Conclusions
Under in vivo conditions, proliferating regions of tumors show increased FLT uptake and higher ENT1 levels than nonproliferating tumor regions.
Methods
The human adenocarcinoma cell line A549 was used to establish tumor xenografts in nude mice. FLT uptake was measured in vivo using PET, and further examined ex vivo using autoradiography. FLT uptake patterns were compared to immunohistochemical (IHC) analysis of ENT1 and the proliferation markers Ki67 and BrdU.
Results
Regional differences in FLT uptake matched differences in IHC proliferation markers. All cells stained for ENT1, but the staining intensity was twice as high for Ki67(+) cells than for Ki67(-) cells. Conclusions: Under in vivo conditions, proliferating regions of tumors show increased FLT uptake and higher ENT1 levels than nonproliferating tumor regions.