAdaptive Responses
ReactiveSpecies
Metabolic Theories of Cancer
Warburg O (1956) Science 123:309-314 Cancer cells exhibit increased rates of glycolysis and slightly
decreased rates of respiration. It was proposed this was the result of “damage” to the respiratory mechanism and tumor cells increased glycolysis to compensate for
this defect.
Weber G (1977) New Engl. J. Med. 296:541-551 Cancer cells exhibit increased rates of pentose phosphate cycle
activity characterized by increases in glucose-6-phosphate dehydrogenase activity.
Oberley LW, Oberley TD, and Buettner GR (1980 and 1981) Med.
Hypoth. 6:49-68; 7:21-42 Tumor cells have aberrant respiration caused by a decrease in
MnSOD activity leading to increased steady state levels of superoxide and hydrogen peroxide that causes DNA damage and activates
signaling pathways leading to uncontrolled growth, the inability to differentiate, and the malignant phenotype.
Genetic Theory of CancerBishop (1987) Science 235:305-311; Varmus (1987)
Science 238:1337-1339
Cancer is a multi-step genetic disease in which mutations resulting in the aberrant expression of
cellular homologues of oncogenes (i.e., Ras, c-Fos, c-Jun, and c-Myc, etc.) associated with growth and
development as well as tumor suppressor genes (i.e., p53) gradually accumulate over time, eventually
resulting in immortalization, the loss of control of cell proliferation, and progression to the malignant
phenotype.
How can we unify metabolic and genetic theories of cancer?
In the mid-1990’s Dr. Yong J. Lee’s laboratory showed:
Within minutes - glucose deprivation-induced activation of signal transduction in (i.e., ERK1, ERK2, Lyn Kinase, JNK, Ras, AP-1, etc.) in
MCF-7/ADR human breast cancer cells.
Within 2-4 hours - glucose deprivation-induced increases in steady state levels of mRNA coding for bFGF and c-Myc in MCF-7/ADR.
Within 4 hours - glucose deprivation-induced clonogenic cell killing in MCF-7/ADR cells.
Molecular and Cellular Biochemistry, 155:163-171, 1996.Journal of Cell Science, 110:681-686, 1997.
Molecular and Cellular Biochemistry, 170:23-30, 1997.Journal of Biological Chemistry, 272:11690-11693, 1997.
This work supported the existence of a mechanistic link between glucose metabolism, signal transduction, and
gene expression governing the malignant phenotype that also governed the survival of cancer cells.
What is this mechanistic link?
Dr. Lee and his collaborators then discovered that all the effects of glucose deprivation in MCF-7 ADR could be suppressed by treatment with the thiol antioxidant, N-acetylcysteine, indicating a causal role for oxidative stress in the effects of glucose deprivation in cancer cells.
Lee YJ, Galoforo SS, Berns CM, Chen JC, Davis BH, Sim JE, Corry PM, and Spitz DR: Glucose deprivation-induced cytotoxicity and alterations in mitogen-activated protein kinase activation are mediated by oxidative stress in multidrug- resistant human breast carcinoma cells. J. Biol. Chem. 1998; 273:5294-5299.
Blackburn RV, Spitz DR, Liu X, Galoforo SS, Sim JE, Ridnour LA, Chen JC, Davis BH, Corry PM, and Lee YJ: Metabolic oxidative stress activates signal transduction and gene expression during glucose deprivation in human tumor cells. Free Radic. Biol. Med. 1999; 26:419-430.
Kinases (ie, Lyn, PKC, etc.)Kinases (ie, Lyn, PKC, etc.)G proteins (ie, Ras, etc.)G proteins (ie, Ras, etc.)
Kinases (ie, Raf, MEK, ERK, JNK, etc.) Kinases (ie, Raf, MEK, ERK, JNK, etc.) PhosphatasesPhosphatases
Trxn. factors (ie, AP-1, etc.)Trxn. factors (ie, AP-1, etc.)
DNADNA
RNA (ie, c-Fos, RNA (ie, c-Fos, c-Jun, c-Myc, c-Jun, c-Myc, bFGF, etc.)bFGF, etc.)
ProteinsProteins
NUCLEUSNUCLEUSGlucoseGlucose
PLASMAPLASMAMEMBRANEMEMBRANE
Glucose 6-phosphateGlucose 6-phosphate
PyruvatePyruvate
PPCPPC
NADPHNADPH
NADP+NADP+
GRGR GPXGPX
GSSGGSSG
GSHGSH HH22OO 22
HH22OO 22OO22••
HH22OOOO22
NADHNADHTCATCA
FADHFADH 22
MITOCHONDRIAMITOCHONDRIA
HH22 OO
HH22OO
HH 22OO 22
GlycolysisGlycolysis
Fatty/AminoFatty/AminoAcidsAcids
??
4e-4e-
11e-e-Site IISite IISite ISite I Site IIISite III
Site IVSite IV
(TR)(TrxPx)
(TrxS2H2)
(TrxSS)
Theoretical model outlining a biochemical rationale for unifying metabolic and genetic theories of cancer.Spitz et al. (2000) Ann. N.Y. Acad. Sci. 899:349-362. ? = thioredoxin, glutaredoxin, and direct redox changes on proteins
Rodent tumor cells had reduced levels of MnSOD activity that were proportional to increased growth rate and lack of ability to differentiate.
Rodent Tumor cells demonstrated mitochondrial abnormalities that were more pronounced in fast growing undifferentiated cancers.
normal liver well differentiated undifferentiatedmitochondria hepatoma hepatoma
slow growing fast growing
Bize IB, Oberley LW, Morris HP (1980) Superoxide dismutase and superoxide radical in Morris hepatomas. Cancer Res. 40(10):3686-93.
Springer EL: Comparative study of the cytoplasmic organelles of epithelial cell lines derived from human carcinomas and nonmalignant tissues. Cancer Res. 1980; 40(3):803-17.
The cytoplasmic organelles of 16 human cell types derived from normal as well as from primary and metastatic carcinomas were characterized by electron microscopy in a blinded fashion.
Mitochondrial pleomorphisms was expressed slightly by normal cells and to a much greater extent by all cell types derived from malignant tissues.
These pleomorphisms were characterized by hypertrophied mitochondria with longitudinal cristal arrangements in almost all the malignant cells lines, but not in any lines derived from nonmalignant tissues of cancerous organs or from normal tissues.
Human cancer cells demonstrated mitochondrial abnormalities that are more pronounced in more malignant tissues.
Increasing mitochondrial superoxide scavenging by increasing expression of MnSOD alters the malignant phenotype of cancer cellsChurch SL, Grant JW, Ridnour LA, Oberley LW, Swanson PE, Meltzer PS, Trent JM: Increased manganese superoxide dismutase expression suppresses the malignant phenotype of human melanoma cells. Proc Natl Acad Sci U S A. 1993; 90(7):3113-7.
Melanoma cell lines over expressing MnSOD cDNAs lost their ability to form colonies in soft agar and tumors in nude mice.
These findings were the first demonstration that stable over expression MnSOD suppressed the malignant phenotype in human cancer cells
These results suggested that increased steady-state levels of superoxide and/or H2O2 significantly contributed to the maintenance of the malignant phenotype in human cancer cells.
Human cancer cells were reported to produce large amounts of H2O2, relative to normal cellsSzatrowski TP and Nathan CF: Production of large amounts of hydrogen peroxide by human tumor cells. Cancer Res. 1991; 51(3):794-8.
Seven human tumor cell lines demonstrated constitutively elevated H2O2 such that cumulative amounts were comparable to the amount of H2O2 produced by phorbol ester-activated neutrophils.
Constitutive generation of large amounts of reactive oxygen intermediates by cancer cells, if it occurs in vivo, might contribute to genomic instability, tumor heterogeneity, invasion, and metastasis.
33Co HT29 SW480 HCT116
No
rmali
zed
Mean
Flu
ore
scen
ce I
nte
nsit
y
0
2
4
6
8 DHE
(B)
Mean
Flu
ore
scen
ce I
nte
nsit
y
0
50
100
150
200
250
DHE DHE / PEGSOD
HCT116 Cells
(C)
Fig 1
*
*
*
*
FHC HT29 SW480 HCT116
No
rmali
zed
Mean
Flu
ore
sscen
ce I
nte
nsit
y
0
10
20
30
40
50
60
DHE DHE + AntA
*
(A)
*
*
#
#
,
# ,
#,
Aykin-Burns N, Ahmad IM, Zhu Y, Oberley LW, and Spitz DR: Inhibition of glucose metabolism causes enhanced cytotoxicity in human cancer vs. normal cells via metabolic oxidative stress. Biochem. J. 2009; 418:29-37.
Human colon carcinoma cells demonstrate increased steady-state levels of superoxide relative to normal human colon epithelial cells and fibroblasts
Mitochondrial electron transport chain blockers make this difference more pronounced
Fig 3
Nor
mal
ized
Mea
n Fl
uore
scen
ce In
tens
ity
0.0
0.5
1.0
1.5
2.0
2.5
HMECMB231
*
*
DHE CDCFH2 CDCF
Aykin-Burns N, Ahmad IM, Zhu Y, Oberley LW, and Spitz DR: Inhibition of glucose metabolism causes enhanced cytotoxicity in human cancer vs. normal cells via metabolic oxidative stress. Biochem. J. 2009; 418:29-37.
Human breast carcinoma cells demonstrate increased steady-state levels of superoxide and hydroperoxides, relative to normal human breast epithelial cells
No
rmal
ized
Su
rviv
al F
ract
ion
0.0001
0.001
0.01
0.1
1
33Co HCT116
(A)
Time (h)
0 24 48 72 96
No
rmal
ized
Su
rviv
al F
ract
ion
0.01
0.1
1
HMEC MB231
(B)
Fig 4
*
#
*
*
#
#
Aykin-Burns N, Ahmad IM, Zhu Y, Oberley LW, and Spitz DR: Inhibition of glucose metabolism causes enhanced cytotoxicity in human cancer vs. normal cells via metabolic oxidative stress. Biochem. J. 2009; 418:29-37.
Human colon and breast carcinoma cells demonstrate increased sensitivity to glucose deprivation-induced cytotoxicity, relative to normal human cells
No
rma
lized
Su
rviv
ing
Fra
cti
on
0.00
0.05
0.10
0.15
0.20
0.25 Bgl II / -GluAdMnSOD/ AdmitCAT/ -Glu
(A)
Fig 5
%G
SS
G0
5
10
15
20
25
30Bgl II/ +GluBgl II/ -GluAdMnSOD/ AdmitCAT/ -Glu
HCT116 MB231
(B)
*
*
*,#
#
#
Ahmad IM, Aykin-Burns N, Sim JE, Walsh SA, Higashikubo R, Buettner GR, Venkataraman S, Mackey MA, Flanagan S, Oberley LW, and Spitz DR: Mitochondrial O2
- and H2O2 mediate glucose deprivation-induced cytotoxicity and oxidative stress in human cancer cells. J. Biol. Chem. 2005;
280(6):4254-4263.
Aykin-Burns N, Ahmad IM, Zhu Y, Oberley LW, and Spitz DR: Inhibition of glucose metabolism causes enhanced cytotoxicity in human cancer vs. normal cells via metabolic oxidative stress. Biochem. J. 2009; 418:29-37.
Mitochondrial O2- and H2O2 mediate glucose deprivation-
induced toxicity and oxidative stress in human cancer cells.
No
rma
lize
d S
urv
ivin
g F
rac
tio
n(r
ela
tive
to
+G
lu f
rom
ea
ch g
rou
p)
10-1
100
GS
SG
(in
GS
H e
qu
iva
len
ts)
(nm
ole
/ m
g)
0
10
20
30
40
48 h/ +Glu48 h/ -Glu
AdBgl II(10 MOI)
AdMnSOD(10 MOI)
AdBgl II(50 MOI)
AdMitCat(50 MOI)
AdBgl II(60 MOI)
AdMnSOD/AdMitCat
(10/50 MOI)
(A)
(B)
*
**
p<0.04 p<0.03 p<0.001
p<0.02
p<0.3
p<0.2
V
iab
ility
(num
ber
of c
ells
exc
lude
dye
/ tot
al n
umbe
r)100
FHC/ 2DG FHC
Time (h)0 24 48 72
Via
bili
ty(n
umbe
r of
cel
ls e
xclu
de d
ye/ t
otal
num
ber)
100
HT29/ 2DG
HT29
(A)
(B)
Fig 6N
orm
aliz
ed S
urv
ivin
g F
ract
ion
0.4
0.6
0.8
1.0
1.2
1.4 HT29 (48 h)
AdBgl IIControl
AdBgl II2DG
AdmitCATAdMnSOD
2DG
(C)
*
#
AdmitCATAdMnSOD
Control
#
(D) Bgl II mitoCAT/MnSOD
SOD activity (U/mg protein) 2.0 15.3
CAT activity (mk/mg protein) 13.1 29.9
Aykin-Burns N, Ahmad IM, Zhu Y, Oberley LW, and Spitz DR: Inhibition of glucose metabolism causes enhanced cytotoxicity in human cancer vs. normal cells via metabolic oxidative stress. Biochem. J. 2009; 418:29-37
Via
bil
ity
(nu
mb
er
of
ce
lls e
xclu
de d
ye
/ to
tal n
um
be
r)
100
FHC/ 2DG FHC
Time (h)0 24 48 72
Via
bil
ity
(nu
mb
er
of
ce
lls e
xclu
de
dye
/ to
tal n
um
be
r)
100
HT29/ 2DG
HT29
(A)
(B)
Fig 6
No
rma
lized
Su
rviv
ing
Fra
cti
on
0.4
0.6
0.8
1.0
1.2
1.4 HT29 (48 h)
AdBgl IIControl
AdBgl II2DG
AdmitCATAdMnSOD
2DG
(C)
*
#
AdmitCATAdMnSOD
Control
#
(D) Bgl II mitoCAT/MnSOD
SOD activity (U/mg protein) 2.0 15.3
CAT activity (mk/mg protein) 13.1 29.9
Human colon carcinoma cells are more sensitive to cell killing by 2-deoxyglucose (2DG), relative to normal colon epithelial cells
2DG-induced cytotoxicity can be inhibited by over expressing mitochondrially targeted catalase and superoxide dismutase
Mutations in mtDNA encoded genes (ND6) can lead to increased ROS and increased metastatic potential that is suppressed by ROS scavengers.Ishikawa K, Takenaga K, Akimoto M, Koshikawa N, Yamaguchi A, Imanishi H, Nakada K, Honma Y, Hayashi J: ROS-generating mitochondrial DNA mutations can regulate tumor cell metastasis. Science 2008; 320(5876):661-4.
Cytoplasmic hybrid (cybrid) technology was used to replace endogenous mtDNA in a mouse tumor cell line that was poorly metastatic with mtDNA from a highly metastatic cell line and the recipient tumor cells acquired the metastatic potential of the transferred mtDNA.
The mtDNA conferring high metastatic potential contained mutations in the gene encoding NADH (reduced form of nicotinamide adenine dinucleotide) dehydrogenase subunit 6 (ND6) that was associated with overproduction of reactive oxygen species (ROS).
Pretreatment of the highly metastatic tumor cells with ROS scavengers suppressed their metastatic potential in mice.
Mutations in nuclear encoded genes that code for electron transport chain proteins (SDH subunits B, C, D) can also lead to increased steady-state levels of superoxide, increased mutation rates, increased genomic instability, and tumorigenesis in rodents as well as being associated with neuro-endocrine tumor formation in humans.Ishii T, Yasuda K, Akatsuka A, Hino O, Hartman PS, Ishii N: A mutation in the SDHC gene of complex II increases oxidative stress, resulting in apoptosis and tumorigenesis. Cancer Res 2005; 65(1):203-9.
Slane BG, Aykin-Burns N, Smith BJ, Kalen AL, Goswami PC, Domann FE, Spitz DR: Mutation of succinate dehydrogenase subunit C results in increased O2
-, oxidative stress, and genomic instability. Cancer Res 2006; 66(15):7615-20.
Bardella C, Pollard PJ, Tomlinson I: SDH mutations in cancer. Biochim Biophys Acta 2011; 1807(11):1432-43.
Owens KM, Aykin-Burns N, Dayal D, Coleman MC, Domann FE, and Spitz DR: Genomic instability induced by mutant succinate dehydrogenase subunit D (SDHD) is mediated by O2
- and H2O2. Free Radic Biol Med 2011; [Epub ahead of print] PMID: 22041456
Conclusions and Speculations:
Cancer cells appear to exist in a condition of metabolic oxidative stress characterized by increased steady-state levels of superoxide and hydrogen peroxide.
This increase in reactive oxygen species (ROS) appears to be compensated for by increases in glucose and hydroperoxide metabolism.
The condition of metabolic oxidative stress in cancer cells may be the result of alterations in mitochondrial oxidative metabolism.
Metabolic oxidative stress appears to contribute to selective sensitivity of cancer vs. normal cells to glucose deprivation-induced cytotoxicity and oxidative stress.
SPECULATION Cancer might represent a constellation of metabolic and/or genetic diseases where the common theme is uncoupling of normal cellular processes that govern cell growth and
differentiation caused by the inappropriate flow of electrons from metabolic oxidation/reduction reactions to redox sensitive proteins governing signal transduction and
gene expression. (Spitz, et al. Ann. N.Y. Acad. Sci. 899:349-362, 2000)
Kinases (Kinases (ieie, Lyn, PKC, etc.), Lyn, PKC, etc.)G proteins (G proteins (ieie, Ras, etc.), Ras, etc.)
Kinases (Kinases (ieie, Raf, MEK, ERK, JNK, etc.) , Raf, MEK, ERK, JNK, etc.) PhosphatasesPhosphatases
TrxnTrxn. factors (. factors (ieie, AP, AP--1, etc.)1, etc.)
DNADNA
RNA (RNA (ieie, c, c--Fos, Fos, cc--Jun, cJun, c--Myc, Myc, bFGF, etc.)bFGF, etc.)
ProteinsProteins
NUCLEUSNUCLEUSGlucoseGlucose
PLASMAPLASMAMEMBRANEMEMBRANE
Glucose 6Glucose 6--phosphatephosphate
PyruvatePyruvate
PPCPPC
NADPHNADPH
NADP+NADP+
GRGR GPXGPX
GSSGGSSG
GSHGSH HH 22OO 22
HH22OO 22OO22••
HH22OOOO22
NADHNADHTCATCA
FADHFADH 22
MITOCHONDRIAMITOCHONDRIA
HH22 OO
HH22OO
HH 22OO 22
GlycolysisGlycolysis
Fatty/AminoFatty/AminoAcidsAcids
??
4e4e--
11ee--Site IISite IISite ISite I Site IIISite III
Site IVSite IV
Kinases (Kinases (ieie, Lyn, PKC, etc.), Lyn, PKC, etc.)G proteins (G proteins (ieie, Ras, etc.), Ras, etc.)
Kinases (Kinases (ieie, Raf, MEK, ERK, JNK, etc.) , Raf, MEK, ERK, JNK, etc.) PhosphatasesPhosphatases
TrxnTrxn. factors (. factors (ieie, AP, AP--1, etc.)1, etc.)
DNADNA
RNA (RNA (ieie, c, c--Fos, Fos, cc--Jun, cJun, c--Myc, Myc, bFGF, etc.)bFGF, etc.)
ProteinsProteins
NUCLEUSNUCLEUSGlucoseGlucose
PLASMAPLASMAMEMBRANEMEMBRANE
Glucose 6Glucose 6--phosphatephosphate
PyruvatePyruvate
PPCPPC
NADPHNADPH
NADP+NADP+
GRGR GPXGPX
GSSGGSSG
GSHGSH HH 22OO 22
HH22OO 22OO22••
HH22OOOO22
NADHNADHTCATCA
FADHFADH 22
MITOCHONDRIAMITOCHONDRIA
HH22 OO
HH22OO
HH 22OO 22
GlycolysisGlycolysis
Fatty/AminoFatty/AminoAcidsAcids
??
4e4e--
11ee--Site IISite IISite ISite I Site IIISite III
Site IVSite IV
(TR)(TrxPx)
(TrxS2H2)
(TrxSS)
Theoretical model outlining a biochemical rationale for unifyingmetabolic and genetic theories of cancer.Spitz et al. (2000) Ann. N.Y. Acad. Sci. 899:349-362. ? = thioredoxin, glutaredoxin, and direct redox changes on proteins
Clinical Implications: Therapy If glucose metabolism is increased in cancer cells to
compensate for excess hydroperoxide production from mitochondrial respiration, then inhibiting glucose and hydroperoxide metabolism while forcing cells to derive energy from respiration should preferentially
kill cancer cells, relative to normal cells.
Combinations of agents designed to take advantage of this hypothesis might include:
Inhibitors of Glucose Metabolism (ie., 2-deoxyglucose, etc.) Inhibitors of the Pentose Phosphate Cycle (ie., DHEA, etc.)
Inhibitors of Hydroperoxide Metabolism (ie., BSO, AUR, BCNU)
Dietary Manipulation (high protein/fats, no carbohydrates)
Agents that Increase the Metabolic Production of Prooxidants and Increase Oxidative DNA Damage (ie., Radiation, quinones, Cisplatin, Paclitaxel, inflammatory mediators, etc.)
Inhibitors of glucose and hydroperoxide metabolism selectively (relative to normal cells) enhance cancer cell killing as well as selectively sensitizing cancer cells to therapeutic agents. Lin X, Zhang F, Bradbury CW, Kaushal A, Li L, Spitz DR, Aft R, and Gius D: 2-Deoxy-d-glucose-induced cytotoxicity and radiosensitization in tumor cells is mediated via disruptions in thiol metabolism. Cancer Res 2003; 63:3413–3417.
Simons AL, Ahmad IM, Mattson DM, Dornfeld KJ, and Spitz DR: 2-Deoxy-D-glucose combined with cisplatin enhances cytotoxicity via metabolic oxidative stress in human head and neck cancer cells. Cancer Res 2007; 67(7): 3364–70.
Coleman MC, Asbury CR, Daniels D, Du J, Aykin-Burns N, Smith BJ, Li L, Spitz DR, Cullen JJ : 2-deoxy-D-glucose causes cytotoxicity, oxidative stress, and radiosensitization in pancreatic cancer. Free Radic Biol Med 2008; 44(3):322-31.
Fath MA, Diers AR, Aykin-Burns N, Simons AL, Hua L, and Spitz DR: Mitochondrial electron transport chain blockers enhance 2-deoxy-D-glucose induced oxidative stress and cell killing in human colon carcinoma cells. Cancer Biol Ther 2009; 8(13):1228-36.
Hadzic T, Aykin-Burns N, Coleman MC, Zhu Y, Jacobson G, and Spitz DR: Paclitaxel combined with inhibitors of glucose and hydroperoxide metabolism enhances breast cancer cell killing via H2O2-mediated oxidative stress. Free Radic Biol Med 2010; 48(8):1024-33. (in press).
Sinthupibulyakit C, Ittarat W, St Clair WH, St Clair DK: p53 Protects lung cancer cells against metabolic stress. Int J Oncol. 2010; 37(6):1575-81.
Shutt DC, O'Dorisio MS, Aykin-Burns N, Spitz DR: 2-deoxy-D-glucose induces oxidative stress and cell killing in human neuroblastoma cells. Cancer Biol Ther 2010; 9(11):853-61.
Sharma PK, Bhardwaj R, Dwarakanath BS, Varshney R: Metabolic oxidative stress induced by a combination of 2-DG and 6-AN enhances radiation damage selectively in malignant cells via non-coordinated expression of antioxidant enzymes. Cancer Lett. 2010; 295(2):154-66.
Fath M, Ahmad IM, Smith CJ, Spence JM, Spitz DR: Enhancement of carboplatin-mediated lung cancer cell killing by simultaneous disruption of glutathione and thioredoxin metabolism. Clin Cancer Res. 2011; [Epub ahead of print]
Scarbrough PM, Mattson DM, Gius D, Watson WH, and Spitz DR: Simultaneous inhibition of glutathione- and thioredoxin-dependent metabolism is necessary to potentiate 17AAG-induced cancer cell killing via oxidative stress. Free Radic Biol Med 2011; (in press).
Clinical Implications: Imaging
If glucose metabolism is increased in cancer cells to compensate for increased production of prooxidants by
mitochondrial metabolism, then alterations in glucose metabolism and mitochondrial function should be proportional to susceptibility to therapies based on taking advantage of this metabolic defect
to selectively kill cancer cells.
Use FDG-PET imaging to correlate changes in glucose metabolism (FDG uptake) with sensitivity to:
Radiation + 2DG Cisplatin + 2DG
Simons AL, Fath MA, Mattson DM, Smith BJ, Walsh SA, Graham MM, Hichwa RD, Buatti JM, Dornfeld KJ, and Spitz DR: Enhanced response of human head and neck cancer xenograft tumors to Cisplatin combined with 2-deoxy-D-glucose correlates with increased 18F-FDG uptake as determined by PET imaging. Int J Radiat Oncol Biol Phys 2007; 69(4):1222-1230.
Conclusions and Speculations: Metabolic oxidative stress appears to contribute to the selective sensitization of cancer vs. normal cells to 2DG and inhibitors of glutathione and thioredoxin metabolism in a variety of human cancer cell models.
Inhibition of glucose and hydroperoxide metabolism may provide a biochemical target for selectively enhancing cytotoxicity and oxidative stress in cancer cells treated with conventional therapeutic agents (radiation and/or chemotherapy) that cause oxidative stress in clinical trials.
Taking advantage of fundamental differences in oxidative metabolism between cancer vs. normal cells to design combined modality cancer therapies, could provide improve outcomes while limiting normal tissue injury by allowing for the de-escalation of doses of highly cytotoxic agents while maintaining or improving efficacy of cancer cell killing.
Thanks for your attention!Supported by: R01CA133114; R21CA139182; R21CA161182; T32CA078586; P30CA086862