Epigenetic Regulation of Hemidesmosome Signaling in Pancreatic Cancer

胰腺导管腺癌(PDAC)是人类最具侵袭性的癌症之一，其发病率不到8% 确诊后存活超过五年的患者。PDAC治疗的一个主要障碍是高度的 促结缔组织增生性肿瘤间质。间质中非肿瘤细胞和细胞外基质(ECM)的含量 与促进侵袭性肿瘤生长和抑制有效的药物输送有关。ECM已经 长期以来，人们认为主要由基质细胞产生，包括癌症相关成纤维细胞(CAF)。 然而，我们对异种移植瘤模型、CAF和PDAC细胞的体外共培养以及激光的表征 捕获显微解剖的肿瘤显示，PDAC细胞表达很大比例的ECM。 此外，这些研究揭示了依赖于CaF的PDAC细胞的重新编程，从而允许 肿瘤组织中ECM成分的表达。我们之前已经证明，BET家族 染色质适配器在PDAC肿瘤的生长中起关键作用，它通过调节PDAC和 基质细胞。在这项工作的基础上，我们发现PDAC中ECM的表达受到广泛的调控 下注蛋白质。在这些依赖于BET的基因中，有半桥粒的组成部分，这是一种多蛋白质 从细胞外基质向细胞骨架网络传递信号的复合体。这项提案将审查 BET蛋白介导PDAC细胞内钙调素依赖的ECM表达的机制 定义XVII胶原蛋白的生物学作用，它是半桥粒的一个关键亚单位。在此的具体目标1中 应用，低传代PDAC细胞系和永生化的PDAC来源的CAF培养将被用于 研究CAF介导BET依赖性ECM-1表达的转录机制 在PDAC细胞中编码基因。在特定的目标2中，我们将使用肿瘤模型来暂时调节 用XVII胶原蛋白的表达来确定CAF诱导的PDAC细胞XVII胶原蛋白表达是否起作用 对PDAC肿瘤生长的影响。下游胶原XVII信号通路将在肿瘤中被分析以阐明 该信号在肿瘤生物学中的作用机制。

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive human cancers, with less than 8% of patients surviving beyond five years after diagnosis. A key impediment to the treatment of PDAC is a highly desmoplastic tumor stroma. The abundance of non-neoplastic cells and extracellular matrix (ECM) in the stroma have been implicated in promoting aggressive tumor growth and inhibiting effective drug delivery. The ECM has long been thought to be primarily produced by stromal cells, including cancer associated fibroblasts (CAFs). However, our characterization of xenograft tumor models, in vitro co-cultures of CAFs and PDAC cells, and laser capture microdissected tumors has revealed that PDAC cells express a large proportion of the ECM. Furthermore, these studies revealed a CAF-dependent reprogramming of PDAC cells that allows for the expression of ECM components observed in tumors. We have previously demonstrated that the BET family of chromatin adaptors play key roles in the growth of PDAC tumors by regulating pathways in both PDAC and stromal cells. Building on this work, we have found the expression of the ECM in PDAC is broadly regulated by BET proteins. Among these BET-dependent genes are components of the hemidesmosome, a multiprotein complex that mediates signaling from the ECM to the cytoskeletal network of cells. This proposal will examine the mechanisms by which BET proteins mediate the CAF-dependent expression of the ECM in PDAC cells and define the biological role of Collagen XVII, a critical subunit of hemidesmosomes. In Specific Aim 1 of this application, low passage PDAC cell lines and immortalized PDAC-derived CAF cultures will be utilized to examine the transcriptional mechanisms by which CAFs mediate the BET-dependent expression of the ECM- encoding genes in PDAC cells. In Specific Aim 2, we will employ tumor models that temporally regulate the expression of Collagen XVII to define whether CAF-induced expression of Collagen XVII in PDAC cells contribute to PDAC tumor growth. Downstream Collagen XVII signaling pathways will be analyzed in tumors to elucidate the mechanisms by which this signaling contributes to tumor biology.