Russo J, Calaf G, Russo I H
Department of Pathology, Fox Chase Cancer Center, Philadelphia, PA 19111.
Crit Rev Oncog. 1993;4(4):403-17.
This work was undertaken with the purpose of clarifying the factors that modulate the transformation of human breast epithelial cells. For accomplishing this goal, it was necessary to establish the adequate culture conditions for maintaining primary cultures of breast tissue for their treatment with genotoxic agents. It also was determined whether primary cultures generated from these tissues maintained the basic biological properties of the host. In this work we have been able to show that the in vivo developmental stage of the gland is important in the expression of an early transformation phenotype after treatment with chemical carcinogens in vitro; furthermore, that the culture conditions, mainly the calcium concentration in the medium, are important in the selection of that specific phenotype. Four carcinogens, 7,12-dimethylbenz(a)anthracene (DMBA), benzo(a)pyrene (BP), methyl-N-nitro-nitrosoguanidine (MNNG), and N-methyl-N-nitrosourea (NMU) were used for treating primary human breast epithelial cell (HBEC) cultures. Ten out of 20 samples tested expressed survival efficiency in agar methocel. The immortalized human breast epithelial cell line MCF-10 was treated with the same chemical carcinogens, which induced point mutations in codons 12 and 61 and the expression of malignant phenotypes in treated cells. MCF-10 cells transfected with the mutated c-Ha-ras gene exhibited the same malignant phenotypes shown by carcinogen-treated cells, mainly tumorigenesis in SCID mice. It was concluded that both chemical carcinogens and mutated ras gene induce malignant transformation of immortalized HBEC, which suggests that the critical point in the transformation pathway is the immortalization of the cell.
本研究旨在阐明调节人乳腺上皮细胞转化的因素。为实现这一目标，有必要建立合适的培养条件以维持乳腺组织原代培养物，以便用基因毒性剂对其进行处理。还确定了从这些组织产生的原代培养物是否保持宿主的基本生物学特性。在本研究中，我们已经能够表明，腺体的体内发育阶段在体外经化学致癌物处理后早期转化表型的表达中很重要；此外，培养条件，主要是培养基中的钙浓度，在该特定表型的选择中很重要。使用四种致癌物，即7,12-二甲基苯并(a)蒽（DMBA）、苯并(a)芘（BP）、甲基-N-硝基-亚硝基胍（MNNG）和N-甲基-N-亚硝基脲（NMU）来处理人乳腺上皮细胞（HBEC）原代培养物。在20个测试样本中，有10个在琼脂甲基纤维素中表现出存活效率。永生化人乳腺上皮细胞系MCF-10用相同的化学致癌物处理，这些致癌物在第12和61密码子中诱导点突变，并在处理后的细胞中诱导恶性表型的表达。用突变的c-Ha-ras基因转染的MCF-10细胞表现出与致癌物处理细胞相同的恶性表型，主要是在SCID小鼠中发生肿瘤。得出的结论是，化学致癌物和突变的ras基因都诱导永生化HBEC的恶性转化，这表明转化途径中的关键点是细胞的永生化。
