Tissue folate binding protein levels in transgenic mice with tumors and innon-transgenic controls

Localized folate deficiency may be a risk factor for cancer. Since, folate binding proteins (FBP) and reduced folate carrier proteins (RFC) mediate ce llular transport of folate, we compared FBP concentrations in several organ s from tumor-bearing transgenic (TBT) mice and tumor-free non-transgenic co ntrols (NTC) of the same strain, age, and fed identical diets. Liver, splee n, brain, small intestine and kidney were individually homogenized in phosp hate-buffered saline (PBS) and separated into membrane, cytoplasmic, mitoch ondrial/lysomal and nuclear fractions (confirmed with marker enzymes). Homo genates and fractions was analyzed for total protein, and FBP. We used rabb it anti-bovine milk antibody and ELISA to measure FBP. FBP concentrations i n kidney, small intestine, and spleen of TBT mice were higher than those of NTC mice; the opposite was true in liver and lung. FBP seemed to be upregu lated in kidneys (all fractions), small intestine (all fractions), and sple en (cytoplasmic and nuclear fractions only) of TBT mice compared to NTC mic e; the opposite appeared true in liver (all fractions) and lung (all fracti ons). FBP concentrations in brain, heart, and muscle of TBT mice were not d ifferent from those in brain, heart and muscle of NTC mice. A longitudinal study will determine if these changes in FBP concentrations precede tumor o nset. (C) 1999 Elsevier Science Inc. All rights reserved.