Molecular and serological studies of human papillomavirus among patients with anal epidermoid carcinoma

Blood-based biomarkers of human papillomavirus-associated cancers: A systematic review and meta-analysis

BACKGROUND

Despite the significant societal burden of human papillomavirus (HPV)-associated cancers, clinical screening interventions for HPV-associated noncervical cancers are not available. Blood-based biomarkers may help close this gap in care.

METHODS

Five databases were searched, 5687 articles were identified, and 3631 unique candidate titles and abstracts were independently reviewed by 2 authors; 702 articles underwent a full-text review. Eligibility criteria included the assessment of a blood-based biomarker within a cohort or case-control study.

RESULTS

One hundred thirty-seven studies were included. Among all biomarkers assessed, HPV-16 E seropositivity and circulating HPV DNA were most significantly correlated with HPV-associated cancers in comparison with cancer-free controls. In most scenarios, HPV-16 E6 seropositivity varied nonsignificantly according to tumor type, specimen collection timing, and anatomic site (crude odds ratio [cOR] for p16+ or HPV+ oropharyngeal cancer [OPC], 133.10; 95% confidence interval [CI], 59.40-298.21; cOR for HPV-unspecified OPC, 25.41; 95% CI, 8.71-74.06; cOR for prediagnostic HPV-unspecified OPC, 59.00; 95% CI, 15.39-226.25; cOR for HPV-unspecified cervical cancer, 12.05; 95% CI, 3.23-44.97; cOR for HPV-unspecified anal cancer, 73.60; 95% CI, 19.68-275.33; cOR for HPV-unspecified penile cancer, 16.25; 95% CI, 2.83-93.48). Circulating HPV-16 DNA was a valid biomarker for cervical cancer (cOR, 15.72; 95% CI, 3.41-72.57). In 3 cervical cancer case-control studies, cases exhibited unique microRNA expression profiles in comparison with controls. Other assessed biomarker candidates were not valid.

CONCLUSIONS

HPV-16 E6 antibodies and circulating HPV-16 DNA are the most robustly analyzed and most promising blood-based biomarkers for HPV-associated cancers to date. Comparative validity analyses are warranted. Variations in tumor type-specific, high-risk HPV DNA prevalence according to anatomic site and world region highlight the need for biomarkers targeting more high-risk HPV types. Further investigation of blood-based microRNA expression profiling appears indicated.

HPV prophylactic vaccines and the potential prevention of noncervical cancers in both men and women

Human papillomavirus (HPV) is a necessary cause of cervical cancer. In addition, on the basis of the fulfillment of a combination of viral as well as epidemiological criteria, it is currently accepted that a proportion of anal, oropharyngeal, vulvar, and vaginal cancers among women and anal, oropharyngeal, and penile cancers among men are etiologically related to HPV. At these noncervical sites with etiologic heterogeneity, HPV-associated cancers represent a distinct clinicopathological entity, which is generally characterized by a younger age at onset, basaloid or warty histopathology, association with sexual behavior, and better prognosis, when compared with their HPV-negative counterparts. Currently available estimates indicate that the number of HPV-associated noncervical cancers diagnosed annually in the US roughly approximates the number of cervical cancers, with an equal number of noncervical cancers among men and women. Furthermore, whereas the incidence of cervical cancers has been decreasing over time, the incidence of anal and oropharyngeal cancers, for which there are no effective or widely used screening programs, has been increasing in the US. The efficacy of HPV vaccines in preventing infection at sites other than the cervix, vagina, and vulva should, therefore, be assessed (eg, oral and anal). Given that a substantial proportion of cervical cancers (approximately 70%) and an even greater proportion of HPV-associated noncervical cancers (approximately 86% to 95%) are caused by HPV16 and 18 (HPV types that are targeted by the currently available vaccines), current HPV vaccines may hold great promise (provided equivalent efficacy at all relevant anatomic sites) in reducing the burden of HPV-associated noncervical cancers, in addition to cervical cancers.

Human papillomavirus type 16 E5 protein as a therapeutic target

Cervical cancer is a progressive disease with an onset of one to two decades on average. During the productive replication stage, the Human papillomavirus (HPV) genome is maintained episomally in the infected cervical epithelium and early gene products, including E5, are expressed. Therefore, E5 has a potential to contribute to the HPV-associated carcinogenic process. In invasive malignancies, the HPV genomes are commonly integrated into the host genome, and E6 and E7 genes remain intact. However, the E5 is lost or, if present, under-expressed as compared with the E6 and E7 proteins. This suggests that E5 may play a critical role in the genesis of cervical cancer but less of a role in its persistence or progression. In the initiation of neoplasia and the premalignant stage, there are fewer malignant cells than in the invasive malignancies. Moreover, cells in the invasive malignant stage are found to have a very low level of MHC class I and II, which could hamper the presentation of the antigen and lead to a decreased immune response. Since the E5 protein is likely to play a role during the early tumorigenesis stage, a therapeutic vaccine to target and eliminate the E5-expressing cells may be a good strategy to prevent premalignant lesions from progressing toward invasive cervical cancers. This paper provides an overview of HPV-induced cervical carcinogenesis and strategies for designing prophylactic and therapeutic vaccines to prevent and cure the cervical cancer. In particular, focus will be on the rationale of targeting the E5 protein to develop therapeutic vaccines.

Human papillomavirus infection as a risk factor for anal and perianal skin cancer in a prospective study

Human papillomavirus has emerged as the leading infectious cause of cervical and other anogenital cancers. We have studied the relation between human papillomavirus infection and the subsequent risk of anal and perianal skin cancer. A case-cohort study within two large Nordic serum banks to which about 760 000 individuals had donated serum samples was performed. Subjects who developed anal and perianal skin cancer during follow up (median time of 10 years) were identified by registry linkage with the nationwide cancer registries in Finland and Norway. Twenty-eight cases and 1500 controls were analysed for the presence of IgG antibodies to HPV 16, 18, 33 or 73, and odds ratios of developing anal and perianal skin cancer were calculated. There was an increased risk of developing anal and perianal skin cancer among subjects seropositive for HPV 16 (OR=3.0; 95%CI=1.1-8.2) and HPV 18 (OR=4.4; 95%CI=1.1-17). The highest risks were seen for HPV 16 seropositive patients above the age of 45 years at serum sampling and for patients with a lag time of less than 10 years. This study provides prospective epidemiological evidence of an association between infection with HPV 16 and 18 and anal and perianal skin cancer.

Induction of chemosensitivity in nasopharyngeal carcinoma cells using a human papillomavirus regulatory sequence and the thymidine kinase gene

Nasopharyngeal carcinoma (NPC) is a human cancer of epithelial cell origin. Infection by Epstein-Barr virus has been shown to be closely associated with this tumor. Recent studies have indicated that another common epitheliotropic virus, human papillomavirus (HPV), is also found in a significant number of NPC cases. In this study, we evaluated the feasibility of using the HPV regulatory long control region (LCR) to drive the expression of the thymidine kinase (tk) gene to achieve chemosensitivity for gene therapeutic treatment of NPC. Testing HPV-11-LCR-tk constructs in NPC cell lines in the presence of ganciclovir (GCV) led to 50-60% cell death of transfected cells. The therapeutic efficacy was further tested in an in vivo model using nude mice transplanted with tumors derived from transfected NPC cells. Injection of 50 mg/kg body weight GCV twice daily for 14 days resulted in visually complete regression of the transplanted NPC tumor loads within 20 days after GCV treatment. Taken together, results from this pilot study indicate the feasibility of the development of a gene therapeutic protocol based on the chemosensitive gene constructs described in this paper.

Detection and typing of human papillomavirus in anal epidermoid carcinomas: sequence variation in the E7 gene of human papillomavirus Type 16

INTRODUCTION

Human papillomavirus, particularly Type 16, plays a central role in the development of anogenital squamous-cell carcinomas. A common sequence variation of human papillomavirus Type 16 in cervical cancer cell lines and in cervical cancer tissues from Korean patients was recently reported. The present study was performed to determine the integration type of human papillomavirus DNA in anal epidermoid carcinoma and to identify the common sequence variations in the human papillomavirus Type 16 E7 gene that had been previously reported.

METHODS

Twenty-one formalin-fixed, paraffin-embedded specimens collected from 29 patients with anal epidermoid carcinomas treated at the Seoul National University Hospital over a ten-year period (1989-1998) were investigated. Genomic DNA from the 21 specimens was extracted and analyzed using the polymerase chain reaction with a general primer and a type-specific primer for human papillomavirus Types 16 and 18. Direct sequencing was performed. As a control, 13 normal anal epithelia available from these patients were microdissected. As another control, 21 hemorrhoidal squamous epithelia obtained from a demographically adjusted group were also analyzed.

RESULTS

Human papillomavirus Type 16 DNA was present in all 21 anal epidermoid carcinomas. All controls were negative for human papillomavirus DNA. Sequence analysis revealed that 57 percent (12/21) specimens showed two types of sequence variation in the E7 gene. One variant with a single nucleotide change at position 647 (amino acid 29, AAT-->AGT, asparagine to serine) was found in 38 percent (8/21) of the samples. This variant has been detected in cervical cancers from Korean patients: 19 (39 percent) of 49 cervical cancer tissues and 6 (50 percent) of 12 cervical cancer cell lines. Another single nucleotide change at position 645 (amino acid 28, TTA-->TTC, leucine to phenylalanine) was found in 19 percent (4/21) of the samples. These two variants exhibit a change of amino acid affecting the critical sites for Rb binding.

CONCLUSION

Human papillomavirus Type 16 was found to be present in all 21 anal epidermoid carcinomas. Furthermore, in the Korean population, the most common sequence variant found in cervical

Interaction of the papillomavirus transcription/replication factor, E2, and the viral capsid protein, L2

The minor capsid protein L2 of papillomaviruses (PVs) likely plays a role in the selective encapsidation of PV DNA in viral capsids and in the infectivity of PV virions. The L2 protein also can cause the relocalization of the PV early protein, E2TA, to nuclear subdomains known as promyelocytic leukemia oncogenic domains (PODs) in which it is localized. E2TA is a transcriptional transactivator that also plays a critical role in viral DNA replication. In this study, we investigated whether L2, in causing the relocalization of E2TA, alters the activities of E2TA. We provide evidence that L2 inhibits the transcriptional transactivation function of E2, but it does not specifically inhibit the capacity of E2 to support viral DNA replication. We also investigated whether the colocalization of E2 and L2 to PODs and the ability of L2 to inhibit the transcriptional transactivation activity of E2TA might be mediated through a direct interaction between these two proteins. Using an in vitro protein-protein association assay, we found that L2 binds to E2TA. Two regions in E2TA were found to mediate this interaction. One of those domains is present in an alternative E2 gene product, E2TR, which is an antagonist to E2TA. Here we show that the L2 protein also relocalizes the E2 transcriptional repressor, E2TR, to the nuclear subdomains. These data suggest that the ability of L2 to relocalize E2 proteins to PODs is mediated through a direct interaction with L2.

Antibodies against human papillomavirus type 6 capsids are elevated in men with previous condylomas

Serum samples from 47 men with current condylomas, 32 men with a history of condylomas and from 205 men with no history of genital wart disease, who were attending sexually transmitted disease (STD) clinics at two different hospitals in Stockholm, were analyzed for the presence of immunoglobulin G (IgG) and A (IgA) antibodies to capsids of human papillomavirus types 6 and 11. IgG to HPV type 6 was found among 35% of patients with a history of condylomas compared to 10% of controls (p = 0.0003), but only among 27% of patients with current condylomas. Antibodies to HPV 6 and to HPV 11 showed a very limited correlation, suggesting that the antibodies are HPV-type restricted. The results strengthen conclusions from a previous serological study indicating that IgG antibodies against HPV 6 develop late during condylomatous disease and mostly reflect previous exposure to the virus.

A recurrent pattern of chromosomal aberrations and immunophenotypic appearance defines anal squamous cell carcinomas

Squamous cell carcinomas of the anus are rare neoplasias that account for about 3% of large bowel tumours. Infections with human papillomaviruses are frequently detected in these cancers, suggesting that pathogenic pathways in anal carcinomas and in carcinomas of the uterine cervix are similar. Little is known regarding recurrent chromosomal aberrations in this subgroup of squamous cell carcinomas. We have applied comparative genomic hybridization to identify chromosomal gains and losses in 23 cases of anal carcinomas. A non-random copy number increase of chromosomes 17 and 19, and chromosome arm 3q was observed. Consistent losses were mapped to chromosome arms 4p, 11q, 13q and 18q. A majority of the tumours were aneuploid, and most of them showed increased proliferative activity as determined by staining for Ki-67 antigen. p53 expression was low or undetectable, and expression of p21/WAF-1 was increased in most tumours. Sixteen cancers were satisfactorily tested for the presence of HPV by consensus L1-primer polymerase chain reaction; nine were HPV positive, of which eight were positive for HPV 16.

Properties of HPV-positive and HPV-negative anal carcinomas

Evidence of human papillomavirus (HPV) can be found in up to 85 per cent of anal carcinomas. In the vulva, a discrete subset of HPV-positive carcinomas which show koilocytic morphology and distinct clinical features has recently been identified (warty carcinoma). The morphological and prognostic features of HPV-positive and HPV-negative anal carcinomas were compared in this study of the tumour distribution of HPV DNA. Vulval and anal neoplasia are similar in many ways and we have also looked to see if their similarity extends to 'warty' morphology in relation to HPV status. Thirty-five resection specimens of anal carcinoma were examined with biotin-labelled probes for HPV 6, 11, 16, and 18 DNA, using a non-isotopic in situ hybridization (ISH) technique. No tumour was found to contain HPV 6, 11, or 18. Twenty-four (72 per cent) showed positivity for HPV 16 DNA. Staining was homogeneous and independent of local squamous, basaloid, or ductal differentiation. The majority of tumours showed staining suggestive of episomal, non-productive HPV infection. HPV-positive tumours were more likely to occur in the anal canal than perianally and to show a mixed squamous and basaloid appearance. No difference between the two groups was found in patient age, presence of adjacent dysplasia, ductal differentiation, or prognosis. There was no correlation between condylomatous tumour morphology and HPV 16 DNA positivity; thus, a subset equivalent to vulval warty carcinoma could not be identified.

T-cell proliferative response to human papillomavirus type 16 peptides: relationship to cervical intraepithelial neoplasia

The incidence of human papillomavirus (HPV)-related cervical intraepithelial neoplasia (CIN) and cervical cancer is increased with immunodeficiency, but the role of immune response, including cell-mediated immunity, in disease prevention is not well understood. In this study, T-cell proliferative responses to six synthetic peptides with predicted immunogenic determinants from the HPV-16 E4, E6, E7, and L1 open reading frames were analyzed in 22 sexually active women with new-onset CIN and 65 sexually active women without cervical disease, characterized by cytology, colposcopy, and HPV testing. T-cell proliferative responses were demonstrated to all six HPV-16 peptides. Although not statistically significant, rates of reactivity to E6 (24-45) were higher among sexually active women without disease (26%) than among women with current CIN (7%), as was the overall number of peptides stimulating a response. Women with CIN may not respond to selected HPV antigens as well as women without disease do.

Prospective study on the development of antibodies against human papillomavirus type 6 among patients with condyloma acuminata or new asymptomatic infection

The development over time of antibodies to human papillomavirus type 6 (HPV 6) was studied prospectively in a group of 26 condyloma patients receiving multiple treatments, as well as in 17 healthy subjects with a new HPV 6 infection. The condyloma patients provided serum samples during 2-12 visits over a period of 1-20 months, and the levels of IgA, IgG and IgM antibodies to HPV 6, 11 and 16 capsids, and to HPV 6-derived peptide antigens were determined. Among the capsid antibodies, the IgG and IgA responses against HPV 6 were the most prominent, whereas IgM was detected only in a few patients. During follow-up, seroconversion to HPV capsids was found in six patients and antibody peaks disappeared during follow-up in nine patients. There was no association between serology and cure of the wart. One hundred twenty subjects who reported multiple sexual partners, but found negative for HPV DNA at multiple anogenital and oral sites, provided serum samples and swabs for HPV DNA analysis at 2-7 visits during 4-74 months. Seventeen subjects acquired HPV 6 DNA and were included in the study. Serum IgA, IgG and IgM antibodies to HPV 6 capsids were induced concomitantly with the acquisition of viral DNA (P = 0.02, 0.002 and 0.006, respectively), and declined again when the viral DNA was no longer detectable. In conclusion, antibodies to HPV 6 did not predict the clinical course of condylomatous disease, but appear to be useful mainly as epidemiological markers of viral exposure.

Anal carcinoma--a histological review

Epidemiological evidence of an association between anal carcinoma and symptomatic HIV-related disease suggests that the number of cases of this disease may increase significantly over the next few years. The role of oncogenic HPV types in the pathogenesis of anal carcinoma is substantiated by both epidemiological evidence that tumours are associated with a past history of anal warts and by experimental evidence showing that over 85% of tumours contain HPV 16/18 DNA on PCR. The physical state of the virus in the tumour cell genome is currently under investigation, and cellular interactions between HPV, HIV and other sexually transmitted viruses require further research. Clinical studies have shown that patients with anal warts and those who are HIV positive also show an increased tendency to develop dysplasia within the anal epithelium. However, the malignant potential of dysplasia remains unclear and, it presents problems in management, particularly when multifocal and high grade. Problems in classification of anal carcinomas involve both the site of the tumours and the histological appearance. Despite the difficulties which exist in estimating the origin of a tumour from canal or margin, this information does appear to have clinical significance and should therefore continue to be assessed. Recent morphological and keratin studies have emphasized the heterogeneity of these tumours and have revealed a similar heterogeneous profile of keratin expression in the normal anal epithelium. These results support the body of opinion which suggests that, with the exception of small cell carcinoma and adenocarcinoma, anal carcinomas should be considered as squamous cell tumours which are able to display a range of further morphological characteristics within which ductal differentiation and mucin production appear to carry the worst prognosis. Although there is no universally accepted staging system for anal carcinoma, depth of invasion and extent of spread at the time of diagnosis are the most important clinical factors determining survival and response to therapy. Randomized clinical trials are now under way to compare the outcome of various combinations of radiotherapy and chemotherapy, which have replaced radical surgery as a first line treatment and resulted in a significant decrease in patient morbidity from this disease.

Sexually transmitted diseases and anal manifestations of AIDS

During the past 20 years, there has been an increased use of the anorectum for erotic pleasure. Consequently, this has led to an overwhelming rise in sexually transmitted diseases (STDs) of the anus and rectum. It is important that surgeons involved with the care of colon and rectal disorders be familiar with each of these diseases. The recent AIDS epidemic has been a challenge to the medical community. Equally as challenging is the management of common anorectal disorders in the AIDS patient. AIDS not only influences the manner in which STDs present but is associated with its own spectrum of anorectal disorders. Discussion and management of STDs and anorectal disorders of AIDS patients are presented.