The integration of HPV-18 DNA in cervical carcinoma.

AIMS: Little information is available on the patterns of integration into the host chromosomal DNA of cervical carcinomas of human papillomavirus type 18 (HPV-18) DNA, which is associated with up to 20% of these carcinomas. Because integration of the viral genome may be extremely important in the pathogenesis of cervical carcinoma, the aim of this study was to investigate which regions of HPV-18 DNA are integrated into the cellular DNA of cervical carcinomas. METHODS: Southern analysis using four subgenomic probes covering the entire HPV-18 genome was used to map viral DNA integrated within cellular DNA. The polymerase chain reaction (PCR) was used to confirm the presence of specific regions of the viral genome. RESULTS: In all 11 carcinomas there was a single major HPV-18 DNA integrant, retaining approximately 4000 bp of HPV-18 DNA, indicating that approximately half of the virus genome had been lost upon integration. Southern analysis suggested strongly that the viral breakpoint was within the E1/E2 gene boundary, with concomitant loss of part or all of the E2 ORF (open reading frame), all of the E4, E5, and L2 ORFs and part of the L1 ORF. These data were supported by the PCR results, which confirmed that the region of integrated HPV-18 DNA from nucleotides 6558 to 162 was present in all the carcinoma samples studied. Assuming that no genomic rearrangements, deletions, or insertions had occurred, 4131 bp of integrated HPV-18 DNA could be accounted for in eight cervical carcinoma samples. The results of Southern analysis also suggested that integration of HPV-18 DNA may have occurred at a specific host chromosomal site. CONCLUSIONS: Broadly, the viral sequences retained upon HPV-18 integration resemble those found when HPV-16 is integrated. However, it appears that the HPV-18 E2 region is more consistently deleted.     

原位杂交检测HPV-16E6,-18E6在喉癌组织中的表达

目的 检测HPV L1和16/18DNA在喉癌组织中的表达,探讨HPV在喉癌发生中的作用.方法 用原位杂交(ISH)检测123例喉癌组织及123例"正常人"的喉粘膜上皮组织中HPV-16/18 mRNA.结果 在123例喉癌标本中,ISH检出HPV-16E6的阳性率为46.34%,HPV-18E6的阳性率为35.77%.123例"正常人"的喉粘膜ISH结果表明:低危型HPV的阳性率与喉癌相近;高危型HPV的阳性率虽远远低于喉癌,但随着组织病变程度加重阳性率逐渐升高.对上述结果用SPSS 10.0软件进行case-control X2分析,HPV-16感染会增加喉上皮病变的风险(OR=14.58),感染HPV-18时,喉上皮病变的风险(OR=10.77).结论 HPV-16感染是重庆地区喉癌的重要发病因素;HPV-16感染后E6片段的保留并持续表达与喉组织的癌变进程密切相关;HPV-16感染会增强喉上皮病变的风险,而HPV-18有协同作用.     

The prevalence of HPV-18 and variants of E6 gene isolated from cervical cancer patients in Taiwan.

BACKGROUND: Cervical cancer is the second most common cancer in women worldwide. It has been considered that human papillomavirus (HPV) is associated with cervical cancer. Currently, more than 80 different serotypes of HPV have been characterized and they are divided into low- and high-risk groups. The most common types that lead to cervical cancer are HPV-16 and -18. The viral oncogenes E6 and E7 are associated with the development of cervical cancer. In previous study, the variants of HPV-16 E6 gene have been reported. It suggests that variants may influence the morbidity of carcinogenesis, but the variant study on HPV-18 remains unknown. OBJECTIVES: To identify the variants of integrated HPV-18 E6 gene in the prevalent infection of HPV-18 of cervical cancer patients. STUDY DESIGN: 25 cervical cancer patients were clinically identified and the biopsies were obtained. The infectious HPV types were identified by PCR and Southern blotting analysis. The DNA fragments of the integrated HPV-18 E6 were amplified by PCR and cloned. The nucleotide sequences were obtained by sequencing. RESULTS: The prevalence of HPV infection in our 25 cases was HPV-18 (100%) and 7 out of these 25 cases (28%) were co-infected with HPV-16. The most dominant mutation among 25 tested patients was a silence mutation C183G of the E6 coding region. CONCLUSIONS: The prevalent HPV infectious serotype is HPV-18, which differs from the worldwide prevalent type. The identified HPV-18 E6 variants had a unique silence mutation located on C183G in E6 coding region.     

Development of a sensitive and specific nanoparticle-assisted PCR assay for detecting HPV-16 and HPV-18 DNA

Carcinoma precursor lesion caused by persistent infection of human papillomavirus (HPV) types 16 and 18 is known as a principal inducer of cervical cancer. Therefore, rapid and effective detection of HPV-16 and HPV-18 infection at early stage is an important strategy for preventing such disease. In this study, a novel duplex nanoparticle-assisted polymerase chain reaction (nanoPCR) assay was developed to detect both of the two genotypes simultaneously. Two pairs of primers for nanoPCR were designed based on the conserved region within the early 6 (E6) gene of HPV-16 and HPV-18, respectively. After optimizing reaction conditions, the nanoPCR assay displayed 10-fold more sensitive than that of conventional PCR and showed high specificity. The detection limit of nanoPCR was 1.7 × 10¹ copies/μL for HPV-16, 1.2 × 10² copies/μL for HPV-18, and no cross-reaction was detected after using other viruses or HPV subtypes as templates. Of 209 clinical samples collected from patients, as also confirmed by sequencing, the nanoPCR method gave consistent results with conventional PCR assay: 7 positives for HPV-16, 4 positives for HPV-18, and no co-infection. Here is the first report to introduce a reproducible nanoPCR assay for detecting HPV DNA with high sensitivity and specificity, which may point out a useful diagnostic tool for potential clinical application.     

Conservation of HPV-16 E6/E7 ORF sequences in a cervical carcinoma.

A cervical carcinoma that contained human papillomavirus (HPV)-16 homologous DNA was analyzed. Each tumor cell genome contained a single, incomplete copy of HPV-16 DNA. The E6 and E7 open reading frames (ORFs) were completely conserved relative to other published HPV-16 sequences. Much of the non-coding region (NCR) was free of base changes, including complete conservation of several regulatory elements. Multiple mutations were identified in the remaining integrated HPV-16 DNA, which was composed of parts of the L1 and E1 ORFs. The extraordinary conservation of the E6/E7 DNA sequence, as compared with other regions of the integrated HPV-16 DNA, supports the role of E6/E7 in tumorigenesis.     

人乳头瘤病毒16型E＿6E＿7基因反义质粒对人宫颈癌细胞恶性的逆转作用

构建可为地塞米松诱导表达的人乳头瘤病毒１６型（ＨＰＶ－１６）Ｅ＿６Ｅ＿７基因反义质粒（ｐ１６ａｓＥ＿６Ｅ＿７Ｎｅｏ），利用磷酸钙沉淀法将其分别转染到ＨＰＶ－１６阳性的人宫颈癌细胞株Ｃａｓｋｉ和ＨＰＶ阴性的人宫颈癌细胞株Ｃ－３３Ａ中。地塞米松诱导反义质粒表达后，ＣａｓＫｉ细胞失去其恶性表型，而Ｃ－３３Ａ细胞的生长特性及恶性行为未发生变化。说明反义质粒能够改变Ｃａｓｋｉ细胞的恶性表型，且这种改变是通过特异性抑制Ｅ＿６Ｅ＿７基因表达实现的。     

Unscheduled DNA replication origin activation at inserted HPV 18 sequences in a HPV-18/MYC amplicon

Oncogene amplification is a critical step leading to tumorigenesis, but the underlying mechanisms are still poorly understood. Despite data suggesting that DNA replication is a major source of genomic instability, little is known about replication origin usage and replication fork progression in rearranged regions. Using a single DNA molecule approach, we provide here the first study of replication kinetics on a previously characterized MYC/papillomavirus (HPV18) amplicon in a cervical cancer. Using this amplicon as a model, we investigated the role DNA replication control plays in generating amplifications in human cancers. The data reveal severely perturbed DNA replication kinetics in the amplified region when compared with other regions of the same genome. It was found that DNA replication is initiated from both genomic and viral sequences, resulting in a higher median frequency of origin firings. In addition, it was found that the higher initiation frequency was associated with an equivalent increase in the number of stalled replication forks. These observations raise the intriguing possibility that unscheduled replication origin activation at inserted HPV-18 viral DNA sequences triggers DNA amplification in this cancer cell line and the subsequent overexpression of the MYC oncogene.     

Identification of peptides presented by HLA class I molecules on cervical cancer cells with HPV-18 infection.

In this work we eluted peptides from purified class I MHC molecules, isolated from a novel human cervical carcinoma cell line (INBL), generated in our laboratory and positive for HPV-18 infection. A fraction of these peptides was capable of stimulating T lymphocytes obtained from a donor matched for HLA-Cw4 and who was also HPV-18+. Direct N-terminal Edman degradation of these peptides, revealed the sequence (XQFPIFLQF) that matched 85% with the sequence NVFPIFLQM localized in between the 54 and 62 residues of the HPV-18 L1 protein. After stimulation with the synthetic peptide NVFPIFLQM, T lymphocytes from the donor were capable to lyse INBL cells. Our results provide evidence of the existence of naturally occurring viral epitopes presented on cervical cancer cells by the HLA-Cw4 allele, that could be useful for immunotherapy on this type of patient.     

HPV-18 immortalization of human keratinocytes

The oncogenic potential of human papillomavirus type 18 which is found in a significant number of cervical and penile cancer biopsies was tested in primary human keratinocytes derived from neonatal foreskin. Viral DNA and a gene for resistance to neomycin were introduced into these cells by calcium phosphate transfection. Selection of cells in G418 led to the isolation of resistant colonies which were propagated in culture. Four cell lines termed FE-A, FEH 18L, FEP18-5, and FEP18-11 have been maintained in culture for 1 1/2-2 years and were selected for further analysis. In all cases the viral DNA was integrated into the cellular genome and the early genes were transcribed, including RNA complementary to the E2, E6, and E7 open reading frames. Radioimmunoprecipitation showed that all cell lines synthesized the E6 and E7 proteins. However, none of the cell lines tested were tumorigenic. The differentiation capacity of these cells was analyzed by assessing their ability to proliferate clonally after exposure to 1.2 mM calcium chloride. All four cell lines were resistant to this stimulus and formed colonies upon return to regular growth medium whereas normal cells differentiated terminally. K6a and K14 keratin RNA expression was down-regulated in the HPV immortalized cell lines compared to primary human epithelial cells.     

HPV DNA in plasma of patients with cervical carcinoma.

BACKGROUND: HPV DNA has been detected in metastatic tumour and HPV plasma viraemia may indicate a poor prognosis and a high risk for metastasis. OBJECTIVE: Detection of HPV DNA in plasma of patients with cervical carcinoma. STUDY DESIGN: A cross-sectional study was done, wherein cervical biopsies and plasma samples were collected from 58 women with invasive cervical carcinoma, 10 women with cervical intraepithelial neoplasia (CIN) and 30 control women in the same age range. Polymerase chain reaction (PCR) was employed to detect the presence of HPV DNA. Samples positive for HPV DNA were typed by restriction fragment length polymorphism (RFLP). To confirm that the HPV sequence in plasma was identical to that in tissue, sequencing was done on all the paired plasma and tissue samples. RESULTS: All the 30 paired cervical tissue and plasma samples from the controls were negative for HPV DNA. HPV DNA was detectable in cervical tissues of 55 (94.8%) of 58 patients with invasive cervical carcinoma and in all 10 patients (100%) with CIN and in eight (11.8%) of the total 68 plasma samples from patients. All eight plasma samples were from women with invasive cervical carcinoma with three each in stages IIIB and IV and one each in stages IIB and IB, respectively. Of the eight positive samples, seven were typed as HPV-16 and 1 as HPV-58. HPV types detected in cervical tissue and plasma pairs from these eight patients correlated as revealed by RFLP and sequencing. A patient with stage IB cancer had detectable HPV DNA in the external iliac lymph node, removed at Wertheims hysterectomy, which was histopathologically free of tumour. The HPV type in the node, was the same as that present in the paired tissue and plasma sample. CONCLUSIONS: HPV DNA is detectable in the plasma of patients with advanced cervical cancer.     

Detection of HPV-16 DNA by PCR in histologically cancer free lymph nodes from patients with cervical cancer.

The prognostic value of detection of human papillomavirus (HPV) type 16 DNA in histologically cancer free lymph nodes was assessed in left obturator lymph nodes from cervical cancer patients with HPV-16 positive primary tumours. HPV-16 DNA was detected by polymerase chain reaction in 12 of 35 patients with histologically cancer free lymph nodes. Of these 12 patients, only one developed a recurrence, suggesting HPV-16 DNA detection in cancer free lymph nodes has no prognostic value.     

新疆维吾尔族妇女宫颈癌组织中人乳头状瘤病毒16型上游调控区DNA多态性分析

目的 探讨新疆南部地区维吾尔族妇女官颈癌组织中人乳头状瘤病毒16型（human papillomavirus16，HPV-16）上游调控区（upstream regulatory region，URR）的变异及其与新疆维吾尔族妇女官颈癌发生的关系。方法 从19份中国新疆南部地区维吾尔族妇女官颈癌活检组织标本中提取DNA，以此DNA为模板，PCR扩增HPV-16 URR DNA片段，PCR产物直接测序或克隆后测序，分析新疆维吾尔族妇女官颈癌组织HPV-16URR DNA多态性。结果 PCR检测结果显示宫颈癌组织中HPV-16 URR阳性率为89．47％（17／19）；测序和序列分析表明，与HPV-16原型比较，HPV-16URR核苷酸多处发生变异，URR在核苷酸水平上形成11种突变模式（XJU-1～XJU-11），XJU-1和XJU-4突变模式各占23．53％（4／17），其余各突变模式均占5．88％（1／17），各模式与HPV-16URR原型比较，同源性在98．50％～99．68％之间。在各位点的突变中，7192位（G→T）、7520位（G→A）的突变（100％，17／17）在新疆地区趋于恒定，该两处突变在亚裔美洲型（从）中普遍存在，与病毒感染及官颈癌发生相关；7729位（A→C）、7843位（A→G）、7792位（C→T）的突变可显著提高启动子的转录活性；其余突变尚未见报道，部分突变为新疆地区分离的HPV-16 URR所特有。结论 中国新疆南部HPV-16 URR基因发生变异，HPV-16 URR的突变与HPV-16的系统发生以及新疆维吾尔族妇女高发宫颈癌存在一定关系。     

宫颈癌HPV16,18 DNA定量分析

目的为了研究HPV16/18病毒载量与宫颈癌危险性的关系.方法 FQPCR用于HPVDNA的检测,卡方检验用于阳性率的分析,t检验用于病毒DNA量的分析.结果宫颈癌妇女高危型阳性率显著高于湿疣组妇女;病毒载量也显著高于后者.结论宫颈癌与高危型HPV感染相关,随病毒载量增加致癌危险性增大.     

Physical status of HPV-16 in esophageal squamous cell carcinoma.

BACKGROUND: Infection with high-risk human papillomavirus (HPV) has been implicated as one of the risk factors of esophageal squamous cell carcinoma (ESCC). Integration of viral DNA into host genome is essential for carcinogenesis since it promotes disruption of the HPV E2 gene, leading to abnormal expression of E6 and E7 oncoproteins. OBJECTIVES AND STUDY DESIGN: To investigate the viral integration status of HPV-16 infection in ESCC, 35 HPV-positive ESCC specimens collected from Chinese patients were subject to real-time quantitative PCR for determination of physical status of HPV-16 by analyzing the ratios of E2 to E6 genes. RESULTS: Our results showed that only 8.6% (3/35) of the HPV-16 positive specimens harbored exclusively the episomal form (i.e. E2/E6 ratio > or = 1), whereas the remaining 91.4% contained either only the integrated form (5.7%, with E2/E6 ratio = 0) or a mixture of episomal and integrated forms of viral molecules (85.7%, with E2/E6 ratios > 0 but < 1). Amongst the 30 cancer specimens carrying mixed integrated and episomal forms, 28 had E2/integrated E6 ratios of less than 1, indicating a predominance of integrated form of viral genes in these lesions. CONCLUSION: Our finding of frequent integration of viral DNA in the host genome suggests that integration HPV-16 is common in ESCC from Chinese patients and implies that HPV infection may play a role in the pathogenesis of ESCC.     

Differences in transformation activity between HPV-18 and HPV-16 map to the viral LCR-E6-E7 region.

Homologous, subgenomic fragments of the viral LCR and E6/E7 transforming genes of HPV-18 and HPV-16 were amplified from several primary cervical, penile, and vulvar tumors and cloned into a pUC-18-derived vector. When assayed by a quantitative transformation assay using primary human keratinocytes, the subgenomic regions of HPV-16 and HPV-18 exhibited transforming activities similar to that of the full-length, prototype HPV genomes. More importantly, the HPV-18 LCR-E6-E7 region was approximately 10- to 50-fold more active than that of HPV-16. These studies demonstrate (1) that the transforming activity differences previously observed between prototype HPV-16 and HPV-18 map to the LCR-E6-E7 region, and (2) that individual and independent isolates of HPV-16 and HPV-18 exhibit consistent differences in transforming potential, even when isolated from different anatomic sites.     

Human papillomavirus type 16 integration in cervical carcinoma in situ and in invasive cervical cancer

Integration of human papillomavirus type 16 (HPV-16) into the host DNA has been proposed as a potential marker of cervical neoplastic progression. In this study, a quantitative real-time PCR (qRT-PCR) was used to examine the physical status of HPV-16 in 126 cervical carcinoma in situ and 92 invasive cervical cancers. Based on criteria applied to results from this qRT-PCR assay, HPV-16 was characterized in carcinoma in situ cases as episomal (61.9%), mixed (i.e., episomal and integrated; 29.4%), and integrated (8.7%) forms. In invasive cervical cancer samples, HPV-16 was similarly characterized as episomal (39.1%), mixed (45.7%), and integrated (15.2%) forms. The difference in the frequency of integrated or episomal status estimated for carcinoma in situ and invasive cervical cancer cases was statistically significant (P = 0.003). Extensive mapping analysis of HPV-16 E1 and E2 genes in 37 selected tumors demonstrated deletions in both E1 and E2 genes with the maximum number of losses (78.4%) observed within the HPV-16 E2 hinge region. Specifically, deletions within the E2 hinge region were detected most often between nucleotides (nt) 3243 and 3539. The capacity to detect low-frequency HPV-16 integration events was highly limited due to the common presence and abundance of HPV episomal forms. HPV-16 E2 expressed from intact episomes may act in trans to regulate integrated genome expression of E6 and E7.