Mechanism for arsenic induced carcinogenesis

摘要 染色体不稳定性（CIN）通过促进非整倍体而促进癌发生。众所周知，砷 诱导非整倍体，然而砷诱导非整倍体介导的分子机制 致癌作用尚待描述。我们已经鉴定了一种在大肠杆菌中过表达的miRNA（hsa-miR-186）， 砷诱导的鳞状细胞癌，并且当在人角质形成细胞中过表达时诱导CIN。 该miRNA在ZRANB 2基因的内含子9内编码，并作为ZRANB 2的一部分共转录。 成绩单。这种嵌入的microRNA通过microRNA成熟从内含子RNA中加工出来 机械. ZRANB 2编码一个含有两个锌指的选择性剪接因子，每个锌指具有四个半胱氨酸 配位锌。这些类型的锌指是亚砷酸盐置换锌的目标。我们假设 慢性砷暴露通过从锌指中置换锌而破坏ZRANB 2功能;细胞 稳态机制诱导ZRANB 2转录;同时增加的hsa-miR-186导致CIN 促进砷诱发的致癌作用。该项目将确定hsa-miR-186在砷中的作用 在人角质形成细胞中诱导CIN，以及砷如何调节ZRANB 2结构和功能 exposure.以下具体目标将被追求来测试这一假设：1。确定hsa-miR-186的作用 永生化角质细胞（HaCaT细胞）的致癌转化。2.确定的机制 亚砷酸盐对ZRANB 2结构和功能的破坏; 3.确定hsa-miR-186过表达的可能性 诱导染色体不稳定性和亚砷酸盐抑制ZRANB 2定向剪接的潜力， 角质形成细胞这些目标的成功完成将证明一种新的表观遗传机制， 对砷暴露的环境压力的反应，并证明这种反应导致 染色体不稳定性（CIN）与砷诱导的皮肤癌发生有关。这一机制可能发挥了 砷在其他器官中的致癌作用。因此，hsa-miR-186可能是一种生物标志物， 砷暴露患者体内致癌。砷暴露干扰的证明 mRNA剪接模式的研究将为砷致疾病机制的研究开辟新的领域。

Abstract Chromosomal instability (CIN) contributes to carcinogenesis by promoting aneuploidy. Arsenic is well known to induce aneuploidy, however the molecular mechanism by which arsenic induces aneuploidy-mediated carcinogenesis is yet to be delineated. We have identified a miRNA (hsa-miR-186) that is overexpressed in arsenic-induced squamous cell carcinoma and that induces CIN when overexpressed in human keratinocytes. This miRNA is encoded within intron 9 of the ZRANB2 gene and is co-transcribed as part of the ZRANB2 transcript. Such embedded microRNAs are processed out of the intronic RNA by the microRNA maturation machinery. ZRANB2 encodes an alternative splicing factor containing two zinc fingers each with four-cysteines coordinating the zinc. These types of zinc fingers are targets for arsenite displacement of zinc. We hypothesize that chronic arsenic exposure disrupts ZRANB2 function by displacing zinc from the zinc fingers; cellular homeostatic mechanisms induce ZRANB2 transcription; coincident increased hsa-miR-186 leads to CIN contributing to arsenic-induced carcinogenesis. This project will determine the role of hsa-miR-186 in arsenic induced CIN in human keratinocytes, and how ZRANB2 structure and function are modulated by arsenic exposure. The following specific aims will be pursued to test this hypothesis: 1. Determine role of hsa-miR-186 in carcinogenic transformation of immortalized keratinocytes (HaCaT cells).; 2. Determine mechanism of arsenite disruption of ZRANB2 structure and function; 3. Determine potential of hsa-miR-186 over-expression to induce chromosomal instability and potential of arsenite to inhibit ZRANB2 directed splicing in primary keratinocytes. Successful completion of these aims will demonstrate a novel mechanism for epigenetic response to the environmental stress of arsenic exposure and demonstrate that this response causes chromosomal instability (CIN) linked to arsenic-induced skin carcinogenesis. This mechanism likely plays a role in arsenic-induced carcinogenesis in other organs as well. Thus, hsa-miR-186 could be a biomarker for arsenic induced internal cancers in arsenic exposed patients. Demonstration of arsenite-exposure disturbance of mRNA splicing patterns will open a new area of research into mechanisms of arsenic induced disease.