Tumor lactate content predicts for response to fractionated irradiation of human squamous cell carcinomas in nude mice.
OBJECTIVE
The present study was performed to test the hypothesis that lactate accumulation correlates with the radioresistance of malignant tumors due to the radical scavenging capacity of lactate or metabolic intermediates of glycolysis, such as pyruvate.


METHODS
Five human head and neck squamous cell carcinoma cell lines (HNSCCs) xenografted in nude mice were treated with a clinically relevant irradiation protocol with 30 fractions within 6 weeks. The radiation dose necessary to locally control 50% of the tumors (TCD50) ranged from 47.4 to 129.8 Gy. Concentrations of glucose, lactate, and ATP in viable tumor regions as potential indicators of glycolytic activity were assessed with structure-associated quantitative bioluminescence imaging.


RESULTS
Mean lactate concentrations of the different tumor cell lines were in the range of 7.3-25.9 micromol/g. TCD50 values were positively correlated with tumor lactate levels (R = 0.9824, p = 0.0028).


CONCLUSIONS
The data obtained support the hypothesis that tissue lactate content correlates with radioresistance in solid human tumors. Furthermore, the results suggest that tumor lactate content determined non-invasively by proton magnetic resonance spectroscopy imaging may be used to predict for radioresistance of malignancies in the clinic; the data also imply that transient inhibition of glycolysis during treatment might possibly sensitize tumors to irradiation.
Quennet
Verena
V
Institute of Physiology and Pathophysiology, University of Mainz, Germany.
Yaromina
Ala
A
Zips
Daniel
D
Rosner
Andrea
A
Walenta
Stefan
S
Baumann
Michael
M
Mueller-Klieser
Wolfgang
W
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000737:chemistry* / Q000532:radiotherapy; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D019583:Dose Fractionation, Radiation; D005260:Female; D006258:Head and Neck Neoplasms / Q000737:chemistry* / Q000532:radiotherapy; D006801:Humans; D019344:Lactic Acid / Q000032:analysis*; D051379:Mice; D008819:Mice, Nude; D011379:Prognosis; D011836:Radiation Tolerance; D016896:Treatment Outcome; D023041:Xenograft Model Antitumor Assays
D019344:Lactic Acid