Objective: Recently [11C] or [18F] labeled choline has been developed as a promising tracer for cancer detection. However choline may not be best agent, as the development of in vivo 1H-decoupled, NOE-enhanced 31P- MRS enabled the resolution of the resonances of phosphorylethanolamine (PEt) and phosphorylcholine (PCho) peaks that normally overlap under the broad phosphomonoester peak (PME). In human non-Hodgkin's lymphoma in vivo, the PEt/PCho ratio was reported as 2.9 +/- 1.0 (n = 11). The objective of this work was to compare radiolabeled choline with ethanolamine as an agent for cancer detection using various cancer cell lines.
Results: Cell uptake of [14C] ethanolamine and [14C] N, N'-dimethyl ethanolamine was compared to [14C] choline uptake in a wide variety of different cancer cell lines. Our data clearly demonstrates that, ethanolamine and N, N'-dimethyl ethanolamine showed 2-7 fold more uptake than choline. We showed that proliferating fibroblasts have significantly higher uptake of ethanolamine and N, N'-dimethyl-ethanolamine, than does growth arrested fibroblasts. Time course studies in A172 cells indicate continuous linear uptake of ethanolamine after four hours of tracer exposure, which was halted if tracer containing, media was replaced with regular media after one hour. The androgen stimulated and depleted study with prostate cancer cell lines showed that increased trapping of radiotracers in cells is well correlated with their proliferation status.
Methods: We carried out comparison of radiolabeled choline and ethanolamine by cell uptake study using 8 different cancer cell lines. To evaluate the response of radiotracers towards proliferation we also carried out their cell uptake study of androgen dependent and androgen independent cells in androgen stipulated and deprived media.
Conclusions: Our data demonstrate that ethanolamine and N, N'-dimethyl ethanolamine are taken up by a wide variety of tumor cells significantly better (2-7 fold) than the clinically utilized radiolabeled choline tracer.