Biology and Immunology of Pancreatic Cancer Stem Cells in a Novel Mouse Model

描述(申请人提供)：最近的证据表明，肿瘤是由具有自我更新和分化能力的不同细胞驱动的分层生长，称为癌症干细胞(CSCs)。由于缺乏模拟人类疾病的简单小鼠模型，研究实体肿瘤中的CSCs的能力受到了阻碍。我们最近发现，当小鼠胰腺CSCs被引入免疫系统正常的组织相容受体中时，产生的胰腺肿瘤在组织学形态和疾病进展模式方面类似于人类胰腺导管腺癌(PDA)。本项目的目的是研究小鼠胰腺肿瘤干细胞的免疫反应，并识别区分这些细胞和非肿瘤细胞的分子。我们最近发现，在LSL-KrasG12D/+；LSL-P53 R172H/+；PDX-1-Cre小鼠胰腺癌模型中，从肝转移癌分离的细胞在体外生长并显示CSC标记。此外，只要将500个细胞注射到免疫活性强、组织相容的小鼠体内，就可以产生组织学上与人类胰腺癌难以区分的分化肿瘤。原发肿瘤和转移部位迅速被宿主免疫细胞渗透。我们将1)从原代和转移性肿瘤细胞中建立克隆性小鼠胰腺CSC系，并从形态、染色体稳定性和肿瘤干细胞特性方面对这些克隆系进行鉴定；2)研究荷瘤和肿瘤初期小鼠对CSCs和非CSCs的细胞免疫应答；3)利用基因图谱鉴定CSCs和非CSC肿瘤细胞中上调的基因；4)评估针对CSCs表达的分子的短发夹状RNA(ShRNA)药物在体外阻止这些细胞的生长和体内肿瘤生成的能力；5)探讨CXCR4在CSC生长和转移中的作用及宿主细胞(包括免疫细胞)对CXCR4表达的影响。这个项目的发现应该会阐明胰腺癌的生物学，并导致确定这种毁灭性疾病的新治疗靶点。 相关性：该模型非常接近于人类胰腺癌，为研究胰腺干细胞提供了一种新的手段。由于我们的CSCs具有在胰腺癌中常见的相同的基因突变(Kras，P53)，并且表达与人类胰腺CSCs相同的分子标记，因此关于这些细胞生物学的知识应该被证明对设计更有效的人类胰腺癌治疗方法是有用的。

DESCRIPTION (provided by applicant): Recent evidence suggests that tumors grow in hierarchies driven by distinct cells with the ability to self renew and differentiate, called cancer stem cells (CSCs). The ability to study CSCs in solid tumors has been hampered by a lack of simple mouse models that mimic human disease. We recently discovered mouse pancreatic CSCs that, when introduced into histocompatible recipients with normal immune systems, generate pancreatic tumors that mimic human pancreatic ductal adenocarcinoma (PDA) in terms of histologic appearance and pattern of disease progression. The objective of this project is to study the immune response to murine pancreatic CSCs and identify molecules that distinguish these cells from non-CSC tumor cells. We recently discovered that in the LSL-KrasG12D/+; LSL-p53 R172H/+; Pdx-1-Cre mouse model of pancreatic cancer, cells isolated from liver metastases grow in vitro and display CSC markers. Moreover, as few as 500 cells injected into immunocompetent, histocompatible mice can generate differentiated tumors that are histologically indistinguishable from human pancreatic adenocarcinoma. Primary tumors as well as sites of metastases are rapidly infiltrated with host immune cells. We will 1) generate clonogenic murine pancreatic CSC lines from primary and metastatic tumor cells and characterize these lines with respect to their morphology, chromosomal stability, and cancer stem cell properties; 2) characterize the cellular immune response to CSCs and non-CSCs in tumor-bearing and tumor-naive mice; 3) use gene profiling to identify genes that are upregulated in CSCs versus non-CSC tumor cells; 4) evaluate the ability of short hairpin RNA (shRNA) agents directed at molecules expressed by CSCs to block the growth of these cells in vitro and their generation of tumors in vivo; and 5) evaluate the role of CXCR4 in CSC growth and metastasis and assess the effects of host cells, including immune cells, on CXCR4 expression. The findings from this project should elucidate the biology of pancreatic cancer and lead to the identification of new therapeutic targets for this devastating disease. RELEVANCE: This model, which closely mimics human pancreatic cancer, provides a novel means to study pancreatic CSCs. Since our CSCs have the same genetic mutations (Kras, p53) commonly found in pancreatic cancer and express the same molecular markers as human pancreatic CSCs, knowledge gained about the biology of these cells should prove useful in the design of more effective therapies for human pancreatic cancer.