Schleger C, Becker R, Oesch F, Steinberg P
Institute of Toxicology, University of Mainz, Mainz, Germany.
Hepatology. 1999 Mar;29(3):834-8. doi: 10.1002/hep.510290305.
A particular point mutation of the tumor suppressor gene p53, namely a G-->T transversion at the third base of codon 249, is frequently detected in primary hepatocellular carcinomas from patients living in areas where the levels of dietary exposure to aflatoxin B1 and the rates of infection with the hepatitis B virus are very high. Very recently, a nontumorigenic liver epithelial cell line (HACL-1) with a finite life-span and expressing a number of hepatocyte-specific markers was established from a human hepatocellular adenoma in our laboratory. To analyze the role of mutated p53 in the immortalization of human liver cells, we transfected HACL-1 cells with an expression vector containing a human p53 complementary DNA mutated at the third base of codon 249 and analyzed the consequences of this gene transfer on the growth properties of this cell line. HACL-1 cells transfected with mutant p53 showed no increase in their life-span (when compared with HACL-1 cells transfected with the antibiotic resistance gene alone) and did not grow in soft agar, whereas transfection of wild-type p53 into HACL-1 cells led to a proliferation stop. Thus, these results strongly support the view that the mutation at codon 249 of the p53 gene may serve as a fingerprint for aflatoxin B1-induced hepatocellular carcinomas, but is not, by itself, sufficient to immortalize human liver cells.
肿瘤抑制基因p53的一种特定点突变，即密码子249第三位的G→T颠换，在生活于黄曲霉毒素B1饮食暴露水平和乙肝病毒感染率都非常高的地区的患者的原发性肝细胞癌中经常被检测到。最近，我们实验室从一例人肝细胞腺瘤中建立了一种具有有限寿命并表达多种肝细胞特异性标志物的非致瘤性肝上皮细胞系（HACL-1）。为了分析突变型p53在人肝细胞永生化中的作用，我们用一个含有在密码子249第三位发生突变的人p53互补DNA的表达载体转染HACL-1细胞，并分析这种基因转移对该细胞系生长特性的影响。用突变型p53转染的HACL-1细胞（与单独用抗生素抗性基因转染的HACL-1细胞相比）寿命没有延长，并且在软琼脂中不能生长，而将野生型p53转染到HACL-1细胞中则导致细胞增殖停止。因此，这些结果有力地支持了这样一种观点，即p53基因密码子249处的突变可能是黄曲霉毒素B1诱导的肝细胞癌的一个特征，但它本身并不足以使人肝细胞永生化。
