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

描述（由申请人提供）：最近的证据表明，肿瘤在具有自我更新和分化能力的不同细胞（称为癌症干细胞（CSCs））的驱动下分层生长。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的能力一直受到阻碍。我们最近发现，当将小鼠胰腺CSCs引入具有正常免疫系统的组织相容性受体时，产生的胰腺肿瘤在组织学外观和疾病进展模式方面模仿人类胰腺导管腺癌（PDA）。本项目的目的是研究小鼠胰腺csc的免疫应答，并鉴定区分这些细胞与非csc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，肝转移细胞体外生长并显示CSC标记物。此外，只需将500个细胞注射到具有免疫能力、组织相容性的小鼠体内，就能产生组织学上与人类胰腺腺癌没有区别的分化肿瘤。原发肿瘤和转移部位被宿主免疫细胞迅速浸润。我们将1)从原发和转移性肿瘤细胞中生成克隆性小鼠胰腺CSC细胞系，并对这些细胞系的形态、染色体稳定性和癌症干细胞特性进行表征；2)描述荷瘤小鼠和肿瘤初发小鼠对CSCs和非CSCs的细胞免疫反应；3)利用基因谱法鉴定csc与非csc肿瘤细胞中上调的基因；4)评价短发夹RNA （short hairpin RNA, shRNA）靶向CSCs表达的分子在体外阻断CSCs生长和体内肿瘤生成的能力；5)评估CXCR4在CSC生长和转移中的作用，评估宿主细胞（包括免疫细胞）对CXCR4表达的影响。该项目的研究结果将阐明胰腺癌的生物学特性，并为这种毁灭性疾病找到新的治疗靶点。

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.