Targeting tumor-microenvironment interaction to overcome leukemia chemoresistance

描述(由申请人提供)：在过去的几年里，许多癌症类型的存活率都有了显著的提高。然而，对化疗的耐药性仍然是临床上的一个主要问题。在识别促进癌细胞对化疗耐药的分子变化和细胞内在机制方面取得了显着进展。然而，人们对这些细胞作为微小残留病(MRD)持续存在的机制知之甚少。虽然众所周知，MRD的存在与治疗后复发和预后不良密切相关，但化疗后MRD存活的机制尚不清楚。我感兴趣的是揭开癌细胞在体内产生化疗耐药性的机制。为了研究这个问题，我使用了Ph+前B细胞急性淋巴细胞白血病(Ph+ALL)的小鼠模型。这个模型是基于表达人bcr-abl的小鼠前B细胞，当注射到受体小鼠中时，这些细胞产生局限于造血组织的白血病表型。为了发现化疗反应的媒介，我们进行了体内RNAi基因筛查，使用了1300个shRNAs文库。该文库包括与细胞微环境过程和旁分泌信号有关的基因。为了验证筛查的结果，我们选择了在接受一线化疗(环磷酰胺或阿霉素)治疗后，与未治疗的样本相比，发夹代表最显著减少的候选患者。使用这种方法，我们已经在体内确定了几个与细胞微环境过程和旁分泌信号有关的候选蛋白质，这些蛋白质起源于一线化疗药物的作用。为了揭示这些蛋白质用来调节治疗反应的机制，我提出了以下具体目标：1.在Ph+ALL小鼠模型中评估遗传筛选中确定的候选因子在治疗反应中的作用。2.确定这些候选蛋白介导耐药的基本机制。研究这些候选基因的下游信号如何汇聚到DNA损伤所产生的信号网络中。我们相信，从这一筛选中获得的结果将揭示未确定的细胞内在和外在药物靶点，当这些靶点被抑制时，可以增强一线化疗药物，如环磷酰胺和多柔比星的效果。

DESCRIPTION (provided by applicant): Survival rates for many cancer types have improved significantly in the last few years. However, resistance to chemotherapy remains a major issue in the clinic. There has been remarkable progress in identifying molecular alterations and cell-intrinsic mechanisms that promote resistance to chemotherapy in cancer cells. However little is known about the mechanisms acquired by these cells to persist as a minimal residual disease (MRD). While it is generally known that the presence of an MRD highly correlates with relapse after therapy and poor prognosis, the mechanisms underlying the survival of the MRD after chemotherapy remain unclear. I am interested in uncovering the mechanisms used by cancer cells to develop resistance to chemotherapy in vivo. To study this problem, I am using a mouse model of Ph+ pre-B cell acute lymphoblastic leukemia (Ph+ ALL). This model is based on mouse pre-B cells expressing human BCR-ABL that generate a leukemic phenotype restricted to hematopoietic tissues upon injection into recipient mice. To uncover mediators of chemotherapy response, we performed an in vivo RNAi genetic screen, using a library of 1300 shRNAs. This library included genes that have been implicated in cell microenvironment processes and paracrine signaling. In order to validate the results from the screen, we selected candidates that showed the most significant reduction in hairpin representation upon treatment with front-line chemotherapies (cyclophosphamide or doxorubicin) when compared to the untreated sample. Using this approach, we have identified several candidate proteins implicated in cell microenvironmental processes and paracrine signaling originating from the action of the front-line chemotherapeutics, in vivo. To uncover the mechanisms utilized by these proteins to mediate therapy response, I propose the following specific aims: 1. Assess the role of candidate factors identified in a genetic screen in therapy response in a mouse model of Ph+ ALL. 2. Identify the basic mechanisms of drug resistance mediated by these candidate proteins. Investigate how downstream signaling from these candidates converge on signaling networks emanating from DNA damage. We believe that the results obtained from this screen will uncover uncharacterized cell intrinsic and extrinsic drug targets that, when inhibited, can potentiate the effects of front-line chemotherapeutics, like cyclophosphamide and doxorubucin.