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

在本研究项目中，我们对人脑肿瘤体外和体内合成的转化和/或生长促进因子进行了研究。在人脑胶质瘤组织培养上清液中，克隆形成因子(S)的低分子量小于20Kd。兔抗低分子组分抗体与50Kd以上的大分子蛋白反应，在培养上清液中检测不到低分子蛋白。另一方面，该抗体与胶质瘤细胞提取液中的17Kd蛋白发生反应。用凝胶电泳法分离17Kd蛋白，免疫新西兰大白兔。用免疫亲和层析法从抗血清中获得单抗多克隆抗体。人们意识到细胞内的17Kd蛋白与血小板衍生生长因子(PDGF)的单体在免疫学上是相同的。17Kd的单体迅速组装成更高分子量的形式，其中56Kd的蛋白质是最稳定和最主要的17Kd的单体…更多的蛋白质没有被磷酸化，而组装的形式都被磷酸化了。在人脑胶质瘤细胞培养上清液中可检测到56Kd蛋白。从胶质瘤细胞匀浆中提纯的56Kd蛋白可诱导培养细胞形成褶皱膜并重组肌动蛋白纤维。人脑肿瘤是通过手术获得的，并在-70℃下保存直到使用，它包括不同数量的PDGF相关蛋白，以单体形式到组装形式。PDGF相关蛋白的表达与肿瘤类型无关，如良、恶性星形细胞瘤、髓母细胞瘤、脑膜瘤、神经鞘瘤和神经细胞瘤。在每种肿瘤类型中，用BrdU单抗进行体内S时相标记的肿瘤，其增殖活性高的肿瘤往往比低增殖活性的肿瘤表达更多的PDGF相关蛋白，我们推测脑肿瘤合成和分泌PDGF相关蛋白是保持肿瘤潜能的最重要的蛋白质之一。较少

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