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.
School of Medicine and Sylvester Cancer Center, The University of Miami, Miami, FL, USA.
Theodore J
TJ
Lampidis
Metin
M
Kurtoglu
Johnathan C
JC
Maher
Huaping
H
Liu
Awtar
A
Krishan
Valerie
V
Sheft
Slawomir
S
Szymanski
Izabela
I
Fokt
Witold R
WR
Rudnicki
Krzysztof
K
Ginalski
Bogdan
B
Lesyng
Waldemar
W
Priebe
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