Expression of alpha2-macroglobulin receptor/low density lipoprotein receptor-related protein on surfaces of tumour...

alpha2-Macroglobulin receptor/low density lipoprotein receptor-related protein (alpha2 MR/LRP) is a multifunctional cell surface receptor that binds and endocytoses several structurally and functionally distinct ligands. Very little is known about the expression and function of alpha2 MR/LRP in tumour cells. The aim of this study was to quantify the number of alpha2 MR/LRP on surfaces of human tumour cells by flow cytometry. Using human alpha2 MR/LRP monoclonal antibody 8G1, human peripheral blood lymphocytes (negative control cells), monocytes (positive 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 Quantum Simply Cellular bead standards, the number of alpha2 MR/LRP binding sites per cell was assessed. The flow cytometric method to quantify of alpha2 MR/LRP described here is simple and reliable. All the human tumour cell lines so far examined express alpha2 MR/LRP at different levels from approximately 300 to approximately 10000 sites per cell.