Evidence for deficiency of low density lipoprotein receptor on human colonic carcinoma cell lines

Cells from six human colonic 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 lipoprotein-deficient 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 demonstrated the presence of LDL receptors. Thus, five of six colon tumor cell lines were unable to overcome a mevinolin block in cholesterol metabolism indicating that these cells were deficient in LDL receptors.