DNA repair gene mutations and prostate cancer

前列腺癌(PCA)是人类最易遗传的癌症之一，遗传风险估计高达60%； 然而，潜在的遗传遗传结构在很大程度上仍未得到解释。我们独一无二的访问 收集了211个PCA家庭的446份血液样本，使以家庭为基础的创新方法成为可能 确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定向测序数据 使用来自所有PCA家族的样本和完整外显子组测序(WES)数据，对48个癌症风险基因进行了分析 使用来自PCA家族子集的样本。我们发现了45个家族性功能丧失和错觉 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都参与了 在同源定向DNA修复(HDR)中，一种无错误的DNA双链断裂(DSB)修复。DSB可以 雄激素受体(AR)诱导转录应激的结果，并增加雄激素的癌症风险- 有反应的组织，如前列腺。作为对雄激素刺激的反应，TOP2B拓扑异构酶和 LINE-1内切酶被招募到活性转录位点并诱导DSB。积累的证据 提示HDR的丢失将促进其他容易出错的修复途径，如替代的非同源 末端连接，导致突变积累和基因组不稳定。我们已经确认的突变都是 生殖系突变，代表潜在的致病遗传因素。因此，我们假设功能性的 HDR途径的缺陷，由于HDR基因的功能丧失和错义突变，导致 基因组不稳定性与主成分分析。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中的功能缺陷 基因突变；2)确定核酸酶EXO5和EXD2以及解旋酶HFM1和FANCM在 切除AR诱导的TOP2B连锁DSB的DNA末端，用于前列腺细胞的HDR；3)评估 AR信号和HDR通路在前列腺癌发生中的意义我们强大的研究团队包括Dr。 沈炳辉(联系希望之城[COH])和于晓春博士(MPI；COH)，两位都是 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- 林芳(内布拉斯加州大学医学中心合办)。我们将测试HDR基因突变作为风险的作用 前列腺癌的因素和确定将hdr基因突变与不合法联系起来的潜在分子机制(S) DNA修复和PCa发育。拟议工作的完成将大大增进我们对 HDR在癌症，尤其是前列腺癌中的作用。我们将使用一种创新的方法来识别新的与PCA相关的 基于家族遗传和功能丧失和错义突变评估的HDR缺陷。 这些见解将通过增加生物标志物的可用性来影响该领域，以便进行早期诊断和提供 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.