Regulation of Genomic Instability in Early Breast Cancer

早期乳腺癌基因组不稳定性的调控 翻译后摘要：我们最近对人类乳腺细胞的研究，使我们能够确定一个以前未发现的 在人乳腺上皮细胞（HMEC）的罕见亚群中的表型。如前所述， 从健康女性的活检组织中生长的大多数上皮细胞对增殖有反应， 在放置于培养物中后，屏障约为15至20个种群倍增器。在短暂的逮捕（称为 在培养中的“选择”），一种罕见的细胞亚群（~ 10 4至10 -5）生长超过初始屏障， 在培养中繁殖数月。这些“后选择”HMEC的典型特征是特定细胞周期的丧失 控制和大量染色体异常的积累。因为这群 当细胞在培养物中生长时，它们接近第二个生长平台，其中几乎100%的细胞具有 染色体异常这些观察结果挑战了细胞如何以及何时获得 通过提供细胞内在机制，在肿瘤形成过程的早期， 会同时产生多种基因变化这些细胞是在没有强制性暴露于 已知物理、病毒或化学诱变剂。最后，这些细胞具有确定的特征， 通常在癌细胞中发现，可以解释它们的起源。“后选择”HMEC不表达p16， 重要的细胞周期蛋白依赖性激酶抑制剂，它们缺乏适当的检查点控制， 基因组完整性如果这些细胞在体内出现，它们可能代表人类发育的最早阶段。 乳腺癌发生这些观察也发现了新的机会。它们可能提供潜在的 用于评估个体对肿瘤转化的易感性的标记物以及 预防和治疗。多种标记物清楚地识别体外不同的细胞状态， 允许在体内鉴定具有这些性质的细胞。值得注意的是，我们发现的 “后选择”HMEC模拟了乳腺癌癌前病变中观察到的许多变化。我们 假设上述体外“选择后”HMEC的性质与以下关键相关： 乳腺上皮细胞在体内的转化过程。本应用程序的目标是（1） 确定p16失活如何促成“选择后”HMEC表型，（2）确定 “选择后”HMEC的起源，3）确定体内检测到的类似细胞是否（a）存在于 在乳腺癌高风险个体中增加其频率，和（B）表现出特征 和（4）检查HMEC中的选择性细胞周期检查点对照。这些研究可能 为预防或治疗乳腺癌提供新的靶点。

Regulation of Genomic Instability in Early Breast Cancer Abstract:Our recent studies on human mammary cells has allowed us to identify a previously undetected phenotype in a rare subpopulation of human mammary epithelial cells (HMEC). As previously reported, the majority of epithelial cells that grow from biopsy tissue from healthy women respond to a proliferation barrier around 15 to 20 population doublings after placement in culture. After a transient arrest (called "selection" in culture), a rare subpopulation of cells (~ 10 4 to 10 -5) grow beyond the initial barrier and propagate for months in culture. These "post-selection" HMEC are typified by loss of specific cell cycle controls and the accumulation of a tremendous number of chromosomal abnormalities. As this population of cells is grown in culture, they approach a second growth plateau in which virtually 100% of the cells have chromosomal abnormalities. These observations challenge traditional views of how and when cells acquire genomic changes in cancer by providing a cell intrinsic mechanism that, early in the neoplastic process, generates multiple simultaneous genetic changes. These cells are generated without obligatory exposure to known physical, viral or chemical mutagenic agents. Finally, these cells possess defined characteristics that are often found in cancer cells and may explain their origin. "Post-selection" HMEC do not express p 16, an important cyclin dependent kinase inhibitor, they lack proper checkpoint control and they do not maintain genomic integrity. Should these cells arise in vivo, they could represent the earliest steps in human mammary carcinogenesis. These observations also identify novel opportunities. They may provide potential markers for assessing susceptibility to neoplastic transformation in individuals as well as potential targets for prevention and therapy. Multiple markers clearly identify the different cellular states in vitro and have allowed for the identification of cells with these properties in vivo. Remarkably, the changes we detect in "post-selection" HMEC mimic many of the changes seen in premalignant lesions in breast cancer. We hypothesize that the above-described properties of "post-selection" HMEC in vitro are critically relevant to the transformation processes of mammary epithelial cells in vivo. The goals of this application are to (1) determine how p16 inactivation contributes to the "post-selection" HMEC phenotype, (2) determine the origins of "post-selection" HMEC, 3) determine if similar cells detected in vivo are (a) present in increased their frequencies in individuals at high risk for breast cancer, and (b) exhibit characteristics of stem cells, and (4) examine selective cell cycle checkpoint controls in HMEC. These studies may provide novel targets for prevention or treatment of breast cancer.