Transformation related proteins of human brain tumors in vivo and in vitro.

点击翻译按钮获取中文摘要

In the present research project, we have studied on transforming and/or growth promoting factors synthesizedby human brain tumors in vitro and in vivo.In tissue culture media of human glioma, colony-forming factor (s) was low molecular weight less than 20Kd. The rabbit antibody against to the low molecule fraction reacted with high molecule proteins over 50Kd and unable to detect low molecule proteins in culture media. On the other hand, the antibody reacted with 17Kd protein in extracts of glioma cells. The 17Kd protein was electrophereficauy isolated and was immunized to New Zealand white rabbits. The monospecic polyclonal IgG antibody was obtained from the antiserum using immunoaffiny colum chromatography. It was realized that the intracellular 17Kd protein was immunologically identical to a monomer of pletelet derived growth factor (PDGF). The 17Kd monomer promptly assembled to higher molecular weight forms, in which 56Kd protein was the most stable and predominant The 17Kd monomer … More protein was not phosphorylated, while the assembled forms were all phosphorylated. The 56Kd protein was detectable in media of human glioma cell cultures. The 56Kd protein purified from glioma cell homogenates induced cultured cells to forming ruffle membranes and reorganizing actin fibers. Human brain tumors, which was surgically obtained and stored in -70^0C until use, included variuos amounts of PDGF-related proteins as a monomeic form to assembled forms. The amounts of PDGF related proteins were not corelated to tumor types, such as benign or malignt astrocytoma, medulloblastoma, meningioma, neurinoma and neurocytoma. In each tumor type, the tumors possesing higher proliferative activity, which was measured with in vivo S-phase labelling technique using BrdU monoclonal antibody, tended to having higher amounts of PDGF-related proteins than tumors with low proliferative activity.We presume that brain tumors synthesize and secrete PDGF-related proteins as one of the most essential proteins for keeping neoplastic potentials. Less