Humane Papillomaviren

Human papillomaviruses (HPV) are the most important cause of cervical cancer and other carcinomas. The course and outcome of HPV infections depend on the HPV subtype, the anatomy of the infection site and the differentiation status of the host cells. Approximately 30 HPV types, which are divided into low-risk and high-risk types, are specialized for infecting the skin and mucous membranes in the anogenital region. A genital HPV infection often occurs even at the first sexual contact. The HPV prevalence varies in different population groups, depending on age, social class and cultural background. Generally, the immune system can overcome an HPV infection within 2 years; however, recovery from an infection with an HPV type does not result in lifelong immunity. Persistent or parallel infections with different HPV types increase the risk of developing cervical cancer. Malignant transformation of an infected epithelial cell requires the overexpression of the viral oncogenes E6 and E7. For complete malignant transformation of the host cell, the HPV DNA must be integrated into the host genome. During this process gene sections of the viral DNA are destroyed, frequently involving the E2, E1 or L1 genes. Current vaccines can only immunize against some of the 18 high-risk HPV and only provide limited protection against cervical carcinoma; therefore, even vaccinated women should attend regular screening checks by a gynecologist. State of the art PCR-based tests for detection of HPV are established in the clinical routine and allow infections to be detected objectively, sensitively and at an early stage but the quality of the results significantly varies between tests.     

Relationship between telomerase activation and HPV 16/18 oncogene expression in squamous intraepithelial lesions and squamous cell carcinomas of the uterine cervix.

SILs (squamous intraepithelial lesions) comprise a wide spectrum of clinically and biologically heterogeneous lesions ranging from benign proliferations to precancerous lesions. Telomerase activation plays a critical role in cellular immortalization and might be important for malignant progression. The viral oncogenes E6 and E7 are the principal transforming genes of high-risk HPVs and are important in HPV-associated immortalization and neoplastic transformation. In this study we investigated the relationship between telomerase activity, telomerase RNA, and HPV 16/18 oncogene expression in low- and high-grade SILs and SCCs (squamous cell carcinomas) of the cervix uteri. Telomerase activity was examined by the TRAP-assay and expression of the telomerase RNA (hTR) and HPV 16/18 E6/E7 oncogenes by RNA/RNA-in situ hybridization (ISH). The associated HPV-type was determined by PCR. Telomerase activity was observed in 25/29 (86%) SCCs, 31/41 (76%) high-grade SILs, 6/14 (43%) low-grade SILs, and 1/28 (3.6%) normal cervical tissues. Expression of hTR and viral oncogenes increased significantly with histopathologic severity of the lesion (p < 0.0001). A correlation was found between telomerase activity and intensity of viral oncogene expression. These findings suggest that telomerase activation occurs early in cervical carcinogenesis and is predominantly found in high-grade SILs and cervical SCCs. Our findings support current experimental data that suggest that telomerase is at least partially activated by viral oncogenes of high-risk HPV types. Telomerase activity with concomitant strong viral oncogene expression might therefore characterize a subset of lesions that are at risk for malignant progression.     

Frequent allelic imbalance of tumor suppressor gene loci in cervical dysplasia.

In addition to human papillomavirus (HPV) infection, loss of heterozygosity (LOH) at tumor suppressor gene loci has been frequently observed in cervical cancer. Thus, it may be assumed that detection and characterization of specific LOH profiles in preneoplastic lesions, in addition to HPV typing, might facilitate assessment of progression risk of cervical dysplasia. In this study, the type and frequency of allelic imbalance (allelic loss or allelic reduction) were analyzed in 24 unrelated cervical lesions using 14 polymorphic microsatellite markers at different tumor suppressor gene loci. No allelic loss was observed in four condylomatous lesions, whereas 2 of 13 (15%) CIN I lesions displayed allelic loss at 3p25 and 5q11-13. In high-grade lesions, however, allelic loss occurred in four of six (66%) cases at multiple chromosomal regions (3p14-25, 5p15, 5q11, 5q21, 11p15, and 17q21). Allelic reduction was observed in 4 of 13 (30%) low-grade lesions and 3 of 6 (50%) high-grade lesions. LOH was confined to lesions infected by high-risk HPV types. These data suggest that chromosomal instability is an early event in cervical carcinogenesis. The detection of LOH on multiple chromosome 3p loci in 50% of high-grade lesions suggests that a specific marker panel encompassing this region might enable better assessment of which lesions are likely to regress, persist, or progress.     

Cervical Cancer: Development of Targeted Therapies Beyond Molecular Pathogenesis

It is well-known that the human papillomavirus (HPV) is the causative agent of cervical cancer. The integration of HPV genes into the host genome causes the upregulation of E6 and E7 oncogenes. E6 and E7 proteins inactivate and degrade tumor suppressors p53 and retinoblastoma, respectively, leading to malignant progression. HPV E6 and E7 antigens are ideal targets for the development of therapies for cervical cancer and precursor lesions because they are constitutively expressed in infected cells and malignant tumors, but not in normal cells, and they are essential for cell immortalization and transformation. Immunotherapies are being developed to target E6/E7 by eliciting antigen-specific immune responses. siRNA technologies target E6/E7 by modulating the expression of the oncoproteins. Proteasome inhibitors and histone deacetylase inhibitors are being developed to indirectly target E6/E7 by interfering with their oncogenic activities. The ultimate goal for HPV-targeted therapies is the progression through clinical trials to commercialization.     

Ätiologie und Pathogenese des Zervixkarzinoms

Epidemiological studies have confirmed that human papillomaviruses (HPV) play a causal role in cervical carcinogenesis. Cervical cancer is considered to be the rare consequence of a persistent infection with so called high-risk (HR)-HPV types. The most common HR-HPV types are HPV16, 18, 31, 33 and 45, the DNA of which can be detected in about 80% of cervical cancers. A constitutive strong expression of the viral oncogenes E6 and E7 is a decisive step for the transformation to malignancy. These proteins deregulate cell proliferation and induce genetic instability, promoting the accumulation of mutations which are crucial for the acquisition of phenotypic properties such as invasive growth, angiogenesis and metastasis. Several cofactors which support HPV infection or prevent its elimination, as well as factors which act independently of HPV, also contribute to carcinogenesis.     

Role of human papillomavirus in the carcinogenesis of squamous cell carcinoma and adenocarcinoma of the cervix

Human papillomavirus (HPV) infection is the most common sexually transmitted disease, with more than 80% of the population infected at some time in their life. In rare cases, this infection may lead to cervical cancer. Virtually all squamous cell carcinomas and the overwhelming majority of adenocarcinomas of the cervix are HPV positive. HPV integration in the genome will lead to inactivation of the p53 pathway and the Rb pathway. Integration is essential for the onset of cervical carcinogenesis, but is probably not sufficient for progression to invasive cervical cancers. It is likely that several cofactors, such as environmental, viral and host-related factors, are necessary for the development of cervical cancer. There are several similarities and differences between the two major histological types. This article will address the role of HPV in cervical carcinogenesis as well as the molecular biology involved in the process.     

Immune responses against virus and tumor in cervical carcinogenesis: Treatment strategies for avoiding the HPV-induced immune escape

Despite the availability of prophylactic vaccines against human papillomavirus (HPV), cervical cancer (CC) is still a major problem globally. It is the cancer with the second highest incidence and the third highest mortality in women worldwide, but, in less developed countries, it is an even greater problem being the second most common cause of cancer death. Although HPV infection is one of the most common sexually transmitted diseases, and high-risk HPV16 is the most frequent genotype involved, only a small number of HPV-infected women develop high-grade squamous intraepithelial lesions whereas, in the remainder of the women, the virus disappears spontaneously. There is a lot of evidence to support the view that host-dependent immunologic status and HPV-induced immune evasion are responsible for persistent HPV infection and subsequent development of cervical neoplasia. Therefore, the role of the immune system, not only in viral clearance but also in tumor antigen recognition, is particularly relevant in the case of cervical carcinogenesis. A better understanding of these processes would help in the development of therapeutic vaccines. This review aims to explain which immune cells and molecules are involved in the process of viral and tumor recognition, how their failure can lead to cervical carcinoma and what are the main therapeutic strategies so far tested in preclinical models and clinical trials to stimulate the immune system in cervical carcinoma.     

Human papillomavirus and cervical carcinogenesis

Epidemiological studies show that infection with a subset of genital human papillomavirus (HPV) infections is the major risk factor for the subsequent development of cervical cancer. Experimental studies show that that the E6 and E7 genes of these high risk HPVs are oncogenes that deregulate key cell cycle controls. In the normal infectious cycle high level expression of these genes is confined to non-dividing differentiated cells: HPV oncogenesis requires deregulation of viral and cellular genes permitting inappropriate expression of E6 and E7. These are rare events but viral persistence and chronic exposure to steroid hormones increase the probability of this deregulation.     

Tumor suppressor genes: new pathways in gynecological cancer

The Retinoblastoma (Rb-1) and p53 genes appear to play an important role in controlling cell division, and mutations in Rb-1 and p53 have been reported widely in non-gynecological cancers. Unlike other cancer-related genes, which become activated during carcinogenesis, it is the loss of wild type p53 and Retinoblastoma protein (RB) function that is thought to contribute to cancer development. These genes therefore, have been called tumor suppressor genes since normal function appears to be necessary for negative control of cell growth. Several viral oncoproteins have been shown to interact with RB and p53. It seems likely that the formation of these complexes inactivates the cellular protein resulting in an overall effect similar to somatic mutation of the Rb-1 or p53 genes. The HPV16 transforming proteins E7 and E6 complex with protein products of Rb-1 and p53, respectively. In HPV positive anal and cervical tumors the normal function of RB and p53 may be inhibited by these viral proteins and so mutation within the RB-1 and p53 gene coding sequences would not appear to be a necessary step in the genesis of these tumors. However, in HPV negative tumors from the same tissues, loss of wild type Rb-1 and p53 activity may only be achieved by somatic mutation of these genes.     

Extended effects of human papillomavirus 16 E6-specific short hairpin RNA on cervical carcinoma cells

Most cervical carcinomas express high-risk human papillomavirus (HPV) E6 and E7 oncogenes. Small interfering RNA can mediate sequence-specific inhibition of gene expression in mammalian cells. To find a most effective short hairpin RNA (shRNA) for HPV16 E6 messenger RNA (mRNA) and investigate the extended effects of the HPV16 E6 shRNA on cervical carcinoma cells, we stably transfected SiHa cells with four shRNA expression vectors (E6A-D). HPV16 E6A shRNA was found to be the most efficient in our study, which caused the reduction of HPV16 E6 mRNA to 10% in SiHa cells but did not reduce HPV18 E6 mRNA expression in HeLa cells. We subsequently demonstrated that E6A could stably express shRNA and effectively reduce HPV16 E6 and E7 viral genes expression in SiHa cells for more than 4 months. After E6 and E7 repression, there was a dramatic accumulation of p53, p21, and hypophosphorylated pRb proteins in cells. Furthermore, cell proliferation, colony formation ability, tumorigenicity, and in vitro cell invasive capability were suppressed substantially in E6A-transfected cells. These results suggest that the use of shRNA expression vector may be a potential approach for the treatment of persistent HPV infection and HPV-positive cervical carcinoma.     

Human papillomavirus, Epstein-Barr virus and p53 mutation in vulvar intraepithelial neoplasia

OBJECTIVE: To clarify the role of human papillomavirus (HPV) and Epstein-Barr virus (EBV) infection in vulvar carcinogenesis in relation to the mutated p53 gene. STUDY DESIGN: Polymerase chain reaction (PCR) was used to amplify DNA sequences of the viruses and PCR-single-strand conformation polymorphism analysis to screen for p53 gene mutations in exons 5-8 from formalin-fixed, paraffin-embedded blocks including 10 undifferentiated vulvar intraepithelial neoplasia (VIN) specimens. RESULTS: HPV and EBV DNA was found in 75% (6/8) and 0% (0/10) of VIN tissues, respectively. Oncogenic HPV 16 was the predominant type. HPV DNA extraction was not possible in 2 VIN specimens. p53 Gene mutation was shown in 20% (2/10) of VIN lesions. No correlation was found between p53 gene mutation the presence of viral HPV or EBV DNA. Mutated p53 was equally distributed between HPV-positive and -negative VIN cases. CONCLUSION: Our results suggest that although most undifferentiated VIN lesions are associated with HPV infection, p53 mutations may occur independent of viral infection even in the presence of oncogenic HPV. HPV, but not EBV or p53 gene mutation, can play a role in the pathogenesis of undifferentiated VIN.     

Cervical cancer vaccines: progress and prospects

Cervical cancer remains a leading cause of cancer-related mortality in women, particularly in developing countries. The causal association between genital human papillomavirus (HPV) infection and cervical cancer has been firmly established and the oncogenic potential of certain HPV types has been clearly demonstrated. In recognition of the causal association of cervical cancer with this sexually transmitted viral infection, substantial interest has arisen to develop effective prophylactic and therapeutic vaccines. Prophylactic strategies currently under investigation focus on the induction of effective humoral and cellular immune responses that are potentially protective against subsequent HPV infection. Papillomavirus-like particles have been synthesized to induce neutralizing antibody responses, and impressive immunoprophylactic effects have been demonstrated in both animals and humans. For the treatment of existing HPV infection, techniques to augment cellular immunity by enhancing viral antigen recognition are under investigation. Vaccines targeting the oncogenic proteins E6 and E7 of HPV-16 and -18 are the focus of current clinical trials for cervical cancer patients. It is hoped that the development of successful HPV-specific vaccines will diminish the costs of existing cervical cancer screening programs and reduce the morbidity and mortality associated with the treatment of cervical neoplasias.     

Cervix dysplasias: study of Rb and p53 gene expression and correlation with mitotic activity

OBJECTIVE: Certain HPV types have transforming properties. These oncogenic activities are related to the abilities of the viral proteins E6 and E7 to inhibit the products of two cellular tumor suppressor genes (p53 and Rb respectively). But the early steps of cervical carcinogenesis are not well known. The goal of our study was to evaluate cervical intraepithelial neoplasia (CIN) for the tumor suppressor genes p53 and pRb, the HPV status and the mitotic activity, in order to better understand the mechanism of carcinogenesis. MATERIAL AND METHODS: Twenty formalin-fixed paraffin-embedded cone biopsies were selected because they contained adjacent to normal epithelium different grades of CIN. Immunohistochemistry was performed for evaluation of PCNA, pRb and p53. Expression of these different biomarkers was assessed with the help of an image analysis system, in the different epithelial layers of the different normal and pathological cervical areas. The results were compared to normal controls. RESULTS: There is an increase of PCNA expression in normal epithelium adjacent to CIN, compared to normal controls. As tissues progress from adjacent normal epithelium to condylomatous lesion and to the different grades of CIN, PCNA expression increases (mainly in the superficial epithelial layers). For p53 and pRb, the expression is increased in the basal and parabasal layers of adjacent normal epithelium and condylomatous lesions. The observance of histologic signs of CIN is associated with a disappearance of p53 and pRB expression. CONCLUSIONS: These results indicate that the early steps of cervical carcinogenesis involve proliferative dysregulation in relation to the p53 and pRb modulatory mechanism. So expression of viral proteins of HPV is probably the earlier step of carcinogenesis in cervical carcinoma.     

Molecular aspects of ovarian cancer

Ovarian cancer is caused by genetic alterations that disrupt proliferation, apoptosis, senescence and DNA repair. Approximately 10% of ovarian cancers arise in women who have inherited mutations in cancer susceptibility genes (BRCA1 or BRCA2). The ability to perform genetic testing allows identification of women at increased risk who can be offered prophylactic oophorectomy or other interventions aimed at preventing ovarian cancer. The vast majority of ovarian cancers are sporadic, resulting from the accumulation of genetic damage over a lifetime. Several specific genes involved in ovarian carcinogenesis have been identified, including the p53 tumour suppressor gene and HER2/ neu andPIC3KA oncogenes. The recent availability of expression microarrays has facilitated the simultaneous examination of thousands of genes, and this promises to extend further our understanding of the molecular events involved in the development of ovarian cancers. Hopefully, this knowledge can be translated into effective screening, treatment, surveillance, and prevention strategies in the future.     

宫颈癌变进展中人乳头瘤病毒甲基化的研究

高危型人乳头瘤病毒（HPV）持续感染是宫颈癌发生的直接原因,然而HPV感染后多数可被宿主免疫机制清除,只在部分病例中HPV感染持续存在并与宿主细胞DNA整合,导致宿主细胞癌变。HPV表观遗传学的改变在病毒整合及致宿主细胞癌变中起一定作用。对目前有关HPV表观遗传学特点在影响HPV自身表达和宫颈病变进展中作用的文献加以综述,了解HPV DNA甲基化状态在宫颈癌发生、发展中的作用。HPV基因表观遗传学状态有可能成为临床诊断和判断预后的分子标记物。     

The quantitative analysis of E6 HPV and P53 genes expression by QPCR (TaqMan) in the assessment of surgical treatment range in vulvar carcinoma induced by HTV infection.]

OBJECTIVES: Human Papilloma Virus (HPV) infections especially 16 and 18 are risk factors for squamous cell vulvar cancer. E6 protein of HPV joins the tumor suppressor protein P53 and promotes its degradation. This is one of the possible mechanisms of viral oncogenes action. DESIGN: In this study the quantitative analysis of mRNA copies E6 HPV 18 and mRNA P53 expression in vulvar cancer tissue was performed. The expression of analysed genes was applied in the assessment of surgical treatment range. MATERIALS AND METHODS: The specimens from a 26 year old woman with vulvar squamous cell cancer stage II FIGO treated surgically modo Way were analysed. The number of DNA and mRNA copies E6 HPV and P53 were examined basing on Q-PCR standard curves for beta-actine by use of Perkin Elmer-kit and the sequence detector ABI PRISM 7700-Taq Man application. RESULTS: The overexpression of mRNA E6 HPV and P53 in analysed specimens was found. The highest number of mRNA copies in cancer tissue was ascertained. In lichen sclerosus and lymphonoduli tissue lower number of analysed copies was found. CONCLUSION: The quantitative analysis of E6 HPV and P53 genes expression can be useful in the assessment of surgical treatment range in vulvar cancer and can also be used as a prognostic marker.     

Human papillomavirus genital infection in modern gynecology: genetic and genomic aspects

HPV (human papillomavirus) is a virus responsible for many female and male genital tract diseases. It is a small nonenveloped virus with icosahedral symmetry that contains a double-stranded DNA genomes of approximately 7,900 bp. Approximately 200 different HPVs have been characterized, classified in mucosal and cutaneous viruses, responsible for a wide spectrum of clinical conditions, from simple feet and hands warts to genital cancer. Their genome is functionally distinct in three regions. The condition of the host immune system is one of the factors that can strongly influence the natural history of HPV infection. The primary response to viral infection is cell-mediated, so conditions that compromise the immune system increase the viral infection risk. The molecular mechanisms involved in the onset of the cervical carcinoma are well defined, and they are mainly associated to the ability of the proteins E6 and E7 to neutralize the activity of p53 and retinoblastoma protein, respectively. The infection of HPV is mainly diagnosed through molecular methods. Several assays have been developed for the simultaneous identification of HPV types, the majority of which are polymerase chain reaction-based assays. Side by side with these assays, the emerging technology of the DNA chip may offer a reliable diagnostic tool for discriminating easily between many HPV genotypes.     

Human papillomavirus DNA in glandular dysplasia and microglandular hyperplasia: presumed precursors of adenocarcinoma of the uterine cervix

Presumed precursors of adenocarcinoma of the uterine cervix were investigated with specific techniques to identify human papillomavirus (HPV) DNA. The presence of HPV DNA in 36 lesions of glandular dysplasia and 16 lesions of microglandular hyperplasia of the uterine cervix was studied by in situ hybridization using 3H-labeled HPV 16 and HPV 18 DNA probes. Only two of 36 lesions (6%) of glandular dysplasia contained HPV 18 DNA, although 64% of coexisting adenocarcinoma in situ, microinvasive adenocarcinoma, and cervical squamous intraepithelial neoplasia III lesions contained HPV 18 and/or HPV 16 DNA. Two lesions of HPV 18 DNA-positive glandular dysplasia coexisted with adenocarcinoma in situ that contained the same type of HPV DNA. None of the microglandular hyperplasia lesions contained HPV 16 DNA or HPV 18 DNA. These results suggest that, if HPV infection is an initial step toward carcinogenesis, it is unlikely that glandular dysplasia and microglandular hyperplasia are precursor lesions of adenocarcinoma of the uterine cervix. A large proportion of glandular dysplasia may represent reactive lesions of endocervical columnar epithelium. Two lesions of HPV 18 DNA-positive glandular dysplasia may represent well-differentiated components of adenocarcinoma in situ of the uterine cervix.     

A study of women's knowledge regarding human papillomavirus infection, cervical cancer and human papillomavirus vaccines

AIMS: Human papillomavirus (HPV) infection is a common sexually transmitted viral infection and is associated with the development of cervical cancer. HPV vaccines are now undergoing phase 3 clinical trials in Australia. It is likely that an HPV vaccine will become licensed for use in the near future. METHODS: Ninety women aged 18-30 years from three different groups (those attending a dysplasia clinic, a local university health service and participants currently involved in a phase 3 HPV vaccine trial) completed a questionnaire assessing their knowledge base regarding HPV infection, cervical cancer, Pap tests and HPV vaccines. RESULTS: Respondents demonstrated good understanding of the Pap test and interpretation of an abnormal result. Most respondents (89%) had heard of HPV and attributed a number of different clinical symptoms to infection. For women who had not heard of an HPV vaccine, 79% of respondents stated that the most common resource they would use to obtain further information is their general practitioner. DISCUSSION: Many women do not understand the risk factors for HPV infection, the clinical problems it may cause and the potential long-term complications of infection. Few women have heard of a HPV vaccine, but most women surveyed would approach their general practitioner for more information if one became available. CONCLUSION: This study highlights the need for further education regarding HPV infection and the potential long-term complications such as cervical cancer. It also demonstrates that education of general practitioners regarding an HPV vaccine is essential, as this is the most likely resource women will use to obtain further information in the future.