Maloney T, Wei W Z
Michigan Cancer Foundation, Detroit 48201.
Cancer Immunol Immunother. 1990;30(6):367-73. doi: 10.1007/BF01786887.
High-resolution two-dimensional polyacrylamide gel electrophoresis (PAGE) was employed to reveal tumor-associated polypeptide changes, using the BALB/c C4 line mouse mammary model system, for which phenotypic and immunogenic alterations accompanying tumor progression are well defined. In the first set of experiments, polypeptide patterns from 20 micrograms whole tissue lysates of normal mammary gland, C4 preneoplastic hyperplastic alveolar nodule outgrowth (HAN) and spontaneous tumor from C4 HAN were compared. In order to normalize for differential cellularity and extracellular protein content in the whole tissues, our analysis included polypeptide patterns from serum, increased concentration of protein from whole normal mammary gland, and primary cultures of epithelial cells from normal gland, HAN and tumor. Using a computer-based image-analysis system, 90 polypeptides were identified in C4 tumor that were absent in C4 HAN, normal mammary gland and serum. None of the 90 polypeptides could be shown to represent a definite qualitative change in the protein composition of tumor epithelium as they were found to be either present in a higher concentration of protein from whole normal gland, or present in the primary epithelial culture from HAN, or absent in the primary epithelial culture from tumor. Conversely in the second set of experiments, when epithelial cultures were used as the starting point for comparisons to locate tumor-associated polypeptides, none of the 15 polypeptides that were present in cultures from three different tumors, and absent in the culture from normal mammary gland was specific to C4 tumor, as they were present in whole tissues of normal gland. Thus our experimental approach detected significant quantitative but no qualitative polypeptide changes in whole tumor tissue, or in tumor-derived epithelial cell cultures. This finding may reflect the limitations of the two-dimensional PAGE method, and warrants caution in the use of such gel analysis alone to identify tumor-associated proteins.
利用BALB/c C4系小鼠乳腺模型系统，采用高分辨率二维聚丙烯酰胺凝胶电泳（PAGE）来揭示肿瘤相关多肽的变化，该模型系统中肿瘤进展过程中伴随的表型和免疫原性改变已得到明确界定。在第一组实验中，比较了正常乳腺、C4癌前增生性肺泡结节（HAN）的20微克全组织裂解物以及C4 HAN的自发肿瘤的多肽图谱。为了对全组织中不同的细胞密度和细胞外蛋白质含量进行标准化，我们的分析包括血清的多肽图谱、来自全正常乳腺的蛋白质浓度增加以及来自正常腺体、HAN和肿瘤的上皮细胞原代培养物。使用基于计算机的图像分析系统，在C4肿瘤中鉴定出90种多肽，而这些多肽在C4 HAN、正常乳腺和血清中不存在。这90种多肽中没有一种能被证明代表肿瘤上皮细胞蛋白质组成的明确定性变化，因为它们要么存在于全正常腺体中蛋白质浓度较高的情况下，要么存在于HAN的原代上皮培养物中，要么在肿瘤的原代上皮培养物中不存在。相反，在第二组实验中，当以上皮培养物作为比较起点来定位肿瘤相关多肽时，在来自三种不同肿瘤的培养物中存在且在正常乳腺培养物中不存在的15种多肽中，没有一种是C4肿瘤特有的，因为它们存在于正常腺体的全组织中。因此，我们的实验方法检测到全肿瘤组织或肿瘤来源的上皮细胞培养物中存在显著的定量但无定性的多肽变化。这一发现可能反映了二维PAGE方法的局限性，并且在仅使用这种凝胶分析来鉴定肿瘤相关蛋白质时需要谨慎。
