Harris C C, Reddel R, Pfeifer A, Iman D, McMenamin M, Trump B F, Weston A
Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD.
IARC Sci Publ. 1991(105):294-304.
Six families of activated protooncogenes, ras, raf, fur, neu, jun and myc have so far been associated with human lung cancer. Human bronchial epithelial cells in vitro are being used to investigate the functional role of these specific oncogenes and growth regulatory genes in carcinogenesis and tumour progression. When transferred into normal human bronchial epithelial cells by the highly efficient protoplast fusion method, the v-Ha-ras oncogene initiates a cascade of events leading to decreased responsiveness of these cells to inducers of squamous differentiation, aneuploidy and, less frequently, 'immortality' and tumorigenicity with metastasis in athymic nude mice. Transfection of the SV40 T antigen gene results in nontumorigenic cell lines that have a nearly normal pathway of terminal squamous differentiation and can be transformed into malignant cells by transfected Ha-ras, N-ras or Ki-ras. The combination of transfected c-myc and c-raf-1 also transforms human bronchial epithelial cells into neoplastic cells that exhibit some phenotypic traits found in small-cell carcinomas. These and other results indicate that proto-oncogenes dysregulate the pathways of growth and differentiation of human bronchial epithelial cells and play an important role in human carcinogenesis. Analyses of allelic deletion and somatic cell hybrids are being used to identify the chromosomal localization of tumour suppressor genes. We have examined 54 non-small-cell bronchogenic carcinomas with 13 polymorphic markers. Loss of heterozygosity was more frequent than among 23 squamous-cell carcinomas than among 23 adenocarcinomas or eight large-cell carcinomas. Loss of heterozygosity for chromosome 17p was found in 89% of cases of squamous-cell carcinoma and 18% of adenocarcinomas. Analysis of chromosome 11 for allelic deletions revealed two commonly deleted regions (11p13 and 11p15.5). Somatic cell hybrids between normal human bronchial epithelial cells and Hut292DM, a lung carcinoma cell line, had a finite lifespan in vitro and were nontumorigenic in athymic nude mice. Tumour suppressive effects of individual or combinations of specific human chromosomes on Hut292DM are being examined by formation of microcell-cell hybrids. Chromosome 11 has tumour suppressor activity in these hybrids. Both of these studies suggest that tumour suppressor genes play a dominant role in lung carcinogenesis and provide in-vitro model systems for isolating these genes by subtraction library and insertional mutagenesis techniques.
目前已发现有六个家族的原癌基因（ras、raf、fur、neu、jun和myc）与人类肺癌有关。体外培养的人支气管上皮细胞正被用于研究这些特定原癌基因和生长调节基因在致癌作用和肿瘤进展中的功能作用。当通过高效的原生质体融合方法将v-Ha-ras原癌基因导入正常人支气管上皮细胞时，会引发一系列事件，导致这些细胞对鳞状分化诱导剂的反应性降低、出现非整倍体，较少见的是出现“永生性”以及在无胸腺裸鼠中发生转移并具有致瘤性。转染SV40 T抗原基因会产生非致瘤性细胞系，这些细胞系具有近乎正常的终末鳞状分化途径，并且可通过转染Ha-ras、N-ras或Ki-ras转化为恶性细胞。转染的c-myc和c-raf-1的组合也可将人支气管上皮细胞转化为肿瘤细胞，这些肿瘤细胞表现出一些在小细胞癌中发现的表型特征。这些以及其他结果表明，原癌基因会使人类支气管上皮细胞的生长和分化途径失调，并在人类致癌作用中发挥重要作用。等位基因缺失分析和体细胞杂交正在被用于确定肿瘤抑制基因的染色体定位。我们用13个多态性标记物检测了54例非小细胞支气管癌。杂合性缺失在23例鳞状细胞癌中比在23例腺癌或8例大细胞癌中更常见。在89%的鳞状细胞癌病例和18%的腺癌病例中发现了17号染色体短臂的杂合性缺失。对11号染色体进行等位基因缺失分析发现了两个常见的缺失区域（11p13和11p15.5）。正常人支气管上皮细胞与肺癌细胞系Hut29 DM之间的体细胞杂交体在体外具有有限的寿命，并且在无胸腺裸鼠中不具有致瘤性。通过形成微细胞-细胞杂交体来检测特定人类染色体单独或组合对Hut29 DM的肿瘤抑制作用。11号染色体在这些杂交体中具有肿瘤抑制活性。这两项研究均表明，肿瘤抑制基因在肺癌发生中起主导作用，并为通过消减文库和插入诱变技术分离这些基因提供了体外模型系统。
