Genotype-Phenotype Correlation of CTNNB1 Mutations Reveals Different β-Catenin Activity Associated With Liver Tumor Progression
Genotype-Phenotype Correlation of CTNNB1 Mutations Reveals Different β-Catenin Activity Associated With Liver Tumor Progression
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DOI：
10.1002/hep.28638
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发表时间：
2016-12-01
期刊：
影响因子：
13.5
通讯作者：
Zucman-Rossi, Jessica
中科院分区：
文献类型：
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作者：
Rebouissou, Sandra;Franconi, Andrea;Zucman-Rossi, Jessica
CTNNB 1突变激活β-连环蛋白是肝细胞癌（HCC）和腺瘤（HCA）中常见的体细胞事件，特别是与恶性转化的风险相关。我们的目的是了解CTNNB 1突变类型、肿瘤表型和恶性转化中β-连环蛋白激活水平之间的关系。为此，我们分析了220例HCA、373例HCC和17例交界性HCA/HCC病变中的CTNNB 1突变谱。通过定量逆转录聚合酶链反应和免疫组织化学（IHC）评估肿瘤中的β-连环蛋白活化水平，通过TOP-Flash测定评估细胞中的β-连环蛋白活化水平。总体而言，与腺瘤相比，恶性突变肿瘤中β-连环蛋白活性更高，这与HCC和HCA中CTNNB 1突变的不同谱有关。在良性肿瘤中，我们定义了与特定突变相关的三种水平的β-连环蛋白激活：（1）S45，K335和N387突变导致弱激活;（2）T41突变与中度活性相关;（3）高度活性突变包括外显子3缺失和β-TRCP结合位点（D32-S37）内的氨基酸取代。因此，在体外，K335 I和N387 K突变体显示出比S33 C更低的活性。具有高度活性突变的肿瘤表现出强烈/均匀的谷氨酰胺合酶（GS）染色，并与恶性肿瘤相关。相比之下，弱突变体表现出GS染色的异质性模式，并且在HCA中更常见，除了在20%的突变HCA和HCC中相似地鉴定的S45突变体;然而，在大多数HCC中，弱S45突变体等位基因被复制，导致最终的高β-连环蛋白活性。结论：CTNNB 1基因突变和S45等位基因重复导致的β-连环蛋白高活性与恶性转化相关。因此，应使用精确的IHC标准或突变筛查来鉴定具有S45的HCA和所有高/中度突变体。
CTNNB1 mutations activating beta-catenin are frequent somatic events in hepatocellular carcinoma (HCC) and adenoma (HCA), particularly associated with a risk of malignant transformation. We aimed to understand the relationship between CTNNB1 mutation types, tumor phenotype, and level of beta-catenin activation in malignant transformation. To this purpose, CTNNB1 mutation spectrum was analyzed in 220 HCAs, 373 HCCs, and 17 borderline HCA/HCC lesions. beta-catenin activation level was assessed in tumors by quantitative reverse-transcriptase polymerase chain reaction and immunohistochemistry (IHC), in cellulo by TOP-Flash assay. Overall, beta-catenin activity was higher in malignant mutated tumors, compared to adenomas, and this was related to a different spectrum of CTNNB1 mutations in HCCs and HCAs. In benign tumors, we defined three levels of beta-catenin activation related to specific mutations: (1) S45, K335, and N387 mutations led to weak activation; (2) T41 mutations were related to moderate activity; and (3) highly active mutations included exon 3 deletions and amino acid substitutions within the beta-TRCP binding site (D32-S37). Accordingly, in vitro, K335I and N387K mutants showed a lower activity than S33C. Tumors with highly active mutations demonstrated strong/homogeneous glutamine synthase (GS) staining and were associated with malignancy. In contrast, weak mutants demonstrated heterogeneous pattern of GS staining and were more frequent in HCAs except for the S45 mutants identified similarly in 20% of mutated HCAs and HCCs; however, in most of the HCCs, the weak S45 mutant alleles were duplicated, resulting in a final high beta-catenin activity. Conclusion: High beta-catenin activity driven by specific CTNNB1 mutations and S45 allele duplication is associated with malignant transformation. Consequently, HCAs with S45 and all high/moderate mutants should be identified with precise IHC criteria or mutation screening.