QUANTITATIVE STUDIES OF ONCOGENIC TRANSFECTION

（申请人描述）基于啮齿动物细胞的体外致癌转化试验是研究辐射致癌作用的有力研究工具。首先，它们是高度量化的；C3H、10T1/2细胞和小鼠胚胎细胞的新鲜外植体都是如此。其次，可以利用胚胎细胞研究特定基因对辐射诱导转化的影响。其次，利用基因敲除小鼠的胚胎细胞研究特定基因对辐射诱导转化的影响。基于人类细胞的转化试验不是定量的，但与寻找参与致癌过程的基因更相关。将解决五个问题，所有这些问题都直接关系到该计划项目的主要总体目标，即了解α粒子诱导肿瘤发生的机制。(1)在细胞质被一个或多个α粒子穿过，但没有一个粒子穿透细胞核的细胞中，转化能被诱导吗？(2)转化是否存在“旁观者效应”，即在不被直接击中但与遭受跨核或跨细胞质α -粒子横断的细胞接触和交流的细胞中是否可以诱导转化？旁观者效应发生的条件是什么？(3)一对α粒子穿过细胞核所产生的转化发生率是否取决于粒子的时空分离？(4) α -颗粒在小鼠胚胎细胞中诱导转化的发生率是否取决于ATM基因的状态？(5)在α -颗粒转化的人类细胞中，特定基因是否一直不受调控或下调？

DESCRIPTION: (Applicant's Description) In vitro assays for oncogenic transformation based on rodent cells represent a powerful research tools for investigating radiation carcinogenesis. First, they are highly quantitative; this is true for both C3H, 10T1/2 cells and fresh explants of mouse embryo cells. Second, the influence of specific genes on radiation induced transformation can be studied by using embryo cells. Second, the influence of specific genes on radiation induced transformation can be studied by using embryo cells from knock-out mice. Transformation assays based on human cells are not as quantitative, but are more relevant for seeking genes involved in the oncogenic process. Five questions will be addressed, all of which relate directly to the primary overall goal of this program project, namely an understanding of the mechanisms of alpha-particle induced oncogenesis. (1) Can transformation be induced in cells in which the cytoplasm has been traversed by one or more alpha-particles, but none have penetrated the nucleus? (2) Is there a "bystander effect" for transformation- i.e. can transformation can induced in cells which are not directly hit, but are in contact and the communication with cells suffering trans-nuclear or trans- cytoplasmic alpha-particles transversals? What are the conditions for the bystander effect to be manifest? (3) Does the transformation incidence resulting from a pair of alpha-particles through the cell nucleus depend on the spatial and temporal separation of the particles? (4) Does the incidence of transformation induced by alpha-particles in mouse embryo cells depend on the status of the ATM gene? (5) Are specific genes consistently unregulated or down-regulated in human cells transformed by alpha-particles.