Uncovering the Molecular Basis of Phenotypic Diversification in BRAF-mutant Melanoma

已知肿瘤的异质性有助于不同患者的治疗结果。 到靶向治疗。它主要是在基因突变的背景下进行研究的，这些突变 既可以是预先存在的，也可以是因药物治疗而获得的。然而，我们发现了一些迹象 在正常情况下，随着时间的推移，表型多样化，我们认为这是由非 遗传过程。为了研究这种多样化，我们使用了互补的概念 来自生态理论，被称为下注对冲和表型可塑性。简而言之，我们认为癌症 细胞群体在正常情况下使他们的“赌注”多样化，以增加生存机会。 任何数量的环境变化。在这个理论的基础上，表型可塑性表明 细胞在由分子特征定义的细胞状态的景观中移动。这些 过程与各种生物过程有关，包括细菌生存， 干细胞分化，上皮向间充质转化。初步数据载于 实验室提示BRAF突变黑色素瘤细胞系可能存在复杂的药物反应动力学 由非遗传异质性引起的。单细胞来源的BRAF突变体的“克隆” 黑色素瘤细胞株SKMel5已被产生并发展为细胞亚系，其具有 对药物治疗表现出不同的表型。在研究其中一个子系对 通过抑制BRAF，我们观察到随着时间的推移，表型的变化。使用数学方法 假设非遗传定义状态之间的表型可塑性的模型，我们已经 能够为这一实验观察提供理论基础。在这项提案中，我们试图 辨别这些状态的存在，识别分子决定因素，并监控动态 实时的表型多样化。

Tumor heterogeneity has been known to contribute to diverse patient outcomes in response to targeted therapies. It has primarily been studied in the context of genetic mutations that are either pre-existing or acquired in response to drug treatment. However, we have discovered signs of phenotypic diversification in normal conditions over time, which we think is driven by non- genetic processes. In order to study this diversification, we have used complimentary concepts from ecological theory known as bet-hedging and phenotypic plasticity. Briefly, we think cancer cell populations diversify their “bets” in normal conditions in order to increase chances of survival to any number of environmental changes. Underlying this theory, phenotypic plasticity suggests cells move around in a landscape of cell states, defined by molecular characteristics. These processes have been implicated in a variety of biological processes, including bacterial survival, stem cell differentiation, and epithelial-to-mesenchymal transitions. Preliminary data in the laboratory suggests complex drug-response dynamics in BRAF-mutant melanoma cell lines, likely resulting from non-genetic heterogeneity. Single-cell derived “clones” of the BRAF-mutant melanoma cell line SKMel5 have been generated and developed into cell sublines, which have shown differential phenotypes to drug treatment. In studying one of these sublines' response to BRAF inhibition, we have observed phenotypic diversification over time. Using a mathematical model that assumes phenotypic plasticity between non-genetically defined states, we have been able to form a theoretical basis for this experimental observation. In this proposal, we attempt to discern the existence of these states, identify molecular determinants, and monitor dynamic phenotypic diversification in real time.