Melanoma NRAS/BRAF Mutations: A Population-Based Study

描述（由申请人提供）：黑色素瘤的发病率正在迅速增加，仍然是一种潜在的致命疾病，医疗选择不佳，预防方法存在争议。 由于这一疾病的负担日益加重及其致命性，预计改进预防、早期诊断和治疗方法将日益重要。 NRAS和BRAF是RAS-RAF-MEK-ERK-MAP细胞信号传导途径中的介质，是迄今为止描述的用于黑色素瘤的最常见的突变癌基因。 然而，尽管在原发性人黑色素瘤中鉴定了这些突变，但黑色素瘤中NRAS和BRAF突变的频率和突变谱尚未完全表征，并且关于这些突变与黑色素瘤异质性、前驱病变、风险和预后的相关性的知识库中存在关键空白。 本研究的具体目的是：（1）确定原发性皮肤侵袭性黑色素瘤中NRAS和BRAF体细胞改变的基于人群的频率和突变谱及其与组织学亚型和潜在前驱病变的相关性，以及（2）确定NRAS和BRAF突变表型与已知预后指标和风险因素之间的相关性。 在本研究中，收集了2000年北卡罗来纳州约300例恶性黑色素瘤连续患者。 完整的流行病学资料，病理学，肿瘤块已获得这些患者。 将使用高灵敏度单链构象多态性（SSCP）分析技术结合PCR产物直接测序检测和表征NRAS和BRAF体细胞突变。 将确定这些突变的基于人群的频率，并在病理学不同的黑色素瘤亚型（浅表扩散性、恶性雀斑样痣、结节性和肢端雀斑样痣）之间进行比较。 在与痣相关的黑色素瘤样本中，将使用激光捕获显微切割单独分析该组分的突变。 突变表型将与亚型、潜在的前驱病变、风险因素和预后指标相关。 这项研究的数据有望阐明NRAS和BRAF在黑色素瘤发生、进展和异质性中的作用，最终实现更好的预防、分类和治疗。 阐明这些突变如何与环境和遗传因素发生关系，应该会导致更多基于证据的风险因素避免建议。 此外，了解突变是如何与前体发生关系的，应该提供关于哪些潜在的前体应该被去除的信息。 这项研究也有望导致新的血友病靶点的鉴定，以及最近开发的NRAS和BRAF信号传导抑制剂的更有效测试。

DESCRIPTION (provided by applicant): Melanoma, which is rapidly increasing in incidence, remains a potentially fatal disease with poor medical treatment options and controversial methods of prevention. Because of the increasing burden of this disease and its lethality, improved methods of prevention, early diagnosis and treatment are expected to be of increasing importance. NRAS and BRAF, mediators in the RAS-RAF-MEK-ERK-MAP cell signaling pathway, are the most commonly mutated oncogenes thus far described for melanoma. However, despite the identification of these mutations in primary human melanomas, the frequency and mutational spectrum of NRAS and BRAF mutations in melanoma have not been fully characterized and there is a critical gap in the knowledge base regarding the association of these mutations with heterogeneity, precursor lesions, risk, and prognosis in melanoma. The specific aims of this study are to: (1) determine the population-based frequency and mutational spectrum of NRAS and BRAF somatic alterations in primary cutaneous invasive melanoma and their associations with histologic subtype and potential precursor lesions, and (2) determine associations between NRAS and BRAF mutational phenotypes and known prognostic indicators and risk factors. For this study, a group of approximately 300 consecutive patients with malignant melanoma in North Carolina in the year 2000 has been assembled. Complete epidemiologic data, pathology, and tumor blocks have been obtained for these patients. NRAS and BRAF somatic mutations will be detected and characterized using the highly sensitive technique of single strand conformational polymorphism (SSCP) analysis combined with direct sequencing of PCR products. The population-based frequency of these mutations will be determined and compared between pathologically distinct subtypes of melanoma (superficial spreading, lentigo maligna, nodular, and acral lentiginous). In melanoma samples associated with a nevus, this component will be analyzed separately for mutations using laser capture microdissection. Mutational phenotype will be associated with subtype, potential precursor lesions, risk factors, and prognostic indicators. The data derived from this study is expected to clarify the role of NRAS and BRAF in the development, progression and heterogeneity of melanoma, ultimately leading to better prevention, classification and treatment. Elucidation of how these mutations might arise in relationship to environmental and hereditary factors should result in more evidence-based recommendations for risk factor avoidance. In addition, understanding how mutations arise in relationship to precursors should provide information regarding which potential precursors should be removed. This study is also expected to lead to identification of new hemotherapeutic targets and more efficient testing of inhibitors for NRAS and BRAF signaling, which have recently been developed.