Neutralizing antibody to herpes simplex virus type 1 in patients with oral cancer

An Appreciation of a Giant in Orofacial Sciences Research-John Greenspan

Professor John S. Greenspan died on March 31, 2023. He was a renowned and accomplished academic, dentist/scientist, pathologist, and administrator who made sustained and significant international impacts on numerous fields over half a century. John was arguably best known for his work with his wife, Dr. Deborah Greenspan, on the oral aspects of AIDS and the role of viruses in oral epithelial and salivary gland lesions. He had a lifelong interest in Sjögren's syndrome, culminating in the leadership of the Sjögren's International Collaborative Clinical Alliance. He was also widely recognized as one of the leading investigators into the understanding of oral mucosal diseases, including recurrent aphthous stomatitis. He and his colleagues' major contributions to HIV research and care included the discovery of the oral lesion "hairy leukoplakia," its etiological association with Epstein-Barr virus, and other oral lesions in the natural history of HIV disease. In recent years, John turned his attention to global oral health inequalities, helping to establish the International Association for Dental Research's Global Oral Health Inequalities Research Network and serving as its first president. He led many organizations with humble authority, knowledge, wit, and wisdom and mentored colleagues from all over the world, especially from lower- and middle-income countries. John leaves a very special legacy based on example and scientific curiosity, and his work has not only made a lasting impact on his colleagues but also translated to abiding benefit for patients.

The oral microbiota and its role in carcinogenesis

Despite decades of research, cancer continues to be a major global health concern. In recent years, the role played by microorganisms in the development and progression of cancer has come under increased scrutiny. The aim of the present review is to highlight the main associations between members of the human oral microbiota and various cancers. The PubMed database was searched for available literature to outline the current state of understanding regarding the role of the oral microbiota and a variety of human cancers. Oral squamous cell carcinoma (OSCC) is associated with carriage of a number of oral bacteria (e.g., Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus sp.), certain viruses (e.g., human papilloma virus, human herpes virus 8, herpes simplex virus 1 and Epstein-Barr virus) and yeast (Candida albicans). Moreover, members of the oral microbiota are associated with cancers of the esophagus, stomach, pancreas, colon/rectum and lung. Furthermore, the present review outlines a number of the carcinogenic mechanisms underlying the presented microbial associations with cancer. Such information may one day help clinicians to diagnose neoplastic diseases at earlier stages and prescribe treatments that take into account the possible microbial nature of carcinogenesis.

Conversion of Normal To Malignant Phenotype: Telomere Shortening, Telomerase Activation, and Genomic Instability During Immortalization of Human Oral Keratinocytes

Normal somatic cells terminate their replicative life span through a pathway leading to cellular senescence, which is triggered by activation of p53 and/or pRb in response to critically shortened telomere DNA. Potentially neoplastic cells must first overcome the senescence checkpoint mechanisms and subsequently activate telomerase to propagate indefinitely. Although telomerase activation is closely associated with cellular immortality, telomerase alone is not sufficient to warrant tumorigenicity. Environmental factors, including chemical carcinogens and viral infection, often contribute to aberrant changes leading to tumorigenic conversion of normal cells. Of particular importance in oral cancer development are tobacco-related chemical carcinogens and human papillomavirus (HPV) infection. To describe the molecular mechanisms by which these environmental factors facilitate the genesis of oral cancer, we first established an in vitro multistep oral carcinogenesis model by sequential exposure of normal human oral keratinocytes (NHOK) to "high risk" HPV and chemical carcinogens. Upon introduction of the HPV genome, the cells bypassed the senescence checkpoint and entered into an extended, but not immortal, life span during which telomere DNA continued to shorten. In a few immortal clones surviving beyond the crisis, we found a marked elevation of telomerase activity and stabilization of telomere length. Furthermore, the E6 and E7 oncoproteins of "high risk" HPV disrupted the cell cycle control and DNA repair in immortalized HOK, and enhanced mutation frequency resulting from genomic instability. However, HPV infection alone failed to give rise to a tumorigenic cell population, which required further exposure to chemical carcinogens in addition to HPV infection. Analysis of the data presented suggests that oral carcinogenesis is a series of discrete genetic alterations that result from a continued genotoxic challenge by environmental risk factors. Our in vitro model may be useful for investigators with interest in furthering our understanding of oral carcinogenesis.

Assesment of Correlation of Herpes Simplex Virus-1 with Oral Cancer and Precancer- A Comparative Study

INTRODUCTION

Most common malignant neoplasm in the oral cavity is squamous cell carcinoma. Herpes simplex virus (HSV) may enhance the development of oral carcinoma in individuals who are already at increased risk of the disease because of tobacco consumption and cigarette smoking and so must be considered as a possible etiologic agent in oral cancer and precancer.

AIM

To assess and compare the correlation of HSV-1 in oral cancer and precancerous lesions/conditions with healthy subjects.

MATERIALS AND METHODS

The study comprised of 150 subjects who were divided into three groups as oral cancer, precancer and control group. Their blood samples were collected and were tested for HSV-1 IgG antibody level, using 'Herpe Select-1' ELISA kit.

RESULTS

There was statistically insignificant difference between the HSV-1 IgG level in cancer and precancer but statistically significant difference was found between the HSV-1 IgG level among control group and cancer/precancer.

CONCLUSION

The present study clearly indicates that quantitative estimation of IgG antibody against HSV-1 in cancer/precancer patients will give the clue in the etiology of cancer or precancer. However, further studies with a large sample size should be carried out to determine the role of HSV-1 in etiology of oral cancer and precancer.

Role of viruses in oral squamous cell carcinoma

The etiology of oral squamous cell carcinoma (OSCC) is complex and involves many factors. The most clearly defined risk factors are smoking and alcohol, which substantially increase the risk of oral SCC. However, despite this clear association, a substantial proportion of patients develop OSCC without exposure to them, emphasizing the role of other risk factors such as genetic susceptibility and oncogenic viruses. Some viruses are strongly associated with OSCC while the association of others is less frequent and may depend on co-factors for their carcinogenic effects. Therefore, the exact role of viruses must be evaluated with care in order to improve the diagnosis and treatment of OSCC.

Oral cancer: risk factors and molecular pathogenesis

INTRODUCTION

Oral cancer is one of the most common cancers and it constitutes a major health problem particularly in developing countries. It is one of the leading causes of death. Tobacco and alcohol consumption appears to be the major determinants of oral cancer.

MATERIALS AND METHODS

The literature search was carried out in NCBI Pubmed database using keywords "oral cancer", "risk factor", "epidemiology" and "patho*". Some basic information was also obtained from textbook and medical university websites.

RESULTS

Several risk factors have been well characterized to be associated with oral cancer with substantial evidences. The development of oral cancer is a multistep process involving the accumulation of genetic and epigenetic alterations in key regulatory genes. Experimental pathological studies of oral cancer in animal models and direct molecular genetic analysis of oral cancer subjects in recent times have revealed a substantial amount of knowledge on specific gene alterations or other genetic mechanisms involved in initiation and subsequent progression.

CONCLUSION

Considering known risk factors, oral cancer appears to be to a certain extent, a preventable disease. Recent development of molecular picture of pathoprogression and molecular genetic tools opens the avenue for easier diagnosis, better prognostication and efficient therapeutic management.

Oral cancer; the evidence for sexual transmission

The incidence of oral cancer amongst young adults is increasing in many European and high incidence countries. Most oral cancer is aetiologically linked to the use of tobacco and/or alcohol but nearly two decades ago, we produced the first evidence for the presence of viral nucleic acids in oral squamous cell carcinoma (OSCC) tissues, hypothesising that there may be a viral involvement in at least some OSCC. Subsequently, human papillomaviruses (HPV) in particular have been implicated in OSCC. Antibody responses to HPV are seen and HPV-DNA detected in tumours by us and many others, the virus being mainly HPV-16, the genotype associated with ano-genital cancer. Recent studies have indicated that HPV may be aetiologically important particularly in some types of oropharyngeal cancer, at least in tonsillar carcinogenesis, and may represent an alternative pathway in carcinogenesis to the established factors of tobacco and alcohol. Studies of patients with OSCC have suggested possible sexual transmission of HPV.

Oral squamous cell carcinoma; from an hypothesis about a virus, to concern about possible sexual transmission

Nearly two decades ago, we produced the first evidence for the presence of viral nucleic acids in oral squamous cell carcinoma (OSCC) tissues, hypothesising that there may be a viral involvement in at least some OSCC. Subsequently, human papillomaviruses (HPV) in particular have been implicated in OSCC. Antibody responses to HPV are seen and HPV-DNA detected in tumors by us and many others, the virus being mainly HPV-16, the genotype associated with ano-genital cancer. HPV are seen by in situ hybridisation only in tumour and premalignant tissue but not in surrounding normal mucosa suggesting HPV has a causal relationship. HPV may also be integrated in the host genome, further suggesting a causal role. Studies of patients with OSCC have suggested possible sexual transmission of HPV. Recent studies have indicated that HPV may be aetiologically important particularly in some types of oropharyngeal cancer, at least in tonsillar carcinogenesis, and may represent an alternative pathway in carcinogenesis to the established factors of tobacco and alcohol. We have come a very long way in the two decades since our first suggestion of a viral aetiopathogenesis was greeted with incredulity, and data from on-going studies by the International Agency for Research on Cancer, Johns Hopkins Oncology Center and others are eagerly awaited.

Attenuation of the natural course of herpes simplex virus infection in human oral epithelial cell cultures by smokeless tobacco extracts suggests the possibility of a synergistic mechanism for carcinogenesis

High prevalence of both tobacco use and latent herpes simplex virus type 1 suggests the opportunity for synergism between these agents as cocarcinogens. In this study, postprimary human oral epithelial cell cultures were infected with herpes simplex virus type 1 pretreated with 2% extracts of either loose leaf, moist, or dry snuffs. Cultures were subsequently periodically exposed to the tobacco. Parameters measured included percentage of cultures undergoing active virus production, onset and time course of cytopathic effects, and concentration of virus released into the media over time. Results showed inhibition of both herpes simplex virus-mediated cell lysis and viral replication by tobacco extracts. This is the first time that these phenomena have been demonstrated in normal human oral epithelial cells. The work described here provides evidence to support a hypothesis that herpes simplex virus type 1 and smokeless tobacco may act synergistically in oral carcinogenesis.

High prevalence of hepatitis C virus antibody and RNA in patients with oral cancer

We have investigated the correlation between the prevalence of hepatitis C virus (HCV), which is detectable in saliva, and oral cancer and other digestive tract cancers in the Northern Kyushu region of Japan. Anti-HCV antibodies were detected in sera from 24 of the 100 patients with oral cancer (24%, p < 0.05 vs the control group, p < 0.01 vs the stomach cancer group), in 11 of 104 patients with non-malignant diseases receiving dental treatment (the control group, 10.6%), and in 12 of 113 patients with stomach cancer (10.6%). HCV-RNA was detected in sera from 17 of 100 oral cancer patients (17%, p < 0.05 vs the control group) and 4 of 104 patients of the control group (3.9%). These results indicate a high prevalence of HCV infection in oral cancer patients, which warrants a systematic study of etiological associations between oral cancer and HCV.

Expression of the mutagenic peptide of herpes simplex virus type 1 in virus-infected cells

A fragment of DNA from within the minimum transforming region (mtr-1) of herpes simplex virus type 1 (HSV-1) is known to raise the mutation frequency of cells. This activity has been attributed to a viral protein whose properties are largely unknown. Antiserum was raised to a synthetic peptide of a predicted amino acid sequence from the protein, and was found to react with cells that were infected by HSV-1 in an ELISA and by immunocytochemical staining. A combination of immunoprecipitation and immunoblotting techniques confirmed that the epitope is located at the carboxy terminus of the UL26 gene product and is downstream of epitopes that are recognized by two monoclonal antibodies. The mutagenic peptide was different from the conventional gene product of UL26 in that: (a) It was expressed from a different reading frame, (b) It was expressed earlier in infection, and (c) It bound DNA, and thus could be separated by DNA-cellulose chromatography. An RT-PCR experiment revealed two deletions in the cDNA, suggesting that RNA splicing could account for the frameshift. Examination of the DNA sequence of the region also revealed a potential ribosomal frame-shift site. The mutagenic peptide of HSV-1 is therefore a product of the UL26 gene which is expressed with a different carboxy terminus early in infection, and this could be due either to RNA splicing or to ribosomal frame-shifting.

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.

Antibody to a mutagenic peptide of herpes simplex virus in young adult patients with cancer of the head and neck

Cancer of the head and neck has been associated with herpes simplex virus type-1 by serologic studies that have used virus particles or complex mixtures of viral proteins as antigens. Recently a peptide was found to be encoded by the transforming region of the virus that is mutagenic and is postulated to be involved in cell transformation. Sera from young adult patients with head and neck cancer and from control subjects were examined for the presence of antibody to this peptide with the use of an enzyme-linked immunosorbent assay. Antibody to the peptide was detected in many sera and showed a significant correlation with antibody to the virus in sera from control subjects. Antipeptide antibodies were largely of the IgM isotype, and patients had significantly higher levels of antibody than control subjects. This study is consistent with an association between HSV-1 and head and neck cancer and suggests that this viral peptide should be investigated further for its role in carcinogenesis.

In vitro and animal studies of the role of viruses in oral carcinogenesis

The linkage of herpes simplex virus (HSV) and human papillomavirus (HPV) to the development of oral cancer has been studied. In spite of the presence of viral nucleic acids in some human oral cancer specimens, HSV alone is not carcinogenic in animals: repeated viral inoculation to mouse or hamster oral mucosa fails to produce tumours or histopathological evidence of malignancy. However, HSV demonstrates co-carcinogenicity in vivo: viral inoculation significantly enhances the oncogenic capacity of chemical carcinogens in the oral cavity of mice and hamsters. Though the detailed mechanisms of HSV cocarcinogenicity are unknown, HSV promotes the chemical carcinogen-induced activation of certain cellular proto-oncogenes and inactivation of p53 tumour suppressor gene. Human papillomaviruses type 16 (HPV-16) and 18 (HPV-18) demonstrate oncogenicity by transforming normal human oral keratinocytes in vitro. While normal cells exhibit a limited life-span, cells transformed by these viruses show immortality and altered morphology in comparison with their normal counterparts. The HPV-immortalised cells contain multiple copies of intact viral genome integrated into cellular chromosomes. These cells also express several viral-specific mRNAs including viral E6/E7 mRNAs. Notably, these cells contain low levels of p53 protein and overexpressed cellular myc proto-oncogene compared to their normal counterpart; however, the immortilised cell lines are non-tumorigenic in nude mice.

Viruses in the aetiology of oral carcinoma? Examination of the evidence

This paper examines the evidence for an aetiological role for viruses in the development of oral carcinoma. Several viruses have been sought in oral cancer and evidence found for some, particularly herpes simplex and human papillomavirus. However, the evidence also suggests that these viruses are ubiquitous agents and a number of criteria must be met before these potentially oncogenic agents can reliably be implicated in human carcinogenesis. In contrast, there is no evidence that viruses such as adenovirus, Epstein-Barr virus, and retroviruses play any role in oral carcinogenesis.

Viruses and chronic disorders involving the human oral mucosa

Viruses have been implicated in the etiology of several chronic disorders of the oral mucosa. Most of these associations have been with DNA viruses, particularly certain herpesviruses, which are associated, for example, with some cases of erythema multiforme and with hairy leukoplakia. Papillomaviruses are associated with various papillomatous lesions, focal epithelial hyperplasia, and possibly with some carcinomas. Viruses may possibly be associated with recurrent aphthae, Behçet's syndrome, and some dermatoses. The literature concerning these possible associations is reviewed. However, much more research needs to be done before the full story of viral associations with oral mucosal disorders can be written.

Changing trends in oral cancer in the United States, 1935 to 1985: a Connecticut study

An extensive epidemiologic study was undertaken in an attempt to analyze patterns of oral cancer distribution and demography in Connecticut between 1935 and 1985. Sources of data for the investigation included both the Connecticut Tumor Registry (CTR) and the University of Connecticut Oral Pathology Biopsy Service. During the 51-year study period, 9,708 cases of primary oral cancer were reported to the CTR. Male age-adjusted incidence rates for overall oral cancer remained stable between 1935 and 1964 (14.5 to 14.8 per 100,000), with a gradual decline to 10.9 per 100,000 in the early 1980s. In contrast, age-adjusted rates for females advanced approximately threefold, from 1.4 per 100,000 in the 1930s to 4.1 per 100,000 in the early 1980s. There was a decrease in age-specific rates of oral cancer in males aged 70 and older; in contrast, age-specific incidence rates in females increased steadily over the same period. It was also found that female birth cohorts born in 1900 and later exhibited higher oral cancer incidence rates than those of previous cohorts. Between the 1960s and the present, male patients 30 to 39 years of age exhibited a nearly fourfold increase in oral cancer incidence; this was not observed among similarly aged females. Connecticut counties with highest oral cancer incidence rates in both sexes were the more densely populated Hartford and New Haven counties. In general, the picture of oral cancer, as revealed through analysis of cases accessioned by the University biopsy service between 1975 and 1986, exhibited similar trends to those disclosed by analysis of CTR data.(ABSTRACT TRUNCATED AT 250 WORDS)

Viruses and oral cancer

Oral cancer is a disease with a complex etiology. There is evidence for important roles of smoking, drinking, and genetic susceptibility, as well as strong indications that DNA viruses could be involved. The herpes simplex virus type 1 has been associated with oral cancer by serological studies, and animal models and in vitro systems have demonstrated that it is capable of inducing oral cancer. Papillomaviruses are found in many oral cancers and are also capable of transforming cells to a malignant phenotype. However, both virus groups depend on co-factors for their carcinogenic effects. Future research on viruses and oral cancer is expected to clarify the role of these viruses, and this will lead to improvements in diagnosis and treatment of the disease.

Synergism of herpes simplex virus and tobacco-specific N'-nitrosamines in cell transformation

Previous studies indicate that herpes simplex virus (HSV) enhances the carcinogenic activity of smokeless tobacco and tobacco-related chemical carcinogens in animals. Since tobacco-specific N'-nitrosamines (TSNAs) such as N'-nitrosonornicotine (NNN) and 4-(N-methyl-N'-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are major chemical carcinogens of smokeless tobacco and are known to be responsible for the development of oral cancers in smokeless tobacco users, the combined effects of TSNAs and HSV in cell transformation were investigated. Exposure of cells to NNN or NNK followed by virus infection resulted in a significant enhancement of transformation frequency when compared with that observed with chemical carcinogens or virus alone. This study suggests that TSNAs and HSV can interact together and show synergism in cell transformation.

Three cell lines from hamster buccal pouch tumors induced by topical 7,12-dimethylbenz(a)anthracene, alone or in conjunction with herpes simplex virus inoculation

Three squamous carcinoma cell lines HBPC-1, HBPC-2, and HBPC-3 were established from hamster buccal pouch tumors induced by topical 7,12-dimethylbenz(a)anthracene (DMBA) treatment alone, topical DMBA treatment in conjunction with type 1 herpes simplex virus (HSV-1) inoculation, and topical DMBA application in combination with type 2 HSV (HSV-2) inoculation, respectively. The cells were epithelial in morphology, had a doubling time of approximately 18 h, and required bovine serum for optimal growth. They demonstrated an in vitro anchorage-independent growth and produced squamous cell carcinomas when transplanted into normal hamster pouch submucosa. The carcinoma cell lines equally expressed cellular hst, src, abl, and raf proto-oncogenes that were not expressed in the normal hamster pouch epithelial cells. An equal amount of fos gene expression was noticed in the normal pouch epithelial cells, HBPC-1 and HBPC-3, but the HBPC-2 expressed less fos poly(A+)RNA than the other cell lines. The myc proto-oncogene was also expressed both in the normal pouch epithelial cells and in the cancer cell lines. However, the size and number of expressed myc poly(A+)RNA in the normal cells and cancer cell lines differed. Although the normal cells and HBPC-1 expressed a single myc transcript, 1.7-kilobase (kb) and 2.3-kb, respectively, both HBPC-2 and HBPC-3 expressed two myc poly(A+)RNAs, 1.7-kb and 2.3-kb.

Active HSV-1 immunization prevents the cocarcinogenic activity of HSV-1 in the oral cavity of hamsters

Previous investigations have demonstrated that herpes simplex virus (HSV) increased the oral carcinogenic activity of 7,12-dimethylbenz[a]anthracene (DMBA) probably by enhancing the DMBA-induced amplification and overexpression of c-erb-B-1 proto-oncogene in hamster buccal pouch epithelium. The present study investigated the effect of active type 1 HSV (HSV-1) immunization on the development of oral cancer induced by HSV-1 and DMBA, alone or in combination, in the hamster buccal pouch. The results were similar to our previous report in that HSV-1 significantly enhanced the oncogenic effect of DMBA, and the numbers of pouches harboring tumor nodules and the numbers and sizes of tumors developed by topical DMBA were significantly increased by HSV-1 inoculation to the site of the DMBA application. Although HSV-1 immunization did not alter the carcinogenic activity of DMBA in animals receiving topical DMBA in combination with mock inoculation, it prevented the cocarcinogenic effect of HSV-1 in animals receiving topical DMBA in conjunction with HSV-1 inoculation. These data indicate that active HSV-1 immunization completely obstructs the co-oncogenic effect of HSV-1 in the oral cavity of hamsters.

Oral cancer

In the U.S. oral cancer accounts for 2.1% of all cancers and 1% of cancer deaths. Two to three times as many males as females are affected. Blacks have more intra-oral cancer than whites, and their incidence and mortality rates have increased in recent years. The etiologic process very likely involves several factors. The major etiologic agents are tobacco (all types) and alcoholic beverages. Herpes simplex virus, human papilloma virus, and Candida have been implicated. Host factors include poor state of dentition, nutritional aberrations, cirrhosis of liver, lichen planus, and immunologic impairmant. Cellular changes include amplification of some oncogenes, alterations in antigen expression, production of gamma-glutamyl transpeptidase, and disturbance of keratin and involucrin production. Experimentally, cancer is readily produced on the hamster cheek pouch and rat oral mucosa. Unlike oral cancer in humans, most experimental lesions are exophytic, and they rarely metastasize.

Effect of snuff extract on the replication and synthesis of viral DNA and proteins in cells infected with herpes simplex virus

The water-extractable component of snuff (snuff extract) inhibits the replication of herpes simplex virus (HSV) by suppressing the synthesis of viral DNA. This process probably causes HSV to be oncogenic. To further understand the mechanism of inhibitory action of snuff extract on HSV replication, the effect of snuff extract on the synthesis of viral DNA and proteins in type 1 HSV (HSV-1) infected cells was investigated. Snuff extract inhibited the synthesis of viral DNA and altered the production of certain classes of viral proteins. The syntheses of ICP4, a viral alpha-protein, and ICP8, a beta-protein, were not generally reduced by noncytotoxic concentrations of snuff extract (where ICP = infected cell polypeptide). However, snuff extracts significantly inhibited the production of ICP gC (glycoprotein C), a gamma 2-protein, and the inhibition was in a concentration-dependent fashion: the higher the concentration of snuff extracts, the greater the inhibition. Based on the fact that the production of alpha- and beta-proteins is absolutely necessary for and precedes the viral DNA synthesis and that viral gamma 2-proteins are mostly produced by the newly synthesized viral DNA, it is concluded that snuff extract inhibits HSV-1 DNA replication directly rather than indirectly via the alteration of viral protein synthesis.

Orofacial herpes simplex virus infections: current concepts in the epidemiology, pathogenesis, and treatment, and disorders in which the virus may be implicated

Herpes simplex virus (HSV) is the causal agent of herpetic stomatitis, recurrent herpes labialis, and the recurrent intraoral infections seen particularly in the immunocompromised patient. HSV has also been implicated in some erythema multiforme, cranial neuropathies, Behçet's syndrome, and oral squamous carcinoma. Recent advances in understanding of HSV, epidemiology, pathogenesis, and treatment are reviewed because there have been numerous advances over the past 5 years.

Herpes simplex virus enhances the 7,12-dimethylbenz[a]anthracene (DMBA)-induced carcinogenesis and amplification and overexpression of c-erb-B-1 proto-oncogene in hamster buccal pouch epithelium

We studied the effects of herpes simplex virus type 1 (HSV-1) inoculation and topical 7,12-dimethylbenz[a]anthracene (DMBA) application, alone or in combination, on the carcinogenesis and on the amplification and expression of various cellular proto-oncogenes in hamster buccal pouch tissue. Topical DMBA treatment produced tumor formation in pouches, but HSV-1 inoculation, alone caused no neoplastic changes. In pouch tissues receiving both DMBA application and HSV-1 inoculation, the development of initial leukoplakia and tumor has hastened and enhanced in comparison with those receiving DMBA alone. Topical DMBA application to pouch tissue induced an amplification and an increase in the expression of cellular erb-B-1 (c-erb-B-1) proto-oncogene in the epithelial tissue, whereas repeated infection with HSV-1 alone did not. Topical DMBA combined with HSV-1 inoculation, however, resulted in greater amplification and expression of c-erb-B-1 proto-oncogene in the pouch epithelial tissue compared to the DMBA alone. These data indicate that HSV-1 inoculation significantly increases the carcinogenic activity of DMBA, in part, by probably enhancing DMBA-induced amplification and expression of c-erb-B-1 proto-oncogene in hamster buccal pouch tissue.

Induction of oral cancer by 7,12-dimethylbenz[a]anthracene in rats with liver cirrhosis

The effects of carbon tetrachloride-induced liver cirrhosis and xerostomia on oral carcinogenesis were studied in rats given the lipid-soluble carcinogen 7,12-dimethylbenz-[a]anthracene (DMBA). The first carcinoma was detected after only 1 month of DMBA applications. After a further 8 months 85% of the animals had developed one or more squamous cell carcinomas. The latency period for DMBA-induced oral cancer in cirrhotic rats with xerostomia was markedly reduced in comparison with previous findings from xerostomic rats without liver cirrhosis. The results support earlier epidemiologic studies indicating a relationship between liver cirrhosis and oral cancer.

Effect of smoked tobacco tar on the growth, cytolytic action, DNA synthesis, and gene expression of herpes simplex virus

Previous experiments have shown that topical application of smoked tobacco tar condensate to HSV-infected oral mucosae of mice promotes neoplastic changes. Although HSV is an oncogenic virus, the virus must be inactivated and lose its cytolytic activity to be oncogenic in vitro and in vivo. Therefore, we investigated the effect of the water-extractable components of smoked tobacco tar condensate (smoked tobacco tar extract) on the growth, cytolytic activity, DNA synthesis, and gene expression of type 1 herpes simplex virus (HSV-1). Diluted tar extracts in tissue culture medium markedly inhibited the replication and cytolytic activity of HSV-1 in vitro. The smoked tobacco tar extract also notably inhibited the synthesis of viral DNA and late gene expression in a dose-dependent manner. The synthesis of alpha- and beta-classes of viral proteins was not affected by the extract. Therefore, it is probable that the smoked tobacco tar extract inhibits the synthesis of viral DNA directly rather than indirectly by depressing early gene expression.

Effect of DMBA on oral cancer development in hamsters with latent HSV-1 infections in trigeminal ganglia

This study examined the effect of 7, 12-dimethyl-benz(a)anthracene (DMBA), polycyclic aromatic hydrocarbon carcinogen, on pathologic changes in buccal pouch mucosa of hamsters with latent herpes simplex virus type 1 (HSV-1) infections in their trigeminal ganglia. Of the pouches receiving DMBA treatment, the average number of tumors per pouch was significantly higher (p less than 0.01) in pouches of animals with HSV-1 infections as compared to those that received DMBA only. Of the pouches receiving DMBA, the average cumulative tumor diameter (the sum of the tumor diameters in each group divided by the number of pouches in that group) was notably greater in animals with latent HSV-1 than in animals that had not been infected; however, this difference was not significant. The DMBA-treated hamsters that had latent infections also displayed a higher severity and prevalence of histopathologic changes in their pouch mucosa. This study indicates that latent HSV-1 and DMBA show synergism in the development of tumors and precancerous histopathologic changes in hamster buccal pouch mucosa. An unexpected finding was that among the HSV-1 infected animals, 95% of the ganglia from animals treated with DMBA showed latent HSV-1 virus on explanation culture, whereas only 10% of the ganglia from infected animals that received mineral oil, rather than DMBA, contained latent virus.

The effects of benzo(a)pyrene, nicotine, and tobacco-specific N-nitrosamines on the generation of human lymphokine-activated killer cells

The effects of four major components of snuff (fine-cut smokeless tobacco) on the development of lymphokine-activated killer cells (LAK) were measured in vitro. Of the components tested: nicotine, N'-nitrosonornicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo(a)pyrene (BaP), only BaP suppressed LAK cytotoxicity against tumour targets and LAK DNA synthesis during 3- and 7-day incubations. BaP concentrations of 0.1-1.0 micrograms/ml suppressed lymphocyte proliferation only; there was no effect on tumour cell proliferation at these concentrations. BaP had no effect on tumour target killing when incubated during 4 h natural killer (NK) or LAK cytotoxicity assays. There was no effect on LAK binding of tumour targets after 3 days culture with BaP concentration of 0.1-1.0 micrograms/ml. These data confirm that a water-soluble extract of snuff has anti-cytolytic and anti-proliferative effects on peripheral blood lymphocytes. As NK and LAK cells are important in preventing tumourigenesis and metastasis, suppression of these cells may favour neoplastic growth associated with snuff-dipping.

Establishment of two cell lines from hamster buccal pouch tumors induced by topical 7,12-dimethylbenz(a)anthracene and topical DMBA in conjunction with herpes simplex virus infection

Two cell lines designated HBPC-1 and HBPC-2 have been established from hamster buccal pouch tumors induced by topical 7,12-dimethylbenz(a)anthracene (DMBA) and DMBA in conjunction with type 1 herpes simplex virus infection, respectively. The cells are epithelial in morphology, have a doubling time of approximately 18 h, and require bovine serum for optimal growth. The karyotype is aneuploid, with several marker chromosomes, and the cells produce squamous cell carcinomas when transplanted into normal hamster pouch tissues.

Inhibition of human lymphokine-activated killer activity by smokeless tobacco (snuff) extract

Chronic snuff dipping has been associated with oral cancer in man and experimental animals. Here, the effects of a water-extract of snuff on the in-vitro development of human lymphokine-activated killer (LAK) activity were examined. The snuff extract inhibited both LAK cytotoxicity and DNA synthesis in a dose-dependent fashion at concentrations of 0.125 to 2.0 per cent; above 2.0 per cent, cell viability decreased significantly. In contrast, the snuff extract had no effect on natural killer-cell cytotoxicity when incubated with fresh peripheral blood lymphocytes in a standard 4 h assay, or on LAK cytotoxicity when incubated only during the final 4 h effector phase. Lymphocyte protein synthesis was generally unaffected by the addition of this extract. Thus, a water-soluble snuff extract appears to suppress LAK activity by inhibiting DNA synthesis. Altered LAK function in the oral mucosa might permit the development of snuff-associated carcinogenesis.

Oncogenic potential of sexually transmitted viruses with special reference to oral cancer

Recent changes in social mores have been accompanied by a noted increase in the frequency of sexually transmitted diseases. Viruses that have been identified as causative agents for a large proportion of these diseases have also been associated with various malignant states. Concomitantly, the number of cases of oral cancer (considered to occur usually around or after the fifth decade of life) reportedly has been increasing among young adults. The oncogenic potential of several sexually transmitted viruses (HSV, HPV, CMV, and LAV/HTLV III) and their possible role in the development of malignant conditions, in particular oral cancer, are discussed in this review.

Effect of tar condensate from smoking tobacco and water-extract of snuff on the oral mucosa of mice with latent herpes simplex virus

Upper lips were inoculated with virus to establish a latent infection in the trigeminal ganglia. During the latent period, tobacco smoke tar condensate or water-extract of snuff were topically applied to the primary inoculation site for two or three consecutive months. Tar condensate induced re-activation of latent HSV in the ganglia of 10 to 20 per cent of animals but snuff extract did not. Infectious virus was also detected in lips after the chronic application of tar condensate in 10 per cent of animals. Three months' exposure to tobacco produced epithelial dysplasia and other changes in a significant number of latent HSV-infected mice, whereas tobacco alone did not induce dysplasia in the labial epithelium of uninfected mice.

Effect of smokeless tobacco on the replication of herpes simplex virus in vitro and on production of viral lesions in hamster cheek pouch

Previous experiments have shown that combination of herpes simplex virus (HSV) infection and simulated snuff-dipping in hamster buccal pouches enhances the development of micro-invasive squamous cell carcinoma in cheek pouch epithelium. The effect has now been determined of water-extractable components of snuff (snuff-extract) on the growth and the cell-lysing activity of HSV. Various dilutions of snuff-extract in tissue culture medium significantly inhibited the growth of HSV in Vero cell monolayers by inhibiting the viral DNA replication. Moreover, HSV was inactivated and its cell-lysing activity lost when it was incubated with snuff-extract in cell-free condition. Snuff also had a similar anti-herpetic effect in vivo; HSV infection of pouch tissues followed by simulated snuff-dipping resulted in significant inhibition of viral growth. Thus snuff interferes with the DNA synthesis and cytolytic activity of HSV in vitro and in vivo, and this in turn, may increase its oncogenic capacity.

Five-year survival of patients with oral cancer and its association with antibody to herpes simplex virus

Levels of antibody to herpes simplex virus type 1 (HSV-1) were measured in 70 patients with untreated squamous cell carcinoma of the mouth. After treatment the actuarial survival was determined at quarterly intervals for 5 years and was found to be associated with the pretreatment level of antibody to the virus. Patients with levels of IgM antibody to HSV-1 which were above the median level had a 5-year survival of only 56% whereas those with levels below the median had a higher survival of 72%. Patients with no detectable IgM antibody to HSV-1 had a 5-year survival of 81%. The reverse was seen with IgG antibody to HSV-1. Patients with higher than the median level of IgG antibody had a 5-year survival of 73%, whereas those with IgG antibody below the median had a 5-year survival of 56%. No relationship was seen between survival and levels of IgA antibody to HSV-1, or between survival and antibody of any class to cytomegalovirus. The data are consistent with the reported association between oral cancer and HSV-1.

Oral cancer induced in hamsters with herpes simplex infection and simulated snuff dipping

A number of epidemiologic studies indicate that snuff dipping is associated with an increased incidence of oral cancer in human beings. Since inactivated herpes simplex virus (HSV) has been shown to induce malignant changes in vitro and in vivo and is partially inactivated by snuff water extract, we examined the histopathologic changes of hamster buccal pouches after exposure to repeated HSV inoculation combined with long-term simulated snuff dipping. One hundred twenty-five Syrian hamsters were divided into seven groups, and the buccal pouches were inoculated with HSV-1, HSV-2, or culture medium. The mock and HSV inoculations were done once a month for 6 consecutive months. In an effort to determine the effect of snuff on the mock- or HSV-inoculated buccal pouches, a consistent amount of a commercially available snuff was placed into both the right and left pouches twice a day in half of the animals. At the end of the 6 months of simulated snuff dipping (4 weeks after the final mock or viral inoculation), the hamsters were killed and the buccal pouches were removed for the histopathologic evaluation. Neither simulated snuff dipping nor HSV infection alone induced neoplastic changes in hamster buccal pouches. However, HSV infection in combination with simulated snuff dipping resulted in epithelial dysplasia and invasive squamous cell carcinoma in more than 50% of the animals.

Phenotypic identification of mononuclear cells in oral premalignant lesions and cancer by monoclonal antibodies

To explore the nature and importance of mononuclear cells of different phenotypes in oral premalignant lesions and oral cancer, we studied biopsy specimens from 21 oral red and/or white lesions (6 hyperkeratosis, 3 mild dysplasia, 4 severe dysplasia and 8 squamous cell carcinoma), using monoclonal antibodies and avidin-biotin-peroxidase complex staining. Peripheral blood samples (PB) from 4 normal subjects and 5 reactive lymph nodes (LN) were used as controls for the technique. T11-positive cells were the predominant phenotype (74-78%) in all cases examined. The T4/T8 ratio in severe dysplasia was significantly lower than that in mild dysplasia (p less than or equal to 0.05). These observations support the hypothesis of a role for cellular immune responses in oral premalignant lesions and oral cancer. The predominance of T cells may represent the local expression of immunity against antigens (viral or other). The decreased T4/T8 ratio observed in severe dysplasia may represent a transitory stage of local immunosuppression, which may be of critical importance for the progression into carcinoma. Phenotypic variations in mononuclear cell infiltrates in these conditions could be diagnostic value.

An epidemiologic study of oral cancer in a statewide network

A case-control study was conducted to investigate the risks of male and female oral, oropharyngeal, and hypopharyngeal cancer associated with poor oral health, mouthwash use, occupation, histories of tobacco and alcohol use, and other factors. Data were collected from all newly diagnosed patients entered into the Wisconsin Head and Neck Cancer Network over an 18-month period (N = 623). The prevalence of painful or ill-fitting dentures was significantly higher among males and females with oral cavity cancer. Relative risks for painful dentures were 5.97 (males) and 1.60 (females); for ill-fitting dentures, the relative risks were 3.15 (males) and 2.15 (females). For males, high relative risks of oropharyngeal cancer were also found to be associated with these indicators of poor dentition. Other indicators of poor oral health, including toothbrushing frequency and prevalence of broken teeth, were not associated with oral cancer. Mouthwash use was not found to carry a risk of oral cavity, oropharyngeal, or hypopharyngeal cancer. The risks of upper aerodigestive cancers with smoking and alcohol were confirmed for males, and lifetime use patterns were explored. Notable sex differences in exposure to alcohol and tobacco were found. There was little evidence that past alcohol use was related to female oral cancer.

Experimental development of herpes simplex virus infection in hamster buccal pouch

In the present study, we have developed an intraoral herpes simplex virus type 1 (HSV-1) infection model in the hamster buccal pouch. This animal model could be used for further oral cancer research related to herpes simplex virus infection.

Combined effect of herpes simplex virus and tobacco on the histopathologic changes in lips of mice

In the present study we have examined the combined effect of HSV-1 inoculation and tobacco application (snuff water extract or smoking tar condensate) on the histopathologic changes of mouse labial mucosa. Two months' exposure to tobacco or HSV-1 inoculation alone did not induce dysplasia in the epithelium of labial mucosa, while HSV-1 inoculation combined with snuff water extract or smoking tar condensate produced epithelial dysplasia and other histomorphologic changes (that is, hyperkeratosis, increased granular cell layer thickness, acanthosis, and increased inflammatory cell infiltration in a significant number of animals). This result indicates that HSV-1 and tobacco could possibly act synergistically in the development of precancerous oral lesions and oral cancer.

Antibody to early and late antigens of herpes simplex virus type 1 in patients with oral cancer

HEp-2 cells were infected with herpes simplex virus type 1 (HSV-1) and harvested at selected times thereafter. IgG, IgA, and IgM antibody to virus antigens present in these cells at each time was measured in sera from oral cancer patients, and in matched controls. The IgA response of oral cancer patients was significantly greater than that of controls both at 8 and at 48 hours after infection, but showed no difference in response to HSV-1 virus particles. IgM antibody detected two peaks of antigen synthesis, at 4 and 48 hours after infection. Oral cancer patients had a stronger IgM response than did controls to both early and late peaks; the latter was significant at the 5% level. Oral cancer patients also had a significantly higher IgM response to the virus particle. These results imply the existence of at least two different HSV-1 antigens associated with oral cancer. Both are late antigens; one is recognized by IgA, and the other is recognized by IgM antibody.

Microbial pathogenicity in oral soft tissue diseases

Recent work implicating microbial factors in the pathogenesis of several oral soft tissue diseases is discussed. These conditions include recurrent aphthous ulceration, oral cancer, Sjogren's syndrome, and the oral lesions of AIDS (the acquired immune deficiency syndrome). This paper reviews some recent work on these topics, with emphasis on investigations in our laboratory.

Effect of snuff and herpes simplex virus-1 on rat oral mucosa: possible associations with the development of squamous cell carcinoma

The purpose of this investigation was to study the effect of snuff and experimentally induced herpes simplex virus type 1 (HSV-1) infection in Sprague-Dawley rats. It was demonstrated that it was possible to obtain 100% development of acute HSV-1 infection in the rat oral mucosa, but only 10% of latent reactive infection of the trigeminal ganglia. The rats were, therefore, acutely infected monthly with virus to simulate recurrence of latent infection. Virus was applied topically to the mucous membrane twice with an interval of one month. Snuff was administered between the virus applications and afterwards to half the virus-exposed animals. Sham-infected rats were given snuff during the same period (18 months). A fourth group of rats were left untreated. A complete post-mortem examination was performed. Two rats exposed to snuff and HSV-1 in combination developed squamous cell carcinoma of the oral cavity. It was also found that rats exposed to snuff alone or in combination with HSV-1 had a higher incidence of tumours or tumour-like conditions than control rats exposed to HSV-1 only. The incidence of malignant tumours was significantly higher in rats exposed to snuff or HSV-1 and snuff in combination than in control animals (p less than 0.05). The results of the study indicate that HSV-1 in combination with snuff exposure may be associated with the development of squamous cell carcinomas of the oral cavity.