The presence of human papillomavirus 16 in neural structures and vascular endothelial cells

Human papillomavirus (HPV) is known as a strictly epitheliotropic pathogen. Our results raised the possibility that HPV 16 is present in neural cells and in the vascular endothelium. By in situ hybridization, we have detected HPV 16 E6 ORF sequence in small blood vessels and peripheral nerves adjacent to oral and cervical cancers. The same structures have clearly shown immunohistochemical reactivity for the E6 oncoprotein. These results were verified by PCR applied to E6 and L1 ORFs following microscopic laser dissection of the immunohistochemically positive nerves and vessels. These observations suggest that HPV 16 DNA and protein are present in neurons and endothelial cells in the vicinity of HPV-associated tumors. The HPV 16 genome presumably exists in a non-replicating form in the neurons and constitutively produces high levels of E6 and E7 proteins with an unknown neuropathological outcome.     

A novel interaction between the human papillomavirus type 16 E2 and E1^E4 proteins leads to stabilization of E2

The E4 (also called E1^E4) and E2 proteins of human papillomavirus type 16 are thought to be expressed within the same cells of a lesion, and their open reading frames overlap, suggesting that they may have a functional relationship. We have examined the effect of co-expression of these two proteins and found that each enhances the level of the other. We also identified the N-terminus of E2 as the first example of a viral protein that directly binds the HPV16 E1^E4 protein. This appears to result in the E2 becoming less soluble and promotes its relocation from the nucleus to the cytoplasm. In addition, the turnover of the E2 protein is decreased in the presence of E1^E4. All this raises the possibility that E1^E4 acts to influence E2 activity by varying the amount of available E2 in the cell.     

Human papillomavirus types 16 and 18 and the prognosis of patients with stage I cervical cancer

OBJECTIVE:

This study sought to evaluate the prevalence of human papillomavirus (HPV) types 16 and 18 in women with clinical stage IB cervical cancer treated by radical hysterectomy with pelvic lymphadenectomy as well as to establish a correlation between HPV type and cancer prognosis.

METHODS:

A single-center cohort study was conducted with 86 patients who had undergone radical hysterectomy for stage I cervical cancer. Prognostic factors and the presence of HPV 16 and 18 were analyzed using a polymerase chain reaction assay. A univariate analysis using Kaplan-Meier curves was conducted to estimate survival.

RESULTS:

The prevalence of HPV 16 in the study group was 65.3%, and the prevalence of HPV 18 was 33.3%. The prevalence of infection with both viruses was 26.9%. Overall survival at 5 years was 91% among women with HPV 18 and 96% among those without this virus type (p = 0.133). Among the women with HPV 16, the overall survival was 94%, whereas this rate was 96% among those without this virus type (p = 0.663). Disease-free survival was unaffected by the presence of HPV type 16 or 18.

CONCLUSION:

In the present study, despite the high prevalence of HPV types 16 and 18, the presence of these virus types did not affect the prognosis of patients with stage I cervical cancer who underwent radical hysterectomy.     

北京地区人乳头瘤病毒16型感染及其E6/E7基因变异与宫颈病变的相关性研究

目的探讨HPV16感染及其E6/E7基因变异与宫颈病变的相关性。方法采用导流杂交技术进行HPV感染分型检测,PCR扩增出80份HPV16阳性宫颈病变的E6/E7基因、克隆入pMD18-T载体,双向测序分析基因变异与宫颈病变相关性。结果HPV16在宫颈病变患者中的检出率最高为33.3%(154/463),与病变程度相关(P<0.05)。E6/E7基因72份测序成功,DNA序列变异发生率为88.9%(64/72)。氨基酸序列E6-D32E(T96G)和E7-N29S(A86G)位点突变同时伴随存在,D32E/N29S的检出率为38.9%(28/72),与宫颈病变程度相关(P<0.05)。结论HPV16是北京地区来源的宫颈病变中最常见的致病型,其D32E/N29S变异与病变程度相关。     

人乳头瘤病毒16型E5转化基因的克隆及原核表达

目的建立人乳头瘤病毒16型E5基因的无性繁殖系,为进一步研究其致癌机理作准备.方法用PCR技术从HPV16质粒DNA中扩增出E5基因序列,连接到pGEM-T载体,将阳性的重组pGEM-T用BamH Ⅰ/EcoRⅠ双酶切并回收目的片段连接到原核表达载体pGEX-2T,转化DH5α菌株.取工程菌,IPTG诱导表达,SDS-PAGE电泳鉴定.结果①经PCR、测序和双酶切鉴定,认为HPV16E5正确插入上述表达载体,建立了该转化基因的无性繁殖系.②经IPTG诱导的pGEX-2T-E5质粒表达出约42KD的融合蛋白,分析含有约16KD HPV16 E5蛋白,与预期含HPV16 E5的融合蛋白分子量相符.结论①采用PCR克隆技术,扩增HPV16 E5转化基因目的片段,将其克隆到pGEM-T载体在国内首次建立了HPV16 E5转化基因的无性繁殖子.②成功构建HPV16 E5基因的原核表达质粒,并表达出GST-E5融合表达蛋白.     

Quantitative measurement of Human Papillomavirus type 16 L1/L2 DNA methylation correlates with cervical disease grade

BackgroundPersistent infection with Human Papillomavirus (HPV) type 16 causes the majority of cervical cancers. Genital HPV infection is very common, but neoplastic progression is uncommon. There is an urgent need to identify biomarkers associated with cervical neoplasia that can be used to triage women who test positive for HPV.ObjectivesTo assess the ability of quantitative measurement of HPV16 DNA methylation to separate samples of different cytology grades and cervical cancers, and determine which of the assessed regions of the HPV genome and individual CpGs are most informative.Study designDNA methylation was quantified by pyrosequencing of bisulphite converted DNA from liquid based cytology samples from 17 women with normal cytology and 20 women with severe dyskaryosis, and from fixed tissue from 24 women with cervical cancer. Methylation was assessed in the HPV Long Control Region (LCR), E2 and L1/L2 regions.ResultsIn cervical cancers, increased HPV DNA methylation was present in all regions. Increased methylation was also observed in severely dyskaryotic relative to normal samples, but only in the E2 and L1/L2 regions. The ability of methylation based classifiers to separate the three classes of material was assessed by ROC curve analyses. The best separation between normal and dyskaryotic samples was achieved by assessment of the L1/L2 CpGs at nucleotide positions 5600 and 5609 (AUC = 0.900, 95% CI: 0.793–1).ConclusionsThis study demonstrates the potential of quantification of HPV DNA methylation as a biomarker of cervical neoplasia. An algorithm considering methylation at specific L1/L2 CpGs appeared the most promising model.     

Genetic diversity of human papillomavirus type 16 E6, E7, and L1 genes in Italian women with different grades of cervical lesions

High‐risk human papillomaviruses (HPVs) are risk factors for the development of cervical cancer. HPV 16 is the most common type, being present in about 60% of cervical cancers worldwide. Previous studies have reported upon the association between HPV 16 E6 variants and increased risk of cervical intraepithelial neoplasia and invasive cervical cancer. In this study, the presence of HPV 16 polymorphisms in the E6, E7, and L1 genes was investigated in relation to the presence of high‐grade lesions. Sequencing of the E6 gene revealed the presence of nucleotide mutations resulting in 15 amino acid changes. Of these, the G134D and C136R fall within the CXXC zinger finger domain important for p53 binding. In the E7 gene, four nucleotide variations were identified with two leading to the amino acid substitutions L15V and S31R. The L1 gene showed 13 nucleotide changes leading to 11 amino acid substitutions. Among these, the R364C and N367D are located at the base of the HI‐loop of the L1 protein, considered to be the immunodominant epitope of HPV 16. No significant relationship between HPV 16 variants and high‐grade lesions was found. Phylogenetic analysis showed that all the HPV 16 variants identified belonged to the European lineage, except one which was of the Asian‐American lineage. The European‐350G variant was detected most frequently (22 of 34, 64.7%). The study provides some new data on the genetic diversity of HPV 16 which may help to understand the oncogenic potential of the virus and to improve management of patients. J. Med. Virol. 81:1627–1634, 2009. © 2009 Wiley‐Liss, Inc.     

Primary human cervical carcinoma cells require human papillomavirus E6 and E7 expression for ongoing proliferation

Repression of human papillomavirus (HPV) E6 and E7 oncogenes in established cervical carcinoma cell lines causes senescence due to reactivation of cellular tumor suppressor pathways. Here, we determined whether ongoing expression of HPV16 or HPV18 oncogenes is required for the proliferation of primary human cervical carcinoma cells in serum-free conditions at low passage number after isolation from patients. We used an SV40 viral vector expressing the bovine papillomavirus E2 protein to repress E6 and E7 in these cells. To enable efficient SV40 infection and E2 gene delivery, we first incubated the primary cervical cancer cells with the ganglioside GM1, a cell-surface receptor for SV40 that is limiting in these cells. Repression of HPV in primary cervical carcinoma cells caused them to undergo senescence, but the E2 protein had little effect on HPV-negative primary cells. These data suggest that E6 and E7 dependence is an inherent property of human cervical cancer cells.     

The full-length E1E4 protein of human papillomavirus type 18 modulates differentiation-dependent viral DNA amplification and late gene expression

Activation of the productive phase of the human papillomavirus (HPV) life cycle in differentiated keratinocytes is coincident with high-level expression of E1E4 protein. To determine the role of E1E4 in the HPV replication cycle, we constructed HPV18 mutant genomes in which expression of the full-length E1E4 protein was abrogated. Undifferentiated keratinocytes containing mutant genomes showed enhanced proliferation when compared to cells containing wildtype genomes, but there were no differences in maintenance of viral episomes. Following differentiation, cells with mutant genomes exhibited reduced levels of viral DNA amplification and late gene expression, compared to wildtype genome-containing cells. This indicates that HPV18 E1E4 plays an important role in regulating HPV late functions, and it may also function in the early phase of the replication cycle. Our finding that full-length HPV18 E1E4 protein plays a significant role in promoting viral genome amplification concurs with a similar report with HPV31, but is in contrast to an HPV11 study where viral DNA amplification was not dependent on full-length E1E4 expression, and to HPV16 where only C-terminal truncations in E1E4 abrogated vegetative genome replication. This suggests that type-specific differences exist between various E1E4 proteins.     

乳头瘤病毒16型E6,P53,RB,PCNA在宫颈癌中的表达状态及相关性

应用核酸原位杂交和免疫组织化学技术，检测人子宫颈癌中人乳头瘤病毒（ＨＰＶ）１６型Ｅ６ＯＲＦ与抑癌基因产物Ｐ５３，ＲＢ和增殖细胞核抗原（ＰＣＮＡ）。在４４例宫颈癌石蜡切片中，原位杂交检测出ＨＰＶ１６Ｅ６ＯＲＦ阳性２７例（６１．３６％），其中免疫组化检测出Ｐ５３、ＲＢ、ＰＣＮＡ阳性分别为８例（２９．６３％），１４例（５２．８５％）、２０例（７４．０７％），而在１７例ＨＰＶ１６Ｅ６阴性标本中Ｐ５３、ＲＢ、ＰＣＮＡ阳性分别为７例（４１．１７％），９例（５２．９４％）、１２例（７０．５８％）。而在５例正常宫颈组织中未测出ＨＰＶ１６Ｅ６ＯＲＦ，ＰＣＮＡ只在宫颈组织上皮基底层细胞中表达。统计学分析表明，ＨＰＶ１６Ｅ６与宫颈癌密切相关（Ｐ＜０．０５），ＰＣＮＡ在宫颈癌与正常宫颈组织中有显著性差异（Ｐ＜０．０５）。未能发现宫颈癌组织中ＨＰＶ１６Ｅ６ＯＲＦ与Ｐ５３蛋白相关性（Ｐ＞０．０５）。     

人乳头瘤病毒16型野毒株L1-E7融合基因重组腺病毒载体构建及在293细胞中表达嵌合病毒样颗粒的研究

目的制备人乳头瘤病毒HPV16L1-E7重组腺病毒,以期获得防治宫颈癌的重组腺病毒减毒活疫苗。方法以HPV16型的野毒株HPV16-114/K为模板,利用PCR克隆技术制备HPV16L1-E7融合基因pUC19L1-E7,含L1的1～301氨基酸（AA）和E7的1～60AA的编码DNA序列;并转入腺病毒穿梭质粒pCA14L1-E7,与腺病毒质粒pBHG10共转染293细胞,筛选重组腺病毒rAd5HPV16L1-E7。以PCR、ELISA和Westernblot方法鉴定重组病毒及其表达的L1-E7蛋白,密度梯度超速离心纯化HPV16嵌合L1-E7VLP,电镜观察VLP的形态结构。结果PCR-DNA序列分析表明成功构建了HPV16L1-E7重组质粒pUC19L1-E7;并获得HPV16重组腺病毒rAd5HPV16L1-E7,在293细胞中可高效表达L1-E7蛋白,并形成嵌合病毒样颗粒（cVLP）。结论构建的重组腺病毒rAd5HPV16L1-E7可有效表达HPV16L1-E7cVLP,可进一步用于动物实验,研究其在防治宫颈癌中的作用。     

Sequence variation of human papillomavirus type 16 E7 in preinvasive and invasive cervical neoplasias

Variation in the nucleotide sequence of the HPV 16 E7 gene in preinvasive cervical intra-epitherial neoplasia (CIN) and invasive cervical carcinoma specimens was analyzed. Direct DNA sequencing of PCR-amplified products with primers different from those used for PCR with 5-end labeling generated distinct sequence ladders with a low background, even in specimens containing relatively low copy numbers of HPV. Of 14 cervical neoplasias, 11 cases showed sequence diversity from prototype HPV16, and a total of 22 nucleotide exchanges were detected. Nine of these led to single amino acid exchanges: [Thr⁵] to [Lys⁵] in one case and [Asn²⁹] to [Ser²⁹] in eight cases. The [Ser²⁹] E7 was distributed uniformly among invasive carcinomas and precancerous legions, and was also found in a normal cervix. The [Lys⁵] E7 and [Ser²⁹] E7 had transforming potential similar to the prototype E7 assessed by cooperation with the activatedras gene in rat embryo fibroblasts.