EXPRESSION OF ALPHA-2-MACROGLOBULIN RECEPTOR LOW-DENSITY-LIPOPROTEIN RECEPTOR-RELATED PROTEIN ON SURFACES OF TUMOR-CELLS - A STUDY USING FLOW-CYTOMETRY

alpha 2-Macroglobulin receptor/low density lipoprotein receptor-relate d protein (alpha 2 MR/LRP) is a multifunctional cell surface receptor that binds and endocytoses several structurally and functionally disti nct ligands. Very little is known about the expression and function of alpha 2 MR/LRP in tumour cells. The aim of this study was to quantify the number of alpha 2 MR/LRP on surfaces of human tumour cells by flo w cytometry. Using human alpha 2 MR/LRP monoclonal antibody 8G1, human peripheral blood lymphocytes (negative control cells), monocytes (pos itive control cells), human neonatal foreskin fibroblast cells (NFF) ( positive control cells), three human breast cancer cell lines (BT-20, T-47D, and MCF-7), two human ovarian tumour cell lines (JAM, and CI80- 13S), and five human melanomas (MM418c1, MM253c1, A2058, MM138, MM370) were indirectly labelled with goat anti-mouse IgFITC. The fluorescent signals of stained cells were measured by flow cytometry. Using Quant um Simply Cellular bead standards, the number of alpha 2 MR/LRP bindin g sites per cell was assessed. The flow cytometric method to quantify of alpha 2 MR/LRP described here is simple and reliable. All the human tumour cell lines so far examined express alpha 2MR/LRP at different levels from similar to 300 to similar to 10000 sites per cell. (C) 199 7 Elsevier Science Ireland Ltd.