Nonglycolytic acidification of murine radiation-induced fibrosarcoma 1 tumor via 3-O-methyl-D-glucose monitored by 1H, 2H, 13C, and 31P nuclear magnetic resonance spectroscopy.
The effects of 3-O-methyl-D-glucose (3-OMG) on subcutaneously implanted murine radiation-induced fibrosarcoma 1 tumor were examined with 2H, 13C, and 31P nuclear magnetic resonance (NMR) in situ. Using 31P NMR, changes in tumor high-energy phosphate metabolism were monitored for 2.5 h after i.p. administration of 3-OMG (8.1 g/kg body weight); tumor pH decreased by a mean maximum of 0.52 +/- 0.05 (SE) (n = 10), [PCr] decreased by 54%, [NTP] decreased by 35%, and [Pi] increased by 36%. Tumor blood flow, as measured by 2H NMR monitoring of D2O washout kinetics, decreased by 40% at 1 h and by 47% at 2 h after 3-OMG injection (n = 4). This substantial tumor acidification (pH decrease much greater than 0.1), expected to require a glycolytic substrate (Hwang et al., Cancer Res., 51: 3108-3118, 1991), is surprising in light of the previously documented metabolically inert nature of 3-OMG. In situ 13C NMR spectroscopy, following [6-13C]3-OMG i.p. injection, examined the possibility of the glycolytic metabolism of 3-OMG. However, only the C-6 resonance of 3-OMG was detected (n = 6); no resonances from [6-13C]3-OMG-6-phosphate or [3-13C]lactate were observed. These results confirmed that 3-OMG was not metabolized in radiation-induced fibrosarcoma 1 tumor. At the completion of the in situ 13C NMR experiments, tumors were freeze clamped, and perchloric acid extraction was performed. High-resolution 1H NMR measurement of lactate concentrations showed no statistically significant difference in control tumor extracts (from mice not receiving i.p. injection; n = 5) and in tumor extracts from mice administered i.p. [6-13C]3-OMG (n = 5), indicating that there was no significant increase in lactate level in the tumor extracts from mice administered i.p. 3-OMG due to increased plasma glucose concentration. The results of these 1H and 13C NMR studies indicated that the radiation-induced fibrosarcoma 1 tumor acidification caused by i.p. administration of 3-OMG was not due to a direct (3-OMG----lactate) or an indirect (systemic glucose----lactate) increase in tumor lactic acid levels.
Hwang
Y Y
YY
Department of Chemistry, Washington University, St. Louis, Missouri 63130-4899.
Kim
S G
SG
Evelhoch
J L
JL
Ackerman
J J
JJ
D019325:3-O-Methylglucose; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D002250:Carbon Radioisotopes; D003903:Deuterium; D005260:Female; D005354:Fibrosarcoma / Q000098:blood supply / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D006400:Hematocrit; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000378:metabolism*; D019344:Lactic Acid; D009682:Magnetic Resonance Spectroscopy; D008353:Mannitol / Q000494:pharmacology; D008757:Methylglucosides / Q000494:pharmacology*; D051379:Mice; D008809:Mice, Inbred C3H; D009381:Neoplasms, Radiation-Induced / Q000098:blood supply / Q000378:metabolism*; D009705:Nucleosides / Q000378:metabolism; D010710:Phosphates; D010725:Phosphocreatine / Q000378:metabolism
D001786:Blood Glucose; D002250:Carbon Radioisotopes; D007773:Lactates; D008757:Methylglucosides; D009705:Nucleosides; D010710:Phosphates; D010725:Phosphocreatine; D019325:3-O-Methylglucose; D019344:Lactic Acid; D008353:Mannitol; D003903:Deuterium; D005947:Glucose