Epigenetic Modifications Causing Sex-Specificity of Fatal TIMP-1 Expression in Pancreatic Cancer

胰腺癌异常高的死亡风险决定性地源于其向肝脏的有效转移形成。最近，我们发现这种风险在男性中比在女性中更高，并且肿瘤来源的分泌因子TIMP-1（金属蛋白酶组织抑制剂-1）以独立于生活方式的方式在这种癌症实体中导致肝转移的性别差异。在胰腺癌中，TIMP-1表达在男性特异性升高，而在女性中水平保持不变。调节x染色体上的TIMP-1基因的性别特异性表达的机制是完全未知的。在这个项目中，我们遵循最初的数据，显示TIMP-1在恶性肿瘤细胞及其祖细胞的疾病进展的早期阶段已经越来越多地表达，并且这些细胞的表观遗传重编程因此似乎发挥了核心调节作用。事实上，根据最近的研究，表观遗传重编程被归类为胰腺癌发生过程中新的核心“使能特征”。然而，到目前为止，这些研究还没有考虑到可能的性别差异。我们将研究TIMP-1在体外（人类胰腺癌细胞系）和体外（来自胰腺癌小鼠胰腺组织的类器官）系统中性别特异性表达增加的分子机制基础，以及已经收集和储存的分别从女性和男性患者和小鼠中分离的胰腺肿瘤组织样本。我们通过ATAC-seq分析了TIMP-1启动子的性别依赖性可及性以及TIMP-1基因的远端调控元件，并通过ChIP-PCR分析确定了TIMP-1基因的特定局部表观遗传状态（组蛋白修饰）。组蛋白修饰和dna修饰表观遗传酶对TIMP-1表达的因果关系将通过基因操作（shrna技术敲低，逆转录病毒基因转移过表达）和临床相关抑制剂的药理抑制来研究。我们希望对胰腺癌进展过程中表观遗传调节的性别差异有更深入的了解，这可能有助于在患者中更有针对性地应用表观遗传活性药物（例如HAT-或hdac -抑制剂）进行治疗。

The exceptionally high risk to die from pancreatic cancer decisively arises from its efficient metastasis formation to the liver. Recently we found that this risk is even higher in men than in women and that the tumor-derived secreted factor TIMP-1 (Tissue Inhibitor of Metalloproteinases-1) is responsible for the sex difference in liver metastasis in this cancer entity in a life style-independent manner. In pancreatic cancer, TIMP-1 expression is male-specifically increased, while the levels remain constant in women. The mechanism regulating this sex-specificity of expression of the X-chromosomally located TIMP-1 gene is completely unknown. In this project we follow initial data showing that TIMP-1 is increasingly expressed already at early stages of the progression of this disease by malignant tumor cells and their progenitor cells, respectively, and that epigenetic reprogramming of these cells thereby seems to play a central regulatory role. In fact, based on recent studies, epigenetic reprogramming was classified as novel central ‘enabling characteristic’ during initiation of pancreatic cancer. However, possible sex differences so far have not been considered in those studies. We will investigate the molecular-mechanistic basis for sex-specific increase of TIMP-1 expression in well-established in vitro- (human pancreatic cancer cell lines) and ex vivo- (organoids derived from pancreas tissue from pancreatic cancer-bearing mice) systems, as well as already collected and stored pancreas tumor tissue samples which had been isolated from female and male patients and mice, respectively. We focus on sex-dependent accessibility of the TIMP-1 promoter as well as distal regulatory elements of the TIMP-1 gene via ATAC-seq and determination of the specific local epigenetic status (histone modification) of the TIMP-1 gene by ChIP-PCR analysis. Causal dependencies of TIMP-1 expression from histone- and DNA-modifying epigenetic enzymes will be investigated by genetic manipulation (knockdown by shRNA-technology, overexpression by retroviral gene transfer) and by pharmacological inhibition with clinically relevant inhibitors. We expect central insight into epigenetically regulated sex differences during progression of pancreatic cancer, which may contribute to more targeted therapeutic application of epigenetically active drugs (e.g. HAT- or HDAC-inhibitors) in patients.