骨髓增生异常综合征患者PTPN11基因表达及突变的临床意义

Clinical analysis of PTPN11 gene expression and mutation in myelodysplastic syndromes

目的:探讨骨髓增生异常综合征(MDS)患者PTPN11基因表达特征及其临床意义。方法:采用SYBR Green染料标记定量PCR分析123例MDS患者和30例良性血细胞减少患者骨髓单个核细胞PTPN11mRNA表达;同时采用基于Miseq平台的二代测序法检测上述患者PTPN11全外显子突变情况。结果:与良性对照相比,MDS患者PTPN11基因表达水平明显增高(P=0.009)。按照WHO分类,低危和高危MDS患者PTPN11基因表达水平均高于良性对照(P=0.001;P=0.005),然而低危和高危MDS患者之间PTPN11表达无差别;按照IPSS-R预后分类,较低危、中危和高危MDS患者PTPN11表达水平均高于良性对照(P=0.001;P=0.006;P<0.001),而高危MDS患者PTPN11表达水平高于较低危和中危MDS患者(P=0.003;P=0.004)。根据对照组PTPN11基因表达水平平均值加两个标准差,将MDS患者分为PTPN11高表达组和低表达组。临床分析显示PTPN11高表达组患者外周血中性粒细胞计数、骨髓增殖度、IPSS-R积分风险以及白血病转化率显著高于PTPN11低表达组(P=0.001;P=0.016;P=0.014;P<0.001)。生存分析显示,与PTPN11低表达组患者相比,PTPN11高表达组患者呈现相对缩短的总生存时间(P=0.052)以及明显缩短的无白血病生存时间(P=0.017)。二代测序揭示123例MDS患者存在3例(2.4%)PTPN11突变,均为错义突变(1例p.A72V和2例p.D61V),3例均为RAEB-2患者且最终转化为急性髓系白血病,生存时间均未超过18个月。结论:MDS患者PTPN11基因表达水平增高,预示患者较高的肿瘤增殖度和白血病转化风险;MDS患者PTPN11基因突变频率较低,一旦发生预后较差。

Objective:To investigate the prevalence and clinical characteristics of PTPN11 gene expression and mutations in myelodysplastic syndromes(MDS).Method:The expression of PTPN11 was determined by quantitive PCR based on SYBR green binding in 123 patients with MDS and 30 controls with benign cytopenias.Next-generation sequencing was used to determine the PTPN11 mutations located in all exons.Result:Compared with benign controls,PTPN11 gene expression was significantly increased in MDS patients(P=0.009).According to WHO classification,the expressions of PTPN11 in both low-grade and high-grade MDS were higher than that in controls(P=0.001;P=0.005).However,there was no significant difference in PTPN11 expression between low-grade and high-grade MDS.According to IPSS-R prognosis classification,PTPN11 expressions in lower-risk,intermediate-risk and high-risk MDS patients were all higher than that in controls(P=0.001;P=0.006;P<0.001),and the PTPN11 expression in high-risk MDS patients was higher than those in lower-risk or intermediate-risk patients(P=0.003;P=0.004).Based on the mean value of PTPN11 gene expression level in controls plus two standard deviations,the MDS patients were divided into PTPN11 high expression group and low expression group.Clinical analysis showed that peripheral blood neutrophil count,bone marrow cellularity,IPSS-R score and leukemia transformation rate were significantly higher in the PTPN11 high expression group than those in the low expression group(P=0.001;P=0.016;P=0.014;P<0.001).Survival analysis showed that patients with high PTPN11 expression showed a relatively shorter overall survival(P=0.052)and a significantly shorter leukemia-free survival time(P=0.017)comparing to patients with low PTPN11 expression.The next-generation sequencing revealed PTPN11 mutations in 3 cases(2.4%)among 123 patients with MDS,all of which were missense mutations(one case of p.A72 Vand two cases of p.D61 V),and all three cases were RAEB-2 patients and eventually converted to AML with less than 18 months of survival time.Conclusion:The expression level of PTPN11 gene in patients with MDS is increased,which predicts higher tumor proliferation and risk of leukemia transformation.PTPN11 mutations predict worse prognosis in spite of low frequency in MDS.