Targeting Cancer-Associated Myofibroblasts by DNA Hypomethylation

癌细胞中大量肌成纤维细胞（MFs）的存在最初提出了肌成纤维细胞的概念。 癌症作为一个不愈合的伤口，实验现在已经暗示这些细胞有助于癌症 生长、侵袭和转移。最近，我们的实验室（Tycko与Wang合作）显示， 人胃癌（GCA）和GCA小鼠模型中的肌成纤维细胞（CAF） 与正常的MFs相比， 胃我们现在有大量未发表的数据表明，这些DNA改变的发现 CAFs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的小鼠模型中具有强的抗肿瘤活性，部分通过其对PnCA的作用介导。 CAF的肿瘤支持活性和部分通过其对恶性上皮细胞的直接作用。 基于这些发现，我们目前有4个目标-都集中在DNA甲基化作为治疗 在支持性CAF和富含基质的胃肠道癌的恶性上皮细胞中的靶点。 首先，我们将进行几种类型的分子测定，以确定CAFs是否在全球和基因特异性地积累。 胰腺癌和肝细胞癌中DNA甲基化的改变。第二，我们将使用 混合/同种异体移植实验，以询问去甲基化药物地西他滨是否抑制肿瘤支持 CAFs的功能，我们将分析基因表达和表征间充质干细胞 标记物，以了解其对CAF的作用机制。三是 使用PnCA的体内小鼠模型来测试地西他滨单独或与其它药剂组合， 可以阻止肿瘤进展并导致已建立的PnCA肿瘤消退。这一目标与 地西他滨在PnCA患者中的1期临床试验，我们将进行基于实验室的 药效学研究。我们的第四个也是最后一个目标是在小鼠中使用遗传策略来测试是否 维持甲基转移酶基因Dnmtl的缺失，特别是在MF中，可以减缓或防止肝脏 在肝细胞癌的化学致癌模型中的纤维化和癌症。

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 We now have substantial unpublished data indicating that these findings of altered DNA methylation in CAFs extend to pancreatic carcinoma (PnCA), and that the demethylating drug decitabine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.