Perspectives of NMR in oncology: Intermediate metabolism and tissue characterization of tumors during in vivo growth and regression

This paper summarizes the results obtained on alterations in a) pool sizes of phospholipid metabolites; b) intracellular pH; c) proton relaxation properties in Friend erythroleukemia cell (FLC) tumors at different days after either interferon-sensitive or -resistant FLC implantation in DBA/2 mice and at different days of treatment with murine α/β interferon (IFN). Significant levels of phosphorylethanolamine (PEtn), phosphorylcholine (PCho), glycerophosphorylethanolamine (GroPEtn) and glycerophosphorylcholine (GroPCho) were detected in the /sup 31/P NMR spectra of both subcutaneous (s.c.) and ascitic FLC tumors. Daily treatments with interferon in vivo reduced the levels of PCho, GroPEtn and GroPCho in these tumors and induced increases in intracellular pH. These effects were already significant at early stages of interferon-induced inhibition of tumor growth and regression. Freshly excised interferon-treated s.c. tumors, analyzed in vitro at 5, 10, 20 and 56 MHz exhibited conspicuous reductions in the values of proton spin-lattice relaxation times, with respect to tumors treated with control preparations