您好,欢迎您

【35under35】任思颖医生:病毒感染真的不会引起肺癌吗?

2022年07月31日
作者:任思颖 
医院:中南大学湘雅二医院    

  

               
任思颖
主治医师、副研究员、硕士生导师

中南大学湘雅二医院呼吸科,主治医师、副研究员、硕士生导师
主要从事肺部肿瘤及罕见病诊疗。
上海交通大学医学院临床医学本硕连读,中南大学湘雅医学院医学博士,美国南加州大学博士后
湖南省自然科学优秀青年基金获得者,主持国家自然科学基金等科研课题六项,主持国家发明专利一项,主持中南大学医疗新技术一项
湖南省科技专家库专家成员
中南大学三十佳优秀教师。新冠疫情“战疫先锋”、“奋发有为先进个人”
担任协会任职、杂志编委、参加国内外学术交流会议多项

图片1.png

肺癌是全球排名第一的癌症死因,每年约180万人因此死亡[1]。肺癌分为两大类:非小细胞肺癌(NSCLC),约占肺癌病例的85%;小细胞肺癌(SCLC),约占15%[2]。吸烟是欧美国家肺癌主要病因[3];非吸烟者的肺癌在女性和亚洲人群中更为常见,其分子特征与吸烟者肺癌不同[4]。这表明,肺癌的发生还需要其他因素,其中包括遗传性的基因易感性和感染性因子,如病毒感染[3]

目前为止,已有七种人类病毒导致了全球10-15%的人类癌症,包括爱泼斯坦-巴尔病毒(EBV)、乙肝病毒(HBV)或丙肝病毒(HCV)、人类T淋巴细胞病毒-1(HTLV-1)、人类乳头瘤病毒(HPV)、卡波西氏肉瘤疱疹病毒(KSHV)和默克尔细胞多瘤病毒(MCPyV)[5,6]。越来越多的证据表明,一些病毒对肺癌有潜在致癌作用,如HPV[7-9]、MCPyV[10-12]和EBV[13-15]。据报道,在绵羊体内Jaagsiekte绵羊逆转录病毒(JSRV)通过其病毒包膜蛋白自发地诱发可传播的肺腺癌[16]那么,病毒感染与肺癌发生发展存在哪些机制联系呢?我们通过系统的文献复习,对与肺癌相关的致癌病毒进行全面回顾。

 

1. HPV

1.1 肺癌组织中可检测到HPV

自1979年Syrjanen等人提出HPV参与支气管鳞癌发生发展的报道后[17,18,19],一些研究探讨了HPV感染引发肺癌发生的关系。然而,这些研究的结果并不一致,有些作者赞成这种关系[20-36],其他作者则不赞成[37-43]。HPV感染是最常见的性传播感染,女性一生中感染该病毒的概率超过80%,男性超过90%[44]。在肺癌组织中检测到HPV DNA,但也在外周血、支气管刷洗和肺癌患者的呼气冷凝物中检测到[45-47]。HPV 16和18是全世界肺癌中检测到的两个最常见的基因型[48]。其他经常检测到的高危亚型是HPV 31和33,最普遍的低危亚型是HPV 6和11[19]。最近,Xiong等人进行了荟萃分析比较了肺癌组织(HPV16为19.8%,HPV18为18.59%)与癌旁正常组织(HPV16为5.84%,HPV18为4.29%)中的HPV感染率,发现HPV感染是肺癌的危险因素[7]。

一些研究报告称,亚洲患者的肺癌组织中HPV感染率高于其他洲[7, 9, 19, 20, 25, 26, 32]。Syrjanen等人的研究表明,全世界肺癌组织的平均HPV感染率为26.5%,中国最高(37.7%),北美最低(12.5%),澳大利亚、欧洲、南美和其他亚洲地区分别为18.5%、16.9%、23.9%和17.2%[19]。此外,发现鳞状细胞癌的HPV感染率(25.1%)高于腺癌(15.1%)。这一结果与Xiong等人的研究一致,这可能是由于HPV对鳞状上皮细胞的高亲和力所造成的[7]。他们进一步分析,肺癌组织HPV感染率的巨大差异主要不是由于HPV检测方法造成的,而是由于研究的地理位置和肺癌的组织学类型差异[19]

1.2 HPV进入肺部的传播途径

HPV可以通过身体接触以及从HPV阳性的母亲垂直传播给新生儿,并引起亚临床或临床感染[49]。一些研究表明,HPV可能从呼吸消化道传播到肺部,例如口腔粘膜、食道、喉部或鼻窦粘膜[50-52]。有研究发现患有肛门恶性肿瘤的女性患者患肺癌的风险高于非肛门恶性肿瘤患者[53,54];此外,HPV感染的支气管鳞状细胞癌与HPV感染的生殖器疣形态相似[18],这些结果提示HPV可能从生殖道传播到肺部[55]

血液循环可能是HPV在肺部感染的另一个传播途径。Chiou等人发现,血液循环中的HPV 16 DNA与肺癌组织中的HPV 16 DNA高度相关[46]。他们提出,外周淋巴细胞可以藏匿HPV颗粒,可能参与HPV病毒颗粒的传播。

多项研究证实手术烟雾中存在HPV DNA,以前也有妇科医生在进行激光治疗后患上喉部HPV相关肿瘤的病例报道[56]。此外,Carpagnano等人在肺癌患者呼出的呼吸凝结物中发现了HPV的存在[45]。这些证据提示HPV可能通过呼吸道吸入进行传播。

1.3 HPV与肺部细胞受体相互作用

细胞进入是任何病毒感染宿主细胞的一个基本过程[57]。HPV的宿主细胞进入是通过病毒颗粒与细胞表面受体的结合开始的。硫酸肝素蛋白多糖(HSPG)被认为是HPV最初的附着受体,在细胞外基质和大多数细胞的表面普遍表达,包括1型肺泡上皮细胞的基底膜和内皮细胞及内皮细胞表面[58]。HPV可以特异性地附着在暴露的基底膜HSPG上,随后发生一系列的构象变化,并最终将包裹的质粒DNA转移到宿主细胞中[59]。尽管缺乏HPV感染人类肺细胞系的证据,但肺细胞中HSPG的存在表明HPV可能与这些受体相互作用并进入肺细胞。此外,各种实体瘤的HSPG链/硫酸化模式突变已经被证实[60]。最近有研究报道,HPV衣壳在体内外均可优先结合并感染肺癌细胞,这提示 HPV可参与肺癌致癌过程[61]

1.4 HPV与肺癌预后

目前已有研究探讨了HPV感染对肺癌预后的影响[23, 34, 37, 62-66]。然而,这些研究的结果并不一致,有些作者支持HPV感染的预后作用[34,64-66],有些则支持两者间没有关联[23,37,62,63]。其中,Miyagi等提出,朗格汉斯细胞的高瘤内浸润可能是HPV感染的肺癌预后较好的原因。Wang等人探讨了HPV感染状态在肺腺癌中的预后价值,结果显示HPV感染的肺腺癌患者的预后好于未感染者,死亡率降低了32%[34]。Guo等人进行了荟萃分析,证实了HPV感染与肺腺癌患者生存率提高之间的关联,但鳞状细胞癌患者的生存率没有提高[67]。说到具有促癌潜力的HPV似乎可以改善肺癌患者预后,这似乎是相互矛盾的。我们只能假设,HPV的存在可能会吸引更多的免疫细胞,包括肿瘤微环境中的朗格汉斯细胞,引发更强的抗肿瘤免疫反应,从而改善预后。

1.5 HPV相关NSCLC的致癌机制

1.5.1 HPV-16 E6/7和HIF-1a/HIF-2a

HIF-1a是一个参与调控血管生成的转录因子,在肿瘤的进展、转移和耐药性中起着重要作用[68]。VEGF是HIF途径的关键下游目标之一,通过影响内皮细胞迁移、增殖、通透性及存活来调节血管形成[69]。HIF-1a在HPV感染的NSCLC中的表达往往高于HPV阴性的NSCLC。HPV-16 E6/7癌蛋白通过上调HIF-1a、VEGF和IL-8的表达,在体外和体内均显著促进NSCLC细胞的血管生成[70,71]。PI3K/Akt和c-Jun信号通路可能是HPV-16癌蛋白引发的HIF-1a/VEGF介导的血管生成的原因[70]。HPV-16 E6/7还通过影响包括ZEB1、Snail1、Slug和Twist1在内的上皮-间质转化(EMT)相关转录因子表达,促进EMT过程,进而促进NSCLC进展[72]。此外,HPV-16 E6/7表达上调通过抑制RRAD和p65易位,促进NSCLC细胞中GLUT1表达[73],这一结果提示HPV癌蛋白参与了Warburg效应的调控[74]

另一方面,HIF-2a通过激活包括VEGF在内的下游效应物,具有与HIF-1a类似的促血管生成功能[75]。多个NSCLC细胞系体外实验显示HPV-16 E6/7通过抑制LKB1表达,进而刺激HIF-2a和VEGFR的表达[76]

1.5.2 HPV E6和MMPs/TIMP-3

基质金属蛋白酶(MMPs),在细胞外基质(ECM)中参与降解蛋白质和胶原蛋白,与肿瘤的侵袭和转移有关[77]。体外研究表明,HPV-16 E6可通过刺激肺腺癌细胞中IL-8的表达进而促进MMP-2和MMP-9的表达[78]。另一方面,金属蛋白酶组织抑制剂(TIMP)作为一种MMP抑制剂,可以减少细胞基质的蛋白溶解破坏,以减少癌症转移并改善预后[79]。TIMP-3的杂合性缺失已经涉及到几种癌症类型[80-82]。在HPV-16/18感染的NSCLC中,TIMP-3缺失的频率高于HPV-16/18阴性的NSCLC[63]。TIMP-3缺失通过肿瘤坏死因子a/核因子kB轴促进IL-6的生成,增强了HPV相关NSCLC的恶性行为并造成不良预后[63]

1.5.3 HPV E6和hTERT

人类端粒酶逆转录酶(hTERT)是端粒酶的一个催化亚单位,它的激活参与到人类细胞永生化和恶性转化的过程中[83]。已发现hTERT表达水平在NSCLC癌前病变中是升高,这提示hTERT参与到肺癌发展的早期阶段[84]。在HPV相关的肺癌中,HPV E6似乎能激活hTERT的过度表达[85]。Cheng等人进一步发现在E6诱导的c-Myc促进与hTERT启动子结合的情况下,Sp1与c-Myc互作,激活HPV E6阳性肺癌细胞的hTERT转录[85]。然而,有报道称p53可通过与Sp1结合并阻止其进入hTERT启动子进而抑制hTERT表达[86]。此外,LBK1抑制及随后的Sp1上调也是肺癌发生过程中HPV E6介导的hTERT上调的必要条件[87]

1.5.4 HPV E6和p53

p53可通过诱导细胞周期停止或DNA损伤过程中凋亡来保护基因组的完整性,因此被描述为 "基因组的守护者"。肿瘤抑制因子p53的失活已被发现发生在包括肺癌在内的大多数癌症中。癌基因蛋白E6的经典功能是通过与细胞泛素连接酶E6AP的LxxLL基团结合,诱导p53降解[88,89]。E6介导的p53失活导致染色体不稳定,增加了HPV感染细胞成为恶性的可能性[89]。p21WAF1/CIP1和mdm-2是p53的两个下游目标,在肺部肿瘤中被E6抑制。p21WAF1/CIP1是一种细胞周期蛋白依赖性激酶(CDK)抑制剂,作用于细胞周期蛋白E/cdk2复合物,抑制pRb蛋白磷酸化,从而防止细胞进入S期[90]。p21的诱导是通过p53依赖性[91]或p53非依赖性[92]的途径实现的。mdm-2是一种细胞癌基因产物,调节p53蛋白的活性,而p53蛋白又调节mdm-2基因的转录[93]。人类Dear-box RNA螺旋酶(DDX3)参与RNA代谢调节基因表达过程[94],已被发现可影响病毒相关癌症的发生发展[95]。DDX3的转录受p53的直接调控,DDX3通过增加Sp1在NSCLC细胞中与p21启动子的结合亲和力,协同促进p53激活介导的p21转录[95]。E6介导p53失活通路使p21减少,造成肺癌患者疾病进展和无复发生存期下降[95]

1.5.5 HPV E7和pRb

癌蛋白E7可诱导视网膜母细胞瘤抑制蛋白(pRb)降解,使E2F/pRb/组蛋白去乙酰化酶(HDAC)复合物解离,并使细胞增殖失去控制[96]。p16INK4A是一种细胞周期蛋白依赖性激酶的抑制剂,它被映射到9p21染色体的一个关键区域,并且p16INK4A在富含CpG的启动子区域的超甲基化经常发生在NSCLC中[97,98]。E7介导的pRb降解导致HDAC的释放,在HPV感染相关肿瘤中通过HDAC染色质重塑增加p16INK4高甲基化[99,100]。Wu等人在非吸烟的女性NSCLC患者中证实了p16INK4A高甲基化和HPV感染之间的潜在相关性,发现在HPV感染相关NSCLC患者中p16INK4A高甲基化频率高达70%[100]。同一研究小组进一步指出DNA甲基转移酶3(DNMT3)蛋白的表达与HPV感染有关[101]。 他们认为,HPV感染上调了DNMT3蛋白的表达,随后增加了p16INK4A的高甲基化。

1.5.6 HPV和FHIT丢失

脆弱组氨酸三联体(FHIT)基因位于染色体3p14.2。因异质性缺失(LOH)而改变,在包括肺癌在内的各种人类癌症中偶尔会出现同质性缺失[102, 103]。FHIT的等位基因缺失在肺部肿瘤发生中起着重要作用[104],并可作为一种阴性预后标志物[105]。在HPV感染后,HPV DNA整合到与FHIT相邻的脆弱位点FRA3B,导致该基因的等位基因缺失[106]。一项来自台湾的研究报告说,在HPV阳性的非吸烟女性肺癌患者中,FHIT LOH的频率很高,表明它可能在HPV感染的肺癌发生中起作用[103]。Carpagnano等人在他们的研究中发现3p染色体的微卫星改变(MA)100%存在于HPV阳性的NSCLC患者中[107]。Yu等人进一步指出,FHIT缺失和p53突变可能对HPV感染的肺癌发生有协同作用[108]。Verri等人发现,启动子甲基化和LOH等不同机制相互作用,使FHIT表达失活[109]

HPV E6和EGFR突变

EGFR体细胞突变与NSCLC中HPV的存在有关[110]。一项包括四项研究的荟萃分析显示,与HPV阴性患者相比,HPV阳性患者的EGFR体细胞突变存在率明显更高(P=0.012)[110]。NSCLC中的HPV感染意味着更好的总生存率和对EGFR-TKI治疗的更好反应[111,112]。这一观察结果可以解释为HPV阳性的NSCLC患者更有可能出现EGFR体细胞突变,从而对EGFR-TKI有更好的反应和更好的生存。然而,HPV感染与EGFR突变或对EGFR-TKI的反应之间的关系似乎受到了地域的限制,因为Marquez-Medina等人报告了从西方患者那里得到的负面结果[113]。这种关系的潜在机制仍然是未知的。抗凋亡蛋白抑制剂(IAP),包括cIAP1、cIAP2和XIAP,是一个阻止细胞凋亡的caspase抑制剂家族,被认为是肺癌的一个治疗目标[114]。Wu等人指出,HPV-16 E6通过EGFR/PI3K/AKT途径使cAMP反应元件结合蛋白(CREB)磷酸化而导致cIAP2上调,cIAP2的表达与EGFR突变相关[115]。炎症引起的氧化应激与肺腺癌的发展有关,氧化应激生物标志物8-羟基-2'脱氧鸟苷(8-OH-dG)的水平与肺癌的EGFR突变密切相关[116]。Tung等人发现,HPV16/18 E6通过增加活性氧(ROS)的产生提高了8-OH-dG,而ROS又与HPV16/18 E6合作,促成了NSCLC的EGFR突变[33]

HPV和吸烟暴露

吸烟是众所周知的患肺癌的危险因素之一。然而,只有一小部分重度吸烟者患肺癌。这一现象表明,肺癌的发生还需要其他的共同因素。HPV感染是否与吸烟对肺癌发生有协同作用仍是未知数。Munoz等人证明,HPV16 E6/7转染的肺上皮细胞暴露于香烟烟雾成分(CSC)时,其增殖率和锚定依赖性生长明显升高,表明吸烟和HPV感染之间的功能互动促进了肺癌发生的可能性[117]。Pena等人进一步表明,CSC通过对肺上皮细胞的长控制区(LCR)的影响激活了HPV16 p97启动子[118]。此外,HPV16 E6/7能够增加CSC诱导的氧化性DNA损伤[118]

苯并[a]芘(B[a]P)是香烟烟雾的一种主要成分,与肺癌的发展有关[119]。B[a]P可以增加HPV的病毒和基因组的数量[120]。B[a]P治疗有助于基因启动子高甲基化,这是牵涉到修复基因失活的主要途径[121]。此外,修复基因失活和暴露于B[a]P的组合促进了DNA损伤[122]。有趣的是,HPV与B[a]P协同作用,诱发NSCLC细胞的DNA损伤,促进肺癌的发生,尤其是在女性患者中[123]

其他

HPV E6/7和Mcl-1

骨髓细胞白血病(Mcl)-1是Bcl-2家族的一个抗凋亡成员,有助于控制癌症的发展[124]。Mcl-1的存在与各种癌症类型(包括肺癌)的癌细胞生长和规避凋亡有关[124]。在NSCLC中,IL-6或IL-17和Mcl-1的同时表达与HPV DNA有协同作用[125]。HPV E6/7通过磷脂酰肌醇-3-OH激酶途径导致IL-6或IL-17和Mcl-1的上调表达[126]。因此,肺癌细胞在应对HPV刺激时分泌的高水平IL-6和IL-17所表现的微环境炎症很可能是HPV感染的肺部肿瘤发生的原因[125,126]

HPV E6/7和FOXM1

狐头盒M1(FOXM1)的表达增加与包括NSCLC在内的各种癌症类型的肿瘤进展和不良预后有关[127]。FOXM1被Rb磷酸化释放的E2F通过p53失活而上调,并与HPV-16 E7相互作用,增强大鼠胚胎成纤维细胞的转化潜力[128]。Chen等人未能在HPV阳性的癌细胞包括肺癌细胞中发现E7触发的FOXM1上调[62]。然而,E6通过MZF1/NKX2-1轴触发了FOXM1表达的升高,它激活了β-catenin核易位,随后增强了HPV阳性NSCLC的细胞侵袭性和干性[62]

HPV E6和miR-30c-2/MTA-1

miR-30c-2是肿瘤抑制性microRNAs之一,与肿瘤的发展有关。miR-30c-2的下调通过靶向转移相关蛋白-1(MTA-1)促进NSCLC的侵袭[129]。Wu等人证明,在NSCLC组织中,HPV-16/18 E6与miR-30c-2的表达呈负相关,与MTA-1呈正相关,miR-30c-2和MTA-1的表达水平可以预测NSCLC患者的预后和对化疗的反应[130]

图片2.png

HPV相关的肺部SCLC的实验模型

体外和体内的动物模型被广泛用于HPV研究[131]。目前还没有关于用于研究HPV如何感染和转化肺部细胞的实验模型的数据。重要的是,Carraresi等人最初建立了一个由HPV-16 E6/E7肿瘤蛋白在细胞角蛋白5基因启动子控制下诱导的SCLC转基因小鼠模型[132]。此外,他们开发了两个源自转基因肺SCLC的小鼠细胞系,这两个细胞系都显示出p53和pRB的缺失,并在皮下注射给合体小鼠后持续形成肿瘤[133]。这些发现为HPV诱发SCLC的能力提供了更直接的证据,可能是通过p53和pRB的失活。 

HPV疫苗接种与肺癌的可能联系

预防性HPV疫苗接种,主要覆盖女孩和25岁以下的妇女,目前已被纳入全球60个国家的国家疫苗接种计划[134]。它的目的是形成病毒中和抗体,根据HPV和宫颈肿瘤进展之间的既定关系,预计可以保护宫颈癌的发展。由于HPV可能与肺癌有关,因此有必要在男孩和女孩中引入预防性疫苗接种。毫无疑问,需要更多的证据来确定HPV是人类肺癌的致癌因素,并验证旨在预防宫颈癌的HPV疫苗对肺癌发病率是否有影响。 

2. 梅克尔细胞多瘤病毒(MCPyV)

随着Feng等人在2008年发现梅克尔细胞多瘤病毒(MCPyV)是梅克尔细胞癌(MCC)的致病因子[135],一些作者已经调查了MCPyV在包括肺癌在内的几种人类肿瘤中存在的关联[136-139]。MCPyV感染在人类中很普遍,MCPyV不断从健康皮肤中脱落[140]。此外,MCPyV的DNA片段已在各种解剖位置被检测到,包括下呼吸道[141]。最近的一项研究对10例尸检中的MCPyV存在进行了广泛的器官取样调查,发现MCPyV在肺部样本以及血液和大脑样本中的流行率很高[142]。呼吸道中持续存在的MCPyV可能会促进肺癌的发展。

 MCPyV和肺癌

由于SCLC在组织学上与MCC有相似之处[143, 144],MCPyV是否导致SCLC的发展已经引起了研究人员的注意。研究已经在SCLC组织中检测到病毒DNA序列[145, 146]。然而,有证据表明MCPyV在SCLC中没有作用[147, 148]。此外,MCPyV在NSCLC中的流行程度也得到了调查。研究人员在NSCLC的DNA、RNA和蛋白水平上发现了不同程度的MCPyV感染阳性[11, 149-153]。Hashida等人首次提供了证据,证明在NSCLCs中不仅检测到MCPyV DNA,而且还检测到LT RNA转录物和LT抗原的表达[10]。他们发现,32个SCC中的9个、45个AC中的9个、32个大细胞癌中的1个和3个多形性癌中的1个MCPyV DNA呈阳性[10]。另一项研究显示,NSCLC的分期与MCPyV LT-Ag DNA负荷之间有统计学上的显著差异,这表明病毒负荷可能随着肿瘤的发展而增加[11]

可能的NSCLC特异性致癌机制

目前,既没有人类细胞系,也没有动物模型可供探索MCPyV的肺癌发生。与HPV一样,MCPyV进入细胞遵循2个步骤的附着和进入过程[154],肺细胞中硫酸化糖胺聚糖的大量表达为MCPyV进入肺细胞提供了基础。

MCPyV的DNA整合到宿主细胞基因组中被认为是通过转化的大T(LT)和小T(ST)蛋白的组成式表达而引起MCC,其机制是不同的[155]。然而,MCPyV诱导的NSCLC的发病机制仍有待确定。有人认为,突变的BRAF驱动了肺腺癌的发展[156]。Bax/Bcl-2的异源二聚体诱导了Bax的中和,使细胞凋亡消失[157]。Lasithiotaki等人发现,与MCPyV阴性的NSCLC样本相比,MCPyV阳性的NSCLC样本中BRAF表达增加,Bcl-2下调,这表明MCPyV通过BRAF和Bcl-2的失调在NSCLC中发挥作用[149]。他们进一步证明,NSCLC相关的microRNAs(miR-21、miR-376和miR-145)及其相应的靶基因的表达受到肺癌组织中MCPyV存在的影响,为NSCLC中MCPyV相关的表观遗传机制提供证据[12]。Xu等人通过筛选189个NSCLC样本,发现MCPyV感染和EGFR突变之间存在明显的相关性[152]。他们的发现表明MCPyV感染可能会诱发NSCLC的EGFR突变。如果是这样,就可以解释Lasithiotaki等人提供的MCPyV阳性样本中BRAF表达较高的现象,因为BRAF是EGFR途径的下游靶点[149]。Hashida等人在NSCLC患者中发现两个MCPyV整合位点(5q23.1和11q25)[10]。然而,这两个整合点都不靠近EGFR基因的位置(7p12)[10]。因此,MCPyV感染是否会诱发NSCLC的EGFR突变值得进一步调查。

3. 爱泼斯坦-巴尔病毒(EBV)

EB病毒是一种具有致癌性的淋巴细胞伽马疱疹病毒,感染了全世界90%以上的成年人。它直接参与了各种淋巴增生性疾病和肿瘤性疾病的发病机制,包括未分化的鼻咽癌和不同部位的淋巴上皮瘤样癌(LELC)[158,159]。EB病毒与肺癌的关联根据肿瘤组织类型和地理部位的不同呈现出明显的差异[15,160]。EBV经常在发生在鼻咽癌高发的东亚和东南亚患者的肺部LELC中检测到[13,161-164],但在其他类型的肺癌如腺癌、鳞状细胞癌和SCLC中很少检测到甚至没有检测到[42,165,166]。最近,Wang等人探讨了肺癌中的EBV基因组变异,并报道了从原发性肺癌中分离出的四个新测序的EBV基因组,这些EBV基因组之间具有明显的基因组多样性[15]。 然而,EBV基因组变异是否有助于肺癌的发生仍然未知,值得进一步研究。

众所周知,EBV的细胞进入是由病毒包膜糖蛋白gp350与B细胞和上皮细胞的细胞表面受体CD21相互作用而启动的[167]。一些研究已经证明EBV受体CD21在人类支气管上皮细胞中的表达[168],更具体地说是在2型肺泡上皮细胞中的表达[169],这意味着EBV可能以CD-21依赖性的方式感染并可能转化肺细胞。然而,这还需要进一步调查。  

以前的研究已经测量了肺部LELC患者血浆中的循环EB病毒DNA,并建议其在监测治疗反应方面发挥作用[170,171]。最近,Xie等人在中国南方进行了一项前瞻性的多中心研究,调查了总共429名肺部LELC患者的基线EBV DNA与OS和无病生存(DFS)之间的关系,结果显示,基线EBV DNA拷贝至少为4000拷贝/毫升,预测早期或晚期肺部LELC患者的疾病复发和较差的生存[14]。通过连续抽血,他们发现在治疗后的随访中,血浆EBV DNA经常先于疾病的发展。此外,根治性切除术后持续检测到血浆EBV DNA的患者的OS和DFS明显比术后EBV DNA的患者差[14]。上述发现进一步支持EBV在一部分亚洲肺LELC患者中的致癌作用。

4. 绵羊逆转录病毒(JSRV)

JSRV是一种已知的betaretrovirus,能够诱导绵羊形成可传播的肺癌,称为绵羊肺腺癌(OPA)[172]。OPA的特点是多灶性混合表现为腺癌,其早期病变与表皮为主的腺癌相似,其晚期病变类似于具有乳头状或针状特征的腺癌[173]。  JSRV感染并转化支气管和肺泡上皮细胞,即II型肺细胞和俱乐部细胞[174]。JSRV的细胞受体是透明质酸酶-2(Hyal2),Hyal2已被证明可以介导JSRV Env假型逆转录病毒颗粒进入人类细胞[175]。JSRV的包膜(Env)蛋白是一种致癌蛋白,其致癌性已在绵羊和小鼠体内以及体外的各种细胞系中得到证实,包括人类支气管上皮细胞[16]

鉴于JSRV诱导OPA的能力和OPA与人类腺癌之间的组织学相似性,以及由于发现人类支气管上皮细胞表达Hyal2用于JSRV进入和JSRV Env蛋白在体外转化人类肺上皮细胞,许多研究探讨了JSRV在诱导人类肺癌中的作用[176-183]。De las Heras等人通过使用JSRV外壳蛋白的抗血清对人肺组织进行免疫组化分析,发现在129个人类鳞状腺癌中的30%,65个其他腺癌中的26%,以及7个大细胞癌中的2个都有阳性反应[176]。通过人类肺癌组织阵列,Linnerth-Petrik等人进一步通过免疫染色发现了JSRV Env蛋白的存在,并通过PCR在一部分人类腺癌中发现了JSRV Env和Gag序列[177]。此外,在撒丁岛的肺癌患者的石蜡切片[178]和来自尼日利亚和喀麦隆的非洲人的血液[179]中也检测到了JSRV相关的DNA序列。尽管如此,其他研究组未能通过免疫染色找到JSRV Env和Gag蛋白的证据[182],也未能通过PCR找到人类腺癌中的JSRV DNA或RNA[180,181]。最近,使用高通量测序方法的一种更明确的方法也无法在五个鳞状腺癌中找到JSRV序列的证据[183]。到目前为止,关于JSRV与人类肺腺癌的发展之间的联系,还没有确凿的证据,需要做很多工作。

5. John Cunningham病毒(JCV)

JCV是多瘤病毒家族的一个成员,在全世界范围内感染了很大一部分人口,80%到90%的成年人血清反应呈阳性[184]。最近的文献报道JCV存在于各种类型的人类肿瘤,包括肺癌[185]。JCV的T抗原被认为在JCV相关的致癌过程中起着重要作用[186]。T-抗原可以使肿瘤抑制蛋白p53和pRb失活,并通过直接结合促进β-catenin的稳定和积累而使Wnt信号通路失调,最终导致不受控制的增殖和不死的生存[187]。Giuliani等人首次提出在肺部肿瘤中存在JCV,显示JCV序列只在一种肺癌中扩增[184]。Zheng等人通过靶向JCV T-抗原和103个肺癌和18个正常肺组织中Ki-67、caspase-3、β-catenin、p53和pRb的表达来检查JCV[188]。在他们的研究中,肺癌中JCV的检测率和拷贝数高于正常肺组织。JCV拷贝数与Ki-67的表达呈正相关,与膜β-catenin的表达呈负相关,这表明具有高JC拷贝数的肺癌表现出高增殖和由膜β-catenin介导的细胞粘附力的下调。此外,在肺癌细胞和邻近的肺泡上皮细胞的细胞核中发现JCV T抗原[188]。上述发现以及以前的报告表明,末端a2,6-连接的sialic acid是JCV受体的一个关键成分,在正常肺部大量表达[189],表明JCV可能与肺上皮细胞的恶性转化有关,并支持呼吸道可能是JCV感染的入口的观点[189]。Abdel-Aziz等人通过靶向T抗原、VP和Agnoprotein,探索了62个肺癌和23个正常肺组织中JCV基因组的存在[190]。在大约一半的肺癌病例中检测到JCV基因组,JCV T抗原与p53和β-catenin的核染色明显相关。Sinagra等人最近通过靶向肺腺癌及其周围正常肺组织的T-抗原来研究JCV的基因序列[185]。在13个肺癌组织中,有7个观察到JCV阳性,而周围的正常肺组织没有一个是JCV阳性。Noguchi等人用包括K-19启动子的转基因产生了转基因(TG)小鼠,该转基因对支气管和消化道上皮细胞和JCV T-抗原有特异性,在15只TG小鼠中发现2只肺部肿瘤(13.3%),没有任何转移,表明JCV与实验动物的支气管肿瘤发生可能有关[191]。

病毒相关癌症研究中的挑战和未来展望

病毒感染对癌症造成的全球健康负担很高,但却没有得到重视。据估计,全世界15.4%的癌症都是由传染病原体引起的,其中大部分是病毒[192]。大多数病毒在自然界中无处不在,但只有一小部分受感染的人发生癌症。即便如此,也不应该停止对某些实体癌的病毒病因学的探索。我们现在正进入一个更成熟的研究阶段,认识到相当一部分癌症确实是由病毒引起的。随着新的测序技术的出现,这一比例很可能会增加。发现具有传染性的癌症对于开发抗宿主病毒药物和免疫疗法至关重要。对病毒性癌症重要性的认识已经促成了针对HBV和高危HPV的疫苗以及针对HCV和HIV的靶向治疗,并将在癌症控制方面创造更多机会。

【小结】

全世界范围内的人体肺癌组织中可检测到HPV,肺癌组织中HPV感染率因研究者所在地域不同有很大差异。与其他肺癌病理类型相比,HPV感染率在鳞状细胞癌中似乎更高。多种致癌机制被提出,认为HPV感染在NSCLC致癌过程中发挥作用:有助于肺癌细胞转化的致癌基因转录,诱导EGFR突变,以及病毒克隆整合到细胞基因组等。此外,HPV可能作为吸烟暴露的辅助因素,促进肺癌发生发展。自从发现MCPyV是MCC的致病因子后,MCPyV被认为是肺癌有关的潜在致癌病毒。有限的证据发现MCPyV在肺癌,特别是NSCLC中的作用。与HPV一样,MCPyV也可能在NSCLC中诱发EGFR突变,但其具体机制不明。MCPyV与肺癌之间的关系值得进一步研究。EB病毒可能与肺淋巴上皮瘤样癌有关,位于东亚和东南亚地区的肺淋巴上皮瘤样癌患者组织中经常检测到EB病毒,肺淋巴上皮瘤样癌患者血浆中的循环EB病毒DNA可以预测疾病复发;而EB病毒在其他病理类型的肺癌中的作用似乎不太可能。虽然已知JSRV可通过病毒包膜蛋白诱导绵羊发生肺腺癌,但到目前为止还没有JSRV诱导人类发生肺腺癌的确切性证据。与上述四种病毒相比,JCV的研究较少。期待未来更多的研究来深入了解这些病毒在肺癌发生中的作用,从而达到早期预防早期发现的目的。

参考文献

1. Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA: a cancer journal for clinicians. 2018;68(6):394-424.

2. Molina JR, Yang P, Cassivi SD, Schild SE, Adjei AA. Non-small cell lung cancer: epidemiology, risk factors, treatment, and survivorship. Mayo Clinic proceedings. 2008;83(5):584-94.

3. Alberg AJ, Brock MV, Ford JG, Samet JM, Spivack SD. Epidemiology of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2013;143(5 Suppl):e1S-e29S.

4. Sun S, Schiller JH, Gazdar AF. Lung cancer in never smokers--a different disease. Nature reviews Cancer. 2007;7(10):778-90.

5. Moore PS, Chang Y. Why do viruses cause cancer? Highlights of the first century of human tumour virology. Nature reviews Cancer. 2010;10(12):878-89.

6. Pagano JS, Blaser M, Buendia MA, Damania B, Khalili K, Raab-Traub N, et al. Infectious agents and cancer: criteria for a causal relation. Seminars in cancer biology. 2004;14(6):453-71.

7. Xiong WM, Xu QP, Li X, Xiao RD, Cai L, He F. The association between human papillomavirus infection and lung cancer: a system review and meta-analysis. Oncotarget. 2017;8(56):96419-32.

8. Robinson LA, Jaing CJ, Pierce Campbell C, Magliocco A, Xiong Y, Magliocco G, et al. Molecular evidence of viral DNA in non-small cell lung cancer and non-neoplastic lung. British journal of cancer. 2016;115(4):497-504.

9. Hasegawa Y, Ando M, Kubo A, Isa S, Yamamoto S, Tsujino K, et al. Human papilloma virus in non-small cell lung cancer in never smokers: a systematic review of the literature. Lung cancer. 2014;83(1):8-13.

10. Hashida Y, Imajoh M, Nemoto Y, Kamioka M, Taniguchi A, Taguchi T, et al. Detection of Merkel cell polyomavirus with a tumour-specific signature in non-small cell lung cancer. British journal of cancer. 2013;108(3):629-37.

11. Behdarvand A, Zamani MS, Sadeghi F, Yahyapour Y, Vaziri F, Jamnani FR, et al. Evaluation of Merkel cell polyomavirus in non-small cell lung cancer and adjacent normal cells. Microbial pathogenesis. 2017;108:21-6.

12. Lasithiotaki I, Tsitoura E, Koutsopoulos A, Lagoudaki E, Koutoulaki C, Pitsidianakis G, et al. Aberrant expression of miR-21, miR-376c and miR-145 and their target host genes in Merkel cell polyomavirus-positive non-small cell lung cancer. Oncotarget. 2017;8(68):112371-83.

13. Yeh YC, Kao HL, Lee KL, Wu MH, Ho HL, Chou TY. Epstein-Barr Virus-Associated Pulmonary Carcinoma: Proposing an Alternative Term and Expanding the Histologic Spectrum of Lymphoepithelioma-like Carcinoma of the Lung. The American journal of surgical pathology. 2019;43(2):211-9.

14. Xie M, Wu X, Wang F, Zhang J, Ben X, Zhang J, et al. Clinical Significance of Plasma Epstein-Barr Virus DNA in Pulmonary Lymphoepithelioma-like Carcinoma (LELC) Patients. Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer. 2018;13(2):218-27.

15. Wang S, Xiong H, Yan S, Wu N, Lu Z. Identification and Characterization of Epstein-Barr Virus Genomes in Lung Carcinoma Biopsy Samples by Next-Generation Sequencing Technology. Scientific reports. 2016;6:26156.

16. Monot M, Archer F, Gomes M, Mornex JF, Leroux C. Advances in the study of transmissible respiratory tumours in small ruminants. Veterinary microbiology. 2015;181(1-2):170-7.

17. De Paoli P, Carbone A. Carcinogenic viruses and solid cancers without sufficient evidence of causal association. International journal of cancer. 2013;133(7):1517-29.

18. Syrjanen KJ. Condylomatous changes in neoplastic bronchial epithelium. Report of a case. Respiration; international review of thoracic diseases. 1979;38(5):299-304.

19. Syrjanen K. Detection of human papillomavirus in lung cancer: systematic review and meta-analysis. Anticancer research. 2012;32(8):3235-50.

20. Cheng YW, Chiou HL, Sheu GT, Hsieh LL, Chen JT, Chen CY, et al. The association of human papillomavirus 16/18 infection with lung cancer among nonsmoking Taiwanese women. Cancer research. 2001;61(7):2799-803.

21. Nadji SA, Mokhtari-Azad T, Mahmoodi M, Yahyapour Y, Naghshvar F, Torabizadeh J, et al. Relationship between lung cancer and human papillomavirus in north of Iran, Mazandaran province. Cancer letters. 2007;248(1):41-6.

22. Sarchianaki E, Derdas SP, Ntaoukakis M, Vakonaki E, Lagoudaki ED, Lasithiotaki I, et al. Detection and genotype analysis of human papillomavirus in non-small cell lung cancer patients. Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine. 2014;35(4):3203-9.

23. Chen SP, Hsu NY, Wu JY, Chen CY, Chou MC, Lee H, et al. Association of p53 codon 72 genotypes and clinical outcome in human papillomavirus-infected lung cancer patients. The Annals of thoracic surgery. 2013;95(4):1196-203.

24. de Oliveira THA, do Amaral CM, de Franca Sao Marcos B, Nascimento KCG, de Miranda Rios AC, Quixabeira DCA, et al. Presence and activity of HPV in primary lung cancer. Journal of cancer research and clinical oncology. 2018;144(12):2367-76.

25. Fei Y, Yang J, Hsieh WC, Wu JY, Wu TC, Goan YG, et al. Different human papillomavirus 16/18 infection in Chinese non-small cell lung cancer patients living in Wuhan, China. Japanese journal of clinical oncology. 2006;36(5):274-9.

26. Wang Y, Wang A, Jiang R, Pan H, Huang B, Lu Y, et al. Human papillomavirus type 16 and 18 infection is associated with lung cancer patients from the central part of China. Oncology reports. 2008;20(2):333-9.

27. Wang YH, Chen DJ, Yi TN, Liu XH. The relationship among human papilloma virus infection, survivin, and p53 gene in lung squamous carcinoma tissue. Saudi medical journal. 2010;31(12):1331-6.

28. Yu Y, Yang A, Hu S, Zhang J, Yan H. Significance of human papillomavirus 16/18 infection in association with p53 mutation in lung carcinomas. The clinical respiratory journal. 2013;7(1):27-33.

29. Badillo-Almaraz I, Zapata-Benavides P, Saavedra-Alonso S, Zamora-Avila D, Resendez-Perez D, Tamez-Guerra R, et al. Human papillomavirus 16/18 infections in lung cancer patients in Mexico. Intervirology. 2013;56(5):310-5.

30. Cheng YW, Wu MF, Wang J, Yeh KT, Goan YG, Chiou HL, et al. Human papillomavirus 16/18 E6 oncoprotein is expressed in lung cancer and related with p53 inactivation. Cancer research. 2007;67(22):10686-93.

31. Kato T, Koriyama C, Khan N, Samukawa T, Yanagi M, Hamada T, et al. EGFR mutations and human papillomavirus in lung cancer. Lung cancer. 2012;78(2):144-7.

32. Lin FC, Huang JY, Tsai SC, Nfor ON, Chou MC, Wu MF, et al. The association between human papillomavirus infection and female lung cancer: A population-based cohort study. Medicine. 2016;95(23):e3856.

33. Tung MC, Wu HH, Cheng YW, Wang L, Chen CY, Yeh SD, et al. Association of epidermal growth factor receptor mutations with human papillomavirus 16/18 E6 oncoprotein expression in non-small cell lung cancer. Cancer. 2013;119(18):3367-76.

34. Wang JL, Fang CL, Wang M, Yu MC, Bai KJ, Lu PC, et al. Human papillomavirus infections as a marker to predict overall survival in lung adenocarcinoma. International journal of cancer. 2014;134(1):65-71.

35. Storey R, Joh J, Kwon A, Jenson AB, Ghim SJ, Kloecker GH. Detection of Immunoglobulin G against E7 of Human Papillomavirus in Non-Small-Cell Lung Cancer. Journal of oncology. 2013;2013:240164.

36. Aguayo F, Castillo A, Koriyama C, Higashi M, Itoh T, Capetillo M, et al. Human papillomavirus-16 is integrated in lung carcinomas: a study in Chile. British journal of cancer. 2007;97(1):85-91.

37. Anantharaman D, Gheit T, Waterboer T, Halec G, Carreira C, Abedi-Ardekani B, et al. No causal association identified for human papillomavirus infections in lung cancer. Cancer research. 2014;74(13):3525-34.

38. Argyri E, Tsimplaki E, Marketos C, Politis G, Panotopoulou E. Investigating the role of human papillomavirus in lung cancer. Papillomavirus research. 2017;3:7-10.

39. van Boerdonk RA, Daniels JM, Bloemena E, Krijgsman O, Steenbergen RD, Brakenhoff RH, et al. High-risk human papillomavirus-positive lung cancer: molecular evidence for a pattern of pulmonary metastasis. Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer. 2013;8(6):711-8.

40. Galvan A, Noci S, Taverna F, Lombardo C, Franceschi S, Pastorino U, et al. Testing of human papillomavirus in lung cancer and non-tumor lung tissue. BMC cancer. 2012;12:512.

41. Chang SY, Keeney M, Law M, Donovan J, Aubry MC, Garcia J. Detection of human papillomavirus in non-small cell carcinoma of the lung. Human pathology. 2015;46(11):1592-7.

42. Lim WT, Chuah KL, Leong SS, Tan EH, Toh CK. Assessment of human papillomavirus and Epstein-Barr virus in lung adenocarcinoma. Oncology reports. 2009;21(4):971-5.

43. Silva EM, Mariano VS, Pastrez PRA, Pinto MC, Nunes EM, Sichero L, et al. Human papillomavirus is not associated to non-small cell lung cancer: data from a prospective cross-sectional study. Infectious agents and cancer. 2019;14:18.

44. Chesson HW, Dunne EF, Hariri S, Markowitz LE. The estimated lifetime probability of acquiring human papillomavirus in the United States. Sexually transmitted diseases. 2014;41(11):660-4.

45. Carpagnano GE, Koutelou A, Natalicchio MI, Martinelli D, Ruggieri C, Di Taranto A, et al. HPV in exhaled breath condensate of lung cancer patients. British journal of cancer. 2011;105(8):1183-90.

46. Chiou HL, Wu MF, Liaw YC, Cheng YW, Wong RH, Chen CY, et al. The presence of human papillomavirus type 16/18 DNA in blood circulation may act as a risk marker of lung cancer in Taiwan. Cancer. 2003;97(6):1558-63.

47. Bodaghi S, Wood LV, Roby G, Ryder C, Steinberg SM, Zheng ZM. Could human papillomaviruses be spread through blood? Journal of clinical microbiology. 2005;43(11):5428-34.

48. Zhai K, Ding J, Shi HZ. HPV and lung cancer risk: a meta-analysis. Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology. 2015;63:84-90.

49. Mammas IN, Sourvinos G, Spandidos DA. The paediatric story of human papillomavirus (Review). Oncology letters. 2014;8(2):502-6.

50. Gillison ML, Shah KV. Chapter 9: Role of mucosal human papillomavirus in nongenital cancers. Journal of the National Cancer Institute Monographs. 2003(31):57-65.

51. Chen HB, Chen L, Zhang JK, Shen ZY, Su ZJ, Cheng SB, et al. Human papillomavirus 16 E6 is associated with the nuclear matrix of esophageal carcinoma cells. World journal of gastroenterology. 2001;7(6):788-91.

52. Syrjanen KJ. HPV infections and lung cancer. Journal of clinical pathology. 2002;55(12):885-91.

53. Rabkin CS, Biggar RJ, Melbye M, Curtis RE. Second primary cancers following anal and cervical carcinoma: evidence of shared etiologic factors. American journal of epidemiology. 1992;136(1):54-8.

54. Frisch M, Melbye M. Risk of lung cancer in pre- and post-menopausal women with ano-genital malignancies. International journal of cancer. 1995;62(5):508-11.

55. Li YJ, Tsai YC, Chen YC, Christiani DC. Human papilloma virus and female lung adenocarcinoma. Seminars in oncology. 2009;36(6):542-52.

56. Zhou Q, Hu X, Zhou J, Zhao M, Zhu X, Zhu X. Human papillomavirus DNA in surgical smoke during cervical loop electrosurgical excision procedures and its impact on the surgeon. Cancer management and research. 2019;11:3643-54.

57. Schiller JT, Day PM, Kines RC. Current understanding of the mechanism of HPV infection. Gynecologic oncology. 2010;118(1 Suppl):S12-7.

58. Smits NC, Shworak NW, Dekhuijzen PN, van Kuppevelt TH. Heparan sulfates in the lung: structure, diversity, and role in pulmonary emphysema. Anatomical record. 2010;293(6):955-67.

59. Kines RC, Thompson CD, Lowy DR, Schiller JT, Day PM. The initial steps leading to papillomavirus infection occur on the basement membrane prior to cell surface binding. Proceedings of the National Academy of Sciences of the United States of America. 2009;106(48):20458-63.

60. Hammond E, Khurana A, Shridhar V, Dredge K. The Role of Heparanase and Sulfatases in the Modification of Heparan Sulfate Proteoglycans within the Tumor Microenvironment and Opportunities for Novel Cancer Therapeutics. Frontiers in oncology. 2014;4:195.

61. Kines RC, Cerio RJ, Roberts JN, Thompson CD, de Los Pinos E, Lowy DR, et al. Human papillomavirus capsids preferentially bind and infect tumor cells. International journal of cancer. 2016;138(4):901-11.

62. Chen PM, Cheng YW, Wang YC, Wu TC, Chen CY, Lee H. Up-regulation of FOXM1 by E6 oncoprotein through the MZF1/NKX2-1 axis is required for human papillomavirus-associated tumorigenesis. Neoplasia. 2014;16(11):961-71.

63. Wu DW, Tsai LH, Chen PM, Lee MC, Wang L, Chen CY, et al. Loss of TIMP-3 promotes tumor invasion via elevated IL-6 production and predicts poor survival and relapse in HPV-infected non-small cell lung cancer. The American journal of pathology. 2012;181(5):1796-806.

64. Hsu NY, Cheng YW, Chan IP, Ho HC, Chen CY, Hsu CP, et al. Association between expression of human papillomavirus 16/18 E6 oncoprotein and survival in patients with stage I non-small cell lung cancer. Oncology reports. 2009;21(1):81-7.

65. Iwamasa T, Miyagi J, Tsuhako K, Kinjo T, Kamada Y, Hirayasu T, et al. Prognostic implication of human papillomavirus infection in squamous cell carcinoma of the lung. Pathology, research and practice. 2000;196(4):209-18.

66. Miyagi J, Kinjo T, Tsuhako K, Higa M, Iwamasa T, Kamada Y, et al. Extremely high Langerhans cell infiltration contributes to the favourable prognosis of HPV-infected squamous cell carcinoma and adenocarcinoma of the lung. Histopathology. 2001;38(4):355-67.

67. Guo L, Liu S, Zhang S, Chen Q, Zhang M, Quan P, et al. Human papillomavirus infection as a prognostic marker for lung adenocarcinoma: a systematic review and meta-analysis. Oncotarget. 2017;8(21):34507-15.

68. Jackson AL, Zhou B, Kim WY. HIF, hypoxia and the role of angiogenesis in non-small cell lung cancer. Expert opinion on therapeutic targets. 2010;14(10):1047-57.

69. Ellis LM, Hicklin DJ. VEGF-targeted therapy: mechanisms of anti-tumour activity. Nature reviews Cancer. 2008;8(8):579-91.

70. Zhang E, Feng X, Liu F, Zhang P, Liang J, Tang X. Roles of PI3K/Akt and c-Jun signaling pathways in human papillomavirus type 16 oncoprotein-induced HIF-1alpha, VEGF, and IL-8 expression and in vitro angiogenesis in non-small cell lung cancer cells. PloS one. 2014;9(7):e103440.

71. Li G, He L, Zhang E, Shi J, Zhang Q, Le AD, et al. Overexpression of human papillomavirus (HPV) type 16 oncoproteins promotes angiogenesis via enhancing HIF-1alpha and VEGF expression in non-small cell lung cancer cells. Cancer letters. 2011;311(2):160-70.

72. Liu J, Huang B, Xiu Z, Zhou Z, Liu J, Li X, et al. PI3K/Akt/HIF-1alpha signaling pathway mediates HPV-16 oncoprotein-induced expression of EMT-related transcription factors in non-small cell lung cancer cells. Journal of Cancer. 2018;9(19):3456-66.

73. Gu NJ, Wu MZ, He L, Wang XB, Wang S, Qiu XS, et al. HPV 16 E6/E7 up-regulate the expression of both HIF-1alpha and GLUT1 by inhibition of RRAD and activation of NF-kappaB in lung cancer cells. Journal of Cancer. 2019;10(27):6903-9.

74. Fan R, Hou WJ, Zhao YJ, Liu SL, Qiu XS, Wang EH, et al. Overexpression of HPV16 E6/E7 mediated HIF-1alpha upregulation of GLUT1 expression in lung cancer cells. Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine. 2016;37(4):4655-63.

75. Joshi S, Singh AR, Zulcic M, Durden DL. A macrophage-dominant PI3K isoform controls hypoxia-induced HIF1alpha and HIF2alpha stability and tumor growth, angiogenesis, and metastasis. Molecular cancer research : MCR. 2014;12(10):1520-31.

76. Shao JS, Sun J, Wang S, Chung K, Du JT, Wang J, et al. HPV16 E6/E7 upregulates HIF-2alpha and VEGF by inhibiting LKB1 in lung cancer cells. Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine. 2017;39(7):1010428317717137.

77. Kessenbrock K, Plaks V, Werb Z. Matrix metalloproteinases: regulators of the tumor microenvironment. Cell. 2010;141(1):52-67.

78. Shiau MY, Fan LC, Yang SC, Tsao CH, Lee H, Cheng YW, et al. Human papillomavirus up-regulates MMP-2 and MMP-9 expression and activity by inducing interleukin-8 in lung adenocarcinomas. PloS one. 2013;8(1):e54423.

79. Chetty C, Lakka SS, Bhoopathi P, Kunigal S, Geiss R, Rao JS. Tissue inhibitor of metalloproteinase 3 suppresses tumor angiogenesis in matrix metalloproteinase 2-down-regulated lung cancer. Cancer research. 2008;68(12):4736-45.

80. Barski D, Wolter M, Reifenberger G, Riemenschneider MJ. Hypermethylation and transcriptional downregulation of the TIMP3 gene is associated with allelic loss on 22q12.3 and malignancy in meningiomas. Brain pathology. 2010;20(3):623-31.

81. Wild A, Langer P, Celik I, Chaloupka B, Bartsch DK. Chromosome 22q in pancreatic endocrine tumors: identification of a homozygous deletion and potential prognostic associations of allelic deletions. European journal of endocrinology. 2002;147(4):507-13.

82. Nakamura M, Ishida E, Shimada K, Kishi M, Nakase H, Sakaki T, et al. Frequent LOH on 22q12.3 and TIMP-3 inactivation occur in the progression to secondary glioblastomas. Laboratory investigation; a journal of technical methods and pathology. 2005;85(2):165-75.

83. Horikawa I, Barrett JC. Transcriptional regulation of the telomerase hTERT gene as a target for cellular and viral oncogenic mechanisms. Carcinogenesis. 2003;24(7):1167-76.

84. Lantuejoul S, Soria JC, Morat L, Lorimier P, Moro-Sibilot D, Sabatier L, et al. Telomere shortening and telomerase reverse transcriptase expression in preinvasive bronchial lesions. Clinical cancer research : an official journal of the American Association for Cancer Research. 2005;11(5):2074-82.

85. Cheng YW, Wu TC, Chen CY, Chou MC, Ko JL, Lee H. Human telomerase reverse transcriptase activated by E6 oncoprotein is required for human papillomavirus-16/18-infected lung tumorigenesis. Clinical cancer research : an official journal of the American Association for Cancer Research. 2008;14(22):7173-9.

86. Xu D, Wang Q, Gruber A, Bjorkholm M, Chen Z, Zaid A, et al. Downregulation of telomerase reverse transcriptase mRNA expression by wild type p53 in human tumor cells. Oncogene. 2000;19(45):5123-33.

87. Yang JH, Li XY, Wang X, Hou WJ, Qiu XS, Wang EH, et al. Long-term persistent infection of HPV 16 E6 up-regulate SP1 and hTERT by inhibiting LKB1 in lung cancer cells. PloS one. 2017;12(8):e0182775.

88. Martinez-Zapien D, Ruiz FX, Poirson J, Mitschler A, Ramirez J, Forster A, et al. Structure of the E6/E6AP/p53 complex required for HPV-mediated degradation of p53. Nature. 2016;529(7587):541-5.

89. zur Hausen H. Papillomaviruses and cancer: from basic studies to clinical application. Nature reviews Cancer. 2002;2(5):342-50.

90. Sherr CJ, Roberts JM. CDK inhibitors: positive and negative regulators of G1-phase progression. Genes & development. 1999;13(12):1501-12.

91. el-Deiry WS, Tokino T, Velculescu VE, Levy DB, Parsons R, Trent JM, et al. WAF1, a potential mediator of p53 tumor suppression. Cell. 1993;75(4):817-25.

92. Marchetti A, Doglioni C, Barbareschi M, Buttitta F, Pellegrini S, Bertacca G, et al. p21 RNA and protein expression in non-small cell lung carcinomas: evidence of p53-independent expression and association with tumoral differentiation. Oncogene. 1996;12(6):1319-24.

93. Wu X, Bayle JH, Olson D, Levine AJ. The p53-mdm-2 autoregulatory feedback loop. Genes & development. 1993;7(7A):1126-32.

94. Rosner A, Rinkevich B. The DDX3 subfamily of the DEAD box helicases: divergent roles as unveiled by studying different organisms and in vitro assays. Current medicinal chemistry. 2007;14(23):2517-25.

95. Wu DW, Liu WS, Wang J, Chen CY, Cheng YW, Lee H. Reduced p21(WAF1/CIP1) via alteration of p53-DDX3 pathway is associated with poor relapse-free survival in early-stage human papillomavirus-associated lung cancer. Clinical cancer research : an official journal of the American Association for Cancer Research. 2011;17(7):1895-905.

96. Sherr CJ, McCormick F. The RB and p53 pathways in cancer. Cancer cell. 2002;2(2):103-12.

97. Ulivi P, Zoli W, Calistri D, Fabbri F, Tesei A, Rosetti M, et al. p16INK4A and CDH13 hypermethylation in tumor and serum of non-small cell lung cancer patients. Journal of cellular physiology. 2006;206(3):611-5.

98. Esteller M, Sanchez-Cespedes M, Rosell R, Sidransky D, Baylin SB, Herman JG. Detection of aberrant promoter hypermethylation of tumor suppressor genes in serum DNA from non-small cell lung cancer patients. Cancer research. 1999;59(1):67-70.

99. Finzer P, Kuntzen C, Soto U, zur Hausen H, Rosl F. Inhibitors of histone deacetylase arrest cell cycle and induce apoptosis in cervical carcinoma cells circumventing human papillomavirus oncogene expression. Oncogene. 2001;20(35):4768-76.

100. Wu MF, Cheng YW, Lai JC, Hsu MC, Chen JT, Liu WS, et al. Frequent p16INK4a promoter hypermethylation in human papillomavirus-infected female lung cancer in Taiwan. International journal of cancer. 2005;113(3):440-5.

101. Lin TS, Lee H, Chen RA, Ho ML, Lin CY, Chen YH, et al. An association of DNMT3b protein expression with P16INK4a promoter hypermethylation in non-smoking female lung cancer with human papillomavirus infection. Cancer letters. 2005;226(1):77-84.

102. Sozzi G, Veronese ML, Negrini M, Baffa R, Cotticelli MG, Inoue H, et al. The FHIT gene 3p14.2 is abnormal in lung cancer. Cell. 1996;85(1):17-26.

103. Wang J, Cheng YW, Wu DW, Chen JT, Chen CY, Chou MC, et al. Frequent FHIT gene loss of heterozygosity in human papillomavirus-infected non-smoking female lung cancer in Taiwan. Cancer letters. 2006;235(1):18-25.

104. Sozzi G, Pastorino U, Moiraghi L, Tagliabue E, Pezzella F, Ghirelli C, et al. Loss of FHIT function in lung cancer and preinvasive bronchial lesions. Cancer research. 1998;58(22):5032-7.

105. Burke L, Khan MA, Freedman AN, Gemma A, Rusin M, Guinee DG, et al. Allelic deletion analysis of the FHIT gene predicts poor survival in non-small cell lung cancer. Cancer research. 1998;58(12):2533-6.

106. Wilke CM, Hall BK, Hoge A, Paradee W, Smith DI, Glover TW. FRA3B extends over a broad region and contains a spontaneous HPV16 integration site: direct evidence for the coincidence of viral integration sites and fragile sites. Human molecular genetics. 1996;5(2):187-95.

107. Carpagnano GE, Lacedonia D, Crisetti E, Palladino GP, Saliani V, Zoppo LD, et al. Exhaled HPV infection in lung cancer: role of MA at 3p. Archives of medical research. 2014;45(5):383-7.

108. Yu Y, Liu X, Yang Y, Zhao X, Xue J, Zhang W, et al. Effect of FHIT loss and p53 mutation on HPV-infected lung carcinoma development. Oncology letters. 2015;10(1):392-8.

109. Verri C, Roz L, Conte D, Liloglou T, Livio A, Vesin A, et al. Fragile histidine triad gene inactivation in lung cancer: the European Early Lung Cancer project. American journal of respiratory and critical care medicine. 2009;179(5):396-401.

110. Liang H, Pan Z, Cai X, Wang W, Guo C, He J, et al. The association between human papillomavirus presence and epidermal growth factor receptor mutations in Asian patients with non-small cell lung cancer. Translational lung cancer research. 2018;7(3):397-403.

111. Baba M, Castillo A, Koriyama C, Yanagi M, Matsumoto H, Natsugoe S, et al. Human papillomavirus is frequently detected in gefitinib-responsive lung adenocarcinomas. Oncology reports. 2010;23(4):1085-92.

112. Li M, Deng F, Qian LT, Meng SP, Zhang Y, Shan WL, et al. Association between human papillomavirus and EGFR mutations in advanced lung adenocarcinoma. Oncology letters. 2016;12(3):1953-8.

113. Marquez-Medina D, Gasol-Cudos A, Taberner-Bonastre MT, Samame Perez-Vargas JC, Salud-Salvia A, Llombart-Cussac A. Human papillomavirus in non-small-cell lung cancer: the impact of EGFR mutations and the response to erlotinib. Archivos de bronconeumologia. 2013;49(2):79-81.

114. Schimmer AD. Inhibitor of apoptosis proteins: translating basic knowledge into clinical practice. Cancer research. 2004;64(20):7183-90.

115. Wu HH, Wu JY, Cheng YW, Chen CY, Lee MC, Goan YG, et al. cIAP2 upregulated by E6 oncoprotein via epidermal growth factor receptor/phosphatidylinositol 3-kinase/AKT pathway confers resistance to cisplatin in human papillomavirus 16/18-infected lung cancer. Clinical cancer research : an official journal of the American Association for Cancer Research. 2010;16(21):5200-10.

116. Kawahara A, Azuma K, Hattori S, Nakashima K, Basaki Y, Akiba J, et al. The close correlation between 8-hydroxy-2'-deoxyguanosine and epidermal growth factor receptor activating mutation in non-small cell lung cancer. Human pathology. 2010;41(7):951-9.

117. Munoz JP, Gonzalez C, Parra B, Corvalan AH, Tornesello ML, Eizuru Y, et al. Functional interaction between human papillomavirus type 16 E6 and E7 oncoproteins and cigarette smoke components in lung epithelial cells. PloS one. 2012;7(5):e38178.

118. Pena N, Carrillo D, Munoz JP, Chnaiderman J, Urzua U, Leon O, et al. Tobacco smoke activates human papillomavirus 16 p97 promoter and cooperates with high-risk E6/E7 for oxidative DNA damage in lung cells. PloS one. 2015;10(4):e0123029.

119. Rubin H. Synergistic mechanisms in carcinogenesis by polycyclic aromatic hydrocarbons and by tobacco smoke: a bio-historical perspective with updates. Carcinogenesis. 2001;22(12):1903-30.

120. Alam S, Conway MJ, Chen HS, Meyers C. The cigarette smoke carcinogen benzo[a]pyrene enhances human papillomavirus synthesis. Journal of virology. 2008;82(2):1053-8.

121. Lee MN, Tseng RC, Hsu HS, Chen JY, Tzao C, Ho WL, et al. Epigenetic inactivation of the chromosomal stability control genes BRCA1, BRCA2, and XRCC5 in non-small cell lung cancer. Clinical cancer research : an official journal of the American Association for Cancer Research. 2007;13(3):832-8.

122. Johansson F, Lagerqvist A, Erixon K, Jenssen D. A method to monitor replication fork progression in mammalian cells: nucleotide excision repair enhances and homologous recombination delays elongation along damaged DNA. Nucleic acids research. 2004;32(20):e157.

123. Cheng YW, Lin FC, Chen CY, Hsu NY. Environmental exposure and HPV infection may act synergistically to induce lung tumorigenesis in nonsmokers. Oncotarget. 2016;7(15):19850-62.

124. De Blasio A, Vento R, Di Fiore R. Mcl-1 targeting could be an intriguing perspective to cure cancer. Journal of cellular physiology. 2018;233(11):8482-98.

125. Chang YH, Yu CW, Lai LC, Tsao CH, Ho KT, Yang SC, et al. Up-regulation of interleukin-17 expression by human papillomavirus type 16 E6 in nonsmall cell lung cancer. Cancer. 2010;116(20):4800-9.

126. Cheng YW, Lee H, Shiau MY, Wu TC, Huang TT, Chang YH. Human papillomavirus type 16/18 up-regulates the expression of interleukin-6 and antiapoptotic Mcl-1 in non-small cell lung cancer. Clinical cancer research : an official journal of the American Association for Cancer Research. 2008;14(15):4705-12.

127. Zhang J, Zhang J, Cui X, Yang Y, Li M, Qu J, et al. FoxM1: a novel tumor biomarker of lung cancer. International journal of clinical and experimental medicine. 2015;8(3):3136-40.

128. Luscher-Firzlaff JM, Westendorf JM, Zwicker J, Burkhardt H, Henriksson M, Muller R, et al. Interaction of the fork head domain transcription factor MPP2 with the human papilloma virus 16 E7 protein: enhancement of transformation and transactivation. Oncogene. 1999;18(41):5620-30.

129. Xia Y, Chen Q, Zhong Z, Xu C, Wu C, Liu B, et al. Down-regulation of miR-30c promotes the invasion of non-small cell lung cancer by targeting MTA1. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology. 2013;32(2):476-85.

130. Wu YL, Hsu NY, Cheau-Feng Lin F, Lee H, Cheng YW. MiR-30c-2* negative regulated MTA-1 expression involved in metastasis and drug resistance of HPV-infected non-small cell lung cancer. Surgery. 2016;160(6):1591-8.

131. Christensen ND, Budgeon LR, Cladel NM, Hu J. Recent advances in preclinical model systems for papillomaviruses. Virus research. 2017;231:108-18.

132. Carraresi L, Tripodi SA, Mulder LC, Bertini S, Nuti S, Schuerfeld K, et al. Thymic hyperplasia and lung carcinomas in a line of mice transgenic for keratin 5-driven HPV16 E6/E7 oncogenes. Oncogene. 2001;20(56):8148-53.

133. Carraresi L, Martinelli R, Vannoni A, Riccio M, Dembic M, Tripodi S, et al. Establishment and characterization of murine small cell lung carcinoma cell lines derived from HPV-16 E6/E7 transgenic mice. Cancer letters. 2006;231(1):65-73.

134. Vonsky MS, Runov AL, Gordeychuk IV, Isaguliants MG. Therapeutic Vaccines Against Human Papilloma Viruses: Achievements and Prospects. Biochemistry Biokhimiia. 2019;84(7):800-16.

135. Feng H, Shuda M, Chang Y, Moore PS. Clonal integration of a polyomavirus in human Merkel cell carcinoma. Science. 2008;319(5866):1096-100.

136. Pantulu ND, Pallasch CP, Kurz AK, Kassem A, Frenzel L, Sodenkamp S, et al. Detection of a novel truncating Merkel cell polyomavirus large T antigen deletion in chronic lymphocytic leukemia cells. Blood. 2010;116(24):5280-4.

137. Dworkin AM, Tseng SY, Allain DC, Iwenofu OH, Peters SB, Toland AE. Merkel cell polyomavirus in cutaneous squamous cell carcinoma of immunocompetent individuals. The Journal of investigative dermatology. 2009;129(12):2868-74.

138. Imajoh M, Hashida Y, Nemoto Y, Oguri H, Maeda N, Furihata M, et al. Detection of Merkel cell polyomavirus in cervical squamous cell carcinomas and adenocarcinomas from Japanese patients. Virology journal. 2012;9:154.

139. Sadeghi F, Salehi-Vaziri M, Alizadeh A, Ghodsi SM, Bokharaei-Salim F, Fateh A, et al. Detection of Merkel cell polyomavirus large T-antigen sequences in human central nervous system tumors. Journal of medical virology. 2015;87(7):1241-7.

140. Schowalter RM, Pastrana DV, Pumphrey KA, Moyer AL, Buck CB. Merkel cell polyomavirus and two previously unknown polyomaviruses are chronically shed from human skin. Cell host & microbe. 2010;7(6):509-15.

141. Babakir-Mina M, Ciccozzi M, Lo Presti A, Greco F, Perno CF, Ciotti M. Identification of Merkel cell polyomavirus in the lower respiratory tract of Italian patients. Journal of medical virology. 2010;82(3):505-9.

142. Mancuso G, Antona J, Sirini C, Salvo M, Giacometti L, Olivero C, et al. Frequent detection of Merkel cell polyomavirus DNA in tissues from 10 consecutive autopsies. The Journal of general virology. 2017;98(6):1372-6.

143. van der Heijden HF, Heijdra YF. Extrapulmonary small cell carcinoma. Southern medical journal. 2005;98(3):345-9.

144. Pulitzer MP, Amin BD, Busam KJ. Merkel cell carcinoma: review. Advances in anatomic pathology. 2009;16(3):135-44.

145. Andres C, Ihrler S, Puchta U, Flaig MJ. Merkel cell polyomavirus is prevalent in a subset of small cell lung cancer: a study of 31 patients. Thorax. 2009;64(11):1007-8.

146. Helmbold P, Lahtz C, Herpel E, Schnabel PA, Dammann RH. Frequent hypermethylation of RASSF1A tumour suppressor gene promoter and presence of Merkel cell polyomavirus in small cell lung cancer. European journal of cancer. 2009;45(12):2207-11.

147. Wetzels CT, Hoefnagel JG, Bakkers JM, Dijkman HB, Blokx WA, Melchers WJ. Ultrastructural proof of polyomavirus in Merkel cell carcinoma tumour cells and its absence in small cell carcinoma of the lung. PloS one. 2009;4(3):e4958.

148. Karimi S, Yousefi F, Seifi S, Khosravi A, Nadji SA. No evidence for a role of Merkel cell polyomavirus in small cell lung cancer among Iranian subjects. Pathology, research and practice. 2014;210(12):836-9.

149. Lasithiotaki I, Antoniou KM, Derdas SP, Sarchianaki E, Symvoulakis EK, Psaraki A, et al. The presence of Merkel cell polyomavirus is associated with deregulated expression of BRAF and Bcl-2 genes in non-small cell lung cancer. International journal of cancer. 2013;133(3):604-11.

150. Joh J, Jenson AB, Moore GD, Rezazedeh A, Slone SP, Ghim SJ, et al. Human papillomavirus (HPV) and Merkel cell polyomavirus (MCPyV) in non small cell lung cancer. Experimental and molecular pathology. 2010;89(3):222-6.

151. Gheit T, Munoz JP, Levican J, Gonzalez C, Ampuero S, Parra B, et al. Merkel cell polyomavirus in non-small cell lung carcinomas from Chile. Experimental and molecular pathology. 2012;93(1):162-6.

152. Xu S, Jiang J, Yu X, Sheng D, Zhu T, Jin M. Association of Merkel cell polyomavirus infection with EGFR mutation status in Chinese non-small cell lung cancer patients. Lung cancer. 2014;83(3):341-6.

153. Kim GJ, Lee JH, Lee DH. Clinical and prognostic significance of Merkel cell polyomavirus in nonsmall cell lung cancer. Medicine. 2017;96(3):e5413.

154. Becker M, Dominguez M, Greune L, Soria-Martinez L, Pfleiderer MM, Schowalter R, et al. Infectious Entry of Merkel Cell Polyomavirus. Journal of virology. 2019;93(6).

155. Samimi M, Kervarrec T, Touze A. Immunobiology of Merkel cell carcinoma. Current opinion in oncology. 2020;32(2):114-21.

156. Paik PK, Arcila ME, Fara M, Sima CS, Miller VA, Kris MG, et al. Clinical characteristics of patients with lung adenocarcinomas harboring BRAF mutations. Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2011;29(15):2046-51.

157. Brambilla E, Negoescu A, Gazzeri S, Lantuejoul S, Moro D, Brambilla C, et al. Apoptosis-related factors p53, Bcl2, and Bax in neuroendocrine lung tumors. The American journal of pathology. 1996;149(6):1941-52.

158. Chang CM, Yu KJ, Mbulaiteye SM, Hildesheim A, Bhatia K. The extent of genetic diversity of Epstein-Barr virus and its geographic and disease patterns: a need for reappraisal. Virus research. 2009;143(2):209-21.

159. Deyrup AT. Epstein-Barr virus-associated epithelial and mesenchymal neoplasms. Human pathology. 2008;39(4):473-83.

160. Kheir F, Zhao M, Strong MJ, Yu Y, Nanbo A, Flemington EK, et al. Detection of Epstein-Barr Virus Infection in Non-Small Cell Lung Cancer. Cancers. 2019;11(6).

161. Lin Z, Situ D, Chang X, Liang W, Zhao M, Cai C, et al. Surgical treatment for primary pulmonary lymphoepithelioma-like carcinoma. Interactive cardiovascular and thoracic surgery. 2016;23(1):41-6.

162. Liang Y, Wang L, Zhu Y, Lin Y, Liu H, Rao H, et al. Primary pulmonary lymphoepithelioma-like carcinoma: fifty-two patients with long-term follow-up. Cancer. 2012;118(19):4748-58.

163. Chang YL, Wu CT, Shih JY, Lee YC. Unique p53 and epidermal growth factor receptor gene mutation status in 46 pulmonary lymphoepithelioma-like carcinomas. Cancer science. 2011;102(1):282-7.

164. Chen YP, Chan ATC, Le QT, Blanchard P, Sun Y, Ma J. Nasopharyngeal carcinoma. Lancet. 2019;394(10192):64-80.

165. Chu PG, Cerilli L, Chen YY, Mills SE, Weiss LM. Epstein-Barr virus plays no role in the tumorigenesis of small-cell carcinoma of the lung. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc. 2004;17(2):158-64.

166. Gomez-Roman JJ, Martinez MN, Fernandez SL, Val-Bernal JF. Epstein-Barr virus-associated adenocarcinomas and squamous-cell lung carcinomas. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc. 2009;22(4):530-7.

167. Tanner J, Weis J, Fearon D, Whang Y, Kieff E. Epstein-Barr virus gp350/220 binding to the B lymphocyte C3d receptor mediates adsorption, capping, and endocytosis. Cell. 1987;50(2):203-13.

168. Timens W, Boes A, Vos H, Poppema S. Tissue distribution of the C3d/EBV-receptor: CD21 monoclonal antibodies reactive with a variety of epithelial cells, medullary thymocytes, and peripheral T-cells. Histochemistry. 1991;95(6):605-11.

169. Malizia AP, Egan JJ, Doran PP. IL-4 increases CD21-dependent infection of pulmonary alveolar epithelial type II cells by EBV. Molecular immunology. 2009;46(8-9):1905-10.

170. Ngan RK, Yip TT, Cheng WW, Chan JK, Cho WC, Ma VW, et al. Clinical role of circulating Epstein-Barr virus DNA as a tumor marker in lymphoepithelioma-like carcinoma of the lung. Annals of the New York Academy of Sciences. 2004;1022:263-70.

171. Ngan RK, Yip TT, Cheng WW, Chan JK, Cho WC, Ma VW, et al. Circulating Epstein-Barr virus DNA in serum of patients with lymphoepithelioma-like carcinoma of the lung: a potential surrogate marker for monitoring disease. Clinical cancer research : an official journal of the American Association for Cancer Research. 2002;8(4):986-94.

172. Gray ME, Meehan J, Sullivan P, Marland JRK, Greenhalgh SN, Gregson R, et al. Ovine Pulmonary Adenocarcinoma: A Unique Model to Improve Lung Cancer Research. Frontiers in oncology. 2019;9:335.

173. Youssef G, Wallace WA, Dagleish MP, Cousens C, Griffiths DJ. Ovine pulmonary adenocarcinoma: a large animal model for human lung cancer. ILAR journal. 2015;56(1):99-115.

174. Martineau HM, Cousens C, Imlach S, Dagleish MP, Griffiths DJ. Jaagsiekte sheep retrovirus infects multiple cell types in the ovine lung. Journal of virology. 2011;85(7):3341-55.

175. Rai SK, Duh FM, Vigdorovich V, Danilkovitch-Miagkova A, Lerman MI, Miller AD. Candidate tumor suppressor HYAL2 is a glycosylphosphatidylinositol (GPI)-anchored cell-surface receptor for jaagsiekte sheep retrovirus, the envelope protein of which mediates oncogenic transformation. Proceedings of the National Academy of Sciences of the United States of America. 2001;98(8):4443-8.

176. De las Heras M, Barsky SH, Hasleton P, Wagner M, Larson E, Egan J, et al. Evidence for a protein related immunologically to the jaagsiekte sheep retrovirus in some human lung tumours. The European respiratory journal. 2000;16(2):330-2.

177. Linnerth-Petrik NM, Walsh SR, Bogner PN, Morrison C, Wootton SK. Jaagsiekte sheep retrovirus detected in human lung cancer tissue arrays. BMC research notes. 2014;7:160.

178. Rocca S, Sanna MP, Leoni A, Cossu A, Lissia A, Tanda F, et al. Presence of Jaagsiekte sheep retrovirus in tissue sections from human bronchioloalveolar carcinoma depends on patients' geographical origin. Human pathology. 2008;39(2):303-4.

179. Morozov VA, Lagaye S, Lower J, Lower R. Detection and characterization of betaretroviral sequences, related to sheep Jaagsiekte virus, in Africans from Nigeria and Cameroon. Virology. 2004;327(2):162-8.

180. Yousem SA, Finkelstein SD, Swalsky PA, Bakker A, Ohori NP. Absence of jaagsiekte sheep retrovirus DNA and RNA in bronchioloalveolar and conventional human pulmonary adenocarcinoma by PCR and RT-PCR analysis. Human pathology. 2001;32(10):1039-42.

181. Hiatt KM, Highsmith WE. Lack of DNA evidence for jaagsiekte sheep retrovirus in human bronchioloalveolar carcinoma. Human pathology. 2002;33(6):680.

182. Miller AD, De Las Heras M, Yu J, Zhang F, Liu SL, Vaughan AE, et al. Evidence against a role for jaagsiekte sheep retrovirus in human lung cancer. Retrovirology. 2017;14(1):3.

183. Berthet N, Frangeul L, Olaussen KA, Brambilla E, Dorvault N, Girard P, et al. No evidence for viral sequences in five lepidic adenocarcinomas (former "BAC") by a high-throughput sequencing approach. BMC research notes. 2015;8:782.

184. Giuliani L, Jaxmar T, Casadio C, Gariglio M, Manna A, D'Antonio D, et al. Detection of oncogenic viruses SV40, BKV, JCV, HCMV, HPV and p53 codon 72 polymorphism in lung carcinoma. Lung cancer. 2007;57(3):273-81.

185. Sinagra E, Raimondo D, Gallo E, Stella M, Cottone M, Rossi F, et al. JC Virus and Lung Adenocarcinoma: Fact or Myth? Anticancer research. 2017;37(6):3311-4.

186. White MK, Khalili K. Expression of JC virus regulatory proteins in human cancer: potential mechanisms for tumourigenesis. European journal of cancer. 2005;41(16):2537-48.

187. Khalili K, Del Valle L, Otte J, Weaver M, Gordon J. Human neurotropic polyomavirus, JCV, and its role in carcinogenesis. Oncogene. 2003;22(33):5181-91.

188. Zheng H, Abdel Aziz HO, Nakanishi Y, Masuda S, Saito H, Tsuneyama K, et al. Oncogenic role of JC virus in lung cancer. The Journal of pathology. 2007;212(3):306-15.

189. Eash S, Tavares R, Stopa EG, Robbins SH, Brossay L, Atwood WJ. Differential distribution of the JC virus receptor-type sialic acid in normal human tissues. The American journal of pathology. 2004;164(2):419-28.

190. Abdel-Aziz HO, Murai Y, Hong M, Kutsuna T, Takahashi H, Nomoto K, et al. Detection of the JC virus genome in lung cancers: possible role of the T-antigen in lung oncogenesis. Applied immunohistochemistry & molecular morphology : AIMM. 2007;15(4):394-400.

191. Noguchi A, Kikuchi K, Ohtsu T, Yoshiwara M, Nakamura Y, Miyagi Y, et al. Pulmonary tumors associated with the JC virus T-antigen in a transgenic mouse model. Oncology reports. 2013;30(6):2603-8.

192. Plummer M, de Martel C, Vignat J, Ferlay J, Bray F, Franceschi S. Global burden of cancers attributable to infections in 2012: a synthetic analysis. Lancet Glob Health. 2016;4(9):E609-E16.