Vimentin-dependent utilization of LDL-cholesterol in human adrenal tumor cells is not associated with the level of expression of apoE, sterol carrierprotein-2, or caveolin

SW-13 adrenal tumor cells that lack detectable intermediate filaments (IF-f ree) exhibit an impaired capacity to esterify lipoprotein-derived cholester ol compared with cells that contain vimentin filaments. IF-free cells were found to synthesize and secrete significant amounts of apoE, while apoE sec retion was nearly undetectable in cell lines that spontaneously express vim entin, However, stable transfectants that express a mouse vimentin cDNA exh ibited elevated levels of cholesterol esterification and apoE secretion com pared with untransfected LF-free cells, indicating that apoE secretion is n ot directly related to the capacity of these cells to esterify cholesterol, Some of the cell lines that differed in the level of apoE synthesis and se cretion had similar levels of apoE mRNA, suggesting that the differences in expression involve a post-transcriptional mechanism. Treatment of these ce lls with forskolin and IBMX, 8br-cAMP, or TPA bad no effect on apoE secreti on. The level of sterol carrier protein-2 (SCP2) synthesis and the distribu tion of SCP2 between membrane and soluble cellular fractions was not observ ably different in cells that contained or lacked vimentin, SW-13 cell lines contained little or no detectable caveolin-1 or caveolin-2. These studies demonstrate that the difference in the capacity of these adrenal tumor cell s that contain or lack vimentin filaments to esterify low density lipoprote in-cholesterol is not obviously associated with the level of expression or distribution of apoE, SCP2, or caveolins.