程序性死亡配体 1在儿童急性髓系白血病中的表达及对耐药的影响

目的研究程序性死亡配体 1(PD-L1)在儿童初治急性髓系白血病( AML)中的表达及对白血病细胞耐药的影响。方法收集 2020年 1月至 2021年 1月郑州大学附属儿童医院血液肿瘤科收治的初诊 40例 AML病儿骨髓标本，收集同期进行骨髓检查正常病儿的骨髓标本 18例作为正常对照组，比较两组骨髓中 PD-L1的表达量，并分析初治 AML病儿 PD-L1的表达量与其临床特征之间的关系；慢病毒构建 PD-L1过表达、干扰 PD-L1表达的 AML细胞，细胞活力检测试剂盒( CCK8)检测细胞增殖能力，并计算细胞对柔红霉素的药物敏感性；凋亡实验检测经柔红霉素诱导的细胞凋亡水平。结果与正常对照组 0.887± 0.064相比，初治儿童 AML病儿骨髓单个核细胞 PD-L1的表达量 2.927±0.271显著增高( t=7.34，P<0.001)；根据一个疗程诱导化疗是否达完全缓解( CR)将初治 AML病儿一个疗程达 CR者定义为 CR组，将未达 CR者定义为 NR组，相较于 CR组的 2.346± 0.190，NR组 PD-L1基因的表，达量 5.249±0.662显著增高( t=4.22，P=0.003)；病儿不同发病年龄，性别，法、美、英( FAB)分型，白细胞计数，预后分层间 PD-L1基因相对表达量比较均差异无统计学意义( P>0.05)而 1个疗程诱导化疗是否达 CR与 PD-L1基因相对表达量差异有统计学意义( P=0.018)；过表达 PD-L1的 Molm-13细胞对柔红霉，素具有更高的 IC50值，更低的凋亡率；干扰 PD-L1表达的 THP1细胞对柔红霉素具有更低的 IC50值，更高的凋亡率。结论 PD-L1在初治 AML病儿中表达增高，且 PD-L1的高表达与 1个疗程诱导治疗是否达 CR显著相关； PD-L1可以促进 AML细胞增殖、抑制凋亡，从而导致化疗耐药。

Expression of PD-L1 in childhood acute myeloid leukemia and its influence on drug resistance

Objective To explore the expression of programmed death ligand 1 (PD-L1) in childhood acute myeloid leukemia (AML) and its effect on leukemia cell resistance.Methods Bone marrow samples from 40 children with AML, who were admitted to the Department of Hematology and Oncology of the Children''s Hospital of Zhengzhou University from January 2020 to January 2021, were collected, and bone marrow samples from 18 normal children were collected as normal control groups. The expressions of PD-L1 in the bone marrow of the two groups were compared, and the relationship between the expression of PD-L1 and its clinical features in children with treatment-na-ve AML was analyzed. AML cells that overexpressed and downregulated PD-L1 were constructed, and cell counting kit-8 (CCK8) was used to detect cell proliferation for calculating the daunorubicin sensitivity. Apoptosis assays were used to measure daunorubicin-induced apoptosis levels.Results Compared with the normal control group , the gene expression of PD-L1 in bone marrow mono-nuclear cells of treatment-na-ve AML group was significantly increased (0.887±0.064 vs. 2.927±0.271; t=7.34, P<0.001). According to whether a course of induction chemotherapy achieved complete remission (CR), children with treatment-na-ve AML who achieved CR after one course were defined as CR group, and those who did not achieve CR were defined as NR group. Compared with the CR group, theexpression of PD-L1 in the NR group was significantly increased (2.346±0.190 vs. 5.249±0.662; t=4.22, P=0.003). There was no significant difference in the relative expression of PD-L1 between different age of onset, gender, French-American-British (FAB) classification, white blood cell count, and prognosis stratification (P>0.05), while there were significant differences in CR after one course of induction chemotherapy and relative expression of PD-L1 (P=0.018). Molm-13 cells overexpressing PD-L1 had higher IC50 values and lower apoptosis rates after treatment with daunorubicin; THP1 cells interfering with PD-L1 expression had lower IC50 values and higher apoptosis rates after treatment with daunorubicin.Conclusions The expression of PD-L1 is increased in children with treatment-na-ve AML, and the high expression of PD-L1 is significantly related to whether CR is achieved after one course of induction chemotherapy. PD-L1 can promote proliferation and inhibit apoptosis of AML cells, thus resulting in drug resistance in chemotherapy.