DeGeorgia Sophia Noah, Kaufman Charles K
Division of Medical Oncology, Department of Medicine and Department of Developmental Biology, Washington University in Saint Louis, St. Louis, MO USA.
bioRxiv. 2024 Dec 17:2024.12.12.628224. doi: 10.1101/2024.12.12.628224.
Recent studies indicate that the development of drug resistance and increased invasiveness in melanoma is largely driven by transcriptional plasticity rather than canonical coding mutations. Understanding the mechanisms behind cell identity shifts in oncogenic transformation and cancer progression is crucial for advancing our understanding of melanoma and other aggressive cancers. While distinct melanoma phenotypic states have been well characterized, the processes and transcriptional controls that enable cells to shift between these states remain largely unknown. In this study, we initially leverage the well-established zebrafish melanoma model as a high-throughput system to dissect and analyze transcriptional control elements that are hijacked by melanoma. We identify key characteristics of these elements, making them translatable to human enhancer identification despite the lack of direct sequence conservation. Building on our identification of a zebrafish enhancer necessary for melanoma initiation, we extend these findings to human melanoma, identifying two human upstream enhancer elements that are critical for full expression. Stable biallelic deletion of these enhancers using CRISPR-Cas9 induces a distinct phenotype shift across multiple human melanoma cell lines from a melanocytic phenotype towards an undifferentiated phenotype and is also characterized by an increase in drug resistance that mirrors clinical data including an upregulation of NTRK1, a tyrosine kinase, and potential therapeutic target. These results provide new insights into the transcriptional regulation of in human melanoma and underscore the role of individual enhancer elements and potentially NTRK1 in driving melanoma phenotype plasticity and drug resistance. Our work lays the groundwork for future gene-based and combination kinase-inhibitor therapies targeting regulation and NTRK1 as a potential avenue for enhancing the efficacy of current melanoma treatments.
最近的研究表明，黑色素瘤中耐药性的发展和侵袭性的增加在很大程度上是由转录可塑性驱动的，而不是典型的编码突变。了解致癌转化和癌症进展过程中细胞身份转变背后的机制对于加深我们对黑色素瘤和其他侵袭性癌症的理解至关重要。虽然不同的黑色素瘤表型状态已得到充分表征，但使细胞在这些状态之间转换的过程和转录控制在很大程度上仍不清楚。在这项研究中，我们最初利用成熟的斑马鱼黑色素瘤模型作为高通量系统，来剖析和分析被黑色素瘤劫持的转录控制元件。我们确定了这些元件的关键特征，尽管缺乏直接的序列保守性，但仍可将其转化用于人类增强子的鉴定。基于我们对黑色素瘤起始所必需的斑马鱼增强子的鉴定，我们将这些发现扩展到人类黑色素瘤，确定了两个人类上游增强子元件，它们对完全表达至关重要。使用CRISPR-Cas9对这些增强子进行稳定的双等位基因缺失，会在多个人类黑色素瘤细胞系中诱导出明显的表型转变，从黑素细胞表型转变为未分化表型，其特征还包括耐药性增加，这与临床数据相符，包括酪氨酸激酶和潜在治疗靶点NTRK1的上调。这些结果为人类黑色素瘤的转录调控提供了新的见解，并强调了单个增强子元件以及潜在的NTRK1在驱动黑色素瘤表型可塑性和耐药性方面的作用。我们的工作为未来基于基因的和联合激酶抑制剂疗法奠定了基础，该疗法针对转录调控和NTRK1，作为提高当前黑色素瘤治疗疗效的潜在途径。
