Mechanisms of Radioresistance and Cell Cycle Progression

描述（由申请人提供）：当细胞暴露于损伤 DNA 的物理或化学试剂时，可能会产生有害影响，包括突变、癌症或死亡。然而，有一些机制可以修复损伤、稳定基因组并消除有害影响。在上一个资助期间，重点是了解人类 HRAD9 在辐射或化学暴露后促进生存和基因组完整性的过程中的作用。我们的研究表明，这种进化上保守的基因具有细胞对 DNA 损伤做出反应所需的多种功能，包括细胞周期检查点、DNA 修复和促凋亡活性。最近，我们获得的证据表明 HRAD9 还有另一项重要活动，这也是本提案的重点之一。 HRAD9 可以像 p53 一样充当序列特异性转录因子。 HRAD9 可以结合 p21 启动子中的 p53 共有序列，并在过表达时引起转录。此外，我们证明 HRAD9 可以结合 Cox-2 启动子并反式激活该基因。此外，我们表明 HRAD9 对于 p21 和 Cox-2 的体内辐射诱导至关重要。基于 HRAD9 的这些功能和其他功能，我们还假设了编码蛋白在致癌作用中的作用，现在为 HRAD9 与前列腺癌之间的关系提供了证据。 HRAD9这两种新的活性，即调节转录的能力和在前列腺癌中的作用，将通过解决以下两个假设来进行研究：1.HRAD9是一种序列特异性转录因子，可以通过多个下游靶基因网络的反式激活来调节细胞对DNA损伤的反应，即它控制一种新的损伤反应调节子。实验目标涉及活动的结构要求，以及网络中诱导基因的识别和生物学意义。 2. HRAD9与前列腺癌有因果关系。建议进行实验来检查 HRAD9 在此类癌症中的功能，特别是作为癌基因。这项研究的结果应该更好地定义 HRAD9 作为 DNA 损伤诱导基因的新型调节剂在细胞对 DNA 损伤的反应中的作用，并阐明 HRAD9 在致癌作用中的作用，特别是在前列腺癌中。因此，针对 HRAD9 的研究结果应该会对基础研究以及使用 DNA 损伤剂进行治疗和前列腺癌治疗的临床领域产生影响。该提案重点关注 Rad9 在调节其他基因表达中的作用，这些基因涉及控制细胞生长和维持遗传物质的稳定性。此外，它还涉及 Rad9 在前列腺癌中的功能的详细分析。因此，该项目很重要，因为其结果可能会影响人类健康并导致新治疗策略的开发。

DESCRIPTION (provided by applicant): When cells are exposed to physical or chemical agents that damage DNA, deleterious effects can ensue, including mutation, cancer or death. However, mechanisms are available to repair the damage, stabilize the genome and neutralize harmful effects. During the previous funding period, focus was placed on understanding the role of human HRAD9 in processes that promote survival and genomic integrity after radiation or chemical exposure. Our studies indicate that this evolutionarily conserved gene has multiple functions needed for the cellular response to DNA damage, including cell cycle checkpoints, DNA repair and pro-apoptotic activities. Recently, we obtained evidence that HRAD9 has another important activity, which is one focus of this proposal. HRAD9 can, like p53, act as a sequence specific transcription factor. HRAD9 can bind p53 consensus sequences in the p21 promoter and cause transcription when overexpressed. In addition, we demonstrated that HRAD9 can bind the Cox-2 promoter and transactivate that gene as well. Furthermore, we show that HRAD9 is essential for the radiation induction in vivo of both p21 and Cox-2. Based on these and other functions of HRAD9, we also hypothesized a role for the encoded protein in carcinogenesis, and now provide evidence for a relationship between HRAD9 and specifically prostate cancer. These two novel HRAD9 activities, ability to regulate transcription and a role in prostate cancer, will be pursued by addressing the following two hypotheses: 1. HRAD9 is a sequence specific transcription factor that can regulate the cellular response to DNA damage by transactivation of a network of multiple downstream target genes, i.e., it controls a novel damage response regulon. Experimental aims concern structural requirements of the activity, and the identification and biological significance of inducible genes in the network. 2. HRAD9 is causally related to prostate cancer. Experiments are proposed to examine the function of HRAD9 in this type of cancer, in particular as an oncogene. The results of this study should better define the role of HRAD9 in the cellular response to DNA damage, as a novel regulator of DNA damage-inducible genes, and also elucidate the role of HRAD9 in carcinogenesis, specifically in prostate. As such, the findings focused on HRAD9 should impact on basic research as well as clinical arenas where DNA damaging agents are used for therapy and prostate cancer treatment is a concern. This proposal focuses on the role of Rad9 in regulating expression of other genes involved in controlling cell growth and maintaining stability of the genetic material. In addition, it concerns a detailed analysis of the function of Rad9 in prostate cancer. As such, this project is important since the results could impact on human health and lead to the development of novel therapeutic strategies.