Mechanisms of chemotherapy response and tumor re-initiation in lung cancer

描述（由申请人提供）：使用标准化疗治疗实体瘤通常只导致部分反应。因此，由肿瘤再启动细胞（TRICs）驱动的化疗后肿瘤复发是癌症治疗的核心问题。尽管它很重要，但体内可变治疗反应和肿瘤再启动的机制尚不清楚。在人类中理解这一现象的一个重要问题是，在同一患者化疗前后无法获得匹配的临床样本。与人类肿瘤相似的小鼠肿瘤模型是研究化疗后肿瘤再起始过程的有用工具。然而，很少有研究系统地利用这些模型来了解化疗反应。使用人类肺癌小鼠模型，我们已经确定了一个肿瘤细胞亚群，可以通过它们的细胞表面标记物分离出来，并且对化疗具有增加的内在抗性。我们利用kras驱动的肺肿瘤模型与条件转基因报告基因（tdRFP）杂交，以便通过FACs分离肿瘤细胞。顺铂治疗这些小鼠导致CD44+的数量急剧下降；tdRFP+细胞，提示CD44-细胞具有化疗耐药性。利用一种检测顺铂-DNA加合物的抗体，我们发现CD44-和CD44+肿瘤细胞具有不同的DNA修复能力。该模型中的化学耐药与体外球体形成能力的急剧增加有关。体外球形成能力在CD44-/CD24+亚群中进一步增强。因此，我们发现了化疗耐药与癌症干细胞相关特征（细胞表面标记物异质性、球体形成）之间的关系。在本研究中，我们将利用小鼠遗传学、功能基因组学和原发性人类肺癌样本来阐明非小细胞肺癌的化疗耐药机制及其与癌症干细胞表型的关系。

DESCRIPTION (provided by applicant): Treatment of solid tumors with standard chemotherapy often leads only to partial response. Thus, tumor recurrence after chemotherapy driven by tumor-reinitiating cells (TRICs) is a central problem in cancer therapy. Despite its importance, the mechanisms accounting for variable therapy response and tumor re-initiation in vivo are poorly understood. A significant problem in understanding this phenomenon in humans is the inaccessibility of matched clinical samples before and after chemotherapy from the same patient. Mouse models of cancer that closely mimic the human disease are useful tools to study the process of tumor re- initiation after chemotherapy. However, few studies have systematically utilized these models to understand chemotherapy response. Using a mouse model of human lung cancer, we have identified a subset of tumor cells that can be isolated by their cell surface markers and have an increased intrinsic resistance to chemotherapy. We utilized a Kras-driven lung tumor model crossed to a conditional transgenic reporter (tdRFP) in order to facilitate isolation of tumor cells by FACs. Cisplatin treatment of these mice leads to a dramatic decrease in the number of CD44+;tdRFP+ cells, suggesting that CD44- cells are chemotherapy resistant. Using an antibody that detects cisplatin-DNA adducts, we find that CD44- and CD44+ tumor cells have distinct DNA repair capacities. Chemoresistance in this model is associated with a dramatic increase in sphere-forming ability in vitro. In vitro sphere-forming ability is further enriched in a CD44-/CD24+ subpopulation. Thus, we have uncovered a relationship between chemoresistance and characteristics associated with cancer stem cells (cell surface marker heterogeneity, sphere formation). In this proposal, we will utilize mouse genetics, functional genomics and primary human lung cancer samples to elucidate the mechanism of chemoresistance and its relationship to the cancer stem cell phenotype in non-small cell lung cancer. PUBLIC HEALTH RELEVANCE: How tumors respond to chemotherapy and why they become resistant is not completely understood. We will use a mouse model of lung cancer and primary human cancer samples to study the mechanisms of chemotherapy resistance. We focus primarily on understanding how tumor cells repair injury causes by chemotherapy and how they are able to repair this injury and survive.