LDL RECEPTOR STATUS OF HUMAN GLIOBLASTOMA CELLS

Porphyrins are known to associate with plasma lipoproteins, particularly low density lipoproteins (LDLs), and are thus likely to be taken up into cells by the high affinity saturable LDL receptor mechanism.1 We have previously reported that the boronated protoporphyrin, BOPP, is incorporated into the human glioblastoma cell line, SF 767 (derived from a glioblastoma multiforme biopsy specimen obtained from a grade 4 malignant glioma), and requires the presence of lipoproteins for maximum uptake into cells.2 We concluded from these studies that, like other porphyrins, BOPP forms a complex with LDL before it is taken up into the SF 767 cells via the LDL receptor; however, the presence of saturable LDL receptors on SF 767 cells has not been previously demonstrated. We have therefore investigated whether the LDL receptor was present on exponentially growing SF 767 cells. We report here our initial results indicating relatively high levels of LDL-receptors per cell (over 200,000) from the SF-767 line.