Kumar R, Medina D, Sukumar S
Department of Molecular Biology, Squibb Institute of Medical Research, Princeton, New Jersey 08543.
Oncogene. 1990 Aug;5(8):1271-7.
The mammary hyperplastic outgrowth (HOG) line C4, resulted from serial transplantation of a hyperplastic alveolar nodule which arose in a dimethylbenz(a)anthracene (DMBA) treated mouse. The immortalized C4 outgrowth line, on transplantation into syngeneic mice, develops as preneoplastic, hyperplastic outgrowths and subsequently into malignant carcinomas after a long latent period (greater than 6 months). Treatment of mice carrying C4 HOG transplants with DMBA resulted in a reduced latent period for tumor development (less than 3 months) and an increased tumor incidence. DNA's from C4 HOGs and mammary carcinomas of untreated as well as DMBA-treated mice were analyzed for the presence of oncogenes by the NIH3T3 focus forming assay. Transforming H-ras genes were detected in two of 6 preneoplastic HOGs and 10 of 12 carcinomas from DMBA-treated mice. DNAs from neither the HOGs nor the tumors from untreated mice were positive in this assay. The H-ras locus was then directly examined in the 61st codon by in vitro amplification of each of the tissue DNAs using PCR. The location of the activating mutation was determined by hybridization of amplified DNA to mixed sequence oligonucleotide probes. The specific nature of the mutation was defined by RFLPs using XbaI, TaqI and Sau96I restriction enzymes. Six of the H-ras oncogenes in DMBA-promoted tumors were activated by commonly observed A to T transversions at the 61st codon, while five (including an additional tumor with H-ras oncogene revealed by PCR analysis) contained novel A to G transitions. The H-ras oncogene in one DMBA-treated HOG sample was activated by A to T while the second contained an A to G mutations, representative of both modes of mutational activation involved in this model of mammary tumorigenesis. In summary, DMBA-induced point mutated H-ras oncogenes appear to potentiate the progression of hyperplastic outgrowths (HOG) to mammary carcinomas.
乳腺增生性赘生物（HOG）细胞系C4源自一只经二甲基苯并(a)蒽（DMBA）处理的小鼠体内出现的增生性肺泡结节的连续移植。永生化的C4赘生物细胞系移植到同基因小鼠体内后，会发展为癌前增生性赘生物，经过较长潜伏期（超过6个月）后会发展为恶性肿瘤。用DMBA处理携带C4 HOG移植瘤的小鼠，会使肿瘤发生的潜伏期缩短（少于3个月），并增加肿瘤发生率。通过NIH3T3焦点形成试验分析未处理以及经DMBA处理的小鼠的C4 HOG和乳腺癌的DNA，以检测癌基因的存在。在经DMBA处理的小鼠的6个癌前HOG中的2个以及12个癌中的10个中检测到了转化型H-ras基因。在该试验中，未处理小鼠的HOG和肿瘤的DNA均为阴性。然后通过使用PCR体外扩增每个组织DNA，直接在第61密码子处检测H-ras基因座。通过将扩增的DNA与混合序列寡核苷酸探针杂交来确定激活突变的位置。使用XbaI、TaqI和Sau96I限制性内切酶通过RFLP确定突变的具体性质'。在DMBA促进的肿瘤中的6个H-ras癌基因通过第61密码子处常见的A到T颠换被激活，而5个（包括通过PCR分析发现具有H-ras癌基因的另一个肿瘤）包含新的A到G转换。一个经DMBA处理的HOG样品中的H-ras癌基因通过A到T被激活，而另一个包含A到G突变，代表了该乳腺肿瘤发生模型中涉及的两种突变激活模式。总之，DMBA诱导的点突变H-ras癌基因似乎促进了增生性赘生物（HOG）向乳腺癌的进展。
