Human glioblastoma cell lines: Levels of low-density lipoprotein receptor and low-density lipoprotein receptor-related protein

The status of the low-density lipoprotein (LDL) receptor and LDL receptor-r elated protein (LRP) in seven human glioma cell lines was evaluated to exte nd our knowledge of human glioblastoma multiforme tumor metabolism for futu re drug design. Cell lines SF-767, SF-763, A-172, U-87 MG, U-251 MG, U343 M G, and SF-539 were used. Binding of I-125-labeled LDL to these cells at 4 d egrees C was carried out to determine the number of LDL receptors on cells and the affinity of LDL for these receptors, The content of LRP was measure d by immunoblotting. The presence of specific saturable LDL receptors was p roven in six of the cell lines investigated. SF-767 cells revealed high-aff inity LDL binding (equilibrium dissociation constant, K-d = 7 nM) and maxim um binding capacity approximating 300,000 receptors/cell, Most of the remai ning cell lines had relatively lower affinity (K-d = 38-62 nM) but also had very high numbers of receptors (128,000-950,000/cell). All cell lines exhi bited LRP, but the expression was variable. The cell lines SF-539, U-87 MG, and U-343 MG were particularly rich in this protein. The data suggest that glioblastoma cells have high numbers of LDL receptors; however, there is c onsiderable variation in binding affinity. Overall, this finding suggests t hat LDL receptors on glioblastoma cells could potentially be useful for tar geting antitumor agents. LRP, a multifunctional receptor expressed on gliob lastoma cells, also has the possibility for serving as a therapeutic target .