Whitehead R E, Sugawara O, Maronpot R R, Gladen B C, Barrett J C
National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709.
Somat Cell Mol Genet. 1992 Mar;18(2):131-42. doi: 10.1007/BF01233160.
Identification of tumor suppressor gene loci in rodent cell culture systems has relied upon the use of somatic cell hybridization studies. Although normal rodent fibroblasts are capable of suppressing the tumorigenicity of a variety of tumor cells, the lack of complementation in tumor cell x tumor cell hybrids has left the possibility that a single tumor suppressor gene may be responsible for tumor suppression in a particular rodent cell culture system. Using this same approach, we found no evidence for complementation resulting in suppression of the transformed phenotype when three viral oncogene-transformed Syrian hamster embryo (SHE) cell lines and one spontaneously transformed baby hamster kidney (BHK) cell line were fused to benzo[a]pyrene-transformed SHE cells (BP6T-M3). However, v-src oncogene-transformed cell line (srcT) x BP6T-M3 hybrids did demonstrate limited suppression of the transformed phenotype, suggesting at least two complementing tumor suppressor genes in this system. We were able to confirm and extend this finding using another experimental approach with preneoplastic hamster cell lines that are immortal in culture but nontumorigenic in nude mice. We propose that fusion of these preneoplastic cells to various tumor cells may reveal tumor suppressor genes not evident in the tumor cell x tumor cell complementation studies. Subclones of two nontumorigenic, immortal hamster cell lines, 10W and DES4, displayed differing abilities to suppress BP6T-M3 cells in somatic cell hybrids, as quantitated by the ability of the hybrid cells to form colonies in soft agar. With a panel of preneoplastic hamster cell x BP6T-M3 hybrids, a distinct pattern of suppression or expression of the transformed phenotype was observed. Marked differences in this pattern were seen when the same 10W and DES4 subclones were fused to other hamster fibrosarcoma cell lines, indicating different tumor suppressing activities of multiple tumor suppressor genes. Analysis of this data suggests that as few as three or as many as six different tumor suppressor genes may be active in the Syrian hamster embryo cell culture system. Thus, this system may provide a useful model for identifying and studying the effects and regulation of a number of different tumor suppressor genes for fibrosarcomas.
在啮齿动物细胞培养系统中，肿瘤抑制基因位点的鉴定一直依赖于体细胞杂交研究。尽管正常的啮齿动物成纤维细胞能够抑制多种肿瘤细胞的致瘤性，但肿瘤细胞与肿瘤细胞杂交体中缺乏互补作用，这使得单个肿瘤抑制基因可能在特定的啮齿动物细胞培养系统中负责肿瘤抑制成为一种可能性。使用相同的方法，当三种病毒致癌基因转化的叙利亚仓鼠胚胎（SHE）细胞系和一种自发转化的幼仓鼠肾（BHK）细胞系与苯并[a]芘转化的SHE细胞（BP6T-M3）融合时，我们没有发现互补导致转化表型受到抑制的证据。然而，v-src致癌基因转化的细胞系（srcT）与BP6T-M3杂交体确实表现出对转化表型的有限抑制，这表明该系统中至少有两个互补的肿瘤抑制基因。我们能够使用另一种实验方法，即使用在培养中永生但在裸鼠中无致瘤性的癌前仓鼠细胞系，来证实并扩展这一发现。我们提出，将这些癌前细胞与各种肿瘤细胞融合可能会揭示在肿瘤细胞与肿瘤细胞互补研究中不明显的肿瘤抑制基因。通过杂交细胞在软琼脂中形成集落的能力来定量，两种无致瘤性、永生的仓鼠细胞系10W和DES4的亚克隆在体细胞杂交体中对BP6T-M3细胞的抑制能力各不相同。在一组癌前仓鼠细胞与BP6T-M3杂交体中，观察到了转化表型抑制或表达的独特模式。当相同的10W和DES4亚克隆与其他仓鼠纤维肉瘤细胞系融合时，在这种模式中看到了明显差异，这表明多个肿瘤抑制基因具有不同的肿瘤抑制活性。对这些数据的分析表明，在叙利亚仓鼠胚胎细胞培养系统中，可能有少至三个或多至六个不同的肿瘤抑制基因是活跃的。因此，该系统可能为鉴定和研究许多不同的纤维肉瘤肿瘤抑制基因的作用和调控提供一个有用的模型。
