Antibodies to HPV-16 E6 and E7 proteins as markers for HPV-16-associated invasive cervical cancer.

Transforming proteins E6 and E7 of human papillomaviruses (HPVs) are consistently expressed in HPV-associated cervical cancers. In ELISA with four HPV-16 E6-E7 peptides, patients with HPV-16-associated invasive cervical cancer (group 1) had a greater seroreactivity than all other groups, which included patients with HPV-16-associated cervical intraepithelial neoplasia, invasive cervical cancer patients without HPVs, and unaffected controls. A larger proportion of group 1 sera, as compared to sera of all other groups, was reactive with at least one peptide (49% vs 17-27%), and with two or more peptides (22% vs 0-6%). A clear difference between group 1 and all other groups was also found for high ELISA absorbance values to at least one peptide (22% vs 0-8%). This high seroreactivity of group 1 sera was confirmed by a radioimmunoprecipitation assay with in vitro transcribed and translated HPV-16 E7 protein. Sera from 50% of group 1 but only 3% of controls were reactive in this test. Antibodies to HPV-16 E6 and E7 proteins appear to be virus-specific and disease state-specific markers of HPV-associated cervical cancer.     

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.     

HPV16/18和HPV16E6/E7DNA在宫颈癌组织中的表达

目的检测HPV16/18和HPV16E6/E7 DNA在宫颈癌组织中的表达,探讨其在宫颈癌发病中的作用.方法应用PCR和琼脂糖凝胶电泳方法检测46例宫颈癌组织中HPV16/18和HPV16E6/E7DNA.结果 46例宫颈癌中56.5%(26/46)扩增HPV16/18 DNA,其中宫颈鳞癌25例,宫颈腺癌1例.正常对照组20例HPV16/18DNA均为阴性,与宫颈癌组相比差异有显著性(P<0.01).HPV16/18 DNA阳性拷贝对数值为4.32±2.45.HPV16E6,E7DNA分别有53.8%(14/26)、46.2%(12/26)扩增.结论 HPV16/18和HPV16E6/E7 DNA与宫颈癌的发生密切相关,是宫颈癌恶性转化的关键之一,预示着宫颈癌有较强的增殖能力和转移能力.     

Detection of human papillomavirus type 18 E7 oncoprotein in cervical smears: a feasibility study

Persistent infections by high-risk human papillomaviruses (HPVs) are the main etiological factor for cervical cancer, and expression of HPV E7 oncoproteins was suggested to be a potential marker for tumor progression. The objective of this study was to generate new reagents for the detection of the HPV18 E7 oncoprotein in cervical smears. Rabbit monoclonal antibodies against recombinant E7 protein of HPV type 18 (HPV18) were generated and characterized using Western blotting, epitope mapping, indirect immunofluorescence, and immunohistochemistry. One clone specifically recognizing HPV18 E7 was used for the development of a sandwich enzyme-linked immunosorbent assay (ELISA). The assay was validated using recombinant E7 proteins of various HPV types and lysates from E7-positive cervical carcinoma cells. A total of 14 HPV18 DNA-positive cervical swab specimens and 24 HPV DNA-negative-control specimens were used for the determination of E7 protein levels by the newly established sandwich ELISA. On the basis of the average absorbance values obtained from all 24 negative controls, a cutoff above which a clinical sample can be judged E7 positive was established. Significant E7 signals 6- to 30-fold over background were found in 7 out of 14 abnormal HPV18 DNA-positive cervical smear specimens. This feasibility study demonstrates for the first time that HPV18 E7 oncoprotein can be detected in cervical smears.     

Antibody response for L1, E6 and E7 HPV 16 and HPV 18 antigens in Tunisian women with cervical cancer and controls

Results obtained in the present work indicated that the Luminex assay is more sensitive than ELISA. The reactivity to the early antigens E6 and E7 was 37% versus 42% for HPV 16 and 21% versus 20% for HPV 18 among cervical cancer cases using ELISA. However, these ratios were 44% and 61%, respectively, for E6 and E7 HPV 16 versus 28% and 21% for E6 and E7 HPV 18 when using the Luminex technique. Data also indicated that HPV 16 and HPV 18 showed distinct profiles for the different antigens tested. Finally, the differences in antibody responses between cervical cancer cases and benign cases toward the different antigens were significant.     

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.     

Inhibition of CDK activity and PCNA-dependent DNA replication by p21 is blocked by interaction with the HPV-16 E7 oncoprotein

p21 inhibits cyclin-dependent kinase (CDK) activity and proliferating cell nuclear antigen (PCNA)-dependent DNA replication by binding to CDK/cyclin complexes and to PCNA through distinct domains. The human papillomavirus (HPV)-16 E7 oncoprotein (16E7) abrogated a DNA damage-induced cell cycle arrest in vivo, despite high levels of p21. Using cell lysates and purified proteins we show that 16E7 prevented p21 both from inhibiting CDK2/cyclin E activity and PCNA-dependent DNA replication, whereas the nononcogenic HPV-6 E7 had reduced effects. Inactivation of both inhibitory functions of p21 was attained through binding between 16E7 and sequences in the carboxy-terminal end of p21 that overlap with the PCNA-binding site and the second p21 cyclin-binding motif. These data imply that the carboxyl terminus of p21 simultaneously modulates both CDK activity and PCNA-dependent DNA replication and that a single protein, 16E7, can override this modulation to disrupt normal cell cycle control.     

E6/E7 oncoproteins of high risk HPV-16 upregulate MT1-MMP,MMP-2 and MMP-9 and promote the migration of cervical cancer cells

Background: E6 and E7 of high risk human papillomavirus 16 (HPV16) were reported to correlate with the cervical cancer (CC). And the presence of matrix metalloproteinases (MMPs) has also been indicated to be associated with CC. Methods: The present study investigated the expression of MMPs (MT1-MMP, MMP-2 and MMP-9) in CC cells with HPV16-E6/E7 oncoprotein(s) negative or positive, and then determined the regulation of HPV16-E6/E7 oncoproteins on the expression of MMPs (MT1-MMP, MMP-2 and MMP-9) and the migration of cervical cancer Caski and SiHa cells with RNAi technology. Results: It was demonstrated that the overexpression or the knockdown of HPV16-E6/E7 promoted or reduced MT1-MMP, MMP-2 and MMP-9 in CC cells. And the HPV16-E6, -E7 or -E6E7 influenced the migration of CC cells. The overexpression or the knockdown of them promoted or inhibited the migration of C33A or Caski/SiHa cells. Moreover, the chemical inhibition of MMP-2 or MMP-9 significantly reduced the migration of CC Caski or SiHa cells. Conclusions: Our results demonstrated that the E6-HPV16 or E7-HPV16 promoted the activity of MMP-2/9, and contributed to the migration of cervical cells.     

Usefulness of high-risk HPV early oncoprotein (E6 and E7) serological markers in the detection of cervical cancer: A systematic review and meta-analysis

We reviewed the literature on the importance of selected anti-high-risk human papillomavirus (HR-HPV) antibodies (namely, 16/18 and early oncoproteins E6 and E7) as potential serological markers for early detection of individuals at high risk of cervical cancer. We searched for studies in PubMed and Embase databases published from 2010 to 2020 on antibodies against HR-HPV E6 and E7 early proteins and cervical cancer. Pooled sensitivity and specificity for HPV16 and HPV18 antibodies were calculated using a bivariate hierarchical random-effects model. A total of 69 articles were identified; we included three studies with 1550 participants. For the three HPV16/18 E6 and E7 antibody tests, enzyme-linked immunosorbent assay-based assays had a sensitivity of 18% for detecting CIN2+ (95% confidence interval [CI]: 15–21) and a specificity of 96% (95% CI: 92–98), for slot-blot, sensitivity was 28.9% (95% CI: 23.3–35.1) and specificity was 72% (95% CI: 66.6–77.0) for detecting CIN2+, and for multiplex HPV serology assay based on a glutathione S-transferase, sensitivity was 16% (95% CI: 8.45–28.6) and specificity was 98% (95% CI: 97–99) for detecting invasive cervical cancer. HR-HPV16/18 E6 and E7 serological markers showed high specificity, but sensitivity was suboptimal for the detection of cervical cancer in either population screening settings or as point-of-care screening tests.     

An ELISA capture assay for the E7 transforming proteins of HPV16 and HPV18.

ELISA capture assays were established for the E7 transforming proteins of HPV16 and HPV18, based on a range of previously characterised polyclonal and monoclonal antibodies. No cross-reactivity was observed in the ELISAs between HPV18 E7 and HPV16 E7. Immunoreactive E7 protein (iE7) was measured in a series of HPV-transformed cell lines, and ranged from 0.6 to 17.7 ng iE7/mg cell protein. iE7 was labile at 22 degrees C (t1/2 = 37 min) but relatively more stable at 4 degrees C (t1/2 = 210 min). HPV16 E7 protein at concentrations from 0.10 to 0.69 ng iE7/mg cell protein was detected in 5 of 13 smears from women with abnormal cervical cytology. Assay of E7 protein may play a role in the detection of HPV-induced cervical lesions with malignant potential.     

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.     

HPV 16 E7 antibody levels in cervical cancer patients: Before and after treatment

Antibody response to HPV16 E7 oncoprotein may represent a marker of cervical cancer. A HPV16 GST-E7 fusion protein was used in a Western Blot assay to analyse the HPV16 E7 antibody response in 30 patients before and after treatment for cervical carcinoma (stage IIB or IIIB). Patients were treated with three courses of cisplatin/bleomycin therapy followed by surgery, or with surgery alone. Thirteen out of 30 patients had serum antibodies to HPV16 E7 antigen. Three months after chemotherapy little or no change in antibody titre was detected. In contrast, after surgery, a significant decrease in antibody titre was observed in 9/10 patients. In two cases the titre declined to zero 3 and 9 months after treatment, respectively. These results confirm the usefulness of studying anti-HPV16 E7 antibody profile in cervical cancer patients and suggest that the serum response correlates with tumour burden. J. Med. Virol. 54:192–195, 1998. © 1998 Wiley-Liss, Inc.     

Correlation of laryngeal squamous cell carcinoma and infections with either HHV-8 or HPV-16/18

Each year more than 159,000 new cases of laryngeal cancer are diagnosed globally, and more than 9000 patients die due to this malignancy. Viral infections are a known risk factor for this malignancy. Thus, this study aimed to evaluate the role of HPV-16/18 and HHV-8 infection in patients with laryngeal 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.     

Fowlpox virus recombinants expressing HPV-16 E6 and E7 oncogenes for the therapy of cervical carcinoma elicit humoral and cell-mediated responses in rabbits

Background  

Around half million new cases of cervical cancer arise each year, making the development of an effective therapeutic vaccine against HPV a high priority. As the E6 and E7 oncoproteins are expressed in all HPV-16 tumour cells, vaccines expressing these proteins might clear an already established tumour and support the treatment of HPV-related precancerous lesions.     

子宫颈癌、子宫颈上皮内病变组织中SIRT1、HPV 16/18E6的表达及其意义

目的检测子宫颈癌及癌前病变中SIRT1的表达情况,探讨其与临床病理特征的关系。同时检测早期癌蛋白中HPV16/18E6的表达,分析两者的相关性。方法应用免疫组化En Vision法检测30例子宫颈炎、100例子宫颈上皮内病变(高级别、低级别各50例)、30例子宫颈鳞状细胞癌组织中SIRT1和HPV 16/18E6的表达。结果子宫颈癌组织中SIRT1阳性率为93.33%(28/30),高于子宫颈炎组织(13.33%,4/30),差异有统计学意义(P0.05)。子宫颈高级别上皮内病变SIRT1阳性率(88%,44/50)高于低级别上皮内病变(14%,7/50),差异有统计学意义(P0.05)。但高级别上皮内病变与子宫颈癌SIRT1阳性率差异无统计学意义(P0.05);低级别上皮内病变与子宫颈炎中SIRT1阳性率差异无统计学意义(P0.05)。在子宫颈癌中,SIRT1的阳性率与临床分期和组织学分级有关,晚期、分化差的子宫颈癌阳性率高于早期、分化好的子宫颈癌,差异有统计学意义(P0.05)。在子宫颈癌中SIRT1的阳性率(93.33%,28/30)高于HPV 16/18E6(30%,9/30),在子宫颈高级别上皮内病变中SIRT1的阳性率(88%,44/50)高于HPV 16/18E6(28%,14/50),但在低级别上皮内病变中SIRT1的阳性率(14%,7/50)低于HPV 16/18E6(36%,18/50),两者差异有统计学意义(P0.05)。结论 SIRT1的阳性率随着病变程度增加而升高,提示SIRT1与细胞恶性转变有关,其过表达可能促进上皮向高级别内病变乃至子宫颈癌进展。     

Increase of human papillomavirus-16 E7-specific T helper type 1 response in peripheral blood of cervical cancer patients after radiotherapy

It has been suggested that tumour cell lysis by gamma-radiation induces a tumoral antigen release eliciting an immune response. It is not clear how a specific immune response in cervical cancer patients is developed after radiotherapy. This study is an attempt to investigate the role of the human papillomavirus type 16 (HPV-16) E7-specific T helper response before and after radiotherapy. Lymphocytes were isolated from 32 cervical cancer patients before and after radiotherapy and from 16 healthy women. They were stimulated for 12 hr with autologous HPV-16 E7-pulsed monocyte-derived dendritic cells or directly with HPV-16 E7 synthetic peptides: E7(51-70), E7(65-84) and E7(79-98). The cells were stained for CD4, CD69, intracellular interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) cytokines and analysed by flow cytometry. A specific CD4(+) CD69(+) IFN-gamma(+) immune response against HPV-16 E7(79-98) peptide was observed in 10 of 14 patients (71.4%) after treatment, compared with 4 of 14 (28.5%) before radiotherapy (P = 0.039); however, this response was not associated with a successful clinical response. Before treatment, 5 of 31 patients showed a HPV-16 E7(79-98)-specific T helper type 2 (Th2) response. Interestingly, this response was significantly associated with a decrease in disease-free survival (P = 0.027). These results suggest that a Th2-type cellular response could be useful as a predictor of recurrence and poor prognosis. An increase of the HPV-specific immune response was observed after radiotherapy; however, it is not enough to control completely the disease after treatment. Our results support that the E7-specific T-cell IFN-gamma response in cervical cancer patients, rather than reflecting the host's capability of controlling tumour growth, might be an indicator for disease severity.