Roberts A B, Lamb L C, Newton D L, Sporn M B, De Larco J E, Todaro G J
Proc Natl Acad Sci U S A. 1980 Jun;77(6):3494-8. doi: 10.1073/pnas.77.6.3494.
Polypeptides characterized by their ability to confer a transformed phenotype on an untransformed indicator cell have been isolated directly from tumor cells growing both in culture and in the animal, by using an acid/ethanol extraction procedure. Assay of these polypeptides is based on their ability to induce normal rat kidney fibroblasts to form colonies in soft agar. Peptides from murine sarcoma virus-transformed mouse 3T3 cells grown in culture had the highest specific activity in this assay; peptides from sarcomas produced from these cells or from chemically induced transplantable bladder carcinomas of mice were one-third as active; and peptides from a chemically induced rat tracheal carcinoma had only one-tenth the activity. Treatment with either trypsin or dithiothreitol destroyed the activity of all of these materials. The properties of these intracellular polypeptides from both virally and chemically transformed cells are similar to those described for the sarcoma growth factors (SGFs) previously isolated from the conditioned medium of sarcoma virus-transformed mouse 3T3 cells, suggesting the definition of a class of transforming growth factors common to tumor cells of different origins. The transforming peptides from the cultured sarcoma virus-infected cells were separately by gel filtration into two fractions of apparent molecular weight 7000 and 10,000. The major fraction at molecular weight 7000 represented approximately 0.1% of the original cell protein and had a specific activity 50 times that of the original acid/ethanol extract.
通过酸/乙醇提取法，已直接从培养物和动物体内生长的肿瘤细胞中分离出具有在未转化指示细胞上赋予转化表型能力的多肽。这些多肽的测定基于它们诱导正常大鼠肾成纤维细胞在软琼脂中形成集落的能力。在该测定中，来自培养的鼠肉瘤病毒转化的小鼠3T3细胞的肽具有最高的比活性；来自这些细胞产生的肉瘤或小鼠化学诱导的可移植膀胱癌的肽活性为其三分之一；来自化学诱导的大鼠气管癌的肽活性仅为其十分之一。用胰蛋白酶或二硫苏糖醇处理会破坏所有这些物质的活性。这些来自病毒和化学转化细胞的细胞内多肽的性质与先前从肉瘤病毒转化的小鼠3T3细胞的条件培养基中分离出的肉瘤生长因子（SGFs）所描述的性质相似，这表明定义了一类不同来源肿瘤细胞共有的转化生长因子。通过凝胶过滤将来自培养的肉瘤病毒感染细胞的转化肽分离为表观分子量为7000和10,000的两个部分。分子量为7000的主要部分约占原始细胞蛋白的0.1%，其比活性是原始酸/乙醇提取物的50倍。
