Targeting Cancer-Associated Myofibroblasts by DNA Hypomethylation

在癌症中大量的肌成纤维细胞(MFS)的存在最初暗示了 癌症是一种无法愈合的伤口，实验表明这些细胞与癌症有关 生长、侵袭和转移。最近我们的实验室(Tycko与Wang合作)显示，与癌症相关的 人胃癌(GCAS)和小鼠胃癌模型中的肌成纤维细胞(CAF) 与正常的MFS相比，全局降低的DNA甲基化和启动子甲基化的焦点增益 胃。我们现在有大量未公布的数据表明这些改变的DNA的发现 CAF中的甲基化延伸到胰腺癌(PncA)，去甲基化药物地西他滨 (5aza-DC)在pncA小鼠模型中具有较强的抗肿瘤活性，部分通过其对 CAF的肿瘤支持活性部分是通过其对恶性上皮细胞的直接作用实现的。 为了建立在这些发现的基础上，我们目前有4个目标--都以DNA甲基化作为治疗手段 靶向于富含间质的胃肠癌的支持性CAF和恶性上皮细胞。 首先，我们将进行几种类型的分子检测，以询问CAF是否积累了全球性和基因特异性 胰腺癌和肝细胞癌DNA甲基化的改变第二，我们将使用 混合/同种异体移植实验探讨去甲基化药物地西他滨是否抑制肿瘤生长 CAF的功能，我们将分析基因表达并鉴定间充质干细胞 对该药物作出反应的标志物，以深入了解其抗CAF的作用机制。第三，我们将 使用pncA的体内小鼠模型来测试地西他滨单独或与其他药物联合使用， 可防止肿瘤进展并导致已建立的PncA肿瘤的消退。这一目标是相互关联的 地西他滨在患有pncA的人类中的一期临床试验，我们将在实验室进行 药效学研究。我们的第四个也是最后一个目标是在老鼠身上使用遗传策略来测试 缺失维持甲基转移酶基因Dnmt1，特别是在MFS中，可以减缓或防止肝脏 肝细胞癌化学致癌模型中的纤维化与癌症。

The presence in carcinomas of large numbers of myofibroblasts (MFs) originally suggested the concept of cancer as a non-healing wound, and experiments have now implicated these cells as contributing to cancer growth, invasion and metastasis. Recently our labs (Tycko collaborating with Wang) showed that cancerassociated myofibroblasts (CAFs) in human gastric carcinomas (GCAs) and in a mouse model of GCA have globally reduced DNA methylation and focal gains of promoter methylation, compared to normal MFs in the stomach. We now have substantial unpublished data indicating that these findings of altered DNA methylation in CAFs extend to pancreatic carcinoma (PnCA), and that the demethylating drug decitabine (5aza-dC) has strong anti-tumor activity in a mouse model of PnCA, mediated in part through its effects on the tumor-supporting activity of CAFs and in part via its direct effects on the malignant epithelial cells. To build on these findings we have 4 current objectives - all centered on DNA methylation as a therapeutic target in both the supportive CAFs and malignant epithelial cells of stroma-rich gastrointestinal cancers. First, we will carry out several types of molecular assays to ask whether CAFs accumulate global and genespecific alterations in DNA methylation in pancreatic and hepatocellular carcinomas. Second, we will use mixing/allografting experiments to ask whether the demethylating drug decitabine inhibits the tumorsupporting function of CAFs, and we will profile gene expression and characterize mesenchymal stem cell markers in response to this drug to gain insights to its mechanisms of action against CAFs. Third, we will use in vivo mouse models of PnCA to test whether decitabine, alone and in combination with other agents, can prevent tumor progression and lead to regression of established PnCA tumors. This objective is linked to a Phase 1 clinical trial of decitabine in humans with PnCA, for which we will carry out the laboratory-based pharmacodynamic studies. Our fourth and last objective is to use a genetic strategy in mice to test whether deletion of the maintenance methyltransferase gene Dnmtl, specifically in MFs, can slow or prevent liver fibrosis and cancer in a chemical carcinogenesis model of hepatocellular carcinoma.