Evidence for Deficiency of Low Density Lipoprotein Receptor on Human Colonie Carcinoma

Cells from six human colonie adenocarcinoma lines (CaCo-2, HT29, LS174T, SW480, SW403, and SW1417) and a normal skin fibroblast cell line (AG1519) were assayed in vitro for their ability to use low density lipoprotein (LDL). All tumor cell lines grew well in lipoproteindeficient serum, implying that LDL in culture medium was not critical for cell growth. When cell growth was inhibited with mevinolin, a cholesterol synthesis inhibitor, the addition of LDL to the medium had no effect on the growth of cells from five of six tumor cell lines. CaCo-2 cells showed a moderate reversal while the fibroblast control showed total reversal of inhibition. A monoclonal antibody to bovine/human LDL receptor, used in an enzyme-linked immunosorbent assay, indicated that only CaCo-2 cells and human skin fibroblast cells consistently demon strated the presence of LDL receptors. Thus, five of six colon tumor cell lines were unable to overcome a mevinolin block in cholesterol metabo lism indicating that these cells were deficient in LDL receptors.