Tough D F, Feng X, Chow D A
Department of Immunology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Nat Immun. 1995 Jan-Feb;14(1):20-34.
Selective outgrowth of v-H-ras-infected 10T1/2 cells based on the cointroduction of a gene for resistance to geneticin (G418), yielded cells which exhibited an increased capacity to bind polyclonal serum natural antibody (NAb). This demonstrated an NAb-susceptible phase of tumor development which would be a basic requirement for NAb-mediated surveillance of tumors. The ras-oncogene dependence of the high-NAb-binding phenotype provided a model for assessing NAb resistance against ras transformants in vivo and for a comparative analysis of phenotypic and genetic alterations contributing to the progression of ras transformants. Variants were developed through in vitro and in vivo models of tumor progression. T24-H-ras and v-H-ras transformants were isolated in vitro through more rigorous growth conditions, focus formation in the presence of untransformed cells with no selecting drug. These clones expressed p21ras but exhibited little or no increase in NAb binding. Variants recovered following growth from intravenous or threshold subcutaneous (s.c.) inocula of high-NAb-binding ras transformants in syngeneic C3H/HeN mice exhibited decreases in NAb binding but no uniform change in p21ras. Concurring inverse correlations between NAb binding and s.c. tumorigenicity were exhibited by the T24-H-ras transformant clones, the ras transformants grown in vivo, and the v-H-ras-transformed clones isolated in the presence versus the absence of untransformed cells. This consistent inverse correlation, together with the reduced NAb binding of the ras transformants grown in vivo, provides strong evidence that NAb participates in the defense against ras-transformed cells in vivo. The lack of any direct correlation between p21ras expression and the reduction in NAb binding or the increase in tumorigenicity of cells generated through progression in vivo suggested the regulatory action of additional genes. Hybridization studies between high- and low-NAb-binding clones implicated the activation of an additional oncogene and inactivation of an antioncogene in the down-regulation of the ras-induced increases in NAb binding associated with tumor progression.
基于共导入对遗传霉素（G418）的抗性基因，v-H-ras感染的10T1/2细胞的选择性生长，产生了具有增加的结合多克隆血清天然抗体（NAb）能力的细胞。这证明了肿瘤发展的一个对NAb敏感的阶段，这将是NAb介导的肿瘤监测的一个基本要求。高NAb结合表型对ras癌基因的依赖性为评估体内NAb对ras转化体的抗性以及对促成ras转化体进展的表型和基因改变进行比较分析提供了一个模型。通过肿瘤进展的体外和体内模型产生了变体。通过更严格的生长条件在体外分离出T24-H-ras和v-H-ras转化体，在没有选择药物的情况下在未转化细胞存在下形成集落。这些克隆表达p21ras，但NAb结合几乎没有增加或没有增加。在同基因C3H/HeN小鼠中，从高NAb结合ras转化体的静脉内或阈值皮下（s.c.）接种物生长后回收的变体表现出NAb结合减少，但p21ras没有一致变化。T24-H-ras转化体克隆、体内生长的ras转化体以及在有无未转化细胞存在下分离的v-H-ras转化克隆均表现出NAb结合与皮下致瘤性之间的一致负相关。这种一致的负相关，以及体内生长的ras转化体的NAb结合减少，提供了强有力的证据表明NAb参与了体内对ras转化细胞的防御。p21ras表达与通过体内进展产生的细胞的NAb结合减少或致瘤性增加之间缺乏任何直接相关性，提示了其他基因的调节作用。高NAb结合和低NAb结合克隆之间的杂交研究表明，在与肿瘤进展相关的ras诱导的NAb结合增加的下调中，有一个额外的癌基因被激活和一个抗癌基因失活。
