p-AKT/p-mTOR蛋白在儿童Burkitt淋巴瘤中的表达及其与预后的关系

Expression of p-AKT and p-mTOR in pediatric Burkitt lymphoma and their correlation with prognosis

目的探讨PI3K/AKT/mTOR信号传导通路标志蛋白磷酸化丝氨酸苏氨酸蛋白激酶(p-AKT)和磷酸化哺乳动物雷帕霉素靶蛋白(p-mTOR)在儿童Burkitt淋巴瘤(BL)中的表达及其与临床特征和预后的关系。方法收集2011年9月至2018年7月复旦大学附属儿科医院确诊的58例儿童BL病例,同时收集30例反应性增生性淋巴结炎(RH)做对照。采用免疫组织化学法检测p-AKT、p-mTOR在BL及RH对照组织中的表达情况,分析其表达差异及与患儿临床特征和预后的关系。结果58例BL患儿中,确诊后失访6例。接受治疗与随访的52例患儿,男43例,女9例,中位年龄为5岁(2~14岁)。p-AKT、p-mTOR蛋白在儿童BL组织中的表达呈正相关(r=0.759,P<0.001),表达率分别为62.1%(36/58)和60.3%(35/58),均显著高于阴性组(分别33.3%,36.7%;P=0.011,P=0.035)。p-AKT阳性组的高血清乳酸脱氢酶(LDH≥573 IU/L)的比例显著高于阴性组(P=0.006),p-mTOR的表达与血清LDH高及白蛋白球蛋白比值(A/G)低相关(分别P=0.006,P=0.034),而性别、年龄、分期、肿块大小、有无B症状、结外病变数及国际预后指数(IPI)在组间分布差异均无统计学意义(P>0.05)。单因素生存分析显示p-AKT阳性组的5年总生存率(OS)、无进展生存率(PFS)均较阴性组明显降低(分别72.7%比94.7%,χ^2=4.123,P=0.042;66.7%比94.7%,χ^2=5.822,P=0.016)。p-mTOR阳性组的5年OS较阴性组显著降低(71.0%比95.2%,χ^2=4.881,P=0.027),但PFS较阴性组的下降差异无统计学意义(P>0.05)。p-AKT/p-mTOR双阳性组的5年OS、PFS较存阴组(单一蛋白表达缺失或p-AKT/p-mTOR均不表达)显著下降(OS:69.0%比95.7%,χ^2=6.285,P=0.012;PFS:65.5%比91.3%,χ^2=5.405,P=0.020)。多因素Cox回归分析,结果显示p-AKT/p-mTOR双阳性、高LDH和IPI 3~5分是影响BL患儿OS的独立危险因素,p-AKT阳性、p-AKT/p-mTOR双阳性、巨大肿块(>10 cm)、高LDH和IPI 3~5分是影响PFS的独立预后因素(P<0.05)。结论PI3K/AKT/mTOR信号通路关键蛋白p-AKT、p-mTOR免疫组织化学表达是儿童BL诊断的参考和评估预后风险的独立预测因子。

Objective To evaluate the expression of p-AKT and p-mTOR,the key proteins in PI3K/AKT/mTOR pathway in pediatric Burkitt lymphoma(BL),and to investigate the clinical and prognostic significance.Methods Fifty-eight cases of pediatric BL and thirty cases of reactive hyperplastic lymphadenitis(RH)were collected at Children′s Hospital of Fudan University from September 2011 to July 2018.Paraffin sections of tissues were immune stained for p-AKT and p-mTOR,and the expression was assessed and correlated with the clinical features and prognosis.Results A total of 58 cases were diagnosed and 6 cases lost the follow-up.Of the remaining 52 BL patients including 43 males and 9 females,the median age was 5 years(range:2 to 14 years).Regarding to the correlation between the two biomarkers,Spearman test showed that p-mTOR was positively associated with the expression of p-AKT(r=0.759,P<0.001).Of all BL patients,the positive rates of p-AKT and p-mTOR were 62.1%(36/58)and 60.3%(35/58)respectively,both significantly higher than control group(P=0.011,P=0.035 respectively).The presence of p-AKT was significantly associated with higher lactate dehydrogenase(LDH≥573 IU/L)level in patients of the disease(P=0.006),while p-mTOR was increased both in the higher LDH and lower ratio of albumin to globulin(A/G)group(P=0.006,P=0.034 respectively).Expression of p-AKT and p-mTOR did not show any statistical correlation with sex,age,St.jude stage,tumor size,B-symptom present or not,number of extra-nodal sites or international prognostic index(IPI)(P>0.05).Fifty-two patients had a median follow-up of 40 months(range:5-87 months).Univariate analysis showed that p-AKT expression was significant in predicting both inferior OS(5-year estimate,72.7%vs.94.7%,χ^2=4.123,P=0.042)and PFS(5-year estimate,66.7%vs.94.7%,χ^2=5.822,P=0.016).The 5-year OS rate was 71.0%(22/31)for the p-mTOR positive cohort of patients compared to 95.2%(17/21)for p-mTOR negative group(χ^2=4.881,P=0.027);however,there was no statistical significance in 5-year PFS rate(P>0.05).Especially,the 5-year OS and PFS rate of p-AKT/p-mTOR double-positive group were significantly lower than negative control group(including absence of single p-AKT or p-mTOR expression,and absence of both)(OS:69.0%vs.95.7%,χ^2=6.285,P=0.012;PFS:65.5%vs.91.3%,χ^2=5.405,P=0.020).The results of multivariate COX proportional risk regression analysis indicated that p-AKT/p-mTOR double-positive,higher LDH and IPI score 3-5 were independent prognostic factors for both OS and PFS,and the bulky tumor(>10 cm)for PFS of pediatric BL.Conclusion The expression of p-AKT and p-mTOR may be a potential reference for diagnosis and the independent prognostic indicators of pediatric BL.