Objective: To investigate the role of PRDM1 gene inactivaion in the regulation of C-MYC in diffuse large B-cell lymphoma (DLBCL), and to explore the correlation of its immunophenotype and prognosis. Methods: 100 cases paraffin-embedded DLBCL tissues were collected from January 2009 to December 2015 at the First Affiliated Hospital of Xinjiang Medical University along with 20 cases of reactive proliferative lymph nodes as control. Immunohistochemical methods were used to detect the expression of CD20, CD10, MUM1, Ki-67, bcl-6, PRDM1/Blimp1, C-MYC and PAX5 protein. The tumors were classified into two subtypes according to Hans classification.The expression of PRDM1 and C-MYC gene in tumor group and control group was detected by reverse transcription PCR (RT-PCR) and the relationship between PRDM1 and C-MYC gene was analyzed.OCI-LY1 (GCB subtype) and OCI-LY3 (non-GCB subtype) cell lines were transfected with small interfering RNA by cationic liposome reagent transfection, and the expression of C-MYC in the transfected cell lines was detected by RT-PCR and Western blot. The Kaplan-Meier method was used to analyze the prognostic significance of PRDM1/Blimp1 and C-MYC at protein and mRNA levels. Results: There were 27 cases of GCB subtype and 73 cases of non-GCB subtype according to Hans classification. The positive expression of Blimp1 in DLBCL group and proliferative lymph nodes in control group was seen in 26(26.0%) and 20 cases(100%), respectively. There were 58 cases with high expression of PRDM1 at mRNA level, including 22 cases of GCB subtype and 36 cases non-GCB subtype, and the difference was statistically significant (P=0.004). There were differences in PRDM1 gene expression between the two immunological subtypes, serum lactate dehydrogenase (serum LDH) level, presence of B symptoms, tumor primary sites and other clinical pathological parameters, while C-MYC expression was different in gender, IPI score, and serum LDH levels. Upon PRDM1/Blimp1 gene silencing in the two cell lines, C-MYC protein and gene expression were up-regulated in the transfection group, compared with the blank control group and negative control group by reverse transcription PCR and Western blot analyses. Moreover, PRDM1 expression was significantly associated with C-MYC(χ(2)=7.648, P=0.006) at mRNA level. Conclusion: The up-regulation of C-MYC gene expression induced by PRDM1 inactivation in DLBCL may play an important role for the development of DLBCL.PRDM1 protein and mRNA are associated with immunophenotyping and PRDM1 mRNA is a marker of poor prognosis.
目的： 研究PRDM1基因失活对C－MYC的调控在弥漫性大B细胞淋巴瘤(DLBCL)中的作用，探讨其与免疫分型及预后相关性。 方法： 选取2009年1月至2015年12月在新疆医科大学第一附属医院收治DLBCL患者的石蜡包埋组织100例，反应性增生淋巴结20例。免疫组织化学EnVision法检测CD20、CD10、MUM1、Ki－67、bcl－6、Blimp1、C－MYC、PAX5蛋白表达，根据Hans分型法进行免疫分型。逆转录聚合酶链反应(RT－PCR)法检测两组中PRDM1、C－MYC mRNA表达情况。单因素生存分析(Kaplan－Meier)法从蛋白、mRNA水平分析PRDM1/Blimp1及C－MYC与预后相关性。应用阳离子脂质体转染法介导的小干扰RNA(siRNA)转染OCI－LY1[生发中心B细胞型(GCB型)]和OCI－LY3(non－GCB型)细胞系，RT－PCR和Western blot方法检测siRNA转染前后细胞系中C－MYC mRNA和蛋白表达情况。 结果： 100例DLBCL患者中，GCB型27例(27/100，27.0%)，non－GCB型73例(73/100，73.0%)。Blimp1蛋白在肿瘤中阳性表达26例(26/100，26.0%)，反应性增生淋巴结中阳性表达20例(20/20，100.0%)。PRDM1 mRNA高表达58例(58/100，58.0%)，其中GCB型22例(22/27，81.5%)，non－GCB型36例(36/73，49.3%)，两者之间差异有统计学意义(P＝0.004)。同时，在mRNA水平，PRDM1在不同免疫分型、血清乳酸脱氢酶(LDH)水平、B症状、原发部位等临床病理参数表达有差异，C－MYC在性别、国际预后指数(IPI)评分、血清LDH水平之间表达有差异，PRDM1与C－MYC具有显著相关性(χ(2)＝7.648，P＝0.006)。沉默两个细胞系中PRDM1基因后，RT－PCR和Western blot结果显示在OCI－LY1细胞系中C－MYC基因和蛋白在转染组表达较空白对照组及阴性对照组表达上调。 结论： 在DLBCL中PRDM1基因失活所致的C－MYC基因表达上调可能是DLBCL发生的一个重要因素，为相关研究提供实验证据。同时，PRDM1蛋白及mRNA和免疫分型相关，PRDM1 mRNA是提示不良预后的标志。.
Keywords: Genes; Lymphoma, large B-cell, diffuse; Proto-oncogene proteins c-myc.