STEM CELLS AND HEPATOCARCINOGENESIS

描述（来自申请人）：化学性肝癌是一种最常研究的致癌模型，但长期以来一直未得到解答的问题之一是肝细胞癌（HCC）的起源细胞是什么？由Emmanuel Farber倡导的经典细胞途径是HCC从改变的肝细胞通过病灶和癌前结节逐渐发展。然而，对在肝癌发生早期出现的卵圆细胞的研究表明，HCC可能来自位于终末导管内的“双极”肝祖细胞或位于导管附近的多能祖细胞。此外，最近对接受男性供体骨髓移植的雌性小鼠和大鼠的研究表明，肝脏干细胞有两种可能的来源：来自终末导管中的双极祖细胞或来自导管周围干细胞。进一步推测，这些导管周围祖细胞可以通过分化成肝细胞或骨髓细胞可以与肝细胞融合而从循环的骨髓干细胞产生。在具体目标1中，申请人提出开发表达EGFP的转基因Fischer大鼠系，其可用作骨髓移植研究的供体。在具体目标2中，三种致癌模型：a.连续DEN，其特征在于在HCC之前具有很少或没有卵圆细胞的改变的肝细胞的病灶，将用于确定HCC是否来自肝细胞; B. Solt-Farber模型，其特征在于导管卵圆细胞的显著增殖，以确定HCC是否由双极导管前体细胞产生; c.胆碱缺乏-乙醇，一种以卵圆细胞的导管周围增殖为特征的模型，将用于确定癌前病变或HCC是否起源于门静脉周围卵圆细胞。在这些方案中，DDPIV-（小管酶）雌性大鼠将接受来自DDPIV+、EGFP+雄性供体的骨髓移植。将通过供体或受体标记物的存在以及通过肝谱系和沿岸的细胞标记物（适当时）标记鉴定的细胞类型来鉴定通过增殖应答的细胞群体的来源。 在特定目标3中，将测试供体骨髓干细胞与受体肝细胞融合的可能性，并确定HCC病因、进展或转移中融合的可能性。了解癌症的细胞起源对于了解癌症如何演变和制定预防策略至关重要。

Description (from applicant): One of the long standing unanswered questions in one of the most frequently studied models of carcinogenesis, chemical hepatocarcinogenesis, is what is the cell of origin of hepatocellular carcinomas (HCC)? The classic cellular pathway, championed by Emmanuel Farber, is that HCC develop from altered hepatocytes progressively through foci and preneoplastic nodules. However, studies on oval cells, which appear early during hepatocarcinogenesis, indicate that HCC may arise from "bipolar" liver progenitor cells located within terminal ducts or from pluripotent progenitor cells located adjacent to the ducts. In addition, recent studies on female mice and rats receiving bone marrow transplants from male donors indicated two possible origins of liver stem cells: from bipolar progenitor cells in the terminal ducts or from periductal stem cells. It is further postulated that these periductal progenitor cells may arise from circulating bone marrow stem cells either by differentiation into liver cells or that bone marrow cells may fuse with liver cells. In Specific Aim 1, the applicant proposes to develop a transgenic Fischer rat line expressing EGFP which can be used as a donor for bone marrow transplantation studies. In Specific Aim 2, three models of carcinogenesis: a. Continuous DEN, which features foci of altered hepatocytes preceding HCC with little or no oval cells will be used to determine if HCC arise from hepatocytes; b. Solt-Farber model, which features prominent proliferation of ductal oval cells to determine if HCC arise from bipolar ductal precursor cells; c. Choline-deficiency-ethionine, a model which features periductular proliferation of oval cells will be used to determine if preneoplastic lesions or HCC arise from periportal oval cells. In each of these protocols, DDPIV- (canalicular enzyme) female rats will receive a bone marrow transplant from DDPIV+, EGFP+, male donors. The origin of the populations of cells responding by proliferation will be identified by the presence of donor or recipient markers, and the types of cells identified through labeling with both liver lineage and littoral cell markers, when appropriate. In Specific Aim 3, the possibility of fusion of donor bone marrow stem cells with recipient liver cells will be tested and the possibility of fusion in etiology, progression or metastasis of HCC determined. Knowledge of the cellular origin of cancer is critical for understanding how cancer evolves and for developing prevention strategies.