Paquette B
Department of Nuclear Medicine and Radiobiology, Faculty of Medicine, Université de Sherbrooke, Quebec, Canada.
Carcinogenesis. 1996 Jun;17(6):1221-5. doi: 10.1093/carcin/17.6.1221.
The female hormone 17beta-estradiol is involved in the development of breast cancer, an effect usually attributed to its capacity to stimulate the replication of preneoplastic and malignant cells. In this study, we report that 17beta-estradiol enhances the onset of genomic rearrangements, a type of genomic instability, in minisatellite sequences of malignant 10T1/2 mouse cells. Two malignant clones, X-ray-9 and F-17a, previously transformed in vitro by X-rays (600 cGys), and two non-transformed 10T1/2 mouse cell subclones (10T1/2b and 10T1/2c) were divided into two groups. The first group was incubated in the presence of 10(-5) M of 17beta-estradiol (dissolved in ethanol) for 5 days, while the second group was incubated for the same period in culture media containing 0.1% of ethanol. After the incubation both groups of cells were then subcloned, and their DNA was extracted and analyzed with the DNA fingerprinting assay using the probe M (core sequence: 5'-AGGC). A high frequency of genomic rearrangements was observed in the transformed subclones treated with 17beta-estradiol. Nine deletions or additions in minisatellite alleles were observed in six F-17a subclones, while 28 of those genomic rearrangements were found in the 12 X-ray-9 malignant subclones. On the other hand, for the non-transformed 10T1/2b and 10T1/2c cells, no genomic rearrangements were induced by the hormone. After the withdrawal of 17beta-estradiol from the transformed clone X-ray-9, no new genomic rearrangements were detected; while a second incubation with the hormone induced new deletions or additions in minisatellite alleles. This preferential enhancement of genomic instability in malignant 10T1/2 mouse cells suggests that 17beta-estradiol may accelerate the accumulation of mutations, and therefore may represent a mechanism by which the female hormone contributes to breast cancer development.
雌性激素17β-雌二醇参与乳腺癌的发展，这种作用通常归因于其刺激癌前细胞和恶性细胞复制的能力。在本研究中，我们报告17β-雌二醇会增强恶性10T1/2小鼠细胞微卫星序列中基因组重排的发生，基因组重排是一种基因组不稳定性。两个先前经X射线（600 cGy）体外转化的恶性克隆X射线-9和F-17a，以及两个未转化的10T1/2小鼠细胞亚克隆（10T1/2b和10T1/2c）被分为两组。第一组在含有10⁻⁵ M 17β-雌二醇（溶于乙醇）的条件下孵育5天，而第二组在含有0.1%乙醇的培养基中孵育相同时间。孵育后，两组细胞均进行亚克隆，提取其DNA并使用探针M（核心序列：5'-AGGC）通过DNA指纹分析进行分析。在用17β-雌二醇处理的转化亚克隆中观察到高频率的基因组重排。在六个F-17a亚克隆中观察到微卫星等位基因有九处缺失或添加，而在12个X射线-9恶性亚克隆中发现了28处此类基因组重排。另一方面，对于未转化的10T1/2b和10T1/2c细胞，该激素未诱导基因组重排。从转化克隆X射线-9中撤除17β-雌二醇后，未检测到新的基因组重排；而再次用该激素孵育会诱导微卫星等位基因出现新的缺失或添加。恶性10T1/2小鼠细胞中这种对基因组不稳定性的优先增强表明，17β-雌二醇可能会加速突变的积累，因此可能代表了雌性激素促进乳腺癌发展的一种机制。
