A High-Throughput Model for Human Melanoma

描述（由申请人提供）：黑色素瘤的发病率和与疾病晚期相关的死亡率的增加是令人担忧的原因。最近关于靶向黑色素瘤中最常见的改变（突变型BRAF）的治疗剂的功效的报道非常令人鼓舞，并且已经改变了这种疾病的治疗模式。尽管有这些令人印象深刻的临床成功，但相当大比例的患者本质上是 对BRAF抑制剂有抗性的患者和最初有应答的患者最终由于获得性抗性而复发。此外，近一半的黑色素瘤含有野生型BRAF，因此对突变型BRAF抑制剂不敏感。虽然靶向治疗有可能通过提供毒性更小、更有效的个性化治疗策略来彻底改变癌症护理，但最大限度地提高其有效性需要增加对驱动肿瘤形成、进展、维持和耐药性的分子改变的了解。体内模型满足了这一需求。我们已经开发了一种新的黑色素瘤小鼠模型，不仅有助于识别和验证驱动肿瘤生长的改变，而且还提供了一种评估肿瘤进展和治疗策略疗效的方法。重要的是，在我们的模型中可以使用在人类疾病中观察到的相同遗传改变来诱导黑色素瘤，并且特定的基因组合导致肺和脑转移，这是所有黑色素瘤患者死亡的近一半原因。我们已经观察到，尽管它们的高序列和功能相似性，但AKT2和AKT3在体内突变BRAF的情况下促进脑转移的能力显著不同。有趣的是，在缺乏Pten的突变BRAF驱动肿瘤的小鼠中也没有观察到脑转移，Pten被认为通过失调的AKT活性促进黑色素瘤的发展和进展。我们正准备使用我们的新型小鼠模型在体内研究这些肿瘤之间的机制差异。我们假设，三种AKT亚型和Pten丢失诱导脑转移的差异能力是由于差异下游信号传导，并且在这种情况下AKT3的遗传抑制将显著延迟远处转移的发展和生长。为了验证这一假设，我们将定义体内决定AKT亚型特异性黑色素瘤脑转移的功能结构域，使用功能蛋白质组学来鉴定参与促进脑转移的AKT3依赖性效应物，并利用体内遗传方法来评估靶向AKT3对黑色素瘤生长和转移的影响。我们将进一步验证我们在患者黑色素瘤组织中的发现。该项目的长期目标是确定促进脑转移的靶点，以及确定最有可能发生脑转移的黑色素瘤患者亚组的生物标志物，因此将受益于更积极的治疗。

DESCRIPTION (provided by applicant): The increasing incidence of melanoma and mortality associated with advanced stages of the disease are cause for concern. Recent reports on the efficacy of therapeutic agents targeting the most common alteration in melanoma, mutant BRAF, have been very encouraging and have shifted the treatment paradigm for this disease. Despite these impressive clinical successes, a significant percentage of patients are intrinsically resistant to BRAF inhibitors and those who initially respond ultimately relapse as a result of acquired resistance. In addition, nearly half of all melanomas contain wild-type BRAF and are therefore not sensitive to mutant BRAF inhibitors. While targeted therapies have the potential to revolutionize cancer care by providing personalized treatment strategies that are less toxic and more effective, maximizing their effectiveness requires increased knowledge of the molecular alterations that drive tumor formation, progression, maintenance, and resistance. In vivo models fulfill this need. We have developed a novel mouse model of melanoma that not only aids in the identification and validation of alterations that drive tumor growth but also provides a means to assess tumor progression and efficacy of therapeutic strategies. Importantly, melanomas can be induced in our model using the same genetic alterations observed in the human disease and specific gene combinations result in both lung and brain metastases, which are responsible for nearly half of all melanoma patient deaths. We have observed that despite their high sequence and functional similarity, AKT2 and AKT3 significantly differ in their ability to promote brain metastases in the context of mutant BRAF in vivo. Interestingly, brain metastases are also not observed in mice with mutant BRAF-driven tumors that lack Pten, which is believed to contribute to melanoma development and progression through deregulated AKT activity. We are uniquely poised to investigate the mechanistic differences between these tumors in vivo using our novel mouse model. We hypothesize that the differential ability of the three AKT isoforms and Pten loss to induce brain metastases is due to differential downstream signaling and that genetic suppression of AKT3 in this context will significantly delay the development and growth of distant metastases. To test this hypothesis, we will define the functional domain(s) that dictate AKT isoform specific melanoma brain metastases in vivo, use functional proteomics to identify AKT3-dependent effectors involved in promoting brain metastases, and utilize an in vivo genetic approach to evaluate the effect of targeting AKT3 on melanoma growth and metastasis. We will further validate our findings in melanoma tissue from patients. The long-term goals of this project are to identify targets that promote brain metastases as well as biomarkers that identify the subset of melanoma patients that are most likely to develop brain metastases and would therefore benefit from more aggressive therapy.