Mechanism for arsenic induced carcinogenesis

摘要 染色体不稳定(CIN)通过促进非整倍体而促进肿瘤的发生。砷是众所周知的 诱导非整倍体，但砷诱导非整倍体的分子机制 致癌机制尚未确定。我们已经鉴定出一种miRNA(hsa-miR-186)在 在人类角质形成细胞中过表达时可诱发CIN。 该miRNA编码在ZRANB2基因的内含子9内，并作为ZRANB2的一部分被共转录 文字记录。这种嵌入的microRNA通过microRNA的成熟从内含子RNA中加工出来 机械设备。ZRANB2编码一种选择性剪接因子，含有两个锌指，每个锌指含有四个半胱氨酸 协调锌的供应。这些类型的锌指是亚砷酸盐置换锌的靶标。我们假设 慢性砷暴露通过取代锌指上的锌来扰乱ZRANB2的功能； 动态平衡机制诱导ZRANB2转录；hsa-miR-186同时增加导致CIN 导致砷的致癌作用。该项目将确定hsa-miR-186在砷中的作用。 诱导人角质形成细胞CIN及砷对ZRANB2结构和功能的调控 曝光。将寻求以下具体目标来验证这一假说：1.确定hsa-miR-186的作用 永生化角质形成细胞(HaCaT细胞)的致癌转化。 亚砷酸盐对ZRANB2结构和功能的破坏；3.确定hsa-miR-186过表达的可能性 亚砷酸盐诱导染色体不稳定性及抑制ZRANB2基因剪接的潜能 角质形成细胞。这些目标的成功完成将展示表观遗传学的一种新机制 对暴露于砷的环境压力的反应，并证明这种反应导致 染色体不稳定(CIN)与砷诱发的皮肤癌有关。这种机制很可能起到了 在砷诱导的其他器官的致癌过程中也起到了重要作用。因此，hsa-miR-186可能是一种 砷暴露患者的砷诱发内癌。亚砷酸盐暴露扰乱的论证 MRNA剪接模式的研究将为砷致病机制的研究开辟一个新的领域。

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.