NS-398协同顺铂作用人肺腺癌差异蛋白质组分析

背景与目的 实验证明一种高度选择性的COX-2抑制剂--NS-398能增强传统化疗药物顺铂对肺腺癌细胞的生长抑制作用,但其机制尚不清楚.本研究的目的是探讨NS-398与顺铂协同抑制肺腺癌细胞增殖的作用机制.方法 采用二维聚丙烯酰胺凝胶电泳分离NS-398和顺铂作用下肺腺癌细胞的蛋白质,质谱分析法(MALDI-TOF-MS)和数据库查询鉴定其中部分差异蛋白质.结果 NS-398与顺铂联合组表达量下调的差异蛋白点22个,表达量上调蛋白点2个.选择其中17个表达量下调蛋白点、2个表达量上调蛋白点进行质谱鉴定,初步鉴定了NS-398与顺铂联合组6个表达下调的差异蛋白质,其中部分为细胞骨架蛋白,部分为与细胞增殖和凋亡相关的蛋白,部分为细胞代谢途径相关酶.结论 热休克蛋白90和磷酸丙糖异构酶可能参与了NS-398和顺铂对肺腺癌细胞增殖的协同抑制作用.     

基于DIA定量分析技术研究鼻咽癌根治后远处转移患者的血清蛋白质表达

目的:研究鼻咽癌根治后远处转移(rM)和无转移组(CR)患者的血清蛋白质表达谱差异。方法:分别选取5例鼻咽癌根治后发生转移患者及5例无转移患者的血清样本,利用非数据依赖性采集(data-independent acquisition, DIA)质谱技术,比较两组患者的血清蛋白质表达谱,获取差异表达蛋白,并通过GO功能和KEGG通路分析方法对差异蛋白进行富集分析。结果:在所有待测血清样品中最终共鉴定到2 485个蛋白,经筛选共获得差异表达蛋白68个,其中转移组中上调表达蛋白61个,下调表达蛋白7个。富集分析表明差异表达蛋白在补体激活、免疫调控等生物学过程富集,与补体结合及多个酶活性等分子功能密切有关;主要在血液微粒、细胞外区域、细胞外间隙及细胞外泌体等细胞组分间发挥功能。涉及补体与凝血级联、肌动蛋白细胞骨架调控以及细胞凋亡等关键信号通路。结论:血清差异表达蛋白质可能与鼻咽癌转移密切相关,有望成为潜在的鼻咽癌转移预测指标和干预靶点。     

初发与复发鼻咽癌组织中磷酸化蛋白芯片的差异表达分析

[目的]分析复发鼻咽癌和初发鼻咽癌的蛋白质磷酸化表达差异,以期为复发鼻咽癌的发生机制提供分子依据。[方法]选择4例复发鼻咽癌患者和4例初发鼻咽癌患者的组织标本,实验室提取总蛋白,应用磷酸化抗体蛋白质芯片与提取蛋白进行杂交,检测两者之间的差异磷酸化位点。通过phosphosite在线网络数据库分析蛋白质磷酸化位点变化及在信号通路中的作用。[结果]复发鼻咽癌和初发鼻咽癌的蛋白质磷酸化表达不同,共筛选出16个差异磷酸化位点,15个差异蛋白,复发鼻咽癌组织中上调蛋白8个,下调蛋白7个。[结论]初发鼻咽癌和复发鼻咽癌组织之间存在蛋白质磷酸化水平差异,可能与鼻咽癌复发机制有关。     

SELDI-TOF-MS技术筛选鼻咽癌血清肿瘤标志物

摘要：目的筛选鼻咽癌患者血清蛋白差异表达并建立诊断模型,分析不同临床特征患者的血清蛋白质谱差异。方法应用SELDI技术分析102例鼻咽癌患者及118例健康对照的血清样本,Biomarker Wizard和Biomarker Pattern 软件分析两组之间的差异,建立分类树诊断模型并进行盲筛验证;进一步分析鼻咽癌不同临床分型及EB病毒感染状态对患者血清蛋白质表达谱的影响。结果发现鼻咽癌与健康对照之间有25个血清蛋白质谱峰差异有统计学意义（P<0.01), 13个蛋白峰表达下调,12个蛋白峰表达上调。经Biomarker Pattern 软件建立分类树模型,盲法验证其敏感度为97.56％,特异性为88.89％,准确率达92.63％;上行型和下行型鼻咽癌之间发现M/Z为10286Da、7569Da及8149Da的3个血清蛋白质峰差异有统计学意义（P<0.05);EB阳性和EB阴性鼻咽癌间M/Z为9354Da及4596Da的2个血清蛋白质峰差异有统计学意义（P<0.05)。结论SELDI-TOF-MS 技术可筛选出鼻咽癌差异性蛋白并建立鼻咽癌诊断的分类树模型,有望成为鼻咽癌早期诊断的辅助指标;并且用SEDLI技术可以发现一些与鼻咽癌临床特征相关的血清蛋白差异峰。     

用蛋白质组学技术分析鼻咽癌细胞系放射生物学特性的初步结果

目的应用蛋白质组学技术观察不同鼻咽癌细胞系中蛋白表达的差异,以期寻找与鼻咽癌细胞系放射生物学特性相关的蛋白。方法提取细胞总蛋白进行双向凝胶电泳、MALDI-TOF肽质谱指纹图分析、质谱数据的蛋白质库搜寻鉴定。应用Western Blot检测细胞中蛋白质表达。结果差异表达最为显著的蛋白质有9个,与5-8F细胞比较6-10B细胞中4个为下调蛋白,5个为上调蛋白。Western Blot证实CK19和p73在5-8F和6-10B中的表达与蛋白质组结果一致,p73在5-8F中的表达高于6-10B,CK19在6-10B中的表达高于5-8F。结论放射生物学特性不同的鼻咽癌细胞系中存在差异表达蛋白,这可能与其放射生物学特性有关,其中p73可能成为预测的侯选标志物。     

二代测序检测上行型与下行型鼻咽癌中高频突变基因的研究

目的 本文利用二代测序(Next-generation sequencing,NGS)技术对上行型及下行型鼻咽癌基因突变特征进行分析,寻找两者间的差异,探讨高频突变基因与鼻咽癌侵袭及局部区域淋巴结转移的相关性。方法 收集2014年1月—2018年12月于贵州省人民医院确诊的鼻咽癌患者的肿瘤组织样本40例(上行型及下行型鼻咽癌各20例),进行DNA提取,采用Illumina测序平台对400个肿瘤相关基因进行捕获测序,检测突变情况,测序结果结合相关临床资料进行分析。结果 在40例鼻咽癌病理组织标本中,检测到ABCA13、CACNA1F、CELSR2、中心体蛋白170B(Centrosomal protein,CEP170B)基因在下行型鼻咽癌中突变高于上行型鼻咽癌;ABCC2、ALPK2、ASB15、ASRGL1、ATXN2L、BCL9L、C5orf42、CCDC88A、CEBPZ、CELSR3、CEP290、COL4A2、COL6A5、LGR5、LSR、SPEG基因在上行型鼻咽癌中突变高于下行型鼻咽癌。其中CEP170B在下行型鼻咽癌中突变率最高,其突变率为57%;上行型鼻咽癌组与下行型鼻咽癌组肿瘤突变负荷及肿瘤异质性差异均无统计学意义。结论 CEP170B基因在下行型鼻咽癌组高频率突变,因下行型鼻咽癌易发生淋巴结广泛多处转移,结果提示CEP170B基因可能与鼻咽癌发生局部区域淋巴结转移密切相关,可能成为鼻咽癌临床治疗的潜在靶点。     

10Gy X射线照射鼻咽癌移植瘤组织差异表达蛋白质的初步筛选

目的 比较不同放射敏感性的鼻咽癌裸鼠移植瘤组织蛋白质表达的差异,筛选出与鼻咽癌放射抗拒性相关的蛋白质。方法 建立人鼻咽低分化鳞癌细胞（CNE-2）及其放射抗拒性细胞（CNE-2R）裸鼠移植瘤模型,予X射线10 Gy单次照射移植瘤,提取瘤体组织总蛋白质并酶解成肽段,用i TRAQ试剂分别标记后再用二维液相色谱分离,在LTQ-Orbitrap高分辨率质谱仪上鉴定并筛选差异表达的蛋白质,并对差异表达的蛋白质进行基因本体论（Gene Ontology,GO）基因功能分类。结果共鉴定出差异表达的蛋白质61个,其中上调17个,下调有44个,GO分析显示差异表达的蛋白质主要涉及细胞周期调控、分解代谢、信号通路调节、压力应激反应及氧化还原反应等生物学过程。结论 Annexin2、PDIA3、Ubiquitin、14-3-3δ/ζ、CKAP4、HSPA8、NLRC4等差异表达的蛋白质可能与鼻咽癌放射抗拒性相关。     

利用MALDI-TOF-MS分析RAEB型骨髓增生异常综合征患者血清蛋白质组学特征

目的:利用铜螯合磁珠(MB-IMAC Cu)和基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)技术,对比分析难治性贫血伴幼稚细胞增多型(RAEB)骨髓增生异常综合征(MDS)患者血清蛋白质谱特征,寻找差异表达蛋白,构建RAEB型MDS辅助诊断的血清蛋白质组学模型.方法:根据性别及年龄,配比收集RAEB型MDS、急性髓性白血病(AML)和正常人的血清蛋白标本各10例,利用铜螯合磁珠进行蛋白分离,通过MALDI-TOF-MS测定标本的蛋白质谱图,对比分析差异蛋白峰,并构建诊断模型.结果:与正常对照比较,在RAEB患者血清发现47个异常表达峰(P<0.05),其中高表达峰16个,低表达峰31个;以AML患者为疾病对照,获得33个异常表达峰(P<0.05),在RAEB中呈低表达的12个,呈高表达的21个.以基因遗传法构建诊断模型,结果提示,模型的识别准确率均达100%,敏感性达89.42%.结论:MB-IMAC Cu 和MALDI-TOF-MS技术平台有助于RAEB型MDS相关的血清异常表达蛋白的研究,并且能够有效地区分RAEB患者、AML患者和正常人;根据血清差异蛋白质的组合峰所构建的诊断模型可辅助RAEB型MDS的诊断.     

上行型与下行型鼻咽癌患者血清蛋白指纹图谱的检测及意义

目的:通过分析上行型与下行型鼻咽癌的血清蛋白质谱,筛选鼻咽癌蛋白质标志物,为预测鼻咽癌临床分型提供可能的简易方法.方法:应用CM10弱阳离子交换芯片和表面增强激光解吸离子化飞行时间质谱技术(SELDI-TOF-MS)分析22例上行型鼻咽癌和26例下行型鼻咽癌患者的血清标本,采用Biomarker Wizard 3.01及Biomarker Pattern 5.01分析软件对测得的数据进行处理并建立相应的检测模型.结果:通过对上行型、下行型鼻咽癌患者血清蛋白指纹图谱数据的比较,筛选出差异蛋白质峰9个(P＜0.05),相对分子量分别为2 776.27 Da,3 940.04 Da,6 440.51 Da和9 138.54 Da的4个蛋白质峰被选择用于构建分类决策树模型,该模型交叉验证总准确率为81.3%,上行型鼻咽癌患者检出率为77.3%,下行型鼻咽癌患者检出率为84.6%.分别对这4个蛋白质峰进行数据库搜索,得到4种与分子量最为接近的蛋白质.结论:应用SELDI-TOF-MS技术构建的分类决策树模型能达到区分上下型鼻咽癌患者的效果,这可能对鼻咽癌的分子分型、制定个体化治疗方案及预后预测方面有一定的临床意义,可进一步深入研究.     

胃癌细胞耐药相关蛋白质分子的差异展示

目的 寻找新的胃癌细胞耐药相关蛋白质分子,阐明肿瘤耐药的新机制。方法 以胃癌细胞SGC7901和长春新碱诱导的耐药胃癌细胞SGC7901／VCR为研究对象,用固相化pH梯度等电聚焦的二维聚丙烯酰胺凝胶电泳技术展示并比较两种细胞表达的所有蛋白质,凝胶银染法显示耐药与非耐药细胞差异表达的蛋白质分子。结果 在两张银染的凝胶蛋白质图谱上,均有680个可辨识的蛋白质点,绝大多数蛋白点在位置、形状和密度上是一致的。在耐药细胞蛋白质二维电泳图谱中,发现有30个明显差异的蛋白点,并初步确定了其等电点和分子量。其中3个蛋白点表达量很高,但在非耐药细胞中未出现;6个蛋白点丰度明显上调;19个蛋白点丰度明显下调;2个蛋白点在耐药细胞中未出现,但在非耐药细胞中高表达。结论 胃癌耐药细胞中差异表达的蛋白质分子可能与其长春新碱耐药机制相关。     

Altered expression and localization of creatine kinase B, heterogeneous nuclear ribonucleoprotein F, and high mobility group box 1 protein in the nuclear matrix associated with colon cancer

Identification of biomarkers could lead to the development of effective screening tests for colorectal cancer. A previous study from our laboratory showed specific alterations of nuclear structure in colon cancer. In an effort to characterize these biomarkers, protein spots were selected from separations made by two-dimensional gel electrophoresis, which were analyzed by mass spectrometry. The sequences obtained from the isolated spots revealed that they have close similarity to creatine kinase B (CKB) isoforms, heterogeneous nuclear ribonucleoprotein F (hnRNP F) and high mobility group box 1 protein (HMGB1) isoforms. To determine the expression of these proteins in colon cancer, expression was studied in 9 tumor and matched adjacent normal pairs, 5 donor colons, 16 polyps, 4 metastatic liver lesions and matched adjacent normal pairs, and 3 liver donors. CKB and hnRNP F were expressed in 78% and 89% of colon tumors, respectively. hnRNP F had a higher frequency of expression than CKB in premalignant polyps. With the establishment of differential expression of the proteins in colon cancer, their subcellular localization was analyzed. The subcellular fractions studied both showed high protein levels of hnRNP F in colon tumors compared with normal colon tissues. Surprisingly, subcellular levels of CKB were decreased in colon tumors, suggesting that the observed high CKB levels in nuclear matrix extracts are caused by the enhanced localization of CKB to the nuclear matrix during colon tumorigenesis. These results suggest an involvement of hnRNP F and CKB in colorectal cancer. Additionally, they suggest that hnRNP F is a potential marker for colorectal cancer progression.     

应用血清蛋白质组分析筛选人胃癌相关抗原

背景与目的:寻找胃癌特异性或相对特异性标志物是胃癌研究亟待解决的课题.本研究利用血清蛋白质组分析方法,建立人胃癌组织蛋白质双向凝胶电泳图谱以及分别与胃癌患者血清和非癌人群血清的免疫印迹图谱,初步筛选人胃癌相关抗原.方法:运用2-DE分离人胃癌组织的总蛋白质;一个样品跑3块凝胶,1块考马斯亮染显色作为平行胶,另2块分别以胃癌患者自身血清和非癌人群血清作一抗进行免疫印迹分析,获得免疫印迹图谱;对图谱进行比较分析,识别差异反应的蛋白质点,根据差异反应蛋白质点位置在平行胶上找出匹配的蛋白质点;对差异反应的蛋白质点应用MALDI-TOF-MS进行质谱分析鉴定,获得相应的肽质指纹图谱,通过数据库搜索鉴定出差异反应的蛋白质.结果:人胃癌组织2-DE分离后分别与胃癌患者自身血清和非癌人群血清进行免疫印迹,获得分辨率较高的反应图谱;图像分析找出差异反应的蛋白质点14个,质谱鉴定获得hnRNP K、hnRNP H1、hnRNP H2、CK18、Fkbp52与Hsp90复合物、DBP、SBP1、eEF-1、ACTB、CKB、PSMC3、DDAH-1、NADH脱氢酶硫-铁蛋白1等13个蛋白质.结论:获得分辨事较高的人胃癌组织蛋白质组与胃癌患者自身血清及非癌人群血清反应的免疫印迹反应图谱,初步筛选了13个人胃癌相关抗原.为进一步筛选可应用于临床早期诊断、治疗、预后评估及疾病检测的人胃癌分子标志物奠定了基础.     

核不均一核糖核蛋白A2/B1在非小细胞肺癌发病机制中作用的探讨

目的 观察核不均一核糖核蛋白A2/B1(hnRNP A2/B1)在非小细胞肺癌(NSCLC)中的表达及其与DNA修复酶O6-甲基鸟嘌呤-DNA甲基转移酶(MGMT)、8-羟基鸟嘌呤DNA糖苷酶(OGG1)、氧化还原因子1(Ref-1)、DNA依赖性蛋白激酶复合物DNA-PKcs和Ku mRNA之间的相互作用,并进一步探讨其在NSCLC发病机制中的作用.方法 采用免疫组化、Western blot及荧光实时定量PCR方法,检测NSCLC患者癌组织及正常肺组织hnRNP A2/B1的表达.采用免疫共沉淀结合逆转录聚合酶链反应(RT-PCR)方法,研究人肺鳞癌细胞株中hnRNP A2/B1蛋白是否与上述5种DNA修复酶的mRNA直接结合,然后采用免疫组化及荧光实时定量PCR方法,检测NSCLC患者癌组织及正常肺组织MGMT的表达情况.结果 免疫组化染色显示,hnRNP A2/B1定位于细胞核,hnRNPA2/B1在NSCLC癌组织中的表达阳性率(100%)和蛋白表达评分[(5.3±0.9)分]均显著高于正常肺组织[32%和(2.2±0.7)分,P＜0.01],在Ⅲ～Ⅳ期NSCLC组织中的表达略高于Ⅰ～Ⅱ期(P＜0.05),而与年龄、性别、组织学类型及吸烟状况无关(均P＞0.05).通过RT-PCR方法可以从人肺鳞癌细胞株免疫共沉淀产物中扩增出MGMT mRNA,提示hnRNP A2/B1与MGMT mRNA相结合.进一步的免疫组化染色结果显示,在NSCLC组织中,MGMT的表达阳性率为32.0%,明显低于正常肺组织(78.0%),蛋白表达评分[(2.2±0.8)分]也显著低于正常肺组织[(4.1±1.2)分,P＜0.01].荧光实时定量PCR结果显示,NSCLC组织中MGMT mRNA的表达量为1.8(0.6～3.1),明显低于正常肺组织[9.8(6.8～18.3),P＜0.01].结论 HnRNP A2/B1蛋白及mRNA在NSCLC组织中的表达均升高,hnRNP A2/B1与MGMT mRNA相结合,可能通过对MGMT mRNA的转录后调控参与NSCLC的发生.

Abstract：

Objective To study the expression of heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) in non-small cell lung cancer(NSCLC),and the interaction between hnRNP A2/B1 protein and mRNA of DNA repair enzymes O6-methylguanine DNA-methyltransferase(MGMT),8-oxoguanine DNA glycosylase(OGG1),redox factor 1(Ref-1),DNA-dependent protein kinase(including DNA-PKcs and ku). Methods The expression and distribution of hnRNP A2/B1 were detected by immunohistochemistry and Western blot on 50 NSCLC samples from patients who underwent resection in Zhongshan Hospital.The hnRNP A2/B1 mRNA expression was tested by real-time PCR.Coimmunoprecipitation(co-IP) combined RT-PCR was used to investigate whether hnRNP A2/B1 could be bound with the mRNA of the above mentioned 5 DNA repair enzymes in human lung cancer cell line(HTB-182).Then immunohistochemistry and real-time PCR were used to detect the expression of MGMT in the same group of patients. Results HnRNP A2/B1 protein and mRNA expressions were increased in the NSCLC tissues than that in the corresponding normal lung tissues.HnRNP A2/B1 was expressed predominantly in the nuclei of tumor cells.The positive rate and immunohistochemistry score of hnRNP A2/B1 in tumor tissue were significantly higher than that in normal tissue(P ＜0.01).In stage Ⅲ-Ⅳ NSCLC,hnRNP A2/B1 expression was higher than that in stage Ⅰ-Ⅱ.There was no significant differences of hnRNP A2/B1 expression among patients of different age,sex,histological type,and smoking history.The results of co-IP combined RT-PCR suggested that hnRNP A2/B1 is bound with MGMT mRNA,and MGMT expression is decreased in tumor tissue of NSCLC. Conclusions The results of this study show that hnRNP A2/B1 protein and mRNA are highly expressed in NSCLC,and hnRNP A2/B1 is bound with MGMT mRNA,which indicate that it might be one of the mechanisms of hnRNP A2/B1 participating in the pathogenesis of NSCLC.     

hnRNP B1 protein may be a possible prognostic factor in squamous cell carcinoma of the lung

Heterogeneous nuclear ribonucleoprotein (hnRNP) B1 is an RNA-binding protein that is required for the maturation of mRNA precursor. It was previously reported that hnRNP A2/B1 was overexpressed at the early clinical stage of lung cancer, and that hnRNP B1 protein, a splicing variant of hnRNP A2 mRNA, was elevated in lung cancer tissues. In this study, we applied the immunohistochemical method, using anti-hnRNP B1 antibody to analyze the usefulness of the hnRNP B1 antibody as a prognostic marker and also as a marker useful for early detection. A total of 206 specimens were examined. Histological examination revealed this protein to be positive in 79 (71.2%) of 111 squamous cell carcinomas and in 45 (64.3%) of 70 adenocarcinomas, respectively. This protein was also expressed in 24 (63.2%) of 38 roentgenographically occult carcinomas and in seven (63.6%) of 11 dysplastic lesions. These findings suggest the possible participation of this protein in early carcinogenesis. Furthermore, the survival curve of the squamous cell carcinoma patients with hnRNP B1 overexpresseion showed a better prognosis compared with that of the patients without hnRNP B1 expression (P=0.014), whereas in adenocarcinoma patients, there was no such a difference between them (P=0.889). These findings indicate that hnRNP B1 could be a useful marker for the early detection of bronchogenic squamous cell carcinoma and that it may be a prognostic factor in this cell type.     

Identification of up- and down-regulated proteins in gemcitabine-resistant pancreatic cancer cells using two-dimensional gel electrophoresis and mass spectrometry

The prognosis of patients with pancreatic cancer is very poor because of late diagnosis and the lack of response to various therapies. Pancreatic cancer is generally resistant to chemotherapy and is highly fatal. Gemcitabine (GEM) appears to be the only effective agent for treatment of pancreatic cancer. However, a high level of inherent and acquired tumor resistance makes the clinical impact of GEM modest. Proteomic differential display analysis for GEM-sensitive human pancreatic adenocarcinoma cell line KLM1 and GEM-resistant KLM1-R cells by using two-dimensional gel electrophoresis and liquid chromatography tandem mass spectrometry produced 33 protein spots. Of these, 23 were up-regulated and 10 were down-regulated in KLM1-R compared to KLM1 cells. The up-regulated proteins include acidic leucine-rich nuclear phosphoprotein 32 family member A, reticulocalbin-1, gamma-synuclein, microtubule-associated protein RP/EB family, sialic acid synthase, peptidyl-prolyl cis-trans isomerase A, far upstream element-binding protein 2 and catalase. The down-regulated proteins include far upstream element-binding protein 1, gamma-synuclein, galectin-1 and stathmin. Two spots of heat-shock protein 27 were up-regulated in KLM1-R cells. These results suggest an important complementary role for proteomics in the identification of proteins which may play a role in the poor response of pancreatic cancer to GEM.     

Prognostic and diagnostic relevance of hnRNP A2/B1, hnRNP B1 and S100 A2 in non-small cell lung cancer

BACKGROUND: S100 A2 and hnRNP A2/B1 (heterogeneous ribonucleoprotein A2/B1) with its splicing variant hnRNP B1 are proteins which are involved in cellular proliferation, differentiation and protein synthesis and are up-regulated in non-small cell lung cancer (NSCLC). Since previous studies using paraffin-embedded tissues indicated a high potential of these markers for diagnosis and screening the present analysis intended to validate these data applying cryostat sections. METHODS: 78 tumor-infiltrated lung cancer specimens and 66 adjacent histologically tumor-free tissues were analyzed; 11 autopsy specimens from patients who did not suffer from a malignant disease served as a control group. Cryostat sections were stained with monoclonal antibodies against hnRNP A2/B1, hnRNP B1 and S100 A2 and were compared with the previously established immunohistochemical profile of the same patients including EGFR, EGFRvIII, pEGFR, c-erbB-2, c-erbB-3, p53, Ki-67, bcl-2, p120 and microvessel density. Furthermore, these results were correlated with clinical parameters. RESULTS: Expression of hnRNP A2/B1, hnRNP B1 and S100 A2 was increased in the tumor group when compared with the microscopic tumor-free specimens in 10% versus 5% (n.s.), 91% versus 5% and 65% versus 6%, respectively. Increased S100 and A2 hnRNP A2/B1 expressions were negative prognostic factors. With the exception of an increased EGFR expression in hnRNP A2/B1 negative cases the three analyzed markers did not correlate with the immunohistochemical parameters tested previously. CONCLUSION: Comparison between tumor probes and tumor-free specimens of NSCLC patients failed to approve the diagnostic relevance of hnRNP A2/B1 shown in previous studies, whereas hnRNP B1 revealed a high tumor specificity that could be helpful for tumor cell screening. Moreover, S100 A2 and hnRNP A2/B1 confirmed to be valuable prognostic parameters.     

Bortezomib inhibits Burkitt's lymphoma cell proliferation by downregulating sumoylated hnRNP K and c-Myc expression

Bortezomib (Velcal) was the first proteasome inhibitor to be approved by the US Food and Drug Administration to treat patients with relapsed/refractory multiple myelomas. Previous studies have demonstrated that bortezomib inhibits tumor cell proliferation and induces apoptosis by blocking the nuclear factor (NF)-κB pathway. However, the exact mechanism by which bortezomib induces cancer cell apoptosis is still not well understood. In this study, we found that bortezomib significantly inhibited cell proliferation in both human Burkitt''s lymphoma CA46 and Daudi cells. Through proteomic analysis, we found that bortezomib treatment changed the expression of various proteins in distinct functional categories including unfolding protein response (UPS), RNA processing, protein targeting and biosynthesis, apoptosis, and signal transduction. Among the proteins with altered expression, hnRNP K, hnRNP H, Hsp90α, Grp78, and Hsp7C were common to both Daudi and CA46 cells. Interestingly, bortezomib treatment downregulated the expression of high-molecular-weight (HMw) hnRNP K and c-Myc but upregulated the expression of low-molecular-weight (LMw) hnRNP K. Moreover, cell proliferation was significantly correlated with high expression of HMw hnRNP K and c-Myc. HMw and LMw hnRNP K were identified as sumoylated and desumoylated hnRNP K, respectively. Using transient transfection, we found that sumoylated hnRNP K increased c-Myc expression at the translational level and contributed to cell proliferation, and that Lys422 of hnRNP K is the candidate sumoylated residue. Our results suggest that besides inhibiting the ubiquitin-proteasome pathway, bortezomib may inhibit cell proliferation by downregulating sumoylated hnRNP K and c-Myc expression in Burkitt''s lymphoma cells.