PDG Links Stem Cell Niche to Pancreatic Epithelial Renewal, Repair and Cancer

描述（由申请人提供）：干细胞龛负责全身大多数上皮表面的终身更新。这些细胞的失调被认为是导致 在化生和癌症中。迄今为止，对这些体干细胞龛或其对胰腺上皮再生和癌症的贡献知之甚少。我们的实验室最近发现了一种新的上皮干细胞隔室，胰管腺（PDG）。这些腺体独特地表达Shh和TFF 2以及已知存在于祖细胞干细胞龛中的其他发育基因。在急性损伤的反应中，这些腺体能够不对称分裂，产生分化的子细胞，然后迁移到主导管中。在慢性炎症反应中，这些细胞可以经历GI化生和囊性肥大，其在组织学和分子学上类似于侧支IPMN，PDAC的已知前体。对人IPMN的评估显示，PDG形成这些大乳头状突起的增生基底隐窝段。该建议的重点是表征PDG隔室在上皮再生和癌变中的作用。[SA1]在这一目标中提出的实验将确定PDG作为负责上皮更新和再生的上皮祖细胞干细胞龛的作用。我们建议使用一个命运映射，在体内谱系标记策略，专门标记PDG室，结合一个良好的表征模型的急性和慢性胰腺损伤，以确认这些车厢含有上皮祖细胞。在体外和体内的策略，也提出了确定这些细胞是否具有多潜能的能力。我们的初步数据表明，该隔室至少有两个群体的干细胞，标记保留细胞（LRC）和瞬时扩增细胞（TA）。为了更好地描述这两个 我们提出了一个发展的子目标，通过mRNA-Seq从最小（10个细胞）样品中评估转录组，以确定这些细胞的独特标志物，并了解在再生和炎性化生期间调节该隔室的关键途径。[SA2]确定PDG促进胰腺癌前体病变、侧支IPMN和癌症形成的机制。为了实现这一目标，我们建议在小鼠体内使用谱系标记和PDG细胞特异性癌基因激活策略，以鉴定PDG作为IPMN和浸润性癌症的起源区室。通过线粒体突变作图策略，将在人类和小鼠标本中进一步深入了解前体病变形成的机制，以表明IPMN是由生态位演替、单克隆转换和腺体分裂形成的。低、中、高级别异型增生IPMN的mRNA SMART- Seq可以让我们了解参与启动、进展和侵袭的关键途径。了解这个区室如何有助于再生和癌症将为我们提供癌症预防，早期诊断和治疗的新见解。

DESCRIPTION (provided by applicant): Stem cell niches are responsible for life-long renewal of most epithelial surfaces throughout the body. Dysregulation of these cells is believed to result in metaplasia and cancer. To date little is known about these somatic stem cell niches or their contribution to pancreatic epithelial regeneration and cancer. Our laboratory has recently discovered a novel epithelial stem cell compartment, Pancreatic Duct Glands (PDG). These glands uniquely express Shh and TFF2 as well as other developmental genes known to reside in progenitor stem cell niches. In response to acute injury these glands are capable of asymmetric division that gives rise to differentiated daughter cells which then migrate to repopulate the main ducts. In response to chronic inflammation these cells can undergo a GI metaplasia and cystic hypertrophy which histologically and molecularly resemble side-branch IPMN, known precursors of PDAC. Evaluation of human IPMN reveals that PDG form the proliferative basilar crypt segment of these large papillary projections. This proposal is focused on characterizing the role of the PDG compartment in epithelial regeneration and carcinogenesis. [SA1] The experiments proposed in this aim will determine the role of PDG as an epithelial progenitor stem cell niche responsible for epithelial renewal and regeneration. We propose to use a fate mapping, in vivo lineage tagging strategy specifically tagging the PDG compartment, in combination with a well-characterized model of acute and chronic pancreatic injury, to confirm that these compartments contain epithelial progenitor cells. In vitro and in viv strategies are also proposed to determine if these cells have multipotential capacity. Our preliminary data suggests that this compartment has at least two populations of stem cells, label retaining cells (LRC) and transient amplifying cells (TA). In order to better characterize this two stem cell population we propose a developmental sub-aim to evaluate the transcriptome by mRNA-Seq from minimal (10-cell) samples in order to identify unique markers for these cells, as well as understand key pathways that regulate this compartment during regeneration and inflammatory metaplasia. [SA2] To determine the mechanisms by which PDG contribute to the formation of pancreatic cancer precursor lesions, side-branch IPMN and cancer. To accomplish this aim we propose to use in an in vivo lineage tagging and PDG cell-specific oncogene activation strategy in mice to identify PDG as the compartment of origin for IPMN and invasive cancer. Further insight into the mechanisms underlying the formation of precursor lesions will be gained in human and mouse specimens by using a mitochondrial mutational mapping strategy to show that IPMN are formed by niche succession, monoclonal conversion and gland fission. mRNA SMART- Seq of low, moderate and high grade dysplastic IPMN may allow us to understand key pathways involved in initiation, progression, and invasion. Understanding how this compartment contributes to regeneration and cancer will give us new insights into cancer prevention, early diagnosis and treatment.