Detection of human papillomavirus DNA in biopsies of human oral tissue

Update on oral lichen planus: etiopathogenesis and management

Lichen planus (LP) is a relatively common disorder of the stratified squamous epithelia, which is, in many ways, an enigma. This paper is the consensus outcome of a workshop held in Switzerland in 1995, involving a selection of clinicians and scientists with an interest in the condition and its management. The oral (OLP) eruptions usually have a distinct clinical morphology and characteristic distribution, but OLP may also present a confusing array of patterns and forms, and other disorders may clinically simulate OLP. Lesions may affect other mucosae and/or skin. Lichen planus is probably of multifactorial origin, sometimes induced by drugs or dental materials, often idiopathic, and with an immunopathogenesis involving T-cells in particular. The etiopathogenesis appears to be complex, with interactions between and among genetic, environmental, and lifestyle factors, but much has now been clarified about the mechanisms involved, and interesting new associations, such as with liver disease, have emerged. The management of lichen planus is still not totally satisfactory, and there is as yet no definitive treatment, but there have been advances in the control of the condition. There is no curative treatment available; immunomodulation, however, can control the condition. Based on the observed increased risk of malignant development, OLP patients should be offered regular follow-up examination from two to four times annually and asked to report any changes in their lesions and/or symptoms. Follow-up may be particularly important in patients with atrophic/ulcerative/erosive affections of the tongue, the gingiva, or the buccal mucosa. Much more research is required into the genetic and environmental aspects of lichen planus, into the premalignant potential, and into the possible associations with chronic liver, and other disorders. More clinical studies are required into the possible efficacy of immunomodulatory drugs such as pentoxifylline and thalidomide.

Dental factors in the genesis of squamous cell carcinoma of the oral cavity

This study investigated the role of dental factors in the genesis of squamous cell carcinomas of the oral cavity. 99 newly diagnosed patients with advanced head and neck cancer were evaluated for potential demographic, dental and prosthetic risk factors. Patients with extra-oral malignancies were used as controls in the analysis of dental factors in patients with intra-oral cancers. We performed multiple comparisons of these factors against the primary tumour sites. An analysis of dental and prosthetic factors and patients with intra-oral versus extra-oral tumours revealed no significant differences. However, all 28 intra-oral malignancies arose in areas in contact with teeth and/or appliances. For example, all 10 oral tongue lesions arose on the lateral borders and all six floor of (drop) mouth primary tumours developed at the flange extension of a lower denture. Patients with partial or full dentures had significantly lower node (N) scores than patients without a prosthesis. Although this paper suggests a relationship between dental factors and the genesis of oral squamous cell malignancies, a larger prospective study would be required to achieve definitive data. Patients at risk should be followed carefully for the development of chronic irritation from teeth and appliances.

The high risk human papillomaviruses and oral cancer: evidence for and against a causal relationship

Oncogenic human papillomaviruses (HPVs) have been detected in oral squamous cell carcinoma (SCC). HPV16 is the most frequently detected HPV type in oral SCC and is present in up to 22% of cases, either alone or in combination with other HPV types. HPV18 is present in up to 14% of cases. HPV16 and HPV18 are present together in approximately 6% of cases. However, HPV16 and 18 are also detected in normal oral mucosae (10% and 11% of subjects, respectively). These data suggest that high risk HPV infection may be a co-factor in oral carcinogenesis and that latent HPV infection of the oral mucosa is common. A role for HPV infection in oral carcinogenesis is supported by the ability of high risk HPVs to immortalize oral keratinocytes in vitro. Immortalization may involve (i) deactivation of pre-formed tumor-suppressor proteins by viral oncoproteins, (ii) blocking of tumor-suppressor gene transcription as a result of HPV oncogene insertion or (iii) stimulation of cellular oncogene transcription by the upstream insertion of HPV-derived transcription activating sequences. Hence, infection of oral keratinocytes with high risk HPV may be involved in the pathogenesis of some oral SCCs although the evidence implicating HPV in oral carcinogenesis is, at present, mainly circumstantial.

Human papilloma virus in neoplastic and non-neoplastic conditions of the external eye

AIM

Human papilloma virus (HPV) types 16 and 18 have been associated with neoplastic conditions of the conjuctiva. However, the presence of this virus has not been reported in non-neoplastic disorders of the external eye nor has it been studied in normal conjunctival tissues.

METHODS

Ninety six paraffin embedded tissue specimens with neoplastic and non-neoplastic lesions and 19 conjunctiva samples free from overt disease were studied for HPV types 16 and 18 positivity with the polymerase chain reaction.

RESULTS

HPV types 16 and 18 DNA were identified in 57% of in situ squamous cell carcinoma, in 55% of invasive squamous cell carcinoma, in 20% of climatic droplet keratopathy, in 35% of scarred corneas, and in 32% of normal conjunctival tissue obtained during routine cataract extractions.

CONCLUSION

These findings indicate that HPV types 16 and 18 are detectable with the polymerase chain reaction not only in epithelial neoplasms of the ocular mucous membrane but also in non-neoplastic lesions as well as in apparently healthy conjunctiva.

Analysis of prostate tissue DNA for the presence of human papillomavirus by polymerase chain reaction, cloning, and automated sequencing

We have analysed the DNA from 24 prostate tissue biopsies, spanning a range of Gleason grading from benign to grade 5 and mixed randomly with cervical cancer samples of known human papillomavirus (HPV) status, for the prevalence of HPV DNA, in a double-blind study to ensure complete objectivity. Polymerase chain reactions (PCR) were performed using general E1 open reading frame primers for HPV under low stringency conditions, in addition to reactions containing primers specific for HPV16, E2, and E6 open reading frames under higher, more stringent PCR conditions. The presence of cellular DNA was verified by the use of primers for hypoxanthine guanine phosphoribosyl transferase. DNA bands were not detected in the prostate biopsies using the HPV16-specific primers under high-stringency PCR conditions, however a predominant band in the 400 bp region was observed in 15 of the prostate biopsies using the general primers and the low annealing temperature of 40 degrees C. This fragment was excised and cloned into the pT7 blue vector and the sequence of the insert determined. Although the cloned sequences initiated and terminated with the two authentic PCR primers, they did not contain a significant HPV-related open reading frame. Our results indicate that HPV type 16 and closely related types, as detected by the general primer pair, are unlikely initiators of prostate carcinogenesis within our population.

[Detection of human papillomavirus (HVP)-DNA in oral manifestation of lichen planus]

Human papilloma viruses (HPV) can be detected in different epithelia with the help of the polymerase chain reaction (PCR). The role of HPV in the development of anogenital cancers has been intensively studied, and current evidence shows that most cervical cancers are associated with so-called high risk HPV types (e.g. HPV 16 and 18). HPV-infections can also be demonstrated in oral premalignant lesions and squamous cell carcinomas. Depending on the sensitivity of the detection method, 40-67% of leukoplakias, 2.5-76% of squamous cell carcinomas and 0-87% of cases of lichen planus were described to be infected with HPV 16 or 18. Whether lichen planus can be considered as a premalignant lesion is still controversial. By the use of PCR and hybridization we found infections with the high risk HPV types 16, 18 and 31 in 42% (3/7) of the patients with lichen planus. Further investigations with a higher numbers of cases in combination with the analysis of the viral gene expression as well as the clinical and histological control of the corresponding regions are necessary. The aim of these studies is to find out the prognostic value of the HPV infection for this facultative premalignant disease.

Risk factors for oral human papillomavirus in adults infected and not infected with human immunodeficiency virus

BACKGROUND AND OBJECTIVES

To investigate in a cross-sectional study the determinants of oral human papillomavirus infection in 287 individuals who are sexually active.

GOAL

To assess prevalence as well as risk factors for oral human papillomavirus infection.

STUDY DESIGN

One hundred seventy-eight human immunodeficiency virus-seropositive (158 men and 20 women) and 109 human immunodeficiency virus-negative (73 men and 36 women) individuals were recruited consecutively from sexually transmitted disease-human immunodeficiency virus clinics and gastrointestinal endoscopy clinics. Oral brushings were tested with the L1 consensus polymerase chain reaction assay for human papillomavirus detection.

RESULTS

Human papillomavirus DNA was detected in 32 (11.2%) of 287 individuals. Associated with oral human papillomavirus infection on univariate analyses were human immunodeficiency virus infection (odds ratio, 6.9; 95% confidence interval, 2.0-23.2), homosexuality (odds ratio, 3.7; 95% confidence interval, 1.5-9.4), unprotected oral sex (odds ratio, 5.5; 95% confidence interval, 1.6-18.4), syphilis (odds ratio, 2.5; 95% confidence interval, 1.1-6.3), gonorrhea (odds ratio, 4.2; 95% confidence interval, 1.9-9.1), Chlamydia trachomatis (odds ratio, 4.4; 95% confidence interval, 1.8-10.6), and genital herpes (odds ratio, 2.9; 95% confidence interval, 1.3-6.5). Human immunodeficiency virus infection and C. trachomatis were independently predictive of human papillomavirus infection in multivariate stepwise logistic regression.

Human papillomavirus-associated oral epithelial dysplasia (koilocytic dysplasia): an entity of unknown biologic potential

Intraepithelial neoplasia of the female genital tract has long been associated with human papillomavirus infection. To date, there have been no previously published studies of oral dysplasia that have identified light microscopic features predictive of the presence of human papillomavirus. We identified a variant of oral epithelial dysplasia, koilocytic dysplasia, that exhibited light microscopic features suggestive of HPV infection. To determine if these microscopic features were specifically correlated with human papillomavirus infection, DNA in situ hybridization for human papillomavirus 6/11, 16/18, and 31/33/51 was performed on 31 lesions diagnosed histologically as koilocytic dysplasia. Seventeen matched control cases of conventional oral epithelial dysplasia were also analyzed for human papillomavirus. Human papillomavirus DNA was detected significantly more often (p < 0.001) in koilocytic dysplasia (80.6%) than conventional oral epithelial dysplasia (0.0%). Positive cases of koilocytic dysplasia contained either intermediate-risk (31/33/51) or high-risk (16/18) human papillomavirus types whether or not they contained low-risk human papillomavirus types (6/11). The histologic and clinical presentation of koilocytic dysplasia was unique. Lesions demonstrated koilocytes and other microscopic characteristics of human papillomavirus infection, as well as features of conventional epithelial dysplasia. A striking male predominance was noted, as was a relatively young average age of presentation (39.0 years). On the basis of our preliminary analysis, we conclude that oral koilocytic dysplasia represents a unique pathologic entity and that the presence of human papillomavirus can be predicted on light microscopy with at least 80% accuracy. The clinical significance and potential for malignant transformation of koilocytic dysplasia remain to be investigated.

Human papillomavirus in oral premalignant lesions

The aetiology of oral premalignant lesions is generally accepted to be multifactorial. Tobacco and alcohol are established as important cofactors in malignant development in the oral cavity, but in addition microorganisms, such as human papillomavirus (HPV), have gained much interest over the past decade. For many years, HPV has been accepted as an important cofactor in the development of cervical cancer, originating from a mucous membrane with similarities to the oral mucosa. 49 patients with oral premalignant lesions and 20 control patients with normal oral mucosa and no history of HPV infection were examined for the presence of HPV by immune histochemical staining using the peroxidase anti-peroxidase technique (PAP), DNA-DNA in situ hybridisation (ISH), and polymerase chain reaction (PCR) analysed by Southern blot hybridisation with an HPV 16 specific probe. The investigations revealed that HPV was found in 62.5% of the verrucous leucoplakias, 50.0% of the erythroplakias, 45.5% of the homogeneous leucoplakias, 33.3% of erythroleucoplakias and in 12.5% of the nodular leucoplakias. An overall HPV detection rate in the examined premalignant lesions was 40.8% and no patients in the control sample were positive. Concerning oral cancer development, it seems likely that HPV may be a cofactor, as 100% of patients who developed oral cancers within 4-12 years were all positive for HPV, one being positive for HPV 16.

False-positive polymerase chain reaction results for human papillomavirus in lichen planus. Potential laboratory pitfalls of this procedure

BACKGROUND

The polymerase chain reaction (PCR) is a common tool in laboratory evaluation of tissue samples. It has been particularly useful in testing for nucleic acids of infectious organisms implicated in the pathogenesis of cutaneous diseases.

OBJECTIVE

Our purpose was to evaluate archival biopsy material (paraffin-embedded) of lichen planus for human papillomavirus (HPV) DNA with PCR and in situ hybridization (ISH).

METHODS

Tissue sections were obtained from 13 specimens of lichen planus and 10 control tissues. Standard methods for PCR and ISH were used to evaluate the presence of HPV DNA. RESULTS. Initial PCR results demonstrated HPV DNA in 11 of 13 specimens and in none of the control tissue. However, testing for specific HPV types revealed nucleic acid contamination. ISH was negative in all specimens.

CONCLUSION

Accurate evaluation of tissue with PCR is difficult because of the procedure's profound sensitivity. Positive results reported in the literature should be viewed with caution. Potential causes for false-positive and false-negative results should be considered.

Human papillomavirus expression in oral mucosa, premalignant conditions, and squamous cell carcinoma: a retrospective review of the literature

OBJECTIVES

The literature of human papillomavirus detection in normal oral mucosa and oral lesions associated with the dysplastic progression of epithelium was reviewed to help define the role of this virus in the development of oral squamous cell carcinoma.

STUDY DESIGN

All available data from published studies were analyzed by chi-square test for association between the human papillomavirus and age, gender, race, DNA type, location, lesional dysplastic progression, method of detection, tissue preservation, and use of tobacco and alcohol.

RESULTS

Human papillomavirus was identified with increasing frequency in normal oral mucosa (13.5%), benign leukoplakia (14.8%), intraepithelial neoplasia (18.5%), squamous carcinoma (26.2%), and verrucous carcinoma (27%). It was detected in oral squamous cell carcinoma significantly (p < 0.005) more often (37.1%; 122 of 329) in studies that used a high sensitivity assay (polymerase chain reaction) than studies that used moderate sensitivity assays (25.2%; 84 of 334) (e.g., Southern blot hybridization) and low sensitivity assays (16.9%; 61 of 362) (e.g., immunohistochemistry, in situ hybridization). Human papillomavirus DNA was detected significantly more often (p < 0.001) in frozen oral squamous cell carcinoma (51.6%; 115 of 223) than paraffin-embedded tissue (21.7%; 136 of 628). High-risk human papillomaviruses (2, 16, 18) were detected in 81.4% of OSCCs that contained the virus compared with low-risk human papillomavirus genotypes (6, 11) in 17.9% of oral squamous cell carcinoma that contained the human papillomavirus (p < 0.001). In studies that analyzed the use of chemical cofactors, the use of tobacco and alcohol (87.3%) was associated more often with oral squamous cell carcinoma than the presence of human papillomavirus (51.3%), however, the difference was not significant.

CONCLUSION

High-risk human papillomavirus genotypes have a significant association with oral squamous cell carcinoma. However, the presence of this virus in a high proportion of oral normal mucosa makes the virus alone a poor prognosticator of progression to malignancy.

Oral manifestations of selected sexually related conditions

The incidence of certain microbial infections occurring in the oropharynx is well documented, but infection by other pathogens, although highly probable, has not been established with certainty. Considerable recent interest in the incubation period of various infections and improved community surveillance programs combine to ascribe infection to specific incidents. It is prudent for health care personnel to acknowledge the presence of many sexually transmitted diseases in the oropharynx and consider them in the differential diagnosis of many well-established conditions.

Viral infections in the immunocompetent patient

Human herpesviruses and human papillomaviruses are ubiquitous and may cause an array of oral disease. Herpesviruses are unique because recurrent localized disease occurs after the primary infection. Human papillomaviruses are known for their ability to produce benign epithelial proliferations and increasingly are implicated in the development of oral cancer. This article reviews the pathogenesis of common oral lesions induced by these viruses.

Oral lichen planus and its association with squamous cell carcinoma: an update on pathogenesis and treatment implications

Lichen planus of the oral mucosa (OLP) is characterized by lymphocytic mucositis, basal cell lysis, and lymphocyte transmigration into the epithelial compartment. Some reports have suggested a high incidence of oral squamous cell carcinoma (OSCCA) in OLP patients and have implicated OLP as a premalignant lesion. We describe five cases of OSCCA arising in patients with preexisting OLP. At our institution, the incidence of OSCCA in patients with OLP approximates that reported in other series. The immunopathologic basis for OLP, its potential association with malignancy, and the variable clinical picture of OSCCA in patients with OLP are reviewed. Specific recommendations are given for treatment and follow-up of lesions, including the role of future testing with viral and oncogene markers.

Age-dependence of human papillomavirus DNA presence in oral squamous cell carcinomas

The aetiology of oral cancer is thought to be multifactorial. Apart from the two known major risk factors (tobacco and alcohol), a viral aetiology has been proposed, with special reference to human papillomavirus (HPV). 35 cases of oral squamous cell carcinoma (OSCC), seen at the Departments of Oral & Maxillofacial Surgery and Oral Pathology and Otolaryngology of the Free University of Amsterdam, were analysed as well as 12 biopsies of clinically and histologically normal gingival mucosa collected from healthy individuals after tooth extractions, using the polymerase chain reaction (PCR) and two different sets of primers that are able to detect a broad spectrum of HPV types. An overall HPV positivity of 54.3% in OSCC was found, the majority of positive cases (78.9%) harbouring HPV type 16. In contrast, no positivity for HPV was detected in the clinically normal oral mucosal samples analysed. Furthermore, a significant association between HPV presence and age was found: patients older than 60 years showed a lower prevalence of the virus (29.4%) compared with patients below this age (77.8%) (P < 0.05). The results from the present study suggest an association between HPV and OSCC, particularly in patients under the seventh decade.

Prevalence of human papillomavirus 16 and nucleolar organizer region counts in oral exfoliated cells from normal and malignant epithelia

This study was designed to identify the prevalence of human papillomavirus 16 (HPV 16) in oral exfoliated cells from 26 patients with oral cancer and matched healthy volunteers with the use of polymerase chain reaction. In addition, the value of a silver staining technique for nucleolar organizer regions (AgNORs) was also investigated. HPV 16 was detected in 30.8% of the cancer lesions, 26.9% of the unaffected sites, and 15.4% of samples from normal mucosa. AgNOR counts on the same cases were analyzed. Although AgNOR counts are useful in distinguishing between normal and malignant oral exfoliated cells, they provided no additional prognostic information for oral cancer. However, when AgNOR counts were compared with HPV 16-positive and HPV 16-negative counts in cancer lesions, AgNOR counts were higher in HPV-positive lesions. These findings suggest that HPV 16 may play a role in tumor cell proliferation, but it is unlikely to play a significant role alone in the cause of oral cancer. Therefore evidence of HPV 16 infection in oral malignant neoplasms should be cautiously interpreted.

Review article: The role of oncogenes, tumour suppressor genes and growth factors in oral squamous cell carcinoma: a case of apoptosis versus proliferation

Mutation, deactivation and disregulated expression of oncogenes and tumour-suppressor genes may be involved in the pathogenesis of oral squamous cell carcinoma (SCC). Deactivation of the p53 tumour-suppressor gene allows cell proliferation and blocks apoptosis of malignant oral keratinocytes. Mutation in the ras oncogene results in persistent mitogenic signalling. Upregulatioed c-Myc expression, in the presence of growth factors, provides an additional proliferative signal. Loss of retinoblastoma tumour-suppressor gene (Rb) function may contribute to oral keratinocyte hyperproliferation and recent evidence suggests that simultaneous deactivation of both p53 and Rb is required for tumourigenesis. Enhanced Bcl-2 and reduced Fas expression inhibit tumour cell apoptosis and may convey resistance to cytotoxic drugs and T cell-mediated cytotoxicity, respectively. Exogenous mutagens such as tobacco, alcohol and viral oncogenes may cause altered expression of oncogenes and tumour-suppressor genes in some cases of oral SCC. The impact of these mechanisms on future therapies for oral SCC is highlighted.

Search for evidence of three viral agents in radicular (periapical) cysts with immunohistochemistry

Sections from 20 paraffin-embedded radicular cysts and positive-control subjects were subjected to immunostaining procedures after treatment of the sections with polyclonal antibodies was performed to search for evidence of human papilloma virus and herpes viruses 1 and 2 in the lining epithelium. All 20 specimens examined were negative for the presence of all three viruses.

Presence of human papillomavirus sequences in tumour-derived human oral keratinocytes expressing mutant p53

A series of eight oral epithelial cell lines derived from untreated human oral squamous cell carcinomas, which had arisen in patients with different tobacco histories, were examined for the presence of human papillomavirus (HPV) DNA, expression of stable p53 protein and p53 point mutation. Polymerase chain reaction (PCR)-based screening, but not Southern blot analysis, showed HPV-16 early region sequences to be present at low copy number (< 1 copy per cell) in two cell lines at early passage (3-5) in vitro (H400, T45), implying that only subpopulations of cells harboured viral DNA. HPV sequences were undetectable in cells at later passage (12-15), suggesting that viral sequences had been lost during growth in vitro, or that negative selection of HPV-containing cells had occurred. High levels of p53 were detected in the two HPV-positive cell lines and in three others (H103, H314, H357) by Western blotting, suggesting expression of mutant (stable) p53 molecules. A sixth cell line (H157) expressed a truncated p53. Sequence analysis of exons 2-11 of the p53 gene revealed missense mutations in six cell lines, one of which (H413) did not result in high levels of protein, and nonsense mutations in the remaining two cell lines (H157, H376). The results suggest that p53 mutation is a frequent genetic event in oral cancer. In addition, the expression of mutant p53 in oral cancer cells does not preclude a papillomaviral aetiology for these tumours. Analysis of p53 expression alone may result in underestimation of the frequency of p53 mutations in human cancers.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiology of cervical intraepithelial neoplasia: the role of human papillomavirus

The evidence implicating specific HPV types in the aetiology of cervical cancer is now strong enough to establish a causative role. HPV infection of the cervix affects the developing immature metaplastic cells of the transformation zone. Cervical neoplasia can be viewed as the interaction of high risk papillomavirus and immature metaplastic epithelium. Once maturity is reached, there is minimal risk of subsequent development of cervical squamous neoplasia. Exposure to HPV is an extremely common event, especially in young sexually active women. Yet, despite frequent HPV exposure at that phase of life in which the cervical transformation zone is at its most vulnerable, established expressed disease is relatively uncommon. Most studies in which the natural history of CIN is not altered by cervical biopsy reveal a progression rate from low to high grade CIN of less than one third. Where viral type is taken into account, however, the progression rate from normal but high risk HPV-infected cervical epithelium to CIN 2 or 3 is higher. Despite this, most cervical abnormalities will not transform into invasive cancer, even if left untreated. The variance between the high rate of HPV infection, the intermediate rate of CIN and the relatively low rate of cervical cancer establishes a stepwise gradient of disease of increasing severity with decreasing prevalence. In an immunocompetent host, HPV infection alone does not appear to be sufficient to induce the step from high grade CIN to invasion. Epidemiological studies indicating that HPV infection with oncogenic viral types is far more common than cervical neoplasia suggest the necessity of cofactors in cervical carcinogenesis. The long time-lag between initial infection and eventual malignant conversion suggests that random events may be necessary for such conversion, and the spontaneous regression of many primary lesions suggests that most patients are not exposed to these random events. Potential cofactors include cigarette smoking, hormonal effects of oral contraceptives and pregnancy, dietary deficiencies, immunosuppression and chronic inflammation. In those women who develop cervical cancer, malignant progression is rarely rapid, more commonly taking many years or decades. Malignant progression has been documented in patients who presented initially with only low grade HPV-induced atypia. On the other hand, progression may be a misnomer, as 'apparent' progression may really represent adjacent 'de novo' development of higher grade CIN. Although most cervical cancers contain high risk HPV types, up to 15% of such cancers test negative for HPV, raising the possibility that a few, usually more aggressive, cervical cancers may arise from from a non-viral source.(ABSTRACT TRUNCATED AT 400 WORDS)

Trends in oral cancer by subsite in New Zealand

A significant increase in incidence rates for all subsites of oral cancer in men and all but cancer of the salivary glands in women has occurred in New Zealand over the past 35 years. However, only male mortality rates of cancers of the nasopharynx and pharynx (excluding the nasopharynx) have significantly increased during this time period. Significant birth-cohort effects existed in the trends in incidence and mortality for cancers of the tongue, mouth, pharynx (excluding the nasopharynx), and nasopharynx among men. For cancers of the mouth and pharynx (excluding the nasopharynx) an increased risk for men born 1912-1932 existed, while an increased risk of cancer of the tongue occurred for men born 1922 onwards. For nasopharyngeal cancer, men born around 1912 and those born from about 1932 onwards were found to have an increased risk. For women, no consistent trends by birth-cohort were found for any oral subsite of cancer.

European School of Oncology Advisory report to the European Commission for the Europe Against Cancer Programme: oral carcinogenesis in Europe

A European School of Oncology Advisory Group has reviewed current knowledge on the epidemiology, treatment and prevention of cancer of the oral cavity. While the major factors in the aetiology of such cancers are thought to be well understood, i.e. tobacco and alcohol consumption, current increases in the occurrence of the disease, especially in young adults throughout Europe, are cause for concern. The reasons for such increases are not clearly evident and the Advisory Group has suggested further work which is required to be carried out to understand the aetiology. In treatment of the disease there have been no major improvements in survival for patients in recent decades and the importance of examining new radiotherapy modalities and defining the role of chemotherapy is emphasized. Primary prevention of oral cancer could be achieved by stopping smoking tobacco, limiting alcohol consumption to a minimum (2-3 drinks per day) and increasing intake of fruits and vegetables. To supplement these actions, while neither population screening programmes nor screening trials could be recommended by the Advisory Group, initial chemoprevention trials have produced some promising results and this represents an interesting area which is the focus of much current research.

Detection of human papillomavirus in oral lesions using commercially developed typing kits

Biopsy material from 20 oral lesions (19 condylomas and 1 squamous papilloma) previously shown to contain human papillomavirus (HPV) 6 and HPV 11 sequences by in situ hybridization were examined using 3 commercially available HPV typing kits. Sensitivity and specificity were compared with in-house methods. Previous in situ hybridization had detected HPV 6b in 11 (55%) of the biopsies, HPV 6 and 11 in 7 (53%) and HPV 11 alone in 1 biopsy. Only one of the commercial assays (assay 1) detected HPV in all 20 biopsies (11 positive for HPV 6b only, 1 for HPV 11 only and 7 for HPV 6b and 11). The wide spectrum probe of assay 2 detected HPV in only 10 (50%) of the biopsies, and in a further 2 biopsies the hybridization results were difficult to interpret because of background staining. Assay 3 used a combined HPV 6/11 probe and detected HPV in 15 (75%) of the biopsies. Clear hybridization signals were demonstrated in the intermediate and upper layers only of squamous epithelium, as expected from the known association of HPV replication with epithelium differentiation. In most specimens background levels were not a problem, and all commercial assays were easy to use. The findings are discussed in the context of the digestion procedures, sensitivity of the probes provided and the conditions of hybridization, all of which would influence the detection of HPV.

Heat shock protein expression in oral lichen planus

To assess the potential role of heat shock protein (HSP) in the pathogenesis of oral lichen planus (OLP), sections of OLP, normal oral mucosa, non-specific oral ulceration (NSOU) and dysplastic OLP were assessed for HSP expression using avidin-biotin complex immunohistochemistry with an anti-HSP 70 polyclonal antibody. There were statistically significant differences in both the vertical and horizontal staining distribution when other groups were compared with the OLP group (p < 0.01). Using microdensitometry, the mean staining intensity in OLP, dysplastic OLP and NSOU was elevated in comparison with normal oral mucosa (p < 0.001). In a standard tritiated thymidine uptake assay, lymphocytes extracted from nine OLP lesions demonstrated significant proliferation when stimulated with purified protein derivative (PPD), of which HSP is a major constituent, with stimulation indices ranging from 2 to 132. These results are consistent with the hypothesis that, in OLP patients, diverse exogenous agents may cause upregulated expression of HSP by oral mucosal keratinocytes. A reaction of cytotoxic T lymphocytes to these activated keratinocytes may then result in the tissue destruction which is characteristic of OLP lesions.

Association of p53 expression with cytokinetics and HPV capsid antigen prevalence in oral carcinomas

p53 protein expression in oral squamous cell carcinomas (SCCs) was studied in relation to presence of HPV capsid antigens and tumour cell kinetics. The protein and viral antigens were determined from 64 SCCs employing immunoperoxidase and immunofluorescence techniques, respectively. Cell kinetics were assessed by in vitro bromodeoxyuridine labelling. Different levels of p53 were detected in 61% cases. Well-differentiated SCCs (88%) showed increased p53 expression compared with the less differentiated ones. In SCCs with higher cell proliferation rate (LI%, 13.25 +/- 4.64) the expression was almost absent. However, it was higher in stage I than in stage II/III carcinomas and occurred in 54.5% and 75% cases of HPV antigen-positive and -negative (or very little) SCCs, respectively.

Germline and somatic abnormalities of chromosome 7 in Wilms' tumor

Although a gene (WT1) located at chromosome 11p13 is implicated in the development of Wilms' tumor (WT), there is evidence that genes on other chromosomes are also involved. A WT patient presented with a constitutional balanced translocation between chromosomes 1 and 7, t(1;7)(q42;p15), the breakpoints of which could represent a WT predisposition gene in this patient. Cytogenetic analysis of the tumor from this patient revealed an acquired abnormality of the other chromosome 7, resulting in an isochromosome of the long arm and a 46,XY,t(1;7)(q42;p15)c,i(7)(q10) karyotype. The regions of the translocation breakpoints were investigated in a series of 24 WTs using Southern blot analysis. This confirmed the monosomy of 7p and trisomy of 7q in the tumor of the translocation patient, and in addition a loss of chromosome 7p alleles was identified in a WT of a bilaterally affected patient. In addition, two WTs were shown to have an extra copy of chromosome 7 alleles. Multiple copies of chromosome 1q alleles, probably resulting from secondary changes, were observed in two WTs, one of which was also associated with a trisomy of chromosome 7. These results indicate that 7p may contain a tumor suppressor gene involved in WT development, and that duplications of 7q also may play a role in WT development.

Human papillomavirus (HPV) types 2 and 57 in oral verrucae demonstrated by in situ hybridization

Twenty-one cases of verrucae vulgaris (oral warts) were investigated for human papillomavirus (HPV)-group specific antigen by immunocytochemistry and for HPV types 1, 2, 4, 6, 11, 16, 18 and 57 by DNA in situ hybridization with biotinylated probes. Twelve (57%) cases demonstrated the presence of HPV-group specific antigen. Fifteen (71%) cases showed the presence of HPV DNA, 13 of which (87%) demonstrated both HPV types 2 and 57 in the same cells and 2 of which (13%) demonstrated only HPV 2. Six cases were negative for HPV 2 and 57 and all 21 cases (100%) were negative for HPV types 1, 4, 6, 11, 16 and 18. Results indicate the association of a new and as yet unidentified HPV type, closely related to HPV 2 and 57, with oral warts. The identification of both cutaneous type HPV 2 and another type closely related to HPV 2 and 57 in oral verrucae on keratinized and non-keratinized mucosal surfaces indicates the possibility of a latent infection; three patients had a history of warts on their hands, suggesting autoinoculation. This study indicated that future investigations of oral warts, based on a correlation of clinical and histological features with HPV types by DNA in situ hybridization, are called for.

The p53 status of cultured human premalignant oral keratinocytes

Around 60% of oral squamous cell carcinomas (SCCs) have been shown to harbour p53 mutations, and other studies have demonstrated mutant p53 genes in normal and dysplastic squamous epithelium adjacent to these SCCs. In line with these earlier studies we show here that DOK, a keratinocyte cell line derived from a dysplasia, displays elevated levels of p53 protein and harbours a 12 bp in-frame deletion of the p53 gene spanning codons 188-191. In contrast, the coding region of the p53 gene was normal in a series of six benign recurrent laryngeal papillomas and a series of four premalignant oral erythroplakia biopsies and their cell cultures. All but one of these lesions were free of malignancy at the time of biopsy, in contrast to the premalignant lesions studied by previous investigators, but keratinocytes cultured from these lesions all displayed a partially transformed phenotype that was less pronounced than that of DOK. Since three out of four of the erythroplakia patients developed SCC within 1 year of biopsy, these lesions were by definition premalignant. The availability of strains of partially transformed keratinocytes from premalignant erythroplakias which possess normal p53 genes should enable us to test the role of mutant p53 in the progression of erythroplakia to SCC. The premalignant tissues and cultures were also tested for the presence of human papillomavirus (HPV), which is known to inactivate p53 function in some cases. Only the benign papillomas were shown to contain high levels of either HPV 6 or HPV 11 E6 DNA, but not both, and none of the samples contained detectable levels of HPV 16, HPV 18 or HPV 33 E6 DNA or L1 DNA of several other HPV types. There was therefore no evidence to suggest that p53 was being inactivated by a highly oncogenic HPV in these samples.

Rapid and specific diagnosis of t(11;22) translocation in paediatric Ewing's sarcoma and primitive neuroectodermal tumours using RNA-PCR

One case of paediatric Ewing's sarcoma and two peripheral primitive neuroectodermal tumours/extra-osseous Ewing's sarcoma were studied for the characteristic t(11;22) translocation, using a recently described RNA-polymerase chain reaction method (RNA-PCR). PCR products of the expected sizes were obtained from RNA derived from the Ewing's sarcoma and the peripheral primitive neuroectodermal tumours, but not from other paediatric malignancies. Direct sequencing of the RNA-PCR products confirmed the presence of the EWS-FLI-1 fusion transcript. In one case the presence of the translocation was confirmed by cytogenetic analysis. These results highlight the potential use of PCR for the rapid demonstration of diagnostically important tumour specific chromosome rearrangements.

Detection of HPV DNA in oral carcinoma using polymerase chain reaction together with in situ hybridization

This study determined the prevalence of human papillomavirus 16/18 DNA in deparaffinized oral carcinoma specimens on slides with the use of the different sensitivities of in situ hybridization and a technique that combines polymerase chain reaction and in situ hybridization. Human papillomavirus DNA was not detected in the 30 biopsy specimens analyzed by in situ hybridization alone using biotinylated DNA probes specific for human papillomavirus 16/18. Twenty of 30 specimens (66.7%) were found to have human papillomavirus DNA (p < 0.001) with the use of the polymerase chain reaction-in situ hybridization technique. Human papillomavirus 16 was detected in 18 of 26 specimens (69.2%), and 7 of 25 carcinomas (28%) were found to contain human papillomavirus 18. Dual infections were present in 5 of 21 (23.8%) specimens. Human papillomavirus DNA was more prevalent in men (75%) than women (57.1%). However, there was no difference in the mean age of patients with oral carcinoma (men, 67.8 years; women, 67.5 years) who had human papillomavirus and those who did not (67.2 years). Carcinomas associated with dual infections occurred at a lower mean age (59.4 years) than those associated with a single human papillomavirus type (p < 0.005). We conclude that the polymerase chain reaction-in situ hybridization technique enhances our ability to demonstrate human papillomavirus types highly associated with oral squamous cell carcinoma.

Human papillomavirus DNA in oral squamous cell carcinomas and normal mucosa

Human papillomavirus (HPV) infections in oral carcinomas and normal oral mucosa were studied by consensus primer screening and typing for HPV types 6/11, 16 and 18 DNA. After polymerase chain reaction (PCR) the DNA species of interest were identified by Southern blot hybridization with digoxigenin-labeled oligonucleotide probes. Frozen tissue and scrapings were equally suitable for HPV testing and yielded high HPV detection rates in carcinomas. By comparison, HPV analysis of paraffin-embedded material was much less efficient. HPV were demonstrated in 61.5% (16/26) of oral squamous cell carcinomas, high risk HPV 16 and 18 being the preferential types. The frequency of HPV detection in non-neoplastic mucosa of tumor patients decreased clearly with increasing distance from the tumor (range 26.9-3.8%) suggesting focal HPV infections. In contrast, normal buccal mucosa of a group of healthy volunteers contained HPV DNA only in 1% (1/97).

Human papillomavirus type 16 DNA detected by the polymerase chain reaction in non-cancer tissues of the head and neck

Cancer-free tissues from various anatomical subsites in the head and neck were examined by the polymerase chain reaction (PCR) for the incidence of human papillomavirus (HPV) types 16 and 18. We detected HPV-16 DNA in 9 of 103 samples (8.7%), including specimens from the paranasal sinuses, tonsil, hypopharynx and larynx. However, no HPV-16/18 DNA was detected by Southern hybridization in these 9 samples. The significance of the presence of HPV-16 DNA in non-cancer tissues is still unknown, but PCR detection only of high-risk HPV DNA in head and neck cancer should be evaluated cautiously because of its ubiquity in this region.

Somatic allelic loss at the DCC, APC, nm23-H1 and p53 tumor suppressor gene loci in human prostatic carcinoma

We present a restriction fragment length polymorphism (RFLP) analysis of 29 benign and 30 malignant prostatic tumors, using polymorphic DNA probes to the putative tumor suppressor genes DCC (Deleted in Colorectal Carcinoma; chromosome 18q21.3), nm23-H1 (17q21.3), APC (Adenomatous Polyposis Coli; 5q21) and p53 (17p13). Six of 23 evaluable cancers (26%) showed loss of heterozygosity (LOH) at DCC; 5 were advanced stage and one was clinically localized (p < 0.05). Mapping 18q deletions, another (advanced) cancer showed LOH at a locus distal to DCC (18q22), but no LOH at DCC. Three of 15 evaluable cancers (20%), all advanced, showed LOH at APC. Three of eight (38%) cancers, of which 2 were advanced, showed LOH at p53. One high grade/stage cancer of 21 (5%) showed LOH at nm23-H1 (and also at DCC). Combining data, allelic losses at either DCC, APC, or p53 genes were seen in 13% of localized cancers, but in 71% of advanced cancers (p < 0.002). Allelic loss involving nm23-H1 is rare in prostatic carcinoma. We suggest that loss of tumor suppressor genes DCC and/or an unidentified gene located distally on chromosome 18q, APC, or p53 may influence progression in prostatic carcinoma.

Latent papillomavirus infection in cattle

During a long term experiment designed to identify the contribution of bovine papillomavirus type 4 (BPV-4), environmental mutagens and immunosuppressants to the development of carcinomas of the upper alimentary tract of cattle, there was evidence of latent papillomavirus infection. Papillomatosis-free animals, when immunosuppressed either by feeding bracken fern or by azathioprine treatment, developed skin warts containing either BPV-1 or BPV-2. Skin warts appeared also in an immunocompetent animal at sites of damaged skin. It was concluded that the animals harboured latent papillomavirus which was reactivated by immunosuppression and/or physical trauma, causing skin warts. Papillomavirus DNA was also detected in lymphocytes of both experimental and control animals, suggesting that one of the sites of latency may be the circulating lymphocyte.

Squamous cell carcinoma of the oral cavity derived from a skin graft: a case report

A case of oral cancer that had derived from a 19-year skin graft on the left buccal mucosa is reported. The patient had had three previous operations due to squamous cell carcinoma, erosion, and squamous cell carcinoma of the left buccal mucosa, respectively. In the last two operations, skin was transplanted, and the present cancer is believed to have derived from the latter one. The tumor was resected, and a new skin was grafted. In situ hybridization of human papilloma virus (HPV) was carried out; the HPV 16 DNA could not be detected in the specimen. Eight months later, a cervical lymph node metastasis was detected; thus, a radical neck dissection was performed.

Oncogenes, tumor suppressors and viruses in oral squamous carcinoma

The pathogenesis of oral squamous cell carcinoma involves recognised carcinogens in tobacco and/or alcohol but other factors, including viruses, may also have a role. This paper reviews the gene changes revealed in oral carcinoma, the evidence implicating viruses, and mechanisms whereby viruses may affect gene function.

Human herpes simplex-1 and papillomavirus type 16 homologous DNA sequences in normal, potentially malignant and malignant oral mucosa

We have tested a range of normal, potentially malignant and malignant oral mucosal biopsies tissues by Southern blot hybridisation analysis for the simultaneous presence of HSV-1 and HPV type 16 DNA sequences, both of which have been implicated as risk factors in oral carcinogenesis. The results show that: (1) 2/4 patients with lichen planus, 2/4 patients with non-specific keratosis, 1/8 patients with oral carcinoma and 3/5 biopsy specimens of normal oral mucosa contained DNA sequences homologous to the HSV-1, Bam HI-G fragment. (2) HPV-16 homologous DNA sequences were detected in 3/4 patients with lichen planus, 4/4 non-specific keratosis, 4/8 oral carcinomas and in 3/5 biopsy specimens of normal oral mucosa. (3) Overall, only 5 patient biopsy specimens were positive for both HSV-1 and HPV-16 homologous DNA sequences; 2 lichen planus, 2 non-specific keratosis and 1 normal. The data cannot exclude a "hit and run" oncogenic mechanism for HSV but suggest that if HSV-1 and HPV-16 play a synergistic role in the development of oral cancer this may be an early event. Indeed, the data suggest HSV might be more frequently found in potentially malignant lesions than in carcinoma.

Detection of Epstein-Barr virus and human papillomavirus type 16 DNA in hairy leukoplakia by in situ hybridisation and the polymerase chain reaction

Demonstration of Epstein-Barr virus (EBV) is considered desirable for the accurate diagnosis of hairy leukoplakia (HL). Previous studies have reported possible associations with human papillomavirus (HPV) infection although this is not a universal finding. Presence of EBV and HPV 16 was examined in biopsy specimens from 18 cases of HL and ten control specimens by in situ hybridisation using digoxigenin-labelled synthetic oligonucleotide probes and by the polymerase chain reaction (PCR). The presence of EBV was demonstrated in 12 cases by both techniques. Of the remaining six cases EBV could be detected in three by in situ hybridisation but not by PCR; EBV was not detected by either method in a further three cases. All samples were negative for HPV 16 by both techniques under conditions of high stringency, although when stringency of in situ hybridisation was reduced, four samples appeared to harbour HPV DNA sequences. This study provides further evidence to support the role of EBV in the pathogenesis of HL and suggests that HPV 16 is not regularly encountered.

Gene mutations and increased levels of p53 protein in human squamous cell carcinomas and their cell lines

Using immunocytochemical and Western blotting techniques we have demonstrated the presence of abnormally high levels of p53 protein in 8/24 (33%) of human squamous cell carcinomas (SCC) and 9/18 (50%) of SCC cell lines. There was a correlation between the immunocytochemical results obtained with eight SCC samples and their corresponding cell lines. Direct sequencing of PCR-amplified, reverse transcribed, p53 mRNA confirmed the expression of point mutations in six of the positive cell lines and detected in-frame deletions in two others. We also detected two stop mutations and three out-of-frame deletions in five lines which did not express elevated levels of p53 protein. Several of the mutations found in SCC of the tongue (3/7) were in a region (codons 144-166) previously identified as being a p53 mutational hot spot in non-small cell lung tumours (Mitsudomi et al., 1992). In 11/13 cases only the mutant alleles were expressed suggesting loss or reduced expression of the wild type alleles in these cases. Six of the mutations were also detected in the SCCs from which the lines were derived, strongly suggesting that the mutations occurred, and were selected, in vivo. The 12th mutation GTG-->GGG (valine-->glycine) at codon 216 was expressed in line SCC-12 clone B along with an apparently normal p53 allele and is to our knowledge a novel mutation. Line BICR-19 also expressed a normal p53 allele in addition to one where exon 10 was deleted. Additionally 15 of the SCC lines (including all of those which did not show elevated p53 protein levels) were screened for the presence of human papillomavirus types 16 and 18 and were found to be negative. These results are discussed in relation to the pathogenesis of SCC and the immortalisation of human keratinocytes in vitro.

Childhood condyloma acuminatum: association with genital and cutaneous human papillomaviruses

We studied 25 children, age 7 months to 12 years 6 months, with anogenital warts, and their parents. In most children the warts were localized in the anal area, in 3 of 18 girls perianally and on the vulva, and in 4 girls exclusively on the vulva. Southern blot hybridization studies disclosed an association of condylomata with human papillomaviruses (HPV) 6 and 11 in 74% and HPV 2 in 17.4% of patients. The clinical features were similar in warts induced by genital and cutaneous HPVs. Even the HPV 2-associated warts in the vulva of two girls were typical of condyloma acuminatum. In all children with HPV 2-induced condylomata, cutaneous common warts coexisted, also induced by HPV 2. However, three mothers had cutaneous warts, and the children's condylomata were associated with HPV 6. Thus, the mere presence of skin warts in family members does not rule out other sources of infection. Sexual abuse was suspected in four girls and two boys, but was not confirmed in any. Nonsexual transmission could occur by persons with the lesions taking care of children. Perinatal transmission also appears to be an important route of infection in small babies. Infection in utero was probable in one girl in whom anal warts appeared in the first week of life and whose mother had cervical condylomata during pregnancy. This study provides further confirmation of possible nonsexual transmission of genital HPVs and the not infrequent association of childhood condylomata with HPV 2.

Human papillomavirus DNA in the urogenital tracts of men with genital dermatoses: evidence for multifocal infection

In an attempt to assess the multifocal nature of anogenital HPV infection in men, skin biopsies, urethral swabs and urine specimens were obtained from 100 men with genital dermatoses. The specimens were examined for the presence of human papillomavirus (HPV) types 6, 11, 16, 18, 31 and 33 using the polymerase chain reaction and Southern blotting techniques. HPV DNA was detected in one or more specimens from 39 patients, that is 29 of 100 biopsy specimens, 21 (25%) of 85 urethral swab specimens and 6 (10%) of 59 urine specimens. HPV DNA was more common in men with at least 20 lifetime sexual partners and in those who gave a history of anogenital warts. Twelve (18%) of 66 biopsy specimens with no histological evidence of warty change or neoplasia had detectable HPV DNA. HPV DNA was detected no more frequently in the urethral and urine specimens from men with histological evidence of warts or neoplasia than from men without such changes. HPV types 6 and 11 were most common in biopsy specimens with histological changes of typical HPV infection. HPV type 16 was commonest in biopsy specimens with neoplasia and type 18 with other changes. Furthermore, 'high-risk' HPV types were found proportionately more often in urethral swab and urine specimens than in biopsy specimens. There was generally a poor correlation between the detection of HPV DNA at the different sites. A greater understanding of the role of HPV in the production of genital abnormalities is required in order to develop a rational approach to the management of these patients.

Analysis of human papillomavirus DNA in oral squamous cell carcinomas

Evidence from several laboratories suggests that HPV plays a role in the etiology of squamous cell carcinomas of the oral cavity. A multifactorial risk factor profile for the development of oral cancer may include HPV in addition to well-established risk factors such as tobacco and alcohol use. The prevalence of oral carcinomas reported to be associated with HPV has varied widely due to differences in the sensitivity of the assay used for HPV detection. The aims of this study were: (1) to ascertain the prevalence of HPV DNA in oral squamous cell carcinomas using the most sensitive technique available, the polymerase chain reaction; (2) to determine the type of HPV in the tumors; and 3) to correlate the virologic data with other risk factor data obtained from patients' records. Fourteen (78%) of 18 primary tumors, 6 (67%) of 9 normal epithelial tissues from the patients and 5 (100%) of 5 neck metastases were HPV DNA-positive. Of the 14 HPV DNA-positive primary tumors, specific typing revealed HPV 16 in 2, HPV 18 in 2, HPV 16 and 18 in 5, HPV 6/11, 16 and 18 in 4, and HPV 6/11 in 1. HPV types in the normal or metastatic tissue were usually the same as those in the respective primary tumor. There was no significant association between HPV presence and any of 12 factors or patient characteristics studied.

Transmission of human papillomaviruses from mother to child

Exfoliated cervical epithelial cells from women 6 weeks postpartum were analyzed for human papillomavirus (HPV) DNA using the polymerase chain reaction, and results were compared with those from buccal mucosal smears from their babies. Eleven mothers had genital genotypes of HPV in their cervical smears, and the children of 8 of these had HPV of the same genotype in buccal mucosal cell samples. Nineteen mothers had no HPV DNA detected in their cervical smears, and 1 of the buccal mucosal cell samples from their children was positive for HPV DNA (p < 0.0001). Contamination of a child's mouth with 'genital' HPV from a mother's cervix appears to occur commonly at birth or in the perinatal period, and to persist for at least 6 weeks. This observation has implications for the epidemiology and management of HPV associated cancer and precancerous conditions in the cervix and the mouth.

Papillomaviruses in head and neck disease: pathophysiology and possible regulation

Human papillomaviruses (HPVs) are etiologic agents of both benign and malignant epithelial tumors. More than 60 different types of viruses are known, each associated with tissue site and lesion type specificities and differing probabilities of malignant progression. HPVs type 6 and type 11 cause benign papillomas of mucosal squamous epithelium in the aerodigestive tract, with only rare conversion to malignancy. HPV 16 is the most frequently detected HPV in the genital tract, inducing flat lesions with a significant risk of malignant conversion. In the aerodigestive tract, HPV 16 is found only rarely in benign lesions but is detected in 5-20% of squamous carcinomas. In the aerodigestive tract, HPVs frequently cause latent infection, i.e., viral DNA present in tissue but no evidence of clinical or histologic disease. Approximately 10% of the general population may have latent infections. Regulation and activation of latent infections are not well understood, although it is clear that viral functions are tightly regulated by the state of differentiation of the squamous host cell. Control of viral transcription may be the key to prevention of viral activation, and thus control of disease. Among the possible agents under investigation are retinoids, growth factors, anti-sense RNA which interferes with viral expression, and estrogen metabolites. All of these agents modulate either viral expression or cell differentiation or both. It is hoped that in the near future one or more of these agents will be useful in preventing HPV-associated disease.

Southern blot hybridization and PCR in detection of oral human papillomavirus (HPV) infections in women with genital HPV infections

The presence of human papillomavirus (HPV) in biopsies taken from clinically normal buccal mucosa (n = 212) and clinical lesions (n = 60) was examined by Southern blot hybridization (SBH) using 32P-labelled HPV DNA probes. Furthermore, one hundred formalin-fixed, paraffin-embedded biopsies were analyzed by using polymerase chain reaction (PCR), combined with dot blot hybridization and biotinylated HPV DNA probes. With SBH and PCR, 15.4% and 29.4% of the biopsies, respectively, contained HPV DNA. In clinically normal epithelium, 15.6% and 23.1% of the samples were HPV-positive with SBH and PCR, respectively. The HPV types detected in the genital and oral mucosa of index patients differed in all except two cases. Histology could not be relied on distinguishing HPV DNA positive and HPV DNA negative samples. Hand warts were encountered significantly more frequently in patients with a concomitant oral HPV infection. To conclude, oral HPV infections as detected by SBH and PCR are surprisingly common, but similar to the genital tract, the virus seems to exist in a latent form in the vast majority of cases. The frequent concomitant finding of skin warts and oral HPV infection may suggest some kind of HPV-specific immunosuppression.