Mechanistic and Informatics Based Analysis of STAT1 Actions in Pancreatic Cancer

 描述（由申请人提供）：胰腺导管腺癌（PDAC）占胰腺癌的85%，是美国癌症死亡的第四大原因，5年生存率为6%。PDAC肿瘤通常是促结缔组织增生的，具有显著的炎性浸润和免疫应答失调。干扰素（IFN）是先天免疫应答的关键介质，通过与特异性细胞表面受体结合，激活JAK-STAT 1通路，并诱导参与对感染应答的许多基因（最显著的是来自病毒）的表达来发挥作用。虽然IFN在这种抗病毒作用方面最为知名，但最近发现，由非磷酸化STAT 1（U-STAT 1）诱导的基因组成的干扰素相关DNA损伤抗性签名（IRDS）可赋予癌症对遗传毒性应激的抗性。我们的实验室最近建立了一个基因工程小鼠模型（GEMM）的PDAC，其中致癌Kras与删除Rb 1在胰腺中由于Cre介导的重组（KRC小鼠）。通过对来自该GEMM的癌细胞的阵列分析，我们确定它们表现出强的IRDS。为了将这一发现外推到人类PDAC肿瘤，我对来自癌症基因组图谱的RNA-Seq数据进行了聚类，发现41.3%的PDAC患者也具有这种IRDS特征。因此，STAT 1-IRDS通路在PDAC病理生物学中可能是重要的。因此，我计划测试中心假设，STAT 1-IRDS途径有助于在PDAC患者的IRDS签名的化疗和放射抗性的关键方式，该途径可以作为一个有益的治疗目标，在这些患者。为了在临床前验证这一假设，我提出了一种基于机械和信息学的方法，该方法涉及以下具体目标。1)使用基因表达，将GEMM或人胰腺癌细胞系分类为IRDS（+）或（-），并确定IRDS状态是否与肿瘤中U-STAT 1的存在相关，如免疫组织化学染色所示。2)确定在鼠和人胰腺癌细胞系中敲除STAT 1基因在细胞和原位模型中是有益还是有害，以及它是否取决于IRDS状态。3)鉴定STAT 1下游的化疗和放射抗性基因。总的来说，这项研究将确定STAT 1-IRDS通路是否是具有临床前水平IRDS特征的胰腺癌患者的新治疗靶点，并将作为未来临床开发的概念证明。

 DESCRIPTION (provided by applicant): Pancreatic Ductal Adenocarcinoma (PDAC), which comprises 85% of pancreatic cancers, is the 4th leading cause of cancer death in the United States with a 5-year survival of 6%. PDAC tumors are often desmoplastic, with marked inflammatory infiltrates and dysregulated immune responses. Interferons (IFNs), key mediators of the innate immune response, act by binding to specific cell-surface receptors, activating the JAK-STAT1 pathway, and inducing the expression of numerous genes involved in the response to infection, most notably from viruses. While IFNs are most well-known for this anti-viral role, recently, an interferon-related DNA damage resistance signature (IRDS) consisting of genes induced by unphosphorylated STAT1 (U-STAT1) was found to confer resistance to genotoxic stress in cancer. Our laboratory recently established a genetically engineered mouse model (GEMM) of PDAC in which oncogenic Kras is combined with deleted Rb1 in the pancreas due to Cre-mediated recombination (KRC mice). By array analysis of cancer cells derived from this GEMM, we determined that they exhibit a strong IRDS. To extrapolate this finding to human PDAC tumors, I clustered RNA- Seq data from The Cancer Genome Atlas and found that 41.3% of PDAC patients also possess this IRDS signature. Therefore, the STAT1-IRDS pathway could be important in PDAC pathobiology. Accordingly, I plan to test the central hypothesis that the STAT1-IRDS pathway contributes in a crucial manner to chemo- and radio-resistance in PDAC patients with an IRDS signature, and that the pathway could serve as a beneficial therapeutic target in these patients. To test this hypothesis pre-clinically, I propose a combined mechanistic and informatics based approach which involves the following specific aims. 1) Using gene expression, classify GEMMs or human pancreatic cancer cell lines as being IRDS (+) or (-) and determine whether IRDS status correlates with the presence of U-STAT1 in tumors as revealed by immunohistochemical staining. 2) Determine if knockout of the STAT1 gene in murine and human pancreatic cancer cell lines is beneficial or harmful both in cells and orthotopic models and whether it depends on IRDS status. 3) Identify chemo- and radio-resistant genes downstream of STAT1. Collectively, this research will determine if the STAT1-IRDS pathway is a novel therapeutic target in pancreatic cancer patients with an IRDS signature at the pre-clinical level and will serve as a proof of concept for future clinical development.