Expression of the different viral mRNAs of human papilloma virus 6 in a squamous-cell carcinoma of the bladder and the cervix

Human Papillomavirus and Genital Disease in Men: What We Have Learned from the HIM Study

It is currently recognized that in addition to the major impact of human papillomavirus (HPV) infection in females, HPV causes considerable disease in men at the genitals, anal canal, and oropharynx. Specifically, genital HPV infections may progress to genital warts and penile carcinoma. Although studies concerning the natural history of HPV infections and associated neoplasias have mainly focused on women, during the last 2 decades considerable attention has been given in further understanding these infections in men. The HIM (HPV infection in men) Study, the only prospective multicenter study of male HPV natural history, consisted of a large prospective international cohort study in which men from Brazil, the United States, and Mexico were enrolled. The design and protocols of this study allowed unraveling crucial information regarding the relationship between HPV infection and clinical consequences in men, and associated risk factors at each of the anatomic sites where HPV is known to cause cancer in men.

Regulation of HPV transcription

Human papillomavirus infection is associated with the development of malignant and benign neoplasms. Approximately 40 viral types can infect the anogenital mucosa and are categorized into high- and low-risk oncogenic human papillomavirus, depending on their association with the development of cervical carcinoma. High-risk human papillomavirus 16 and 18 are detected in 55% and 15% of all invasive cervical squamous cell carcinomas worldwide, respectively. Low-risk human papillomavirus 6 and 11 are responsible for 90% of genital warts and are also associated with the development of recurrent respiratory papillomatosis. Human papillomavirus preferentially infects mitotic active cells of the basal layer from both mucosal and cutaneous epithelium through microabrasions. The viral life cycle synchronizes with the epithelial differentiation program, which may be due, in part, to the binding of differentially expressed cellular transcription factors to the long control region throughout the various epithelial layers. This review aimed to summarize the current knowledge regarding the mechanisms by which viral gene expression is regulated and the influence of human papillomavirus heterogeneity upon this phenomenon. A better understanding of the regulatory mechanisms may elucidate the particularities of human papillomavirus-associated pathogenesis and may provide new tools for antiviral therapy.

Human Papilloma Virus Infection and Overexpression of P53 Protein in Bilharzial Bladder Cancer

Aims and Background

An association between human papilloma virus (HPV) and bladder cancer has been reported. However, the role of HPV in bilharzial bladder cancer and its prevalence have not yet been clarified.

Study design

We investigated 50 cases for HPV types 16/18 by in situ hybridization. Also, p53 protein expression by immunohistochemistry was evaluated in 41 of the 50 cases, with correlation of these factors to clinicopathologic parameters and tumor relapse after primary treatment.

Results

HPV was detected in 46% of Egyptian bladder carcinomas (23/50 cases). Positivity was 47.8% for squamous cell carcinoma and 36.4% for transitional cell carcinoma. There was a possible viral-bilharzial association as 52.8% of Bilharzial cases, whereas only 12.5% of non-Bilharzial cases were HPV positive (P <0.05). P53 protein was found in 19/41 (46.3%) cases. There was a concordance between HPV and p53 in 58.5% of cases. Neither factor was related to tumor recurrence after primary treatment.

Conclusions

HPV may thus be implicated in the etiology of bilharzial bladder cancer, but a definite causal relationship remains to be demonstrated. HPV together with p53 alterations work in synergy to accelerate the carcinogenic process, as there was concordance in the results of both parameters in 24/41 (58.5%) cases.

Meta-analysis of studies analyzing the role of human papillomavirus in the development of bladder carcinoma

PURPOSE

We aimed to ascertain the degree of association between bladder cancer and human papillomavirus (HPV) infection.

MATERIALS AND METHODS

We performed a meta-analysis of observational studies with cases and controls with publication dates up to January 2011. The PubMed electronic database was searched by using the key words "bladder cancer and virus." Twenty-one articles were selected that met the required methodological criteria. We implemented an internal quality control system to verify the selected search method. We analyzed the pooled effect of all the studies and also analyzed the techniques used as follows: 1) studies with DNA-based techniques, among which we found studies with polymerase chain reaction (PCR)-based techniques and 2) studies with non-PCR-based techniques, and studies with non-DNA-based techniques.

RESULTS

Taking into account the 21 studies that were included in the meta-analysis, we obtained a heterogeneity chi-squared value of Q(exp)=26.45 (p=0.383). The pooled odds ratio (OR) was 2.13 (95% confidence interval [CI], 1.54 to 2.95), which points to a significant effect between HPV and bladder cancer. Twenty studies assessed the presence of DNA. The overall effect showed a significant relationship between virus presence and bladder cancer, with a pooled OR of 2.19 (95% CI, 1.40 to 3.43). Of the other six studies, four examined the virus's capsid antigen and two detected antibodies in serum by Western blot. The estimated pooled OR in this group was 2.11 (95% CI, 1.27 to 3.51), which confirmed the relationship between the presence of virus and cancer.

CONCLUSIONS

The pooled OR value showed a moderate relationship between viral infection and bladder tumors.

Incidence of Low Risk Human Papillomavirus in Oral Cancer: A Real Time PCR Study on 278 Patients

Squamous cell carcinoma is the most frequent malignant tumour of the oral cavity. It is widely known that tobacco and alcohol consumption are the major causes of the development of oral squamous cell carcinoma (OSCC). The human papilloma virus infection has also been postulated as a risk factor for squamous cell carcinoma, although conflicting results have been reported. The aim of this study is to evaluate the presence of high-risk and low-risk type human papillomavirus in a large sample of squamous cell carcinoma limited to the oral cavity by means of quantitative real-time polymerase chain reaction. Data were obtained from 278 squamous cell carcinoma limited to oral cavity proper. Sequencing revealed that 5 samples were positive for HPV type 16, 5 for HPV type 11, and 1 for HPV type 6. Human papillomavirus 11 was detected in 5 tumours out of the 278 examined. The prevalence rate for Human papillomavirus 11 was 1.8% (C.I. 0.7–3.9). The matched case-controls analysis indicated that the prevalence among controls did not significantly differ with respect to cases and that Human papillomavirus 11 alone did not correlate with squamous cell carcinoma.

Análisis estadístico de la influencia del virus del papiloma humano en el desarrollo del carcinoma vesical

INTRODUCTION

The bladder cancer is an important disease by its morbi-mortality and its multifactorialidad. At the moment, between the possible aetiology agents that they have been indicated is the infection by the virus of papilloma human (VPH). The objective study is to analyse, by meta-analysis, the relationship between bladder cancer and infection by human papillomavirus.

MATERIAL AND METHODS

We made a search in the electronic data base MEDLINE of the articles published until September of the 2004 that relate the infection of the VPH to the bladder tumors. Of 414 listed articles, we selected 38 articles.

RESULTS

The articles were classified in two groups, according to they use or non methods based on the detection of the DNA. In articles based on the detection of the DNA, it was that the global proportion from the cases that had contact with the virus, through the detection of the genome was of the 19.4% (95% CI 0.160 to 0.228). Of the total of studies based on the detection of the DNA 8 were selected, to show to a group defined control, in which, the OR was investigated. If we combined the ORs, we obtain an OR estimation of 3.2 (95% CI 1.19 to 8.60) and p = 0.02.

CONCLUSIONS

Most of these studies showed the relation rose at the beginning of the study. Although the majority lacked a group defined control, is possible to analyze the value of the Odds global ratio due to the homogenous behaviour of the studies with defined cases and controls affluent. This demonstrated to association between VPH and the bladder cancer.

Human papillomaviruses 6/11, 16/18 and 31/33/51 are not associated with squamous cell carcinoma of the urinary bladder

OBJECTIVE

To assess high-risk human papillomavirus (HPV), mainly HPV type 16, 18, 31 and 33 (an important aetiological factor in squamous cell carcinoma, SCC, of the anogenital region) in SCC of the urinary bladder.

MATERIAL AND METHODS

Sixteen SCC from the urinary bladder were evaluated using non-isotopic in situ hybridization with a sensitive detection system for the presence of high-risk HPV 16/18, or 31/33/51, and for HPV6/11, a low-risk type commonly found in condylomata. Previously published studies were also reviewed and assessed.

RESULTS

No high-risk HPV was found in any of the SCC of the bladder evaluated. Previous reports identified nine HPV-positive SCC of a total of 105, including the present series. In four of these positive cases, HPV types were found that are considered a high risk in anogenital carcinomas.

CONCLUSION

From the present and previous results, we conclude that HPV has no major role in the pathogenesis of SCC of the urinary bladder.

Synthesis of viral DNA and late capsid protein L1 in parabasal spinous cell layers of naturally occurring benign warts infected with human papillomavirus type 1

We investigated human papillomavirus type 1 (HPV1)-specific transcription, viral DNA replication, and viral protein expression in naturally occurring benign tumors by in situ hybridization, 5-bromodeoxyuridine (BrdU) incorporation, and immunohistochemistry and obtained results different from other HPV-infected benign tumors characterized so far. Moderate amounts of transcripts with a putative coding potential for E6/E7, E1, and E2 were demonstrated from the first subrabasal cell layer throughout the stratum spinosum and granulosum. In addition very large amounts of E4 and L1 transcripts were present in the same epithelial layers. This finding was substantiated by the demonstration of L1 and E4 protein already in the bottom-most spinous cell layer. Furthermore massive amplification of the viral DNA as measured by BrdU incorporation and different methods of in situ hybridization took place in the lowest 5 to 10 suprabasal cell layers. These findings are in contrast to the assumption that late gene expression and viral DNA synthesis are restricted to the more differentiated cell layers of the epithelium and point to differences in the regulation of the vegetative life cycle between different papillomavirus types.

Retinoic acid induces Gpx2 gene expression in MCF-7 human breast cancer cells

We showed previously that the selenium-dependent glutathione peroxidase, GPX-GI, encoded by the Gpx2 gene, is highly expressed in the epithelium of the gastrointestinal (GI) tract and sporadically in breast tissue. To investigate whether Gpx2 gene expression is epithelium specific, we used in situ hybridization to show that Gpx2 mRNA is highly expressed in the crypt epithelium of human intestine. We also used Northern analysis to study human breast cells and found Gpx2 mRNA in human mammary epithelial cell lines as well as freshly isolated normal breast epithelial cells. Because we identified three putative retinoic acid response elements (RARE) in the Gpx2 gene, we examined the regulation of the Gpx2 gene expression by all-trans retinoic acid (RA) in RA-sensitive MCF-7 cells and RA-resistant HT29 cells. Without RA, MCF-7 cells had very low levels of Gpx2 mRNA and a low level of glutathione peroxidase (GPX) activity (17 mU/mg protein), whereas HT29 cells had a high level of Gpx2 mRNA and GPX activity (200 mU/mg protein). RA treatment increased Gpx2 mRNA level 3- to 11-fold and resulted in a fourfold increase of GPX activity (80 mU/mg protein) in MCF-7 cells. Neither Gpx2 mRNA level nor GPX activity was increased in HT29 cells. These results show that the Gpx2 gene is expressed in both breast and intestinal epithelium cells, and suggest that its expression can be highly regulated by retinoic acid, a known differentiation agent.

Human papillomavirus type 6: classification of clinical isolates and functional analysis of E2 proteins

Human papillomaviruses (HPVs) cause a variety of clinical manifestations, including the most prevalent viral sexually transmitted disease, genital warts. HPV-6 is found in a greater number of genital warts than any other HPV. To increase our understanding of the structural and functional relationships between HPV-6 isolates and to provide information for epidemiological studies, the sequences of the E2, E6 and E7 coding regions of HPV-6 genomes in clinical samples were determined. This sequence analysis was performed on isolates originally designated HPV-6a on the basis of analysis of patterns generated by restriction enzyme digestion. It was found that the designation of subtype on the basis of restriction enzyme digestion correlated poorly with the designation of subtype on the basis of sequence comparison; in fact, the clinical isolates were clearly categorized into HPV-6a and HPV-6b groups, with the previously described HPV-6vc being a member of the HPV-6a group. It was also found that the HPV-6a E2 protein is a much less potent activator of transcription than the HPV-16 E2 protein, generalizing our previous results with the HPV-6b E2 protein to this second HPV-6 E2 protein. These studies indicate that the amino acid differences observed between these natural variants of the HPV-6 E2 protein do not affect its function.

Human papillomavirus and bladder cancer

Human papillomavirus (HPV) deoxyribonucleic acid (DNA) has been originally detected in urothelial carcinomas of the bladder in immunocompromized patients. Studies from the general population showed a variable incidence of high risk HPV DNA which ranged from 2.5% to 81%, with HPV 16 DNA occurring more frequently. HPV DNA was detected in both papillary and invasive cancers, although in our experience the overall incidence was low. Most HPV positive cases were of high grade and stage with significant reduced survival or increased recurrence rate after transurethral resection. These results indicate an additional prognostic value of viral infection in bladder cancer. In addition, molecular studies suggest that the HPV related oncoproteins E6 and E7 play a role in bladder carcinogenesis via inactivation and/or degradation of p53 and pRb suppressor gene-associated proteins. The purpose of this review is to provide a brief summary of what is known about HPV and bladder cancer, and to address issues germane to the translation of this information to patient management.

Cell-type-specific separate regulation of the E6 and E7 promoters of human papillomavirus type 6a by the viral transcription factor E2

Gene expression of human papillomaviruses (HPV) is tightly controlled by cellular factors and by the virally encoded E2 protein through binding to distinct sites within the regulatory noncoding region. While for the high-risk genital papillomaviruses a single promoter drives the expression of all early genes, a second promoter present in the E6 open reading frame of the low-risk HPV type 6 (HPV6) would allow an independent regulation of E6 and E7 oncogene expression. In this report, we provide the first evidence that E2 regulates both early promoters of HPV6 separately and we show that promoter usage as well as E2 regulation is cell type dependent. Among the different epithelial cell lines tested, only RTS3b cells allowed an expression pattern similar to that observed in naturally infected benign condylomas. While the E6 promoter was repressed by E2 to 50% of its basal activity, the E7 promoter was simultaneously stimulated up to fivefold. Activation of the E7 promoter was mediated predominantly by the binding of E2 to the most promoter-distal E2 binding site. Repression of the E6 promoter depended on the presence of two intact promoter-proximal binding sites. Mutation of both of these repressor binding sites reversed the effect of E2 on the E6 promoter from repression to activation. In contrast, in HT3 cells we observed an E2-mediated activation of the E6 promoter in the context of the wild-type noncoding region. This indicated that repression of the E6 promoter by binding of E2 to both promoter-proximal binding sites did not function in the cellular environment provided by HT3 cells. These data suggest that the separate regulation of the E6 and E7 promoters of HPV6 is mediated through successive occupation of binding sites with different affinities for E2 depending on the intracellular concentration of E2 and on the cellular environment provided by the infected cell.

Deletion in the L1 open reading frame of human papillomavirus type 6a genomes associated with recurrent laryngeal papilloma

Human papillomavirus (HPV) type 6a genomes with a large deletion in their L1 open reading frames (ORF) were found in two of five recurrent cases of laryngeal papilloma. One of these mutant HPVs had a 186 base pair (bp) deletion near the N-terminus end of the L1 ORF, which encodes a major capsid protein. The other had a 454 bp deletion at the C-terminus end of L1 at which is located a nuclear localising signal (NLS). No other large deletion or insertion was found in the remaining regions of all five HPV6a genomes. The laryngeal papillomas which harboured the mutant viruses showed typical hyperplasia and pathological changes as observed in tumours induced by the wild-type virus. The biological significance of the two large deletions in the late region of HPV6a associated with laryngeal papilloma is discussed.

Detection of polyomaviral DNA sequences in normal and adenomatous human pituitary tissues using the polymerase chain reaction

BACKGROUND

Tumor viruses are known to have a role in the pathogenesis of many types of benign and malignant human tumors. The possible roles of these viruses in the development of human pituitary tumors have not been investigated.

METHODS

The polymerase chain reaction was used to screen human pituitary tumors for human papillomaviral (HPV) and Polyomaviral DNA sequences. Sets of consensus primers, which are capable of amplifying HPV Types 16, 18, and 33 and polyomavirus BK, JC, and SV40, were used in these experiments.

RESULTS

Amplification products were not detected using HPV consensus primers in 30 tumors. Twenty-six of 30 tumors demonstrated an amplification product with polyomaviral primers that hybridized to SV40 and BK internal probes and was confirmed to be SV40 in one tumor by direct sequencing. Ten normal postmortem pituitary samples then were examined similarly with Polyomaviral consensus primers; 8 of 10 normal samples demonstrated a similar amplification product that also hybridized with SV40 and BK internal probes by Southern blotting. Polyomaviral DNA sequences in normal and tumor samples were not present at levels detectable by genomic Southern blotting. Expressed viral protein (large T antigen) was not demonstrated in positive samples by Western blot analysis.

CONCLUSIONS

These findings, that polyomaviral DNA sequences are detectable at low levels in certain normal tissues, are in agreement with those of other groups and, to the authors' knowledge, serve as the first report of polyomaviral latency in human pituitary tissue. A role for polyomaviruses in pituitary tumorigenesis could not be established in this analysis.

Variation of human papillomavirus type 6 (HPV-6) and HPV-11 genomes sampled throughout the world

We examined the genomic diversity of human papillomavirus type 6 (HPV-6) and HPV-11 isolates from different parts of the world by comparing the nucleotide sequences of part of the long control region of three reference clones and 62 HPV-6 and 40 HPV-11 isolates from Africa, Europe, Asia, and North and South America. The genomic sequence of the HPV-6b reference type had to be amended by inclusion of a 94-bp segment, which is also present with minor differences in HPV-6a. Aside from two small inserts typical of all variants related to HPV-6a and three inserts found in HPV-11 variants, no major alterations to the size of the long control regions of these viruses were observed. This corrects the previous impression that these two HPV types are highly polymorphic. Altogether, 19 HPV-6 and 10 HPV-11 variant genomes could be distinguished, and most of the differences were due to point substitutions. The variants of either type were continuously connected in phylogenetic trees rather than clustered separately into subtype groups. Thirteen mutations, namely, the two HPV-6a inserts and 11 substitutions in HPV-6 or HPV-11 variants, reduced the dissimilarity between the types, but they bridged only a small fraction of the genetic distance between the two types. Genomes more obviously intermediate between HPV-6 and HPV-11 were not found and probably do not exist any more. A single HPV-11 variant was found in Africa, but otherwise, no significant correlations of HPV-6 or HPV-11 variants with geography or ethnicity of the patient cohort were found. Functional analysis of diverse enhancer variants showed activities that differed two-to threefold, and it must be considered that transcriptional differences may alter the biology or pathology of these viruses. Similar variants were found in lesions from anatomically different sites and in both benign and malignant lesions.

Transitional cell carcinoma of the bladder: failure to demonstrate human papillomavirus deoxyribonucleic acid by in situ hybridization and polymerase chain reaction

Human papillomaviruses have been implicated in the pathogenesis of a variety of malignancies, particularly those of the anogenital tract. Some recent reports on the presence of human papillomavirus in bladder cancer have raised the possibility that it might be involved in the development of this malignancy as well. To study this concept, a series of 108 transitional cell carcinomas of the bladder were screened for the presence of human papillomavirus deoxyribonucleic acid (DNA) by in situ hybridization with biotin-labeled human papillomavirus cocktail probe and polymerase chain reaction with human papillomavirus L1 consensus primers. Although the positive controls showed strong hybridization signals, no evidence for human papillomavirus DNA was found in any of the bladder carcinomas by in situ hybridization. Similarly, despite the amplification of a 450 bp product in cervical human papillomavirus lesions (used as positive controls), no signals were obtained in any of the bladder tumors studied. beta-globin gene sequences (110 bp), serving as internal controls, were consistently amplified from all tumor samples, suggesting that cellular DNAs from the carcinoma specimens were sufficient for the amplification reaction. These data indicate that human papillomavirus infection is rare in transitional cell carcinoma of the bladder. The significance of these findings is discussed in relation to previous reports on human papillomavirus involvement in bladder carcinomas.

The predominant mRNA class in HPV16-infected genital neoplasias does not encode the E6 or the E7 protein

Human papillomavirus (HPV) type 16 is strongly implicated in the development of progressive neoplasias of the uterine cervix. Its oncogenic potential is decisively determined by the activity of the early gene products E6 and E7. To look for changes in the expression of these genes during tumour progression we cloned subgenomic fragments of HPV16 into RNA expression vectors, which allowed the generation of 35S-labelled riboprobes specific for distinct mRNA classes. Four constructs were made to differentiate between transcripts starting upstream of the E6 ORF or the E1 ORF, and one probe was specific for unspliced E6/E7 region transcripts. Five other constructs were used to identify transcripts covering the E1, E2, E4, L1 and L2 regions. With the help of these constructs, we analyzed by in situ hybridization 2 low-grade intraepithelial neoplasias of the vulva, 1 high-grade neoplasia of the cervix as well as 4 vulvar and 3 cervical carcinomas. Transcripts from the E1, E2, E4, L1 and L2 region that were consistently detected in the differentiated layers of benign lesions were variably expressed in precancers and carcinomas. None of the investigated cases revealed detectable amounts of unspliced E6/E7 transcripts with a coding potential for a full-length E6 protein. In benign lesions, the E7 transcripts were confined to isolated nuclei of differentiated cells, whereas high-grade lesions and invasive cancers showed elevated levels of equally distributed E7-specific signals in the cytoplasm of all tumour cells. The most abundant transcripts observed in intraepithelial neoplasias and in invasive cancers appear to initiate within ORF E7 and therefore have no coding potential for full-length E6 and E7 proteins. Our data show that the actual level of E7-specific transcripts in cancers is lower than anticipated from earlier studies using an ORF E6/E7-specific probe that hybridizes with the 5'-ends of the abundant mRNA class.