DNA repair gene mutations and prostate cancer

前列腺癌（PCa）是最易遗传的人类癌症之一，遗传风险估计高达60%; 然而，基本的遗传基因结构仍然在很大程度上无法解释。我们独特的进入 从211个PCa家庭收集了446份血液标本，使一种基于家庭的创新方法成为可能， 鉴定新的疾病易感基因座。到目前为止，我们已经从一个小组收集了靶向测序数据， 使用来自所有PCa家族的样本和全外显子组测序（WES）数据， 使用来自PCa家族的子集的样品。我们确定了45个家族性功能丧失和错义 32个DNA损伤反应和修复基因的突变。已知这些基因产物中的大多数参与 在同源定向DNA修复（HDR）中，一种无错误类型DNA双链断裂（DSB）修复。DSB可以 雄激素受体（AR）诱导的转录应激，并增加雄激素受体（AR）的癌症风险。 反应组织，如前列腺。在雄激素刺激的反应中，TOP 2B拓扑异构酶和 LINE-1核酸内切酶被募集到激活转录位点并诱导DSB。累积证据 表明HDR的缺失将促进其他易错修复途径，如替代性非同源修复途径， 末端连接，导致突变积累和基因组不稳定。我们发现的突变都是 种系突变，代表潜在的致病遗传因素。因此，我们假设， 由于HDR基因的功能丧失和错义突变，导致HDR途径的缺陷， 基因组不稳定性和PCa。我们设计了以下三个具体目标来检验我们的中心假设： 1)确定PCa相关HDR引起的DNA损伤反应和HDR的功能缺陷 基因突变; 2）确定核酸酶EXO 5和EXD 2以及解旋酶HFM 1和FANCM在 切除AR诱导的TOP 2B连接的DSB处的DNA末端，用于前列腺细胞中的HDR; 3）为了评估生物学效应， AR信号传导和HDR通路在PCa肿瘤发生中的意义。我们强大的研究团队包括博士。 Binghui Shen（联系PI，City of Hope [COH]）和Xiaoxun Yu博士（mPI; COH），均为以下领域的专家： DNA损伤修复和癌症遗传学，以及公认的PCa生物学家孙子杰博士（mPI; COH）和明博士- Fong Lin（co-I;内布拉斯加大学医学中心）。我们将测试HDR基因突变作为风险的作用， 并定义了将HDR基因突变与非法前列腺癌联系起来的潜在分子机制。 DNA修复和PCa发育。完成拟议的工作将大大促进我们的理解 HDR在癌症中的作用，特别是PCa。我们将使用一种创新的方法来识别新的PCA相关的 HDR缺陷基于家族遗传和功能丧失和错义突变的评估。 这些见解将通过增加用于早期诊断的生物标志物的可用性并提供 抗癌药物开发的分子靶点。

Prostate cancer (PCa) is one of the most heritable human cancers, with inherited risk estimates of up to 60%; however, the underlying inherited genetic architecture is still largely unexplained. Our unique access to a collection of 446 blood specimens from 211 PCa families has enabled an innovative family-based approach to identifying novel disease-susceptibility loci. To date, we have collected targeted sequencing data from a panel of 48 “cancer risk genes” using samples from all of the PCa families, and whole-exome sequencing (WES) data using samples from a subset of the PCa families. We identified 45 familial loss-of-function and missense mutations in 32 DNA damage response and repair genes. Most of these gene products are known to participate in homology-directed DNA repair (HDR), an error-free type of DNA double-strand break (DSB) repair. DSBs can result from androgen receptor (AR)-induced transcriptional stress and increase cancer risk in androgen- responsive tissues, such as the prostate. In response to androgen stimulation, both TOP2B topoisomerase and LINE-1 endonuclease are recruited to active transcription sites and induce DSBs. Accumulated evidence suggests that loss of HDR will promote other error-prone repair pathways, such as alternative non-homologous end joining, causing mutation accumulation and genomic instability. The mutations we have identified are all germline mutations, representing potential causal genetic factors. We therefore hypothesize that functional deficiency in the HDR pathway, due to loss-of-function and missense mutations in HDR genes, contributes to genomic instability and PCa. We have designed the following three specific aims to test our central hypothesis: 1) To determine the functional defects in DNA damage response and HDR caused by PCa-associated HDR gene mutations; 2) To define the roles of nucleases EXO5 and EXD2 and helicases HFM1 and FANCM in resecting DNA ends at AR-induced, TOP2B-linked DSBs for HDR in prostate cells; 3) To assess the biological significance of AR signaling and the HDR pathway in PCa tumorigenesis. Our strong research team includes Dr. Binghui Shen (contact PI, City of Hope [COH]) and Dr. Xiaochun Yu (mPI; COH), both experts in the fields of DNA damage repair and cancer genetics, and recognized PCa biologists Dr. Zijie Sun (mPI; COH) and Dr. Ming- Fong Lin (co-I; University of Nebraska Medical Center). We will test the role of HDR gene mutations as risk factors for PCa and define the underlying molecular mechanism(s) linking HDR gene mutations to illegitimate DNA repair and PCa development. Completion of the proposed work will significantly advance our understanding of the role of HDR in cancer, especially PCa. We will use an innovative approach to identify novel PCa-associated HDR defects based on familial inheritance and evaluation of both loss-of-function and missense mutations. These insights will impact the field by increasing the availability of biomarkers for early diagnosis and providing molecular targets for anti-cancer drug development.