Molecular biology of human papillomavirus infection and oncogenesis

HPV Typing in Brazilian Patients witn Epidermodysplasia Verruciformis: High Prevalence of EV-HPV 25

Background:

Epidermodysplasia verruciformis is a rare genetic disorder characterized by development of lesions associated with HPV#5 or HPV#8 in early childhood; malignant transformation occurs in approximately half of individuals during adulthood.

Objective:

Our goal was to study the presence and spectrum of EV-HPV types in Brazilian EV patients, a population that had never been studied in this regard. Patients and MethodsForty-one biopsies from different lesions (benign and skin tumors) and one biopsy from clinically normal skin from each of 20 Brazilian patients with EV were studied for HPV typing using nested PCR.

Results:

EV-HPV DNA was detected in all 41 skin lesions of the patients and was also identified in specimens considered as normal skin from 8 patients (40%). In this study HPV-EV 25 was the most prevalent (70%), and HPV 14d (67%) was highly associated with malignant lesions.

Conclusion:

EV-HPV 25 was the most prevalent in our study. The noteworthy association of EV-HPV type 14d with skin cancers suggests its possible oncogenic role in malignant transformation in this population.

Hypothetic association between human papillomavirus infection and breast carcinoma

High-risk human Papillomaviruses (HPVs) has been proved to be the major cause of cervical cancer. It has been considered that HPV may also cause squamous cell carcinomas of the other sites such as anus, vulva and esophagus. Furthermore, a number of studies have detected HPV DNA in breast carcinoma tissues. This raises the question that whether HPV plays a carcinogenic role in breast carcinomas. On the other hand, human Papillomaviruses do not seem to be able infect normal mammary cells in vitro, nor have HPV infections in human breast glands been observed among patients with AIDS. At present, there is no explanation for these "conflicting observations". In this paper, we propose the hypothesis that mammary epithelial cells that partly lose control in proliferation are more susceptible for persistent HPV infection. The potential role of HPV infection in the carcinogenic steps of breast cancer should be further tested. One possible cost-effective way for further investigation is to conduct a case-control study comparing the prevalence of previous HPV exposure to the breast, such as history of cervical HPV infections and HPV infections in nipples between cases and controls.

Comparison of physician- and self-collected genital specimens for detection of human papillomavirus in men

There is currently no consensus regarding the most appropriate methods of sampling for the detection of genital human papillomavirus (HPV) in men. We employed a recently developed collection method involving abrasion and moistened swabbing of the genital skin surface for the detection of HPV in a cohort of 136 university-affiliated males in Hawaii. Genital specimens collected by physicians using this method were compared with self-collected specimens from the same individuals obtained 24 h later. Self-collected specimens yielded a greater proportion of sufficient specimens than physician-collected specimens. HPV detection was comparable in physician- and self-collected specimens; detection was highest in the penile shaft (51.2% and 51.5%, respectively, P = 0.96), followed by the scrotum (41.2% and 46.2%, P = 0.43), the glans/coronal sulcus (31.9% and 33.1%, P = 0.84), and the foreskin (33.3% and 28.6%, P = 0.74). Site-specific agreement in HPV detection between paired physician- and self-collected samples ranged from 67.2% (kappa = 0.34) for the penile shaft to 95.0% (kappa = 0.89) for the foreskin. There was a high degree of concordance in HPV genotypes in HPV-positive pairs. The most common type was HPV type 84, which comprised approximately 15% of the specimens. The emery paper-swab method offers an efficient sampling method for genital HPV DNA detection in men that could be used both within and outside of the clinical setting.

Multiple inverted follicular keratoses as a presenting sign of Cowden's syndrome: case report with human papillomavirus studies

Inverted follicular keratosis is characterized by a squamous epithelial expansion of the infundibular portion of the hair follicle in an exophytic and endophytic pattern. The lesion is often associated with squamous eddies similar to an irritated keratosis and may have a superficial papillomatous architecture. The lesion most often arises as a solitary nodule on the face of middle age to elderly individuals. Inverted follicular keratosis has been described as a distinct entity by some while others believe that it is related to trichilemmomas and/or verruca vulgares. The cutaneous pathology of Cowden's syndrome is characterized by multiple trichilemmomas. We present a woman who fulfills the clinical criteria for Cowden's syndrome and who initially presented with multiple inverted follicular keratoses. Also, in situ hybridization studies performed on the patient's keratoses do not reveal evidence of human papillomavirus infection.

Human papillomavirus type 16 in head and neck carcinogenesis

The aetiology of squamous cell carcinomas of the head and neck (HNSCC) is multifactorial. Oncogenic human papillomaviruses (HPVs), a causative agent in uterine cervical cancer, have also been repeatedly detected in HNSCC, especially in squamous cell carcinomas of tonsils. Approximately half the HPV DNA-positive HNSCC contain detectable E6/E7 transcripts with wild-type p53, reduced pRb and overexpressed p16 in the tumours. HPV-16 is the predominant type and exists in episomal, integrated, or mixed forms. Tonsillar carcinomas have a remarkably higher viral load than carcinomas at other sites of the head and neck region. HPV-16 DNA has also been detected in tumour-free tonsils. Infection by oncogenic HPVs is a necessary but not a sufficient cause of cancers. Studies on the molecular mechanisms underlying HPV-associated carcinogenesis are difficult, because HPV is not easy to propagate in vitro. HPV-immortalised human tonsillar epithelial cell lines may provide an in vitro model to study co-factors for the HPV-associated tonsillar cancers and to test the effects of anti-viral and anti-tumour agents.

Verrucas. Guidelines for management

Most people will experience infection with human papilloma virus (HPV) at some point in their life. Diagnosis, based on clinical examination, is usually straight forward. Treatment can, however, be challenging. Indications for treatment include pain, interference with function, cosmetic embarrassment, and risk of malignancy. Clearance rates are highest in young, healthy individuals with short duration of infection. Treatment may be with destructive agents (keratolytics, cryotherapy, curettage and cautery, laser, photodynamic therapy), with antimitotic agents (podophyllin, bleomycin, retinoids), with immune stimulants (topical sensitizers, cimetidine), or with topical virucidal agents [formaldehyde (formalin), glutaral (gluteraldehyde)]. As yet, there is no single totally effective treatment for viral warts. Some patients may choose to leave their warts untreated until spontaneous resolution. In those who seek intervention, simple, well tolerated therapies should be chosen initially in preference to more complicated, potentially harmful agents. It is likely that future research will be directed to developing an antiviral agent specific for HPV which would be safe, effective and not prohibitively expensive.

Clinical, histopathologic, and molecular aspects of cutaneous human papillomavirus infections

Human papillomaviruses comprise a large family of double stranded DNA viruses that are the etiologic agents of benign warts and anogenital cancers. At least 82 different human papillomavirus types have been identified and many remain yet uncharacterized. The development of new molecular techniques in recent years has led to an increased understanding of human papillomaviruses and their roles in carcinogenesis. Several clinicopathologic entities arising from human papillomavirus infection encountered by the dermatologist are the subject of the article. The epidemiology, molecular biology, clinical presentation, histologic findings, and treatment of each disorder, where applicable, is discussed.

Human papilloma virus type 16 E6 gene expression in oral exophytic epithelial lesions as detected by in situ rtPCR

OBJECTIVE

We adopted an in situ reverse transcriptase polymerase chain reaction method of detecting and determining the frequency of early (E6) gene expression of human papilloma virus type 16 at the individual cell level in a sample of oral exophytic lesions with various degrees of epithelial hyperplasia and dysplasia in immunosuppressed and immunocompetent patients.

STUDY DESIGN

The significance of differences between the study groups was determined by Mantel-Haenszel chi-square analysis and calculation of odds ratios, accounting for immunosuppression and degree of dysplasia, respectively.

RESULTS

Grouped together, the lesions of dysplasia (mild to severe) and squamous cell carcinoma were found to be 16 times more likely to express human papilloma virus E6 mRNA than the benign lesions (P = .0013); in the lesions of immunosuppressed patients, human papilloma virus 16 E6 was roughly 10 times more likely to be expressed than in those of the immunocompetent patients (P = .0008, accounting for dysplasia).

CONCLUSIONS

Our data indicate that human papilloma virus 16 E6 gene expression, and perhaps integration of the virus in the host genome, might play a role in the development of oral neoplasia in association with immunosuppression.

Functional interaction between the bovine papillomavirus virus type 1 replicative helicase E1 and cyclin E-Cdk2

We have found that the replicative helicase E1 of bovine papillomavirus type 1 (BPV-1) interacts with a key cell cycle regulator of S phase, the cyclin E-Cdk2 kinase. The E1 helicase, which interacts with cyclin E and not with Cdk2, presents the highest affinity for catalytically active kinase complexes. In addition, E1, cyclin E, and Cdk2 expressed in Xenopus egg extracts are quantitatively coimmunoprecipitated from crude extracts by either anti-Cdk2 or anti-E1 antibodies. E1 protein is also a substrate of the cyclin E-Cdk2 kinase in vitro. Using the viral components required for in vitro BPV-1 replication and free-membrane cytosol from Xenopus eggs, we show that efficient replication of BPV plasmids is dependent on the addition of E1-cyclin E-Cdk2 complexes. Thus, the BPV initiator of replication and cyclin E-Cdk2 are likely to function together as a protein complex which may be the key to the cell cycle regulation of papillomavirus replication.

Human papillomavirus-associated tumors of the skin and mucosa

This review discusses diseases of the lower genital tract in which the presence of human papillomavirus (HPV) DNA is well documented. We discuss epidemiologic, clinical, and experimental data supporting a causative role for HPV in mucosal malignancies, with emphasis on the role of viral and host factors in their pathogenesis. Of special interest is the recently discovered association of cutaneous tumors with HPVs, previously known only for tumors in epidermodysplasia verruciformis (EV). The frequent detection of EV-specific or EV-related HPVs in immunosuppressed persons and in cutaneous tumors in the general population supports the importance of EV as a model of cutaneous oncogenesis. We also discuss recent serologic findings based on enzyme-linked immunosorbent assay results with the use of viruslike particles. This is important both for detection of present or past HPV infection and for epidemiologic and immunologic studies. Novel therapeutic modalities for HPV tumors and prospects for prophylactic and therapeutic vaccination are presented.

Persistence of human papillomavirus (HPV) infections preceding cervical carcinoma

BACKGROUND

A persistent genital infection with an oncogene-type of human papillomavirus (HPV) is considered to be essential for the development of most cervical carcinomas. Therefore, HPV analysis has been proposed as a possible complementary cytological screening program. The authors have developed a technique to analyze archival Pap smears, which has enabled them to study the relation between persistent HPV infection and the development of cervical cancer.

METHODS

Nested polymerase chain reaction was used to demonstrate the presence of HPV DNA, and sequencing of the obtained amplimer was performed to establish HPV type. The authors analyzed a series of 88 smears taken 1.5 to 7 years prior to the diagnosis of an HPV-containing cervical carcinoma (12 invasive adenocarcinomas, 18 invasive squamous carcinomas, and 58 squamous carcinoma in situ), which were compared with age-matched controls with no tumor development.

RESULTS

HPV DNA was present in a majority of the smears preceding a cancer, with an odds ratio of around 15 for all tumor groups. Infections with a persisting HPV type were demonstrated in most samples from a series of eight patients, from who multiple smears were available, covering the 7-year period preceding the cancer diagnosis.

CONCLUSIONS

Persisting infection can be demonstrated in exfoliated cells many years before cancer is diagnosed. The results are complementary to those obtained with cytology, that is, HPV is detected also in those at-risk patients whose Pap smears are morphologically normal. However, the results are still insufficient to justify a general recommendation to use HPV testing for health control purposes.

Cellular factors required for papillomavirus DNA replication

In vitro replication of papillomavirus DNA has been carried out with a combination of purified proteins and partially purified extracts made from human cells. DNA synthesis requires the viral E1 protein and the papillomavirus origin of replication. The E2 protein stimulates DNA synthesis in a binding site-independent manner. Papillomavirus DNA replication is also dependent on the cellular factors replication protein A, replication factor C, and proliferating-cell nuclear antigen as well as a phosphocellulose column fraction (IIA). Fraction IIA contains DNA polymerase alpha-primase and DNA polymerase delta. Both of these polymerases are essential for papillomavirus DNA replication in vitro. However, unlike the case with T-antigen-dependent replication from the simian virus 40 origin, purified DNA polymerase alpha-primase and delta cannot efficiently replace fraction IIA in the replication reaction. Hence, additional cellular factors seem to be required for papillomavirus DNA replication. Interestingly, replication factor C and proliferating-cell nuclear antigen are more stringently required for DNA synthesis in the papillomavirus system than in the simian virus 40 in vitro system. These distinctions indicate that there must be mechanistic differences between the DNA replication systems of papillomavirus and simian virus 40.

Detection of several types of human papilloma viruses in AIDS-associated Kaposi's sarcoma

Epidemiological studies indicate that acquired immunodeficiency syndrome (AIDS)-associated Kaposi's sarcoma (KS) may be caused by an infectious, preferentially sexually transmitted agent. Infections with human papilloma viruses are common, sexually transmitted diseases occurring frequently in homosexual men, who are also the main risk group for developing KS. In order to evaluate the possible role of HPV in the development of KS, 24 cutaneous AIDS-associated Kaposi's sarcomas were investigated by the polymerase chain reaction (PCR) and by in situ hybridization for the presence of human papilloma viruses (HPV). HPV DNA sequences were detected in 5 of 24 KS specimens, in 4 of 13 normal skin specimens from AIDS patients without KS and in 5 of 14 skin specimens of HIV-seronegative patients. For the first time, HPV types 6 and 33 were detected by PCR in KS. A higher proportion of HPV types 16/18 was found in AIDS-associated KS specimens, whereas HPV type 33 was seen more often in normal skin specimens of the control group. Apart from the known HPV types 16/18 described in KS, this study demonstrates also the presence of HPV 6 and 33 in this condition.