Pediatric Oncology/Hematology, Erasmus MC-Sophia Children's Hospital, Rotterdam, the Netherlands.
Haematologica. 2011 Mar;96(3):384-92. doi: 10.3324/haematol.2010.031336. Epub 2010 Dec 6.
Dysfunctioning of CCAAT/enhancer binding protein α (C/EBPα) in acute myeloid leukemia can be caused, amongst others, by mutations in the encoding gene (CEBPA) and by promoter hypermethylation. CEBPA-mutated acute myeloid leukemia is associated with a favorable outcome, but this may be restricted to the case of double mutations in CEBPA in adult acute myeloid leukemia. In pediatric acute myeloid leukemia, data on the impact of these mutations are limited to one series, and data on promoter hypermethylation are lacking. Our objective was to investigate the characteristics, gene expression profiles and prognostic impact of the different CEBPA aberrations in pediatric acute myeloid leukemia.
We screened a large pediatric cohort (n=252) for CEBPA single and double mutations by direct sequencing, and for promoter hypermethylation by methylation-specific polymerase chain reaction. Furthermore, we determined the gene-expression profiles (Affymetrix HGU133 plus 2.0 arrays) of this cohort (n=237).
Thirty-four mutations were identified in 20 out of the 252 cases (7.9%), including 14 double-mutant and 6 single-mutant cases. CEBPA double mutations conferred a significantly better 5-year overall survival compared with single mutations (79% versus 25%, respectively; P=0.04), and compared with CEBPA wild-type acute myeloid leukemia excluding core-binding factor cases (47%; P=0.07). Multivariate analysis confirmed that the double mutations were an independent favorable prognostic factor for survival (hazard ratio 0.23, P=0.04). The combination of screening for promoter hypermethylation and gene expression profiling identified five patients with silenced CEBPA, of whom four cases relapsed. All cases characteristically expressed T-lymphoid markers. Moreover, unsupervised clustering of gene expression profiles showed a clustering of CEBPA double-mutant and silenced cases, pointing towards a common hallmark of abrogated C/EBPα-functioning in these acute myeloid leukemias.
We showed the independent favorable outcome of patients with CEBPA double-mutant acute myeloid leukemia in a large pediatric series. This molecular marker may, therefore, improve risk-group stratification in pediatric acute myeloid leukemia. For the first time, CEBPA-silenced cases are suggested to confer a poor outcome in pediatric acute myeloid leukemia, indicating that further investigation of this aberration is needed. Furthermore, clustering of gene expression profiles provided insight into the biological similarities and diversities of the different aberrations in CEBPA in pediatric acute myeloid leukemia.
CCAAT/增强子结合蛋白α（C/EBPα）在急性髓系白血病中的功能障碍除其他原因外，可能是由编码基因（CEBPA）的突变和启动子过度甲基化引起的。CEBPA 突变型急性髓系白血病与较好的预后相关，但这种情况可能仅限于成人急性髓系白血病中 CEBPA 的双突变。在儿科急性髓系白血病中，关于这些突变的影响的数据仅限于一个系列，而且关于启动子过度甲基化的数据也缺乏。我们的目的是研究儿科急性髓系白血病中 CEBPA 不同异常的特征、基因表达谱和预后影响。
我们通过直接测序筛选了一个大型儿科队列（n=252）的 CEBPA 单突变和双突变，并通过甲基化特异性聚合酶链反应筛选了启动子过度甲基化。此外，我们还确定了该队列（n=237）的基因表达谱（Affymetrix HGU133 plus 2.0 芯片）。
在 252 例病例中发现了 34 个突变，其中 20 例（7.9%）有突变，包括 14 例双突变和 6 例单突变病例。与单突变相比，CEBPA 双突变的 5 年总生存率显著提高（分别为 79%和 25%，P=0.04），与 CEBPA 野生型急性髓系白血病（不包括核心结合因子病例）相比也显著提高（47%，P=0.07）。多变量分析证实，双突变是生存的独立有利预后因素（危险比 0.23，P=0.04）。筛选启动子过度甲基化和基因表达谱相结合，确定了 5 例 CEBPA 沉默的患者，其中 4 例复发。所有病例均特征性地表达 T 淋巴细胞标记物。此外，基因表达谱的无监督聚类显示，CEBPA 双突变和沉默病例的聚类，表明这些急性髓系白血病中 C/EBPα 功能失调的共同特征。
我们在一个大型儿科系列中证实了 CEBPA 双突变急性髓系白血病患者的独立良好预后。因此，这种分子标志物可能会改善儿科急性髓系白血病的风险分层。首次提出 CEBPA 沉默病例在儿科急性髓系白血病中预后不良，表明需要进一步研究这种异常。此外，基因表达谱的聚类提供了对儿科急性髓系白血病中 CEBPA 不同异常的生物学相似性和多样性的深入了解。
