急性B淋巴细胞白血病患儿IKZF1编码蛋白IKAROS异常表达研究

The abnormal expression of IKZF1 encoded protein-IKAROS in B-ALL children

摘要:

目的 分析急性B淋巴细胞白血病(B-ALL)患儿的骨髓标本IKAROS(IK)亚型,探讨异常IK亚型的发生频率与预后的关系,并初步研究其相关机制。方法 选择初发B-ALL患儿137例,利用巢式PCR、Sanger测序等分子生物学方法对其进行IK亚型的表达分析,并采用生存曲线探讨异常IK亚型发生频率与预后的关系。结果 137例初发B-ALL患儿中,仅表达IK1和/或IK2(a)正常亚型的患儿105例,32例具有异常IK亚型表达,其中16例表达IK6,14例表达IK4,2例表达IK7,且表达正常IK亚型与表达异常IK亚型组间2.5年无事件生存率差异有统计学意义(P=0.01)。生存曲线分析结果显示,将IK6亚型剔除出异常IK亚型组后,IK4+IK7组与正常IK亚型组间生存率差异无统计学意义(P=0.527),而IK6组生存率仍明显低于正常IK亚型组(P=0.001)。本研究亦从21例复发患儿中,获取10对初-复发成对样本进行IK亚型分析,发现其中8对存在IK亚型表达从初发状态到复发状态不连续情况;且21例复发患儿的复发样本中IK6亚型检出率高达62%,明显高于137例初发患儿IK6亚型检出率(12%)。结论 IK6亚型的表达可作为B-ALL不良预后的标志,且其于复发样本中的高发生率表明,IK6亚型的表达与B-ALL复发密切相关。

Abstract:

Objective To analyze the isoforms of IKAROS in the bone marrow samples from children with acute B-lineage lymphoblastic leukemia (B-ALL) and to investigate the relationship between frequency of dominant-negative (DN) IKAROS isoforms and prognosis of B-ALL, and to preliminarily study the relevant mechanism. Methods A total of 137 children with newly diagnosed B-ALL, who sequentially entered the Department of Hematology and Oncology, Shanghai Children’s Medical Center between January 2005 and September 2010, were included in the study. Nest-PCR, Sanger sequencing, and TA cloning were used to analyze the expression of IKAROS isoforms in these children. The relationship between frequency of DN IKAROS isoforms and prognosis of B-ALL was investigated. Results Of the 137 children with newly diagnosed B-ALL, 16 had expression of IK6, 14 had expression of IK4, and 2 had expression of IK7. There was significant difference in 2.5-year event-free survival between the cohorts of DN IKAROS and non-DN IKAROS (P=0.01). Analysis of the 10 paired of diagnosis/relapse samples from 10 patients with recurrence showed that 8 of 10 paired diagnosis and relapse samples had inconsistent expression of IKAROS isoforms. The rate of IK6 expression in relapse samples from 21 relapse ALL patients was significantly higher than in the 137 children with newly diagnosed ALL (62% vs 12%, P<0.01). Conclusions Expression of DN IKAROS isoforms can be a poor prognostic factor in B-ALL and is closely associated with recurrence of B-ALL.