Human papillomaviruses and cervical neoplasia: a model for carcinogenesis

Cost-effectiveness of a potential vaccine for human papillomavirus

Human papillomavirus (HPV) infection, usually a sexually transmitted disease, is a risk factor for cervical cancer. Given the substantial disease and death associated with HPV and cervical cancer, development of a prophylactic HPV vaccine is a public health priority. We evaluated the cost-effectiveness of vaccinating adolescent girls for high-risk HPV infections relative to current practice. A vaccine with a 75% probability of immunity against high-risk HPV infection resulted in a life-expectancy gain of 2.8 days or 4.0 quality-adjusted life days at a cost of $246 relative to current practice (incremental cost effectiveness of $22,755/quality-adjusted life year [QALY]). If all 12-year-old girls currently living in the United States were vaccinated, >1,300 deaths from cervical cancer would be averted during their lifetimes. Vaccination of girls against high-risk HPV is relatively cost effective even when vaccine efficacy is low. If the vaccine efficacy rate is 35%, the cost effectiveness increases to $52,398/QALY. Although gains in life expectancy may be modest at the individual level, population benefits are substantial.

New developments in the treatment of invasive cervical cancer

Cervical cancer is a preventable disease that is curable when it is detected early. For advanced-stage cancer, the prognosis is worse. Over the years, much progress has been made in radiation therapy and in chemotherapy, but it took three decades for the arrival of concurrent chemoradiation therapy, which significantly improved the survival among women with advanced cervical cancer. This fact underscores the need and the importance for continuing efforts in clinical research. While current standards of therapy are being fine-tuned as more information is being gathered, great strides are being made in the areas of molecular and cancer biology. Novel treatments for cervical cancer appear to be imminent in the near future.

Molecular detection and genotyping of pathogens: more accurate and rapid answers

Rapid molecular methods have enhanced the capabilities of laboratories to identify and characterize microbial pathogens in greater detail. Nucleic acid amplification strategies and advances in amplicon detection have been key aspects in the progress of molecular microbiology. Sophisticated new amplification-detection combinations are resulting in many applications in laboratory testing for infectious diseases. These applications include qualitative detection, sub-species-level DNA fingerprinting, molecular resistance testing and genotyping, and quantitative (viral load) testing. When applied selectively in the laboratory, these applications can enhance diagnostic approaches and clinical management and will probably evolve into standard laboratory and point-of-care testing protocols.

Usefulness of DNA ploidy measurement on liquid-based smears showing conflicting results between cytology and high-risk human papillomavirus typing

To improve the positive predictive value (PPV) for high-risk human papillomavirus (HR-HPV) in primary screening, DNA ploidy was measured on the same liquid-based sample by image cytometry in 984 cases showing discrepancies between cytology and HR-HPV testing. Of the conflicting results, 14.5% corresponded to a cytologic lesion (from atypical squamous cells of undetermined significance to high-grade squamous intraepithelial lesion [HSIL]) without HPV detected, and 85.5% of smears were within normal limits but revealed an HR-HPV infection. A suspect DNA profile was associated significantly with a lesion. In 497 patients who underwent repeated HPV testing, a normal DNA profile at the first smear predicted the clearance of HPV infection (sensitivity, 81.5%; specificity, 45.4%; PPV, 69%; negative predictive value, 62.4%). In persistent HR-HPV infection, a suspect DNA profile at the first smear increased the PPVfrom 10.8% to 22.7% for the detection of a histologically proven HSIL with a sensitivity of 95.2%. DNA ploidy can be used to select smears with high risk of HSIL, especially in cases of persistent HR-HPV infection.

Insulin-like growth factor-binding protein 3 expression increases during immortalization of cervical keratinocytes by human papillomavirus type 16 E6 and E7 proteins

Human papillomaviruses (HPVs) infect cervical epithelial cells and induce both benign and precancerous lesions. High-risk HPVs promote the development of cervical cancer in vivo and can immortalize cervical epithelial cells in vitro, whereas low-risk HPVs cannot. We used cDNA microarrays and quantitative polymerase chain reaction to compare cellular gene expression in primary cervical epithelial cells during a time course after retroviral transduction with either low-risk or high-risk E6/E7 genes. At early passages, cervical cells transduced with high-risk E6/E7 genes demonstrated increased expression of the cell cycle-regulated genes CDC2 and ubiquitin carrier E2-C. At later passages, these same cells exhibited dramatic increases in insulin-like growth factor-binding protein-3 (IGFBP-3) mRNA and both secreted an intracellular protein, with mRNA levels increasing approximately 85-fold. Corroborating these in vitro studies, in situ hybridization of cervical biopsies with an IGFBP-3 riboprobe revealed high levels of expression in high-grade squamous intraepithelial neoplasia but not in normal cervical epithelium. Our in vitro results indicate that overexpression of IGFBP-3 is a late event after E6/E7 expression, and analysis of cervical lesions indicates that overexpression of this gene is also seen in vivo.

Risk of oral cancer associated with human papillomavirus infection, betel quid chewing, and cigarette smoking in Taiwan--an integrated molecular and epidemiological study of 58 cases

BACKGROUND

The association between oral squamous cell carcinoma (OSCC) and human papillomavirus (HPV) 6, 11, 16 and 18 is uncertain. Past reports varied in the methodology and results. We conducted this study using in situ PCR in situ hybridization (ISH) assay which was considered as the most sensitive method for detection of viral DNA. We undertook an epidemiologic survey about the history of betel quid chewing and cigarette smoking, since these habits are common in Taiwan.

METHODS

In situ PCR ISH was performed on the tumor specimens from 29 patients with OSCC and the oral mucosal specimens from 29 patients without OSCC. Their betel quid chewing and cigarette smoking histories were also reviewed.

RESULTS

HPV16, HPV18, betel quid chewing and cigarette smoking were statistically significant risk factors in univariate analysis. HPV6 and 11 were not. Multivariate analysis showed that HPV16 infection (adjusted Odds ratio = 11.20) and betel quid chewing (adjusted Odds ratio = 17.06) remained to be independent factors for OSCC.

CONCLUSIONS

Our results showed that HPV16 and betel quid chewing were two major risk factors for OSCC in Taiwan, indicating that they act through different mechanisms in the pathogenesis of OSCC.

The causal relation between human papillomavirus and cervical cancer

The causal role of human papillomavirus infections in cervical cancer has been documented beyond reasonable doubt. The association is present in virtually all cervical cancer cases worldwide. It is the right time for medical societies and public health regulators to consider this evidence and to define its preventive and clinical implications. A comprehensive review of key studies and results is presented.

Serologic response to human oncogenic papillomavirus types 16, 18, 31, 33, 39, 58 and 59 virus-like particles in colombian women with invasive cervical cancer

The serologic response against virus-like particles (VLP) from 7 high risk genital papillomaviruses was investigated by ELISA in 147 Colombian women with invasive cervical cancer and 147 age-matched cytologically normal and HPV-DNA negative women. Anti-VLP antibodies were detected in 82% of the invasive cervical cancer patients and in 56% of the controls. Detection of antibodies against multiple HPV types is the rule and the presence of high antibody titers was associated with higher survival of cancer patients. Higher anti-VLP seroprevalence was observed in younger cancer patients. In those followed serologically for 1 year, antibodies generally remained at the same level. However, in some patients an increase or decrease in antibody levels occurred simultaneously for multiple HPV types, suggesting cross-reactivity between the HPV types investigated. Investigation of seroreactivity between 8 high risk HPVs suggested that there is some cross-reactivity between phylogeneticaly-related types such as 16, 31, 33 and 58; and 18, 45 and 59. In conclusion, our results confirmed (i) the high rate of HPV infections in Colombia, both in patients with cervical cancer and in the general population, and the particularly high rate of infections due to HPV 31 and 58; and (ii) the validity of anti-VLPs as a marker of present or past HPV infection. The simultaneous appearance or disappearance of antibodies against multiple HPV VLPs suggests that the antibodies detected by ELISA are not always type specific.

Prevalence of anti-human papillomavirus type 16, 18, 31, and 58 virus-like particles in women in the general population and in prostitutes

Genital human papillomavirus (HPV) infection is sexually transmitted. The aim of the study was to characterize serological responses to HPV types 16, 18, 31, and 58 by exploring type-specific virus-like particles (VLPs) in two groups of women with very distinct sexual behaviors. Anti-VLP antibodies for types 16, 18, 31, and 58 and HPV DNA in cervical cells were investigated with 177 prostitutes and 283 age-matched controls from the female general population in Spain. Anti-VLP positivity increased with number of lifetime sexual partners in women from the general population, and no seroresponse was found in virgins. However, in prostitutes HPV infection was characterized by higher multireactivity to three or four VLPs (25%) than the general population (3%) and by a more frequent antibody response to HPV-58 than in the general population. About 75% of the women seropositive for type 58 had been born in a Latin American country. Seroprevalence of HPV and cervical HPV DNA in prostitutes were 14 and 10 times higher than observed in women in the general population (prevalence odds ratio [POR] of HPV seropositivity, 14.04 [95%; CI = 8.4 to 23.6] and POR for HPV DNA, 10.4 [95% CI = 3.9 to 27.6). Our results indicate that prostitutes are at an increased risk of oncogenic HPV infections, and they confirm the validity of anti-VLPs as markers of present or past HPV infection, that the number of sexual partners is the major determinant in acquisition of oncogenic HPV, and that anti-VLPs could be used as a marker of repeated infection in prostitutes.

HPV for cervical cancer screening: is the era of the molecular pap smear upon us?

Based on the best estimates of the prevalence of human Papillomavirus infection in the United States, the overall HPV prevalence in the target population is approximately 20%. The prevalence varies greatly with age, being as high as approximately 50% in the third decade to less than 5% in the sixth. These data have implications for a discussion about the utility of human Papillomavirus testing as a screening procedure.(J Histochem Cytochem 49:1197-1198, 2001)

Prevention of cervical cancer with vaccines

Worldwide, cervical cancer is one of the most common cancers in women. This is especially true in developing countries, where Papanicolaou smear screening, an effective preventive measure against cervical cancer, is insufficiently implemented. With growing evidence for human papillomavirus as a central etiologic factor in cervical neoplasia, development of a vaccine against this virus has emerged as an important objective in prevention of cervical cancer. International efforts in vaccine development have culminated in advancement of various vaccine strategies and initiation of human clinical trials. Reports from animal vaccine trials and early phase I human trials indicate markedly enhanced immune response through vaccination. However, the clinical significance of these results requires confirmation from long-term human trials.

Clues to the pathogenesis of fallopian tube carcinoma: a morphological and immunohistochemical case control study

The purpose of this study was to identify histopathological fallopian tube changes that might be related to the development of fallopian tube carcinoma (FTCA). Each of 14 unilateral cases of the latter was matched with 2 controls for age, hospital, and year of diagnosis. The uninvolved fallopian tube from patients with FTCA, all of which were of serous type, was compared to fallopian tubes from the same side in 28 matched controls. The features evaluated included plical bridging, trapped gland-like structures, inflammation, epithelial stratification, tufting, nuclear atypia, plical atrophy, luminal dilatation, and presence or absence of in situ carcinoma. The significant changes (p < 0.05) in the contralateral tubes of patients with FTCA were luminal dilatation (p = 0.0004), plical atrophy (p = 0.0015), and chronic inflammation (p = 0.0089). FTCA may therefore develop in tubes demonstrating histologic features of chronic healed salpingitis, findings that reflect bilateral tubal disease which apparently antedates the development of the FTCA. p53 stains were strongly positive in 9 of 14 FTCAs and in 5 of 6 foci of in situ carcinoma found in the tubes with unilateral FTCA. No p53 staining was found in any of the contralateral tubes. Serous FTCAs may be etiologically related to antecedent bilateral healed chronic salpingitis and arise from in situ carcinoma in a background of atrophy.

Vaginal adenosis with adenocarcinoma in situ in a woman with no recognised antecedent factors

We present a case of vaginal adenosis with adenocarcinoma in situ in a woman with no recognised antecedent factors. This case demonstrates the importance of continuing thorough colposcopic assessment of the entire lower genital tract with repeated biopsies of all abnormal epithelium in women with persistent or recurrent cervical cytology abnormalities. Successful management requires accurate definition of the vaginal lesion.

Vulvar keratinizing squamous cell carcinoma in a 26-year-old woman

A 26-year-old Hispanic woman complaining of "itching" and "herpetic lesions" on the vulva for 9 months was seen at a university hospital. On physical examination, multiple vulvar masses were noted. Biopsies taken from these lesions showed invasive keratinizing squamous cell carcinoma. The vulvectomy specimen revealed 4 tumor masses, the largest located on the mons pubis. Although the incidence of vulvar intraepithelial neoplasia has increased in recent years, only very few cases of invasive carcinoma have been reported in young women. The tumors that occur at a younger age characteristically have basaloid or warty histology, in contrast to those occurring in older women, which usually are well-differentiated keratinizing carcinomas. We believe this is an unusual case of vulvar squamous cell carcinoma. In addition to our patient's young age, her tumor had a histologic profile usually found in lesions of an elderly woman. The tumor was negative for human papillomavirus by polymerase chain reaction analysis and was positive for p53 by immunohistochemistry.

Pagetoid dyskeratosis of the cervix: an incidental histologic finding in uterine prolapse

Pagetoid dyskeratosis, is considered a reactive process in which a small part of the normal population of keratinocytes is induced to proliferate. The lesion is characterized by pale cells resembling those of Paget's disease within the epidermis. These cells have been seen as an incidental finding in a variety of benign papules most commonly located in intertriginous areas. Among the inductors of the lesion, friction is suspected. To the best of our knowledge, these pale cells have not been reported in the cervix. We describe the location of the lesion in the ectocervix and the incidence of this lesion in a group of 100 unselected patients surgically treated for uterine prolapse. Another group of 100 unselected patients treated for uterine leiomyoma was used as a control. Pagetoid dyskeratosis was found in 37 cases (37%) of uterine prolapse and in five cases (5%) of uterine leiomyomas. The lesion is more common in uterine prolapse (p <0.001) and is not significantly associated with cornification of the epithelium (p = 0.72343). The cells of pagetoid dyskeratosis show an immunohistochemical profile different from the surrounding squamous cells characterized by premature keratinization. Pagetoid dyskeratosis cells have shown positivity for high molecular weight cytokeratin and negative reaction for low molecular weight cytokeratin, epithelial membrane antigen, carcinoembryonic antigen, and human papilloma virus. Pagetoid dyskeratosis cells must be distinguished from artefactual clear cells, glycogen-rich cells, koilocytes, extramammary Paget's disease cells, and pagetoid spread of carcinoma cells to the cervix. In cases in which pagetoid dyskeratosis shows a florid expression, there is a hazard of overdiagnosis. The pathologist should be aware of the histologic features of pagetoid dyskeratosis in the ectocervix to avoid misdiagnosis and unnecessary treatment. Routine histologic study is usually sufficient to identify the lesion.

Oncogenes and tumor angiogenesis: the HPV-16 E6 oncoprotein activates the vascular endothelial growth factor (VEGF) gene promoter in a p53 independent manner

Like other types of pre-malignant lesions and carcinoma, angiogenesis is associated with high-grade cervical dysplasia and with invasive squamous carcinoma of the cervix. Vascular endothelial cell growth factor (VEGF) is known to be one of the most important inducers of angiogenesis and is upregulated in carcinoma of the cervix. Human Papilloma Virus 16 (HPV-16) has been etiologically linked to human cervical cancer, and the major oncogenic proteins encoded by the viral genome, E6 and E7, are involved in the immortalization of target cells. Because several oncogenes including mutant ras, EGF receptor, ErbB2/Her2, c-myc and v-src upregulate VEGF expression, we asked whether HVP-16 E6 oncoprotein could act in a similar fashion. We found that HPV-16 E6-positive cells generally express high levels of VEGF message. Furthermore, co-expression of the VEGF promoter-Luc (luciferase) reporter gene with E6 in both human keratinocytes and mouse fibroblast showed that E6 oncoprotein upregulates VEGF promoter activity, and does so in a p53 independent manner. An E6 responsive region which comprises four Sp-1 sites, between -194 and -50 bp of the VEGF promoter, is also necessary for constitutive VEGF transcription. Taken together, our results suggest the possibility that the HPV oncoprotein E6 may contribute to tumor angiogenesis by direct stimulation of the VEGF gene.

Preventive and therapeutic vaccines for human papillomavirus-associated cervical cancers

'High risk' genotypes of the human papillomavirus (HPV), particularly HPV type 16, are the primary etiologic agent of cervical cancer. Thus, HPV-associated cervical malignancies might be prevented or treated by induction of the appropriate virus-specific immune responses in patients. Sexual transmission of HPV may be prevented by the generation of neutralizing antibodies that are specific for the virus capsid. In ongoing clinical trials, HPV virus-like particles (VLPs) show great promise as prophylactic HPV vaccines. Since the capsid proteins are not expressed at detectable levels by basal keratinocytes, therapeutic vaccines generally target other nonstructural viral antigens. Two HPV oncogenic proteins, E6 and E7, are important in the induction and maintenance of cellular transformation and are coexpressed in the majority of HPV-containing carcinomas. Therefore, therapeutic vaccines targeting these proteins may provide an opportunity to control HPV-associated malignancies. Various candidate therapeutic HPV vaccines are currently being tested whereby E6 and/or E7 are administered in live vectors, in peptides or protein, in nucleic acid form, as components of chimeric VLPs, or in cell-based vaccines. Encouraging results from experimental vaccination systems in animal models have led to several prophylactic and therapeutic vaccine clinical trials. Should they fulfill their promise, these vaccines may prevent HPV infection or control its potentially life-threatening consequences in humans.

Human papillomavirus genotype 16 vaccines for cervical cancer prophylaxis and treatment

More than 11% of the global cancer incidence in females is due to human papillomavirus (HPV) infections, with HPV genotype 16 the most prevalent viral type to infect the cervix. Vaccine strategies currently target HPV 16 genes E6 and E7, constitutively expressed in cervical cancer cells, and L1 and L2, HPV surface antigens. Recent developments in HPV vaccine research are reviewed. Most studies focus on vaccine models showing improved immunogenicity or dual induction of both humeral and cellular systems. Preclinical studies show that (1) L1 /E7 chimeric viral-like proteins induce both neutralizing L1 antibodies and E7-specific T cells; (2) rerouting a cytosolic tumor antigen into the endosomal/lysosomal compartment can improve the therapeutic potency of DNA vaccines; and (3) accelerated E7 protein degradation leads to enhanced antigen presentation in the context of major histocompatability complex class I. Clinical studies show that (1) HPV 16 E7 peptide vaccination can be safely delivered to patients with terminal disease; and (2) HPV-16 capsid proteins harbor at least one HLA-A*201 restricted cytotoxic T lymphocyte (CTL) epitope.