Papillomaviruses and cancer: from basic studies to clinical application

Detection of human papillomavirus-16 in ovarian malignancy

Human papillomavirus is the causal factor for cervical cancer. However, the role of HPV infection in ovarian cancer is unclear. This study aimed to determine the presence of human papillomavirus-16 (HPV-16) in ovarian cancer tissues. Archived human ovarian cancer tissues (N=54 cases, 50 are epithelial cancer, four are nonepithelial cancer) embedded in paraffin blocks were used. Controls are 30 nonmalignant ovarian tissue blocks. In situ hybridisation (ISH) and immunohistochemistry (IHC) were used to detect the presence of HPV-16 and p53 expression. In all, 52 or 36% of the epithelial ovarian tumours detected by ISH or IHC, respectively, were HPV-16 E6 positive. In contrast, only 6.7% of normal ovarian tissues were HPV-16 positive proved by ISH. Human papillomavirus-16 infection was significantly higher in cancer tissues compared to controls with an odds ratio of 16.7 (95% confidence interval [CI]=3.2-71.4, P<0.01). No significant correlation between HPV-16 infection and histological types of cancer was found (P>0.05). p53 gene expression was detected in 42% epithelial ovarian cancers. No correlation between p53 expression and HPV-16 infection was found. The results showed the presence of HPV-16 E6 in ovarian carcinoma, suggesting that HPV infection might play a role in ovarian carcinogenesis.

Human papillomaviruses: targeting differentiating epithelial cells for malignant transformation

Human papillomavirus (HPV) infections play a crucial role in the pathogenesis of cervical neoplasia. Insights into the mechanisms by which HPV infection can, in a small numbers of cases, result in malignancy, comes from the observation that three proteins encoded by high-risk genital HPVs, E6, E7 and to a lesser extent E5, target factors that control the cell cycle and proliferation. These interactions result in abrogation of cell cycle control, chromosomal alterations, telomerase activation, and eventual cell immortalization. In this review, we discuss the functions of E6, E7, and E5 proteins that are most relevant to the malignant progression of HPV-transformed cells.

Human papillomavirus biology and cervical neoplasia: implications for diagnostic criteria and testing

Human papillomaviruses are necessary for the development of cervical neoplasia. Progress in our understanding of the epithelial biology of this common pathogen has greatly influenced current concepts of cervical carcinogenesis. This understanding has provided a framework for understanding the biologic basis of many diagnostic criteria. Furthermore, classification schemes, diagnostic testing, and clinical management have been modified and clarified in light of this knowledge.

Integration of interferon-alpha/beta signalling to p53 responses in tumour suppression and antiviral defence

Swift elimination of undesirable cells is an important feature in tumour suppression and immunity. The tumour suppressor p53 and interferon-alpha and -beta (IFN-alpha/beta) are essential for the induction of apoptosis in cancerous cells and in antiviral immune responses, respectively, but little is known about their interrelationship. Here we show that transcription of the p53 gene is induced by IFN-alpha/beta, accompanied by an increase in p53 protein level. IFN-alpha/beta signalling itself does not activate p53; rather, it contributes to boosting p53 responses to stress signals. We show examples in which p53 gene induction by IFN-alpha/beta contributes to tumour suppression. Furthermore, we show that p53 is activated in virally infected cells to evoke an apoptotic response and that p53 is critical for antiviral defence of the host. Our study reveals a hitherto unrecognized link between p53 and IFN-alpha/beta in tumour suppression and antiviral immunity, which may have therapeutic implications.

Detection of human papillomavirus in Chinese esophageal squamous cell carcinoma and its adjacent normal epithelium

AIM: To investigate the putative role of human papillomavirus (HPV) infection in the carcinogenesis of esophageal squamous cell carcinoma in China.

METHODS: Twenty-three esophageal squamous cell carcinoma samples and the distal normal epithelium from Shanxi Province, and 25 more esophageal squamous cell carcinoma samples from Anyang city, two areas with a high incidence of esophageal cancer in China, were detected for the existence of HPV-16 DNA by PCR, mRNA in situ hybridization (ISH) and immunohistochemistry (IHC) targeting HPV-16 E6 gene.

RESULTS: There were approximately 64% (31/48) patients having HPV-16 DNA in tumor samples, among them nearly two-thirds (19/31) samples were detected with mRNA expression of HPV-16 E6. However, in the normal esophageal epithelium from cancer patients, the DNA and mRNA of HPV-16 were found with much less rate: 34.7% (8/23) and 26.1% (6/23) respectively. In addition, at protein level detected by IHC assay, 27.1% (13/48) tumor samples had virus oncoprotein E6 expression, while only one case of normal epithelium was found positive.

CONCLUSION: HPV infection, especially type 16, should be considered as a risk factor for esophageal malignancies in China.

Hypermethylation of the tumor suppressor gene RASSFIA and frequent concomitant loss of heterozygosity at 3p21 in cervical cancers

Loss of heterozygosity (LOH) at chromosome 3p21 is frequent in cervical cancers. The candidate tumor suppressor gene, RASSF1A located at 3p21.3, is found to be inactivated in several major human cancers, implicating its significance in carcinogenesis. We aimed to investigate the status of RASSF1A in cervical cancers. The mutation and methylation status of RASSF1A were analysed in 4 cervical cancer cell lines, 50 primary cervical cancers including 33 squamous cell carcinoma (SCC), 17 adenocarcinoma (AC) and 11 normal controls. The primary cancer samples were also detected for LOH at 3p21 and human papillomavirus (HPV). Hypermethylation of RASSF1A was detected in 30% of SCC, 12% of AC and in 1 of the 4 cancer cell lines but was absent in all normal cases. Methylation of the cancer cell line was associated with loss of gene expression, which was restored by demethylation. About 67% (8 of 12) of hypermethylated primary cancers showed concomitant LOH at 3p21. No somatic mutation was found in all primary cancer samples or cell lines but 2 cases showed germline polymorphism at codon 133. Oncogenic HPV DNAs were found in most cancer samples. No correlation was detected between RASSF1A-hypermethylation or LOH at 3p21 and age of patient, HPV genotype, tumor grade and stage. Hypermethylation of RASSF1A occurs in a subset of cervical cancers, among which concomitant LOH at 3p21 is common. The results supported that RASSF1A may be one of the cervical cancer-related tumor suppressor genes located at 3p21 regions.

Activated Notch1 inhibits p53-induced apoptosis and sustains transformation by human papillomavirus type 16 E6 and E7 oncogenes through a PI3K-PKB/Akt-dependent pathway

Activated Notch1 (AcN1) alleles cooperate with oncogenes from DNA tumor viruses in transformation of epithelial cells. AcN1 signaling has pleiotropic effects, and suggested oncogenic roles include driving proliferation through cyclin D1 or the generation of resistance to apoptosis on matrix withdrawal through a phosphatidylinositol 3-kinase (PI3K)-PKB/Akt-dependent pathway. Here, we extend the antiapoptotic role for AcN1 by showing inhibition of p53-induced apoptosis and transactivation. Chemical inhibitors of the PI3K pathway block AcN1-induced inhibition of p53-dependent apoptosis and nuclear localization of Hdm2. We show that expression of wild-type p53 does not inhibit synergistic transformation by AcN1 and human papillomavirus E6 and E7 oncogenes. We suggest that activation of Notch signaling may serve as an additional mechanism to inhibit wild-type p53 function in papillomavirus-associated neoplasia.

Progress in prophylactic and therapeutic vaccines for human papillomavirus infection

Virus-like particle (VLP) subunit vaccines composed of the major capsid protein L1 of the genital human papillomaviruses (HPVs) are now in Phase III clinical trials. The vaccines are immunogenic and safe and early results indicate efficacy. VLPs induce strong cell-mediated as well as humoral immune responses and chimeric VLPs including an HPV early protein may have therapeutic potential. Polynucleotide and recombinant viral vaccines encoding nonstructural viral proteins show therapeutic and prophylactic efficacy in animal models and are candidate immunotherapies for established low-grade benign genital infections. Vaccines designed to elicit cytotoxic T-lymphocytes specific for the HPV oncoproteins E6 and E7 show immunogenicity and efficacy in transplantable tumor models in rodents. In Phase I and II trials these vaccines are immunogenic and safe but show limited efficacy.

Intralesional Cidofovir for the Treatment of Severe Juvenile Recurrent Respiratory Papillomatosis: Long-Term Results in 4 Children

OBJECTIVE: We sought to determine the efficacy of intralesional injection of cidofovir in improving resolution of recurrent respiratory papillomatosis (RRP).

STUDY DESIGN AND SETTING: We conducted a prospective, observational trial at an academic tertiary children's hospital.

RESULTS: Four children with RRP requiring more than 6 surgical excisions per year were treated with intralesional cidofovir. Cidofovir (5 mg/mL) was injected into airway sites where papillomas had just been excised using sharp technique. Each patient had 6 treatments performed 6 to 8 weeks apart. Biopsies confirmed benign papilloma lesions in all cases. During treatment with intralesional cidofovir there was diminished growth of the papillomas in each patient. Once cidofovir treatment was stopped, the rate of regrowth and frequency of surgical excision returned to pretreatment levels in 3 of the 4 patients.

CONCLUSIONS: Intralesional cidofovir may provide benefit in reducing the rate of RRP growth while under treatment, but RRP severity returned to pretreatment levels once cidofovir treatment was stopped using this treatment program.

Prevalence of human papillomavirus infection in rural villages of the Bolivian Amazon

Cervical cancer constitutes a major health problem in developing countries like Bolivia. The roles of certain genotypes of human papillomaviruses (HPVs) in the pathogenesis of cervical cancer is well established. The prevalence of HPV infection among sexually active women varies greatly. Information regarding HPV infection in Bolivia is very much scarce, specially in regions like the Amazonian lowland. We studied 135 healthy women living in four rural localities of the Bolivian Amazon. Presence of HPV in DNA extracted from cervical swabs was analyzed using a reverse line hybridization assay. The estimated overall HPV infection prevalence among the studied rural localities was 5.9% (ranging from 0-16.6%). These values were unexpectedly low considering Bolivia has a high incidence of cervical cancer. The fact that Amazonian people seem to be less exposed to HPV, makes it likely that some other risk factors including host lifestyle behaviors and genetic background may be involved in the development of cervical cancer in this population.

Human papillomavirus infection as a prognostic factor in carcinomas of the oral cavity and oropharynx

Although studies have established human papillomaviruses (HPVs) as a risk factor for oral and oropharyngeal cancer, it is not clear whether viral infection affects survival in head and neck malignancies. This investigation examined the relationship between HPV and survival in carcinomas of the oral cavity and oropharynx. Formalin-fixed, paraffin-embedded tumor specimens from 139 newly diagnosed cases were tested for HPVs by PCR and DNA sequencing. Patient and tumor characteristics were obtained from questionnaires, pathology reports and cancer registries. Odds ratios (ORs) and relative risks (RRs) were based on logistic and Cox regression models, respectively. HPVs were detected in 21% of the tumors; 83% were HPV-16. Greater risk of HPV infection was associated with males (OR = 2.9, 95% CI = 1.0-8.6), a history of oral-genital sex (OR = 4.2, 95% CI = 1.5-11.7), and oropharyngeal tumors (OR = 10.4, 95% CI = 3.5-31.2). As tobacco usage increased, the odds of HPV detection decreased (OR = 0.97/pack-year, 95% CI = 0.96-0.99). HPV infected patients had better overall survival (RR = 0.3, 95% CI = 0.1-0.8) than those with HPV-negative tumors. There was an interaction between gender and HPV for overall (p = 0.05) and disease-specific (p = 0.03) survival that suggested that HPV infected males had better prognosis than HPV-negative males, but this was not the case among females. HPV status was identified as an independent prognostic factor in oral and oropharyngeal cancers. This result appeared to be gender-specific, suggesting the need for further study of the interaction between HPV and gender on survival.

Interaction of L2 with beta-actin directs intracellular transport of papillomavirus and infection

Viruses that replicate in the nucleus, including the primary causative agent of cervical cancer, human papillomavirus type 16 (HPV16), must first cross the cytoplasm. We compared the uptake of HPV16 virus-like particles (VLPs) either with or without the minor capsid protein L2. Whereas VLPs containing only the major capsid protein L1 were diffusely distributed within the cytoplasm even 6 h post-infection, VLPs comprising both L1 and L2 exhibited a radial distribution in the cytoplasm and accumulated in the perinuclear region of BPHE-1 cells within 2 h. L2 of HPV16 or bovine papillomavirus was shown to bind to a 43-kDa cellular protein that was subsequently identified as beta-actin by matrix-assisted laser desorption ionization time-of-flight analysis. A conserved domain comprising residues 25-45 of HPV16 L2 was sufficient for interaction with beta-actin. HPV16 L2 residues 25-45 fused to green fluorescent protein, but not green fluorescent protein alone, colocalized with actin and caused cell retraction and disruption of the microfilament network. Finally, wild-type L2, but not L2 with residues 25-45 deleted, facilitated HPV16 pseudovirion infection. Thus, binding of beta-actin by L2 residues 25-45 facilitates transport of HPV16 across the cytoplasm during infection, and blockade of this novel interaction may be useful for prophylaxis.

Molecular interactions of 'high risk' human papillomaviruses E6 and E7 oncoproteins: implications for tumour progression

The aetiology of cervical cancer has been primarily attributed to human papillomaviruses (HPVs). These are characterized by the persistent expression of the two oncogenes, E6 and E7. Experimental studies show that E6 and E7 genes of the high risk HPVs deregulate key cell cycle controls. Recent work has uncovered new cellular partners for these proteins that throw light on many of the pathways and processes in which these viral proteins intervene. This review focuses on the regulation of host proteins by the viral oncoproteins and consequence of such interactions on cell survival, proliferation, differentiation and apoptosis.

Interleukin-6 promotes cervical tumor growth by VEGF-dependent angiogenesis via a STAT3 pathway

Interleukin-6 (IL-6) has received particular attention in the pathogenesis of cervical cancer, although the underlying mechanism remains elusive. This study revealed that IL-6 promotes in vivo tumor growth of human cervical cancer C33A cells, but does not substantially alter their in vitro growth kinetics. The in vivo angiogenic assays showed that IL-6 increases angiogenic activity in human cervical cancer cells, an effect that is specifically associated with upregulation of vascular endothelial growth factor (VEGF). Also, using anti-VEGF antibody to block VEGF function significantly inhibited IL-6-mediated angiogenesis and tumor growth in nude mice, strongly supporting the critical role of VEGF in the IL-6-mediated cervical tumorigenesis. Accordingly, the signaling pathway downstream of IL-6/IL-6R responsible for the regulation of VEGF was investigated. Notably, pharmacological inhibition of PI3-K or MAPK failed to inhibit IL-6-mediated transcriptional upregulation of VEGF. Meanwhile, blocking STAT3 pathway with dominant-negative mutant STAT3D effectively abolished IL-6-induced VEGF mRNA. In transient transfections, a luciferase reporter construct containing the full-length 1.5-kb VEGF promoter or a 1.2-kb fragment lacking the known hypoxic-response element also exhibited the same degree of response to IL-6. Additionally, transient transfection of STAT3D downregulated the 1.2-kb VEGF promoter luciferase reporter stimulated by IL-6. Based on the above phenomenon combined with the concomitant increased tumor expression of IL-6 and VEGF in cervical cancer tissues, we conclude that IL-6 may promote cervical tumorigenesis by activating VEGF-mediated angiogenesis via a STAT3 pathway.

The role of TP53 in Cervical carcinogenesis

Functional loss of the tumor suppressor p53 by alterations in its TP53 gene is a frequent event in cancers of different anatomical regions. Cervical cancer is strongly linked to infection by high-risk human papillomavirus (HPV) types. The viral oncoprotein E6 has the ability to associate with and neutralize the function of p53. E6 interacts with a 100-kDa cellular protein, termed E6 associated protein (E6AP; also called ubiquitin-protein ligase E3A or UBE3A), which functions as an ubiquitin protein ligase. The dimeric complex then binds p53 and E6AP catalyzes multi-ubiquitination and degradation of p53. The ability to promote p53 degradation is an exclusive property of E6 from the high-risk HPV types. Indeed, the low-risk E6 proteins lack this activity, although they can bind p53. Consistent with the E6 function of the high-risk HPV types, the majority of cervical cancer cells have a wild-type p53 gene, but the protein levels are strongly decreased. Several independent studies have shown that in a small percentage of cervical tumors the p53 gene is mutated. However, this event appears to be unrelated to the presence or absence of HPV infection and the nature of the tumor.

Relationship between steroid hormone contraceptives and HPV, cervical intraepithelial neoplasia and cervical carcinoma

Available data demonstrate an increase in the transcription of high-risk papillomaviruses by the 16alpha-hydroxylation of estrogens, which is in line with the epidemiologic data showing an increased cervical carcinogenesis risk for long-term contraceptive-using, HPV-infected women. No evidence exists for an increase in HPV-negative contraceptive users.

Inhibition of human papilloma virus E2 DNA binding protein by covalently linked polyamides

Polyamides are a class of heterocyclic small molecules with the potential of controlling gene expression by binding to the minor groove of DNA in a sequence-specific manner. To evaluate the feasibility of this class of compounds as antiviral therapeutics, molecules were designed to essential sequence elements occurring numerous times in the HPV genome. This sequence element is bound by a virus-encoded transcription and replication factor E2, which binds to a 12 bp recognition site as a homodimeric protein. Here, we take advantage of polyamide:DNA and E2:DNA co-crystal structural information and advances in polyamide synthetic chemistry to design tandem hairpin polyamides that are capable of displacing the major groove-binding E2 homodimer from its DNA binding site. The binding of tandem hairpin polyamides and the E2 DNA binding protein to the DNA site is mutually exclusive even though the two ligands occupy opposite faces of the DNA double helix. We show with circular permutation studies that the tandem hairpin polyamide prevents the intrinsic bending of the E2 DNA site important for binding of the protein. Taken together, these results illustrate the feasibility of inhibiting the binding of homodimeric, major groove-binding transcription factors by altering the local DNA geometry using minor groove-binding tandem hairpin polyamides.

Differences in the ubiquitination of p53 by Mdm2 and the HPV protein E6

The human papillomavirus (HPV) protein E6 can promote the ubiquitination of the p53 tumour suppressor in vitro, providing an explanation for the ability of E6 to induce p53 degradation in vivo and contribute to the potential tumorigenic effect of the virus. Instead, in non-infected cells, p53 levels are primarily destabilised by the ubiquitin E3 ligase activity of the Mdm2 protein. Here we have compared the effects of E6 and Mdm2 on p53 ubiquitination in vivo. We show that whereas in the presence of Mdm2 proteasome inhibitors induce the accumulation of ubiquitinated forms of p53, this does not occur in the presence of E6. Accordingly, we confirm that the effect of E6 and p53 is independent of the six C-terminal lysine residues in p53, which have previously been described to play an important role for effective ubiquitination and degradation of 53 mediated by Mdm2. We also show that other yet unidentified residues in p53 are also susceptible to ubiquitination. These results indicate that E6 does not induce ubiquitination of p53 in the same way as Mdm2 in order to promote its degradation, suggesting important differences between the Mdm2 and E6 effects on p53 degradation.

Phenylbutyrate inhibits growth of cervical carcinoma cells independent of HPV type and copy number

PURPOSE

Inhibitors of histone deacetylase, such as sodium butyrate, block proliferation of cervical carcinoma cells by inhibiting the G1 to S transition of the cell cycle. The derivative phenylbutyrate (PB), characterized by its higher pharmacological half-life, and its metabolite phenylacetate (PA) were tested for their growth-inhibitory function on cervical cancer cells differing in their HPV type, copy number, and integration sites.

METHODS AND RESULTS

Using flow cytometric and Western blot analyses, we show that a 24-h incubation period with PB, but not with PA, was already sufficient to cause a dose-dependent growth arrest by increasing the G1 fraction with a concomitant drop in the S-phase. Consistent with the cell cycle block, only PB, but not PA, induced the cyclin-dependent kinase inhibitors p21(CIP1) and p27(KIP1). The inhibitory effect was not the result of a non-specific cytotoxic effect of PB, since cessation of cellular growth was already completely reversible 5 h after drug removal.

CONCLUSIONS

Due to its broad growth inhibitory properties on different cervical carcinoma cells in vitro, and its low toxic profile demonstrated in preceding clinical studies, PB may serve as an effective drug in handling pre-cancerous lesions and cervical cancer in patients.

Minichromosome maintenance (Mcm) proteins, cyclin B1 and D1, phosphohistone H3 and in situ DNA replication for functional analysis of vulval intraepithelial neoplasia

Vulval intraepithelial neoplasia (VIN) is defined histopathologically by distinctive abnormalities of cellular maturation and differentiation. To investigate the functional properties of VIN, the expression of several proteins involved in the regulation of the cell cycle as well as in situ DNA replication competence was analysed by immunohistochemistry. Snap-frozen vulval biopsies were graded as normal squamous epithelium (n=6), undifferentiated HPV positive VIN 1 (n=3), VIN 2 (n=8) and VIN 3 (n=20). Immunohistochemistry was performed using the following markers: cyclin D1 (expressed in middle/late G1), cyclin B1 (expressed in G2/early M), phosphorylated histone H3 (expressed during mitosis) and minichromosome maintenance (Mcm) proteins 2 and 5 (expressed during the cell cycle, but not in differentiated or quiescent cells). In situ DNA replication competence was used to identify S-phase cells. The percentage of positively stained nuclei in three representative microscopic fields was calculated per biopsy. In normal vulva, the expression of all markers was restricted to the proliferative compartment of the basal layer of the epithelium. In contrast in high-grade VIN, the majority of epithelial cells expressed the Mcm proteins from basal to superficial layer. The detection of cyclins B1 and D1, phospho-histone H3 and in situ DNA replication was also found through the full thickness of these lesions but by a lower proportion of the cells. This is consistent with these markers providing a series of 'snapshots' of the cell cycle status of individual cells. The low-grade VIN showed reduced expression of the cell cycle markers in relation to the level of dysplasia. The combination of these analyses establishes that the majority of VIN cells remain in a functional replicative or prereplicative state of the cell cycle. Clinical application of these analyses may provide a basis for improved diagnosis of VIN.

Prevalence of human papillomavirus infection in women in Busan, South Korea

To investigate the prevalence of and the risk factors for human papillomavirus (HPV) infection in South Korea, we interviewed and examined a randomly selected sample of 863 sexually active women (age range = 20-74 years, median 44) and 103 self-reported virgins from Busan. The presence of DNA of 34 different HPV types in cervical exfoliated cells was tested among sexually active women by means of a PCR-based assay. IgG antibodies against L1 virus-like particles (anti-VLPs) of HPV types 16, 18, 31, 33 and 58 were also evaluated by means of ELISA. The overall prevalence of HPV DNA was 10.4% (95% confidence interval, CI: 8.5-12.7%). The most often found HPV DNA types were HPV 70, HPV 16 and HPV 33; 19.8% (95% CI: 17.2-22.0) of sexually active women had antibodies against one or more HPV types. The most common anti-VLPs were against HPV 18, 31 and 16. Prevalences standardized by age on the basis of the world standard population were 13.0% for HPV DNA and 17.1% for anti-VLPs. The concordance between the 2 HPV markers at an individual level was modest, but the risk factors for detection of HPV DNA and anti-VLPs were similar: number of lifetime sexual partners (odds ratio, OR for >/= 4 vs. 1 = 3.5 and 5.4, respectively), seropositivity for herpes simplex virus-2 antibodies (OR = 2.6 and 2.5, respectively) and being single or divorced. HPV DNA, but not anti-VLPs, were elevated among women whose husbands were thought by their wives to have extra-marital affairs and those who had undergone vasectomy. Among 103 virgins, 4.9% had anti-VLPs (1/73 among those aged 24 years or less).

Stress management and psychoneuroimmunology in HIV infection

Does stress management affect psychological and immune functioning in persons with human immunodeficiency virus infections? Stress-management techniques, such as relaxation training and imagery, cognitive restructuring, coping-skills training, and interpersonal-skills training, may reduce anxiety, depression, and social isolation in HIV-infected persons by lowering physical tension and increasing a sense of control and self-efficacy. A psychoneuroimmunologic model is proposed wherein these psychological changes are hypothesized to be accompanied by an improved ability to regulate neuroendocrine functioning, which in turn may be associated with a partial normalization of immune system functions such as lymphocyte proliferation and cytotoxicity, providing more efficient surveillance of latent viruses that may contribute directly to increased HIV replication and generate opportunistic infections or cancer if left unchecked. Such a normalization of stress-associated immune system decrements are hypothesized to forestall or minimize increases in viral load and expression of clinical symptoms. This model is useful for testing the factors contributing to the health effects of stress-management interventions in HIV-infected persons. In this context, one general research strategy for testing the effects of stress-management interventions is to target them toward the more prevalent psychosocial challenges that HIV-infected people face at various points in the disease process; enroll an HIV-infected population (eg, HIV-positive homosexual and bisexual men) into a randomized trial; and monitor changes in cognitive, affective, behavioral, and social factors in parallel with hormonal, immunologic, viral, and clinical changes over the course of time. This article will review the major psychoneuroimmunologic findings that have emerged using this paradigm and suggest future research directions and clinical applications.

The presence of high-risk HPV combined with specific p53 and p16INK4a expression patterns points to high-risk HPV as the main causative agent for adenocarcinomain situ and adenocarcinoma of the cervix

Adenocarcinoma in situ (ACIS) and adenocarcinoma (AdCA) of the cervix are frequently missed in population-based screening programmes. Adding high-risk HPV (hrHPV) testing to cervical cancer screening might improve the detection rate of ACIS and AdCA. Since the exact proportion of AdCAs of the cervix that can be attributed to hrHPV infection is still a matter of debate, a comprehensive study was performed of hrHPV presence in ACIS and AdCA of the cervix. Archival formalin-fixed specimens of indisputable ACIS (n=65) and AdCA (n=77) of the cervix were tested for hrHPV DNA by GP5+/6+ PCR-enzyme immunoassay (EIA) and type-specific E7 PCR for 14 hrHPV types. Further immunostaining for p16INK4A and p53 was performed to assess alternative pathways of carcinogenesis potentially unrelated to HPV. hrHPV DNA was found in all (100%) ACISs and 72 (94%) cervical AdCAs, whereas none of 20 endometrial AdCAs scored hrHPV-positive. HPV 18 was most prevalent and found as single or multiple infection in 68% of ACISs and 55% of cervical AdCAs. Diffuse immunostaining for p16INK4a, a potential marker of hrHPV E7 function, was significantly more frequent in hrHPV-positive cervical AdCAs (19/20; 95%) than in those without hrHPV (1/5; 20%; p<0.001). Immunostaining for p53, pointing to stabilized wild-type or mutant p53 protein, was significantly more frequent in hrHPV cervical AdCAs negative for hrHPV (p=0.01). No difference in p16INK4a and p53 immunostaining was found between hrHPV-negative cervical AdCAs and endometrial AdCAs. Hence, only a minority of cervical AdCAs displayed absence of HPV DNA and immunostaining profiles suggestive of an aetiology independent of HPV. Since all ACISs and nearly all cervical AdCAs were hrHPV-positive, the incorporation of hrHPV testing in cervical cancer screening programmes is likely to decrease markedly the incidence of cervical AdCA.

The role of human papillomavirus oncoproteins E6 and E7 in apoptosis

The oncogenic potential of 'high risk' human papillomaviruses can be mainly attributed to two small proteins called E6 and E7. Even these oncoproteins have a low molecular size, they are highly promiscuous and are capable to interact with a whole variety of host cellular regulator proteins to elicit cellular immortalization and ultimately complete malignant transformation. To avoid reiterations in summarizing the biochemical and molecular biological properties of E6/E7 in terms of their influence on cell cycle control, the present review is mainly an attempt to describe some regulatory principles by which human papillomavirus (HPV) oncoproteins can interfere with apoptosis in order to escape immunological surveillance during progression to cervical cancer. The models derived from these basic cellular and molecular studies are relevant to our understanding of HPV-induced carcinogenesis. Conversely, experimental procedures aimed at relieving apoptosis resistance, can facilitate the eradication of immunologically suspicious cells and may prevent the accumulation of cervical intraepithelial cell abnormalities in future prophylactic or therapeutic approaches.

Immunization and immunotherapy for cancers involving infection by a human papillomavirus in a mouse model

We describe a protocol for generating a potent cellular immune response against viral-infected cells, and demonstrate its efficacy and safety in a mouse model of human cancer associated with infection by a human papillomavirus (HPV). In the mouse model, the mouse tumor TC-1, which expresses the E7 oncoprotein from HPV-16, is used as a surrogate for human tumors infected with HPV-16. The antigen for the protocol is composed of the E7 oncoprotein conjugated to the Fc region of a mouse IgG1 Ig (E7-mFc). The mFc domain should bind to Fc receptors on dendritic cells, enhancing the processing and presentation of E7 peptides by dendritic cells to T cells, which mediate a cellular immune attack against tumors expressing E7. The E7-mFc antigen was encoded in a replication-incompetent adenoviral vector, called Ad(E7-mFc), for infection of the human kidney cell line 293. The infected 293 cells synthesize the E7-mFc antigen and also infectious Ad(E7-mFc) vector particles for approximately equal 2 days, until the cells lyse and the vector particles are released. To test the protocol for immunization against formation of a TC-1 tumor, the mice first were injected s.c. with 293 cells infected with Ad(E7-mFc), followed by two challenges with TC-1 cells. The immunized mice remained healthy and tumor-free for the 6-month duration of the experiment, and the autopsies showed no toxicity. In the control mice immunized with 293 cells infected with an adenoviral vector that does not encode the E7-mFc antigen, the TC-1 tumor grew continuously and the mice had to be killed within 1 month. To test the protocol for immunotherapy, the mice first were injected with TC-1 cells, followed by s.c. injections of 293 cells infected with Ad(E7-mFc). Tumor growth was prevented or strongly retarded in these mice, in contrast to the continuous tumor growth in the controls. These results suggest that the protocol could be adapted for immunization against human cancers associated with an HPV infection, notably cervical cancer, and for immunotherapy to prevent recurrence of a tumor after surgery.

SV40 and human tumours: myth, association or causality?

An increasing number of scientific reports have described evidence for a polyomavirus, simian virus 40, in a highly select group of human tumours. How did a simian virus infect humans and is the virus a passenger in tumours or is it important in their pathogenesis?