Expression of the alpha 2-macroglobulin receptor on human neoplastic fibroblastoid cells

The alpha 2-macroglobulin membrane-associated receptor (alpha 2MR) has been previously detected on hepatocytes, fibroblasts, macrophages, syncytiotrophoblasts and recently on human malignant blood cells of myelomonocytic leukemia. In cells growing in vitro from human germ cell tumors alpha 2MR mRNA was detected by Northern blotting. Endocytosis of alpha 2M from culture medium was detected in these cells by indirect immunofluorescence. In cell extracts alpha 2M and its degradation products were detected by immunoblotting. The cells expressing alpha 2MR and internalizing alpha 2M were identified as fibroblasts both by their morphology and expression of vimentin intermediate filaments. The role and function of alpha 2MR receptor in the analyzed neoplastic cells of teratomatous origin is discussed.