Immunohistochemical Analysis of BRAFV600E Expression of Primary and Metastatic Melanoma and Comparison With Mutation Status and Melanocyte Differentiation Antigens of Metastatic Lesions
Immunohistochemical Analysis of BRAFV600E Expression of Primary and Metastatic Melanoma and Comparison With Mutation Status and Melanocyte Differentiation Antigens of Metastatic Lesions
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DOI：
10.1097/pas.0b013e318271249e
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发表时间：
2013-03-01
影响因子：
5.6
通讯作者：
Jungbluth, Achim A.
中科院分区：
文献类型：
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作者：
Busam, Klaus J.;Hedvat, Cyrus;Jungbluth, Achim A.
BRAF(V600E)是皮肤黑色素瘤中最常见的突变，已成为转移性黑色素瘤患者治疗的靶点。目前有许多方法可用于确定突变状态。最近，研制出了一株抗突变型BRAF(V600E)的单抗(VE1)。它的使用可以评估整个肿瘤样本中突变蛋白的表达，并可能在选定的病例中更快、更便宜地确定突变状态。然而，要使BRAF(V600E)蛋白表达分析具有临床价值，抗体的高敏感性和特异性是前提。在这项研究中，我们分析了44个已知BRAF(V600E)突变状态的转移性黑色素瘤样本，并进行了BRAF(V600E)蛋白的免疫组织化学表达。在22个缺乏BRAF(V600E)突变的肿瘤中，没有一个是用抗体VE1标记的。这组VE1免疫阴性肿瘤包括4个BRAF(V600E)突变的转移性病变。所有22个已知携带BRAF(V600E)突变的肿瘤样本均呈VE1免疫反应阳性。其中16例在整个肿瘤标本中染色强烈且均匀。然而，6例肿瘤标本同时含有BRAF(V600E)免疫阳性和BRAF(V600E)免疫阴性细胞群。当将BRAF状态与黑素细胞分化抗原的免疫反应性进行比较时，突变型和野生型肿瘤中Melan-A、小眼球转录因子、gp100和酪氨酸酶的表达没有显著差异。除了转移性病变，我们还检测了20例原发黑色素瘤中BRAF(V600E)的表达。10个浅表性播散性黑色素瘤中有7个与VE1抗体呈免疫反应。5个肿瘤呈均一的强免疫反应。在2个原发肿瘤中，染色是局灶性的，仅累及肿瘤的一个亚群。非表面性播散性黑色素瘤无一例免疫反应阳性。在7个原发肿瘤中，可以分析其突变状态：只有携带BRAF(V600E)突变的肿瘤才对VE1免疫阳性。VE1检测突变型BRAF(V600E)具有很高的特异性和敏感性，是一种有价值的临床检测试剂。BRAF表达的异质性可能与对BRAF抑制剂的治疗反应有关。
BRAF(V600E) is the most common mutation in cutaneous melanoma and has become the target of treatment for patients with metastatic melanoma. A number of methods are currently available to determine mutation status. Recently, a monoclonal antibody (VE1) against mutant BRAF(V600E) was generated. Its use permits assessment of the mutant protein expression throughout a tumor sample and may allow faster and cheaper determination of the mutation status in selected cases. However, for BRAF(V600E) protein expression analysis to be of clinical value, high sensitivity and specificity of the antibody is a prerequisite. In this study we analyzed 44 metastatic melanoma samples with a known BRAF(V600E) mutation status with immunohistochemical expression of the BRAF(V600E) protein. None of the 22 tumors that lacked the BRAF(V600E) mutation labeled with the antibody VE1. This set of VE1-immunonegative tumors included 4 metastatic lesions with the BRAF(V600E) mutation. All 22 tumor samples that were known to carry the BRAF(V600E) mutation were immunoreactive with VE1. Sixteen of them stained strongly and homogenously throughout the tumor sample. However, 6 tumor samples contained both BRAF(V600E) immunopositive and BRAF(V600E)-immunonegative cell populations. When the BRAF status was compared with immunoreactivity for melanocyte differentiation antigens, no significant difference in the expression of melan-A, microphthalmia transcription factor, gp100, or tyrosinase was found between mutant and wild-type tumors. In addition to metastatic lesions, we also examined 20 primary melanomas for the expression of BRAF(V600E). Seven of 10 superficial spreading melanomas were immunoreactive with the antibody VE1. Five tumors were strongly and homogenously immunoreactive. In 2 primary tumors the staining was focal, involving only a sub-population of the tumor. None of the nonsuperficial spreading melanomas was immunoreactive. In 7 primary tumors the mutation status could be analyzed: only tumors carrying the BRAF(V600E) mutation were immunoreactive with VE1. The high specificity and sensitivity of VE1 for the detection of mutant BRAF(V600E) suggests a valuable reagent for clinical purposes. Heterogeneity in BRAF expression may be relevant for treatment response to BRAF inhibitors.