Toll-like Receptor Regulation of Pancreatic Tumorigenesis

描述（由申请人提供）：胰腺腺癌与大多数基于上皮的癌症不同，因为肿瘤块绝大多数由纤维炎症基质组成。胰腺肿瘤基质的作用最近得到重视，并已被证明对肿瘤生长和侵袭性至关重要。因此，针对基质是一种有吸引力的实验治疗方法。然而，基质扩张的调节因子以及炎症基质区室和转化的上皮区室之间的生化串扰知之甚少。在本提案中，我们将确定 Toll 样受体 (TLR) 连接是否是基质形成的主要驱动因素。 胰腺癌中的炎症和上皮突变，并阐明了新的下游信号传导机制和介导其影响的炎症细胞亚群。我们发现胰腺癌肿瘤微环境中充满了无菌炎症的副产物，这些副产物可以充当 TLR 的配体。这一观察结果与我们的初步工作相结合，证明 TLR 在浸润人类和小鼠胰腺癌的多种细胞中显着上调，使我们推测 TLR 连接驱动基质进展。此外，我们认为 TLR 抑制可以通过消除炎症结缔组织形成来潜在地预防或治疗早期胰腺癌。在目标 1 中，我们将确定人类胰腺癌的临床病理特征和结果与 TLR 表达之间的关系，以及确定人类慢性胰腺炎进展为胰腺癌是否与 TLR 表达水平相关。我们还将在小鼠模型中测试 TLR 激活对胰腺癌发生的影响。在目标 2 中，我们将检查 TLR 抑制对胰腺肿瘤发生的影响，并确定除了促进肿瘤周围纤维炎症之外，TLR 激活是否在上皮室内具有直接诱变作用。在目标 3 中，我们将研究 TLR 激活下游肿瘤进展的特定细胞和生化介质。我们假设肿瘤周围树突状细胞和巨噬细胞上的 TLR 连接通过典型的 NF-κB 和 MAP-激酶途径导致强烈的炎症。我们强有力的初步数据进一步表明，这些细胞中 TLR 介导的炎症提供了 IL-6 和其他促炎细胞因子，促进 Kras 突变上皮细胞中 STAT3 磷酸化，导致上皮和基质区室中的 Notch 激活。这是对胰腺疾病中 TLR-STAT3-Notch 界面的首次研究。此外，在初步数据的支持下，我们提出这种相互激活循环促进上皮区室中明显侵袭性的致癌表型，其特征是许多细胞周期调节因子（p16、p21、p27、p53、Cyclin B1、Cyclin D1）和致癌基因（c-myc、Rb 和 SHPTP1）的表达失调。我们相信，本提案中的实验将为瘤周炎症和基质-上皮串扰的调节提供重要的见解 胰腺癌的研究，并为我们的工作转化为利用临床级 TLR 抑制剂的有希望的临床试验提供科学基础。

DESCRIPTION (provided by applicant): Pancreatic adenocarcinoma is distinct from most epithelial-based cancers in that the tumor mass is overwhelmingly composed of fibro-inflammatory stroma. The role of the pancreatic tumor stroma has recently risen in profile and has been shown to be essential for both tumor growth and invasiveness. Thus, targeting the stroma is an attractive approach to experimental therapeutics; however, the regulators of stromal expansion and the biochemical crosstalk between the inflammatory stromal compartment and the transformed epithelial compartment are poorly understood. In this proposal we will determine whether Toll-like receptor (TLR) ligation is a primary driver of stromal inflammation and epithelial mutagenesis in pancreatic carcinoma and elucidate the novel downstream signaling mechanisms and inflammatory cellular subsets that mediate its effects. We have found that the pancreatic cancer tumor microenvironment is rife with the byproducts of sterile inflammation that can act as ligands for TLRs. This observation - combined with our preliminary work demonstrating that TLRs are markedly upregulated on a diverse array of cells infiltrating human and murine pancreatic carcinomas - led us to postulate that TLR ligation drives stromal advancement. Moreover, we propose that TLR inhibition can potentially prevent or treat early pancreatic cancer by abrogating inflammatory desmoplasia. In Aim 1 we will determine the relationship between clinico-pathologic features and outcome in human pancreatic cancer and TLR expression as well as determine whether the progression of human chronic pancreatitis to pancreatic cancer is correlated with TLR expression levels. We will also test the effects of TLR activation on pancreatic carcinogenesis in murine models. In Aim 2 we will examine the effect of TLR inhibition on pancreatic tumorigenesis and determine whether TLR activation has direct mutagenic effects within the epithelial compartment in addition to promoting peri-tumoral fibro-inflammation. In Aim 3 we will investigate the specific cellular and biochemical mediators of tumor progression downstream of TLR activation. We postulate the TLR ligation on peri-tumoral dendritic cells and macrophages leads to intense inflammation via canonical NF-κB and MAP-Kinase pathways. Our robust preliminary data further suggest that TLR-mediated inflammation in these cells provide IL-6 and other pro-inflammatory cytokines that promote STAT3 phosphorylation in the Kras-mutated epithelial cells leading to Notch activation in both epithelial and stromal compartments. This is the first investigation of a TLR-STAT3-Notch interface in pancreatic disease. Additionally, bolstered by preliminary data, we propose that this reciprocal activation loop promotes a distinctly aggressive oncogenic phenotype in the epithelial compartment, characterized by dysregulated expression of numerous cell cycle regulators (p16, p21, p27, p53, Cyclin B1, Cyclin D1) and oncogenic genes (c-myc, Rb, and SHPTP1). We believe that the experiments in this proposal will provide important insight into the regulation of peritumoral inflammation and stromal-epithelial cross-talk in pancreatic cancer and provide the scientific basis for the translation of our work to promising clinical trials utilizing clinical-grade TLR inhibitors.