Intracellular Serum Proteins in Cerebral Gliomas and Metastatic Tumours: An Immunoperoxidase Study

Abstract

An immunoperoxidase technique was used to compare the presence of serum proteins in tumour cells in twenty cerebral gliomas and four intracerebral metastatic carcinomas, with the serum protein content of reactive astrocytes around four cerebral infarcts. Rabbit antiserum to human immunoglobulins and albumen was applied to paraffin sections of tumour biopsies and of infarcts from postmortem brains. All the reactive astrocytes surrounding infarcts stained positively for immunoglobulins and albumen. In the gliomas, a continuous range of staining was observed in plump astrocytic tumour cells varying from strongly positive to unstained. Very few poorly-differentiated glioma cells stained for serum proteins; metastatic tumour cells, areas of capillary endothelial proliferation, and spindle cells in gliosarcomas remained unstained. These results suggest that the astrocytic function of serum protein uptake from the extracellular fluid is often lost in poorly-differentiated glioma cells, but is retained to a variable degree by those tumour cells which histologically resemble reactive astrocytes.

Albumin marks pseudopodia of astrocytoma cells responding to hepatocyte growth factor or serum

“…The 1-3 mm pores of gelatin-coated filters recapitulated gaps in tissue. Although others have demonstrated selective accumulation of serum albumin in astrocytomas 5,6 and to some extent on glioma cells, 4,16 this study demonstrated preferential accumulation of albumin on or in pseudopodia of astrocytoma cells using gels, immunoblots, and fluorescent labeling. Protein bands that were increased in pseudopodial lysates on 1D electrophoretic gels were confirmed to be BSA with MS. On immunoblots, with lysate loading equalized for levels of GAPDH, BSA was increased to levels comparable or greater than those of known pseudo-podial proteins, b-actin and ezrin.…”

“…increased permeability of the BBB in these tumors, 31,32 possibly aided by the ability of astrocytic cells to ingest albumin. 4,16 Albumin has a large capacity and high affinity for fatty acids so that the pool of circulating HSA in the bloodstream quantitatively forms an important source of lipids for delivery to tumor cells, with or without the aid of various fatty acid-binding proteins in the recipient cells. 33 Patterns and rates of fatty acid incorporation by glial cells have been found to vary according to the degree of cellular differentiation.…”

“…Although early reports identified albumin in brain tumor tissue and associated cystic fluids, the distribution of albumin between poorly differentiated glioma cells and the interstitium was unclear. [2][3][4] More recently, albumin with a fluorescent label was found after 24 h to be 23-fold higher in the tumor of a C6-glioma model compared to surrounding brain, with the microscopic 'borders' closely corresponding to the distribution of fluorescence. 5 Another study also detected human glioma xenografts in the subcutaneous tissue of mice by administering fluorescein (F)-labeled HSA.…”