D'Abaco G M, Whitehead R H, Burgess A W
Melbourne Tumour Biology Branch, Ludwig Institute for Cancer Research, Victoria, Australia.
Mol Cell Biol. 1996 Mar;16(3):884-91. doi: 10.1128/MCB.16.3.884.
Colon carcinomas appear to arise from the cumulative effect of mutations to several genes (APC, DCC, p53, ras, hMLH1, and hMSH2). By using novel colonic epithelial cell lines derived from the Immorto mouse, named the YAMC (young adult mouse colon) cell line, and an Immorto-Min mouse hybrid, named the IMCE (Immorto-Min colonic epithelial) cell line, carrying the Apc min mutation, we investigated the effect of an activated v-Ha-ras gene on tumor progression. The YAMC and IMCE cell lines are normal colonic epithelial cell lines which are conditionally immortalized by virtue of expression of a temperature-sensitive simian virus 40 (SV40) large T antigen. Under conditions which permit expression of a functional SV40 large T antigen (33 degrees C plus gamma interferon), neither the YAMC nor the IMCE cell line grows in soft agar or is tumorigenic in nude mice. In vitro, when the SV40 large T antigen is inactivated (39 degrees C without gamma interferon), the cells stop proliferating and die. By infecting the YAMC and IMCE cell lines with a replication-defective psi2-v-Ha-ras virus, we derived cell lines which overexpress the v-Ha-ras gene (YAMC-Ras and IMCE-Ras). In contrast to the parental cell lines, under conditions in which the SV40 large T antigen is inactive, both the YAMC-Ras and IMCE-Ras cell lines continue to proliferate. Initally YAMC-Ras cells do not form tumors; however, tumors are visible after 90 days of incubation. IMCE-Ras cells form colonies in soft agar under both permissive and nonpermissive culture conditions. Furthermore, IMCE-Ras cells form tumors in nude mice within 3 weeks. The phenotype of the IMCE-Ras cell line thus clearly demonstrates that a defective Apc allele and an activated ras gene are sufficient to transform normal colonic epithelial cells and render them tumorigenic.
结肠癌似乎源于多个基因（APC、DCC、p53、ras、hMLH1和hMSH2）发生突变的累积效应。通过使用源自永生小鼠的新型结肠上皮细胞系，即名为YAMC（年轻成年小鼠结肠）细胞系，以及携带Apc小突变的永生 - Min小鼠杂交种，即名为IMCE（永生 - Min结肠上皮）细胞系，我们研究了激活的v - Ha - ras基因对肿瘤进展的影响。YAMC和IMCE细胞系是正常的结肠上皮细胞系，它们通过表达温度敏感的猿猴病毒40（SV40）大T抗原而被条件性永生。在允许表达功能性SV40大T抗原的条件下（33摄氏度加γ干扰素），YAMC和IMCE细胞系在软琼脂中均不生长，且在裸鼠中不具有致瘤性。在体外，当SV40大T抗原失活时（39摄氏度且无γ干扰素），细胞停止增殖并死亡。通过用复制缺陷型psi2 - v - Ha - ras病毒感染YAMC和IMCE细胞系，我们获得了过表达v - Ha - ras基因的细胞系（YAMC - Ras和IMCE - Ras）。与亲代细胞系不同，在SV40大T抗原无活性的条件下，YAMC - Ras和IMCE - Ras细胞系均继续增殖。最初，YAMC - Ras细胞不形成肿瘤；然而，培养90天后可见肿瘤。IMCE - Ras细胞在允许和非允许培养条件下均能在软琼脂中形成集落。此外，IMCE - Ras细胞在3周内在裸鼠中形成肿瘤。因此，IMCE - Ras细胞系的表型清楚地表明，有缺陷的Apc等位基因和激活的ras基因足以转化正常结肠上皮细胞并使其具有致瘤性。
