Efficacy of 2-halogen substituted D-glucose analogs in blocking glycolysis and killing "hypoxic tumor cells".
OBJECTIVE
Since 2-deoxy-D-glucose (2-DG) is currently in phase I clinical trials to selectively target slow-growing hypoxic tumor cells, 2-halogenated D-glucose analogs were synthesized for improved activity. Given the fact that 2-DG competes with D-glucose for binding to hexokinase, in silico modeling of molecular interactions between hexokinase I and these new analogs was used to determine whether binding energies correlate with biological effects, i.e. inhibition of glycolysis and subsequent toxicity in hypoxic tumor cells.


RESULTS
Using a QSAR-like approach along with a flexible docking strategy, it was determined that the binding affinities of the analogs to hexokinase I decrease as a function of increasing halogen size as follows: 2-fluoro-2-deoxy-D-glucose (2-FG) > 2-chloro-2-deoxy-D-glucose (2-CG) > 2-bromo-2-deoxy-D-glucose (2-BG). Furthermore, D-glucose was found to have the highest affinity followed by 2-FG and 2-DG, respectively. Similarly, flow cytometry and trypan blue exclusion assays showed that the efficacy of the halogenated analogs in preferentially inhibiting growth and killing hypoxic vs. aerobic cells increases as a function of their relative binding affinities. These results correlate with the inhibition of glycolysis as measured by lactate inhibition, i.e. ID50 1 mM for 2-FG, 6 mM for 2-CG and > 6 mM for 2-BG. Moreover, 2-FG was found to be more potent than 2-DG for both glycolytic inhibition and cytotoxicity.


CONCLUSIONS
Overall, our in vitro results suggest that 2-FG is more potent than 2-DG in killing hypoxic tumor cells, and therefore may be more clinically effective when combined with standard chemotherapeutic protocols.
Lampidis
Theodore J
TJ
School of Medicine and Sylvester Cancer Center, The University of Miami, Miami, FL, USA.
Kurtoglu
Metin
M
Maher
Johnathan C
JC
Liu
Huaping
H
Krishan
Awtar
A
Sheft
Valerie
V
Szymanski
Slawomir
S
Fokt
Izabela
I
Rudnicki
Witold R
WR
Ginalski
Krzysztof
K
Lesyng
Bogdan
B
Priebe
Waldemar
W
D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D003847:Deoxyglucose / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D015195:Drug Design; D019788:Fluorodeoxyglucose F18 / Q000737:chemistry / Q000494:pharmacology; D019298:Glucose-6-Phosphate / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects*; D006219:Halogens / Q000737:chemistry*; D006593:Hexokinase / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D019344:Lactic Acid / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D021281:Quantitative Structure-Activity Relationship; D013816:Thermodynamics
D006219:Halogens; D019788:Fluorodeoxyglucose F18; C078464:2-chloro-2-deoxyglucose; D019344:Lactic Acid; C015785:2-deoxyglucose-6-phosphate; C047515:2-fluoro-2-deoxyglucose-6-phosphate; D019298:Glucose-6-Phosphate; D003847:Deoxyglucose; C472074:HK1 protein, human; D006593:Hexokinase