Human papilloma viruses and p53 mutations in normal,pre-malignant and malignant oral epithelia

HPV infections have been previously observed in oral cancers, and inactivation of the p53 gene has been shown to be one of the most common genetic alterations in human tumors. We examined 179 oral specimens from 70 individuals with histologic findings of either normal mucosa (n = 6) or oral disease that ranged from mild dysplasia to invasive squamous-cell carcinoma (n = 64) to determine the occurrence of both HPV infection and p53 mutations and their relationship with several clinical factors. HPV infection was detected by PCR amplification of viral DNA, and the presence of p53 mutations was assayed using the single-strand conformation polymorphism (SSCP)-PCR technique. HPV infection was found in 31% of individuals with oral disease and was not seen in healthy individuals. Mutations in exons 5, 6, 7 or 8 of the p53 gene were detected in 37.5% of patients with oral lesions and in a biopsy from 1 healthy individual who was a heavy smoker. Approximately one-third of lesions classified as pre-malignant (dysplasia and carcinoma in situ) and 42% of invasive carcinomas contained p53 mutations. The majority of these mutations were G:T transversions located within exons 7 and 8. Tumor tissues from 6 patients with oral lesions were found both to be HPV-16-positive and to contain p53 mutations; of these, 4 were poorly differentiated carcinomas that were diagnosed as late-stage disease. In this study, p53 mutations were detected in the early stages of cancer development. © 1996 Wiley-Liss, Inc.     

Characteristics of mutations in the p53 gene in oral squamous cell carcinoma associated with betel quid chewing and cigarette smoking in Taiwanese

p53 mutations are etiologically associated with the development of oral squamous cell carcinomas (OSCCs) or are associated with exposure to specific carcinogens. In this study, we used PCR-single strand conformation polymorphism and DNA sequencing to analyze the conserved regions of the p53 gene (exons 5-9) in OSCC tumor specimens from 187 patients with varied histories of betel quid, tobacco and alcohol use. Ninety-one of the 187 OSCCs (48.66%) showed p53 gene mutations at exons 5-9. The incidence of p53 mutations was not associated with age, sex, TNM stage, status of cigarette smoking or betel quid chewing. However, alcohol drinkers exhibited a significantly higher incidence (57/101, 56.44%) of p53 mutations than non-users (39.53%, 34/86) (P = 0.02). The effect of alcohol on the incidence of p53 mutations was still statistically significant (RR = 2.24; 95% CI, 1.21-4.15) after adjustment for cigarette smoking and betel quid (BQ) chewing. G:C to A:T transitions were the predominant mutations observed and associated with BQ and tobacco use. Alcohol drinking could enhance these transitions. After adjustment for cigarette smoking and BQ chewing, alcohol drinking still showed an independent effect on G:C to A:T transitions (RR = 2.41; 95% CI, 1.01-5.74). These findings strongly suggest an important contributive role of tobacco carcinogens to p53 mutation in this series of Taiwanese OSCCs and alcohol might enhance these mutagenic effects. As safrole-DNA adducts have been detected in 77% (23/30) of the OSCC tissues from Taiwanese oral cancer patients with a BQ chewing history, we cannot rule out the possibility that safrole or other carcinogens present in the BQ may cause a similar pattern of mutagenesis. Determination of the role of safrole and other carcinogens present in BQ on the pattern of p53 gene mutation in OSCC will require further study.     

Prevalence of high-risk human papilloma virus types and its association with P53 codon 72 polymorphism in tobacco addicted oral squamous cell carcinoma (OSCC) patients of Eastern India.

Human papillomavirus (HPV) infects the squamous epithelial cells of oral cavity and cervix leading to formation of warts that develops into the cancer. Human papillomavirus (HPV)-16 and 18 encode E6 oncoprotein, which binds to and induces degradation of the tumour suppressor protein p53. A common polymorphism of p53, encoding either proline (Pro) or arginine (Arg) at position 72, affects the susceptibility of p53 to E6 mediated degradation in vivo. Oral cancer is a pressing problem in India due to the widespread habit of chewing betel quid, which plays an important role in etiology of this disease. In the present study an attempt has been made to analyze the genetic predisposition of the Indian population to HPV infection and oral carcinogenesis. In our study a total of 110 cases of Oral Cancer highly addicted to betel quid and tobacco chewing are analyzed for HPV 16/18 infection and its association with polymorphism at p53 codon 72. Of these a total number of 37 patients (33.6%) have shown the presence of HPV, among which the presence of HPV-16, 18 and 16/18 coinfection is 22.7%, 14.5% and 10%, respectively. Our results also indicate that the p53 codon 72 genotype frequencies in Indian Oral Cancer patients are 0.55 (Arg) and 0.45 (Pro) as per Hardy-Weinberg equilibrium. In our study, striking reduction in Pro/Pro allele frequency has been found in HPV positive cases, indicating Arg/Arg genotype to be more susceptible to HPV infection and oral carcinogenesis.     

Overexpression of p53 protein in betel- and tobacco-related human oral dysplasia and squamous-cell carcinoma in India

The aetiological factors for oral cancer are not the same in India and in Western countries. Epidemiological studies have shown a correlation between high incidence of oral cancer and heavy consumption of betel and/or tobacco in the Indian population, while this stud/ indicates an association with a genetic change. The p53 tumour-suppressor gene is the most commonly identified mutated gene in human malignancies. Expression of p53 protein was examined in premalignant and malignant oral lesions from Indian patients who were consumers of betel, areca nut and/or tobacco, using anti-p53 monoclonal antibodies PAb 1801 and PAb 421. Cryosections from normal, premalignant or malignant oral mucosa were used for immunostaining and the observations were confirmed by immunoprecipitation. P53 protein was detected in 55% (15/27) premalignant oral lesions (leukoplakia). Strong p53-positive staining was detected in 75% (24/32) of oral squamous-cell carcinomas. Normal oral mucosa did not show positive p53 staining (0/24). The detection of p53 protein in premalignant oral lesions suggests that p53 aberrations are an early event in the development of oral cancer in India. The high incidence of p53 positivity in leukoplakia may be due to differences in aetiological factors. p53 overexpression in premalignant oral lesions is important in view of the significantly earlier onset of leukoplakia in the Indian population compared to the development of oral malignancy, and may be helpful in identifying lesions that are more likely to progress to malignancy. The frequency of p53 protein overexpression was high in premalignant and malignant oral lesions of patients who were heavy consumers of betel, areca nut and tobacco.     

p53 inactivation in chewing tobacco-induced oral cancers and leukoplakias from India

The inactivation of p53 tumour suppressor gene vis-á-vis point mutation, overexpression and degradation due to Human Papilloma virus (HPV) 16/18 infection, was examined in chewing tobacco-associated oral cancers and oral leukoplakias from India. The analysis of mutations was assessed by polymerase chain reaction (PCR) with single strand conformation polymorphism (PCR-SSCP) of exons 5-9 on DNA from 83 oral cancer cases, and the mutations confirmed by direct nucleotide sequencing of the PCR products. p53 protein expression was evaluated by immunohistochemical analysis on paraffin-embedded sections of 62 representative oral cancer biopsies and 22 leukoplakias, using p53-specific monoclonal antibody DO-7. The presence of HPV16/18 was detected in the 83 oral cancer cases by PCR analysis using HPV L1 consensus sequences, followed by Southern hybridization with type-specific oligonucleotide probes. Forty-six per cent (38/83) of oral cancer tumours showed p53 alterations, with 17% (14/83) showing point mutations, 37% (23/62) with overexpression and 25% (21/83) with presence of HPV16 wherein the E6 HPV16 protein degrades p53. HPV18 was not detected in any of the samples. Ninety-two per cent concordance was observed between missense point mutations and overexpression of p53 protein. A significant correlation was not observed between p53 alterations in oral cancer and clinico-pathological profile of the patients. Twenty-seven per cent (6/22) of oral leukoplakias showed p53 overexpression. The overall p53 alterations in oral cancer tissues and oral lesions are comparable to data from the oral cancers reported in the Western countries with smoking and alcohol-associated oral cancers, and suggest a critical role for p53 gene in a significant proportion of oral cancers from India. The overexpression of p53 protein in leukoplakias may serve as a valuable biomarker for identifying individuals at high risk of transformation to malignant phenotype.     

Absence of p53 mutations in benign and pre-malignant male genital lesions with over-expressed p53 protein

Mutations of the tumor-suppressor gene p53 are common in epithelial tumors. Clonal mutations of p53 have been found in cervical and vulvar carcinomas negative for human papillomavirus (HPV), though at least in cervical cancer HPV infection and p53 mutations are not mutually exclusive. We have previously shown that about 40% of male genital warts and bowenoid papulosis lesions exhibit immunohistochemically detectable aberrant p53 protein, irrespective of the presence of HPV DNA. We studied p53 mutations in exons 4–8 with SSCP and sequencing in 13 male patients with 1 to 3 therapy-resistant genital warts or intra-epithelial neoplasias each and in 4 patients with penile squamous cell carcinoma. Thus, 13 genital warts, 6 bowenoid papulosis, 1 Queyrat's erythroplasia and 1 carcinoma in situ were studied. p53 protein was detected immunohistochemically, and HPV status was analyzed with DNA in situ hybridization and amplification of HPV-specific DNA. There was no correlation between p53 protein expression and HPV status. No mutations in exons 5–8 of the p53 gene were found in any of the lesions, and furthermore, no exon 4 mutations were found in lesions positive in p53 immunohistochemistry. In conclusion, over-expression of p53 does not indicate a p53 mutation in male genital warts, pre-malignant lesions or malignant squamous cell carcinomas. Our study thus suggests that p53 mutations are not important, or at least not early, events in male genital carcinogenesis. Int. J. Cancer 77:674–678, 1998. © 1998 Wiley-Liss, Inc.     

Low incidence of p53 mutations in betel quid and tobacco chewing-associated oral squamous carcinoma from India

Mutations of the p53 tumor suppressor gene have been found to be the single most frequent event in human cancers. In India and other southeast Asian countries tobacco chewing with betel quid was attributed to be the major factor in oral carcinogenesis. We have analyzed 72 untreated primary oral squamous cell carcinomas (SCCs) for mutations in the tumor suppressor gene p53 exons 4-9 by PCR-SSCP and DNA sequencing. Sequencing analysis revealed 16 missense mutations, one silent mutation in codon 307 and four A to G substitution polymorphism in codon 213. The incidence of p53 mutation was 21% (15 of 72) excluding the polymorphism and the silent mutation. Eight mutations were clustered in codons 266-282 of exon 8. Of the total mutation events 37.5% were G to A transitions and 31.3% were G to T transversions. These results indicate the possible involvement of tobacco derived nitrosamines and their adducts in the genesis of oral cancer among Indians.     

Presence and persistence of HPV infection and p53 mutation in cancer of the cervix uteri and the vulva

We studied 51 cervical carcinomas, among them 25 squamous-cell carcinomas (SCC) and 26 cervical adenocarcinomas (AdCa), and 40 vulvar SCC for the presence of HPV and mutant p53. HPV was detected by PCR, and p53 alterations by temperature-gradient gel electrophoresis/direct sequencing and immunohistochemistry. HPV, mostly type 16/18, was found in 80.4% of the cervical tumors (92.0% of the SCC and 69.2% of the AdCa), but in only 27.5% of vulvar carcinomas. In contrast, p53 mutations were found in 7.8% and 52.5% of cervical and vulvar tumors respectively. Mutant p53 occurred in pre-invasive vulvar lesions, indicating that this oncogenic factor is involved early in carcino-genesis. Further analysis of recurrent/metastatic lesions of 9 cervical and 14 vulvar tumors also showed remarkable differences: in cervical cancer, HPV was persistent, and p53 mutations absent, whereas in vulvar tumors, HPV was mostly absent or not persistent, and the p53 mutation rate was very high (78.6%). These observations suggest that HPV persistence is an important event for the evolution and maintenance of cervical cancer, whereas for vulvar cancers p53 mutation and not HPV activity is a central oncogenic event. © 1995 Wiley-Liss, Inc.     

Human papillomavirus DNA and p53 status in penile carcinomas

Our study aimed at evaluating the presence of human papillomavirus (HPV) DNA in a series of 84 paraffin-embedded (PET) penile carcinomas. We have also investigated the presence of p53 mutations in these tumors by immunohistochemistry (IHC), single-stranded conformational polymorphism (SSCP) and DNA sequencing. Tissues were submitted to amplification of a 268 bp fragment from the β-globin gene and a fragment of the E6 gene of HPV types 6, 11, 16 and 18. Twenty samples (18 fixed in Bouin's solution and 2 in buffered formalin) were found inadequate and were excluded from the analysis. In the remaining 64 tumors, HPV DNA was found in 26% of the samples. The prevalence of HPV in fresh samples of the same tumors was 56%. The most prevalent type was HPV 16 in both fresh samples and PET. Isotopic in situ hybridization was performed in all PET samples, but only 2 cases were positive, 1 for HPV 16 and 1 for HPV 18. Immunohistochemistry with anti-p53 pAb1801 antibody showed a positive nuclear reaction over more than 5% of tumor cells in 26% of the cases. SSCP of exons 5–8 of the p53 gene was performed on 9 HPV-positive and 12 HPV-negative specimens. Abnormal mobility was found in 26% of the tumors, of which 2 were HPV positive and 5 HPV negative. Point mutations were detected in p53 exons 6 (1 case), 7 (1 case) and 8 (5 cases), showing that high-risk type HPVs and mutated p53 may coexist in these tumors. Our data indicate that a subset of penile carcinomas are etiologically related to HPV and that an overlapping subset may arise from mutational events in the p53 gene. Int. J. Cancer76:779–783, 1998.© 1998 Wiley-Liss, Inc.     

The p16INK4alpha/p19ARF gene mutations are infrequent and are mutually exclusive to p53 mutations in Indian oral squamous cell carcinomas

Eighty-seven untreated primary oral squamous cell carcinomas (SCCs) associated with betel quid and tobacco chewing from Indian patients were analysed for the presence of mutations in the commonly shared exon 2 of p16INK4alpha/p19ARF genes. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing analysis were used to detect mutations. SSCP analysis indicated that only 9% (8/87) of the tumours had mutation in p16INK4alpha/p19ARF genes. Seventy-two tumours studied here were previously analysed for p53 mutations and 21% (15/72) of them were found to have mutations in p53 gene. Only one tumour was found to have mutation at both p53 and p16INK4alpha/p19ARF genes. Thus, the mutation rates observed were 21% for p53, 9% for p16INK4alpha/p19ARF, and 1% for both. Sequencing analysis revealed two types of mutations; i) G to C (GCAG to CCAG) transversion type mutation at intron 1-exon 2 splice junction and ii) another C to T transition type mutation resulting in CGA to TGA changing arginine to a termination codon at p16INK4alpha gene codon 80 and the same mutation will alter codon 94 of p19ARF gene from CCG to CTG (proline to leucine). These results suggest that p16INK4alpha/p19ARF mutations are less frequent than p53 mutations in Indian oral SCCs. The p53 and p16INK4alpha/p19ARF mutational events are independent and are mutually exclusive suggesting that mutational inactivation of either p53 or p16INK4alpha/p19ARF may alleviate the need for the inactivation of the other gene.     

Characteristics of mutations in the p53 gene of oral squamous-cell carcinomas associated with betel-quid chewing in Sri Lanka

Oral squamous-cell carcinoma (SCC) is the most common neoplasm in Sri Lanka, accounting for approximately 30% of all cancers in males. Epidemiologic evidence indicates that there is an unequivocal relationship between betel chewing and oral carcinogenesis, suggesting that there may be specific genetic targets of betel-quid ingredients. The p53 gene has been indicated to be a tumor-suppressor gene that is found in mutated form in common human cancers; however, there are few reports about “carcinogen-specific” p53 mutation. Because of this background, primary resected specimens from 23 oral SCCs, 7 leukoplakias and 2 oral submucous fibrosis were collected from oral SCC patients in Sri Lanka and were used for p53 mutation analysis. Exons 5 through 8 of the p53 gene were examined by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and direct sequencing. Mutations in the p53 gene were frequent (10/23) in oral SCC specimens from Sri Lanka. Moreover, the mutations clustered significantly in exon 5 (7/10) of the p53 gene, and small deletions and inclusions other than point mutations were observed. These results indicate that 1) betel-quid chewing may cause specific genetic changes, including mutation in the p53 gene; 2) mutations in the p53 gene are not rare events in SCC patients who are betel-quid chewers, which contrasts with other reports; 3) exon 5 of the p53 gene could be one of the specific targets for some betel-quid ingredients; and 4) betel-quid chewing may be a critical environmental factor in the development of oral SCC. Int. J. Cancer 77:839–842, 1998.© 1998 Wiley-Liss, Inc.     

Pathogenetic significance of p53 and c-Ki-ras gene mutations and human papillomavirus dna integration in adenocarcinoma of the uterine cervix and uterine isthmus

The pathogenetic significance of p53 and c-Ki-ras gene mutations and genomic integration of human papillomavirus (HPV) DNA was examined in surgically resected specimens of adenocarcinomas of the uterine cervix and isthmus using polymerase chain reaction (PCR), single-strand-conformation polymorphism and Southern blotting analysis. Among 25 cervical adeno-carcinomas, p53 gene mutations between exons 5 and 8 were detected in 32%, and the incidence of these mutations was higher in cases at advanced clinical stages and with high grades of nuclear and structural atypia both in endocervical and in endometrioid types. HPV DNA type 16 or 18 in cervical adenocarcinomas was detected in 35% of cases by PCR and in 29% by Southern blotting, and, in contrast to the p53 mutations, the majority of cases with the HPV DNA were at a relatively early clinical stage with low-grade histological atypia. c-Ki-ras gene mutation was detected in only 4% of cervical adenocarcinomas. Among 8 isthmus adenocarcinomas, the incidence of p53 and c-Ki-ras gene mutations, and the presence and integration of HPV DNA type 16 or 18 were 38%, 50%, 57% and 25% respectively. The pattern of p53 mutations differed between isthmus and cervical adenocarcinomas: all of the mutations in the former were one-base substitutions of the transition type, whereas in the latter nearly half of the mutations were of the transversion type. Among cervical adenocarcinomas, p53 mutations between exons 5 and 8 were indicated as being mostly involved in the pathogenesis and development of biologically aggressive tumors, whereas HPV type 16 or 18 infection appeared to be involved in less aggressive cases. In isthmus adenocarcinoma, c-Ki-ras gene mutation, apart from p53 mutation and HPV-type-16 or ?18 infection, appeared to be involved frequently in cancer development.     

Correlation between p53 gene mutations and circulating antibodies in betel- and tobacco-consuming North Indian population

Alterations in p53 tumour suppressor gene and its expression may be implicated in the pathogenesis of betel- and tobacco-related oral cancer. There is wide regional variation in betel- and tobacco-consuming habits in different parts of the Indian subcontinent. The purpose of this study was to determine the correlations between p53 gene mutations, protein accumulation and serum antibodies in oral precancer and cancer. We analysed 30 potentially malignant oral lesions (leukoplakia) and 30 oral squamous cell carcinomas (SCCs) from northern India because the betel quid-consuming habits are different from those prevalent in other regions of India. p53 mutations were analysed by polymerase chain reaction amplification of genomic DNA and direct sequencing, p53 protein accumulation by immunohistochemical analysis and circulating p53 antibodies by ELISA. p53 gene mutations, analysed within exons 5-9, were observed in five out of 30 (17%) potentially malignant oral lesions and seven out of 30 (23%) oral SCCs. All the mutations were base substitution mutations. Three missense and two nonsense mutations were observed in potentially malignant oral lesions, while six missense and one nonsense mutations were identified in oral SCCs. The probable hot spots for the mutations were identified at codons 126, 136 and 174, which have not been observed thus far. A good correlation was observed between p53 missense mutation, p53 antibodies and p53 protein accumulation in matched potentially malignant and malignant oral lesions. All the potentially malignant and cancerous lesions harbouring missense mutations showed accumulation of p53 protein and the majority of these patients showed circulating p53 antibodies suggesting that serological detection of p53 antibodies may serve as a surrogate marker for p53 alterations in oral lesions.     

p53 mutations in relation to human papillomavirus type 16 infection in squamous cell carcinomas of the head and neck

The relationship between human papillomavirus (HPV) type 16 infection and p53 gene mutations was investigated in squamous cell carcinomas of the head and neck (SCCHN). HPV was detected by general primer-mediated and type-specific PCR. Alterations in the p53 gene were investigated using single-strand conformation polymorphism and sequence analysis in 27 SCCHN, of which 12 were HPV 16-positive and 15 were HPV-negative. Mutations were detected in 2/12 (16.7%) HPV 16-positive and 7/15 (46.7%) HPV-negative tumours; this difference was not statistically significant. The predominant mutations were deletions and C → T transitions; G → T transversions were found in only 2 tumours. Our results indicate that the presence of HPV 16 and p53 mutations is not mutually exclusive and detection of a p53 mutation does not exclude a potential role for HPV 16 in the pathogenesis of a subset of SCCHN. Int. J. Cancer 71: 796-799, 1997. © 1997 Wiley-Liss Inc.     

Prognostic significance of human papillomavirus genomes (type-16, -18) and aberrant expression of p53 protein in human esophageal cancer

The presence and distribution of human papillomavirus ( HPV) DNA or of increased expression of the p53 protein were determined in 71 patients with esophageal squamous-cell carcinoma (SCC) by in situ hybridization with biotinylated DNA probes for HPV- 16, -18,-31 and -33, and immunohistochemical techniques using antibody to p53 protein. Of 71 patients from Kochi prefecture, 24 (Group I) were positive for HPV DNA , including 10 for HPV type-16 and 14 for HPV type-18; in contrast, none were positive for HPV-31 or -33. Of the remaining 47 patients, 24 (Group II) showed positive nuclear staining in cancer cells with p53 antibody. The group of 23 patients with neither HPV nor p53 expression (Group III ) had a significantly better survival rate than Group I or II. These results suggest that HPV- 16 and -18 may play a role in the pathogenesis of esophageal SCC, particularly with regard to its striking geographical distribution; that esophageal cancers do occur in the absence of HPV infection when over-expression of p53 is present; and that the presence of HPV infection and over-expression of p53 may each be a factor indicating a relatively poor prognosis.     

The carcinogenic role of oncogenic HPV and p53 gene mutation in cervical adenocarcinomas

Thirty tumors were collected from our archive of cervical adenocarcinomas. They were examined with respect to the content of oncogenic HPV and presence of mutations in the p53 gene exons 5 through 8. Furthermore, available clinical information on the cases was reviewed. For the detection of p53 gene and presence of oncogenic HPV, PCR followed by direct sequence analysis of the amplified DNA was employed. Seventeen tumors were identified as HPV-positive, comprising both HPV types 18 and 16. Six cases showed a p53 gene mutation, of which five were of the missence and one of the silent type. No statistical correlation between the occurrence of oncogenic HPV and presence of p53 gene mutation (p=0.67) was recorded. Among the tumors with p53 gene mutation, three were HPV-positive and three were HPV-negative. The determination of p53 gene mutations was not related to clinical findings such as the stage of the tumor or presence of metastases of the lymph nodes. However, p53 gene mutations were somewhat more prevalent in low differentiated tumors (p<0.02). The results indicate that oncogenic HPV and p53 gene mutations have independent carcinogenic roles in cervical adenocarcinomas.     

p53 mutations and human papillomavirus DNA in oral squamous cell carcinoma: correlation with apoptosis.

Forty-two oral squamous cell carcinomas (SCCs) were analysed for p53 mutations and human papillomavirus (HPV) infection to examine the prevalency of these factors and correlation with apoptotic index (AI; number of apoptotic cells per 100 tumour cells) of the tumour tissue. In polymerase chain reaction (PCR)-Southern blot analysis, HPV DNAs were detected from 22 out of 42 SCCs (52%) with predominance of HPV-16 (68%). p53 mutations in exons 5-8, screened by nested PCR-single-strand conformation polymorphism (PCR-SSCP) analysis, were observed in 16 of 42 tumours (38%). The state of the p53 gene did not show any correlation with HPV infection. The terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labelling (TUNEL) method was used for detection of apoptotic cells. The mean AI was 2.35, ranging from 0.31 to 6.63. SCCs associated with p53 mutation had significantly lower AI than those without p53 mutation (P < 0.01), whereas no difference in AI was found between SCCs with and without HPV infection. The results of this study confirmed that HPV infection and/or p53 mutations are implicated, but are not mutually exclusive events, in carcinogenesis of oral SCC and also showed that decrease in apoptosis is more closely related to p53 mutation than HPV infection.     

Decreased p21 Expression in HPV-18 Positive Cervical Carcinomas

The aim of this study was to investigate the relationship between different human papillomaviruse (HPV) genotypes and the expression of p53, p21 and p27 in cervical carcinomas. A total of 103 cases of cervical carcinomas were assayed for expression of p53, p21 and p27 by immunohistochemistry. HPV typing was carried out by two polymerase chain reaction-based methods. Overall, HPV prevalence was 97.1% among the cervical carcinomas in this study. HPV-16 was detected in 66% of the tumors, HPV-18 in 7.8%, HPV-16/18 in 7.8% and other HPV types in 15.5%. The expression of p53 and p27 was not related to HPV genotype. However, in the HPV-18 positive cervical carcinomas, expression of p21 was significantly decreased or completely absent (P = 0.019). Our results indicated that down-regulation of p21 was strongly associated with HPV-18 positive cervical carcinomas. The significantly lower expression of p21 protein in HPV-18 positive samples compared to HPV-18 negative cervical carcinomas supports the hypothesis that inactivation and degradation of p21 proteins by HPV-18 E7 may play an important role in the carcinogenesis of HPV-18 positive cervical neoplasia.     

Involvement of viral and chemical factors with oral cancer in Taiwan

BACKGROUND: The association between oral squamous cell carcinoma (OSCC) and viral and chemical factors is uncertain. Therefore the correlation of viral and chemical factors with oral cancer in Taiwan was investigated. METHODS: Thirty-seven paraffin-embedded oral cancer biopsies and 36 normal oral tissue specimens were examined by the polymerase chain reaction method for six viruses: HPV, CMV, EBV, HSV-1, HSV-2 and HHV-8. To elucidate the role of arecoline in the oncogenesis of oral cancer, human buccal fibroblasts, oral submucosal fibroblasts and three cancer cell lines KB, GNM and TSCCa were used for MTT cytotoxity assay and flow cytometry DNA content analysis. RESULTS: Two (5.4%) HSV-1-positive and four (10.8%) HPV-positive cases were recognized in oral cancer biopsies. Among the four HPV-positive tissues, two were further typed as HPV-16, one was identified as HPV-18- and HSV-1-positive; and one contained both HPV-16 and HPV-18. One sample presented HSV-1 only. Arecoline, at a concentration lower than 0.8 micro g/ml, increased cell growth (all cell types); at higher concentrations (25-400 micro g/ml) it was cytotoxic. The cell cycle was demonstrated to be altered either by low or high concentrations of arecoline treatment, depending on the cells treated. CONCLUSIONS: The data demonstrated that HPV, HSV-1 and betel quid chewing were significantly associated with OSCC, but HSV-2, CMV, EBV and HHV-8 were not. We suggest that the most determinative factor for oral cancer may be chemical in nature rather than viral infection.