Expression of p53 mutant nuclear phosphoprotein in oral carcinoma and potentially malignant oral lesions

Expression of p53 in toluidine blue positive oral squamous cell carcinoma lesions and expression of Ki67 in vinegar positive oral squamous cell carcinoma lesions

The aims of this study were to investigate the sensitivity and specificity of toluidine blue and/or vinegar in oral cancer screening and to examine the correlation between clinical screening using toluidine blue and vinegar and the expression of the tumor marker p53 and proliferation marker Ki67, respectively. The study consisted of 87 patients with suspected oral squamous cell carcinoma lesions. Toluidine blue and/or vinegar were applied to the lesions, followed by biopsies. The tissues were diagnosed histopathologically and underwent immunohistochemical process for p53 or Ki67. The results revealed that the sensitivity and specificity of oral cancer screening using toluidine blue were 93% and 46%, respectively; whereas the sensitivity and specificity using vinegar were 85% and 81%, respectively. A statistically significant correlation between the use of vinegar and the expression of Ki67 (p = 0.019) was observed. Although there was a difference in the expression of p53 between specimens that were positive and negative to toluidine blue, the correlation did not reach a significant level. Based on the results from this study, vinegar has a lower sensitivity than toluidine blue but a higher specificity for oral cancer screening. The results of the clinical screening using vinegar correlated with the expression of Ki67 at the cellular level.

A bibliometric analysis of the top 100 most-cited articles in the Journal of Oral Pathology & Medicine (1972-2020)

OBJECTIVE

The steady and continued increase of the Journal of Oral Pathology & Medicine's (JOPM) popularity prompted a bibliometric analysis of the journal. The purpose was to assess the significance and effect of the published research articles in the Journal from 1972 and 2020, aiding the identification of landmark articles. We performed a bibliometric analysis using the top 100 cited papers in the Journal of Oral Pathology & Medicine.

MATERIALS AND METHODS

An extensive review of the Web of Science was undertaken. Standard information such as author details, affiliated institutions, publication year and the country of origin was recorded.

RESULTS

The top 100 cited articles in JOPM were assessed. The maximum and minimum number of citations in the top 100 articles was 1459 and 95, respectively. A total of 16 790 citations were recorded for these 100 articles. Authors were affiliated to 28 different countries, 17 research articles from the UK and 12 from the USA. Other countries furnished seven or fewer articles.

CONCLUSION

This bibliometric analysis provides a synopsis of research published in the journal over a 48-year period. Recent interest in the journal shows a healthy increase in submissions and profile.

Evaluation of epithelial dysplasia adjacent to lip squamous cell carcinoma indicates that the degree of dysplasia is not associated with the occurrence of invasive carcinoma in this site

BACKGROUND

We analyzed the different grades of dysplasia in the epithelium adjacent to lip squamous cell carcinoma (LSCC), as a parallel to actinic cheilitis (AC) that suffered malignant transformation.

METHODS

Forty samples of epithelium adjacent to LSCC were histologically graded according to the World Health Organization (WHO) and the binary systems. The expression of mutated p53 was evaluated through immunohistochemistry.

RESULTS

According to WHO system, 37.5% of the cases were graded as mild, 45% as moderate and 17.5% as severe dysplasia (P = 0.09). Considering the binary system, 90% of the cases were classified as low-risk and 10% as high-risk lesions. Mutated p53 was present in 73.3% of mild, 88.8% of moderate and 71.4% of severe dysplasia cases. Considering the binary system, 80.5% of the low-risk and 75% of high-risk lesions were immunopositive; 62.5% expressed the protein in both tumor cells and adjacent epithelium; 17.5% in adjacent epithelium only, and 7.5% in LSCC islands only (P = 0.03).

CONCLUSIONS

We observed heterogeneous grades of epithelial dysplasia in the epithelium adjacent to LSCC, which indicates that the analysis of AC morphological features is insufficient to predict patient's prognosis and to determine a treatment decision. Positive expression of mutant p53 in mild dysplasia reinforces this idea.

Expression of Cell Cycle-associated Proteins p53, pRb, p16, p27, and Correlation With Survival: A Comparative Study on Oral Squamous Cell Carcinoma and Verrucous Carcinoma

Verrucous carcinoma (VC) is a well-differentiated form of squamous cell carcinoma (SCC) with better prognosis. Differences in molecular pathogenesis between the 2 have not been well-characterized. We conducted this study to evaluate immunohistochemical expression of cell-cycle regulatory proteins p53, pRb, p16, and p27 in SCC and VC, compare the expression in these 2 neoplasms, and assess if these markers have any diagnostic or prognostic value. Sixty cases of SCC with and without lymph node metastasis and 31 cases of VC were studied. Immunohistochemical analysis for p53, pRb, p16, and p27 was performed and the results were analyzed. SCC was most frequent in tongue (52%), whereas VC in buccal mucosa (81%). Mean age of SCC patients was significantly lower than in VC. Majority of SCCs were in stage III and IV (63%), whereas VCs were in stage I and II (84%). p53 immunopositivity was more frequent in SCC (65%) than in VC (23%) (P≤0.001). VC had lower p53 as compared with well-differentiated SCC and SCC without lymph node metastasis. No significant difference was seen in pRb, p16, and p27 expression. Disease-free survival (DFS) at 1 year for SCC was 57% whereas it was 80% for VC (P=0.02). DFS and overall survival of SCC correlated with nodal status and stage; cell-cycle-associated protein expression had no association with DFS. To conclude, p53 immunoexpression differs in SCC and VC, suggesting different pathogenesis, and it may have some utility as an adjunct to morphology to differentiate between the 2. Expression of cell-cycle-associated proteins does not influence survival in SCC.

p53 Expression Helps Identify High Risk Oral Tongue Pre- malignant Lesions and Correlates with Patterns of Invasive Tumour Front and Tumour Depth in Oral Tongue Squamous Cell Carcinoma Cases

Oral tongue squamous cell carcinoma (OTSCC) is the most common oral cancer subtype with a maximum propensity for regional spread. Our objective was to study if p53 expression might have any correlation with aggressive patterns of invasion within oral tongue cancers as well as with the histologically identified degree of oral tongue dysplasia. p53 immunoexpression was studied using immunohistochemistry in early staged OTSCCs (n=155), oral tongue dysplasias, (n=29) and oral tongue normal specimens (n=10) and evaluated for correlations with histological and clinicopathological parameters. Our study (n=194) showed a pattern of p53 expression increasing with different grades of tongue dysplasia to different grades of invasive OTSCC (p=0.000). Among the OTSCC tumours, positive p53 expression was seen in 43.2% (67/155) and a higher p53 labelling index was significantly associated with increased Bryne's grade of the tumour invasive front (p=0.039) and increased tumour depth (p=0.018). Among the OTSCC patients with tobacco habits, (n=91), a higher p53 labelling index was significantly associated with increased risk of local recurrence (p=0.025) and with lymphovascular space involvement (p=0.014). Evaluation of p53 through varying degrees of dysplasia to oral tongue cancer indicates that p53 expression is linked to aggressive features of oral tongue cancers and tongue precancers entailing a closer monitoring in positive cases. Among the OTSCCs, p53 expression is associated with tumour aggressiveness correlating with increased grading of invasive tumour front and tumour depth.

P53 and bcl-2 immunoexpression in patients with oral lichen planus and oral squamous cell carcinoma

OBJECTIVE

The aim of this study was to determine by immunohistochemistry the presence and significance of p53 and bcl-2 proteins in oral lichen planus (OLP) and oral squamous cell carcinoma (OSCC).

STUDY DESIGN

We used 21 cases diagnosed as OLP 16 diagnosed as OSCC and four normal gingival biopsies taken from healthy patients were used as controls. Slides were processed for immunohistochemistry using anti-p53 and anti-bcl-2 monoclonal antibodies.

RESULTS

We found p53 immunoexpression in 71.4% OLP cases and 68.7% OSCC cases, with no immunoexpression in control cases. Bcl-2 was negative for all OLP and OSCC cases, and mild positivity was observed in normal tissue. We found significant correlation among p53 expression and OSCC malignancy.

CONCLUSIONS

Our results suggest that TP53 system mainly promotes a hyperproliferative state by cell cycle arrest of the OLP epithelial cells for repairing damaged DNA nor apoptosis and that anti-apoptotic action of bcl-2 is not important in this disease.

Expression of p53 in leukoplakia and squamous cell carcinoma of the oral mucosa: correlation with expression of Ki67

Aim-To study p53 expression in relation to proliferative status in normal and nondysplastic, dysplastic and malignant lesions of the oral mucosa.Method-The standard avidin-biotin complex (ABC) immunohistochemical staining method was used to study the expression of p53 and Ki67 on frozen sections of oral leukoplakias and carcinomas.Results-Of the leukoplakia and carcinoma samples, 70% expressed p53 in over 5% of cells. In normal mucosa less than 5% of cells expressed p53. The proliferation index, as assessed by expression of Ki67, was highest in the malignant lesions (43%) and lowest in normal mucosa (11%). Statistical analysis revealed that expression of both p53 and Ki67 was correlated significantly with the histopathological stage of the tumour. However, expression of p53 was not correlated with that of Ki67. In leukoplakia lesions with proliferative features p53 immunostaining was less intense than in non-proliferative lesions; this difference was statistically significant.Conclusions-These results emphasise the potential of Ki67 and p53 as biomarkers of carcinogenesis in oral cancer and may also serve as intermediate points for cancer prevention programmes, such as the oral chemopreventive trials. Factors other than p53 may have a more important role in the deregulation of proliferation in pre-malignant oral lesions.

Clinicopathologic and immunohistochemical correlation in sporadic pancreatic endocrine tumors: possible roles of utrophin and cyclin D1 in malignant progression

Pancreatic endocrine tumors (PETs), both functioning and nonfunctioning, are usually well differentiated and progress slowly. The 2004 World Health Organization (WHO) criteria classify PETs according to clinicopathologic features and Ki-67 proliferative index. A tumor associated with poorer prognostic features may be considered "uncertain" in behavior, but the malignant classifications are reserved for tumors showing clear signs of aggressive behavior. It remains difficult to predict malignant progression in any individual PET. The cytoskeletal protein utrophin is encoded on chromosome 6q, a region frequently lost in malignant PETs. Cyclin D1 is a highly regulated mediator of the cell cycle and is frequently overexpressed in sporadic PETs. Sporadic PETs resected or biopsied from 40 patients were identified and classified using WHO criteria (19 benign/uncertain, 21 malignant). Distinctive patterns of biologic activity in unequivocally malignant PETs were demonstrated by immunohistochemistry for utrophin and cyclin D1. Utrophin localized to cell membranes (76% in malignant versus 21% in benign/uncertain PETs, P < .0006) and cyclin D1 staining showed nuclear positivity (67% in malignant versus 17% in benign/uncertain PETs, P < .003). Membranous utrophin localization was associated with significantly reduced patient survival (P = .045). Both membranous utrophin and nuclear cyclin D1 staining were also associated with higher Ki-67 proliferative indices. In our series, neither utrophin nor cyclin D1 was predictive of malignant progression in uncertain (WHO 1.2) PETs. Further studies are warranted to elucidate the role of utrophin and cyclin D1 in the malignant progression of PETs.

Adhesion molecule CD44 expression in non-tumor epithelium adjacent to laryngeal cancer

BACKGROUND

Studies of adjacent non-tumor epithelia (ANTE) of laryngeal cancer have presented contradictory results regarding the expression of the adhesion molecule CD44 and its role as an early event and risk marker for progression to cancer.

METHODS

An immunohistochemical study was performed on changes in CD44 expression in the ANTE and tumor tissue of 112 cases of laryngeal cancer, using the anti-CD44 monoclonal antibody DF1485. The aim was to evaluate the importance of these changes as an early event in laryngeal carcinogenesis.

RESULTS

The ANTE were histologically hyperplastic in 107 cases (95.5%) and presented epithelial dysplasia in 105 cases (93.7%). A significant association between tumor and epithelial CD44 expression was observed in both hyperplastic (p < 0.001) and dysplastic (p < 0.001) ANTE. There was no significant association between ANTE CD44 expression and clinical or histopathological relevant data.

CONCLUSIONS

Loss of CD44 expression in ANTE can be considered an early event in laryngeal carcinogenesis and a marker of major alterations in CD44 expression in the derived tumor tissue.

Genetic portrait of mild and severe lingual dysplasia

Squamous cell carcinoma is the most frequent malignant tumor of the oral cavity and often arises from premalignant lesions. Traditional methods used by the pathologist are subjective and lack the sensitivity to predict accurately which precancers may progress with time. Therefore, it is important to search for markers that may identify progression of premalignant lesions. Microarray technology can be use with this aim. Here, we define the genetic expression profile of lingual dysplasia (DS) progression. By using cDNA microarray containing 19.2K clones and a baseline of 11 normal tissues, we compared 5 mild and 4 severe DS. We identified 270 genes differentially expressed in normal tissue vs. mild DS (i.e. 161 up- and 109 down-regulated) and 181 genes differentially expressed in mild vs. severe DS (i.e. 63 up- and 118 down-regulated). The described genes cover a broad range of functional activities: (a) anti-oxidative, (b) DNA-repair, (c) inflammatory response, (d) cell-adhesion/mobility, (e) extracellular matrix depolymerization, and (f) cell-cycle regulation. The data reported better define DS progression and can help in classifying premalignant lesions.

Adhesion molecule CD44 expression in non-tumour epithelium adjacent to tongue cancer

An immunohistochemical study was performed of changes in the expression of adhesion molecule CD44 in 32 adjacent non-tumour epithelia (ANTE) to lingual carcinomas and in the tumour tissue, using anti-CD44 monoclonal antibody DF1485. The aim was to evaluate the importance of these changes as an early event in lingual carcinogenesis. The ANTE was histologically normal in 22 cases (68.8%) and presented epithelial dysplasia in 10 (32.2%). Three cases of normal and dysplastic ANTE, respectively, were CD44- (9.4%). Negative CD44 expression was significantly more frequent in tumours with lower percentages of CD44+ cancer cells, both in normal (P=0.014) and dysplastic (P=0.033) ANTE. The expression in normal ANTE was also significantly associated with clinical stage (P=0.040) and presence of extracapsular nodal spread (P=0.013). Therefore, loss of CD44 expression in ANTE can be considered an early event in lingual carcinogenesis and a marker of major alterations of CD44 expression in the derived tumour tissue.

Immunohistochemical study of syndecan-1 down-regulation and the expression of p53 protein or Ki-67 antigen in oral leukoplakia with or without epithelial dysplasia

BACKGROUND

Leukoplakia is an oral pre-cancerous lesion that sometimes develops into squamous cell carcinoma. Therefore, leukoplakia with epithelial dysplasia is useful for studying carcinogenesis at the cellular level. The purpose of this study was to evaluate a potential association between the loss of syndecan-1 expression and the expression of p53 protein and Ki-67 antigen, and to identify reliable markers for predicting malignant changes in oral leukoplakia with epithelial dysplasia.

METHODS

Changes in the expression of syndecan-1, p53, and Ki-67 were examined immunohistochemically in 43 cases of oral leukoplakia with or without epithelial dysplasia. The subjects were categorized as: none, 13 cases; mild dysplasia, 5 cases; moderate dysplasia, 17 cases; and severe dysplasia, 8 cases. The expression of these molecules in normal oral epithelia (22 cases) was also investigated.

RESULTS

Strong syndecan-1 expression was observed on the surface of keratinocytes in normal epithelium. Immunopositivity was lost gradually as the extent of epithelial dysplasia increased. In normal epithelium, p53 and Ki-67 appeared mainly in the basal cell layer, while they were more widely distributed in leukoplakia. Specifically, significant changes were observed in the labeling index of p53 and Ki-67 in leukoplakia as epithelial dysplasia progressed from mild to moderate or severe.

CONCLUSION

Our results reveal that overexpression of p53 protein and Ki-67 antigen, and down-regulation of syndecan-1 expression in the lower part of the epithelium, are associated with dysplastic changes. Therefore, the down-regulation of syndecan-1 expression may be the most important reliable marker for dysplastic changes.

Prognosis of oral pre-malignant lesions: significance of clinical, histopathological, and molecular biological characteristics

The concept of a two-step process of cancer development in the oral mucosa, i.e., the initial presence of a precursor subsequently developing into cancer, is well-established. Oral leukoplakia is the best-known precursor lesion. The evidence that oral leukoplakias are pre-malignant is mainly derived from follow-up studies showing that between < 1 and 18% of oral pre-malignant lesions will develop into oral cancer; it has been shown that certain clinical sub-types of leukoplakia are at a higher risk for malignant transformation than others. The presence of epithelial dysplasia may be even more important in predicting malignant development than the clinical characteristics. Three major problems, however, are attached to the importance of epithelial dysplasia in predicting malignant development: (1) The diagnosis is essentially subjective, (2) it seems that not all lesions exhibiting dysplasia will eventually become malignant and some may even regress, and (3) carcinoma can develop from lesions in which epithelial dysplasia was not diagnosed in previous biopsies. There is, therefore, a substantial need to improve the histologic assessment of epithelial dysplasia or, since epithelial dysplasia does not seem to be invariably associated with or even a necessary prerequisite for malignant development, it may be necessary to develop other methods for predicting the malignant potential of pre-malignant lesions. As a consequence of these problems, numerous attempts have been made to relate biological characteristics to the malignant potential of leukoplakias. Molecular biological markers have been suggested to be of value in the diagnosis and prognostic evaluation of leukoplakias. Markers of epithelial differentiation and, more recently, genomic markers could potentially be good candidates for improving the prognostic evaluation of precursors of oral cancer. As yet, one or a panel of molecular markers has not been determined that allows for a prognostic prediction of oral pre-cancer which is any more reliable than dysplasia recording. However, these new markers could be considered complementary to conventional prognostic evaluation.

Epithelial cell proliferation in oral lichen planus

Although the pathogenesis of oral lichen planus (OLP) is not clear, a small proportion of cases with OLP are reported to transform to cancer. We examined the epithelial cell proliferation status of OLP to relate the labelling index to microscopic features surveyed routinely in pathology. Mucosal biopsies obtained from 44 cases diagnosed with OLP with an intact oral epithelium and 10 normal control specimens from Japanese subjects were immunohistochemically stained with MIB and p53 antibodies. The Ki67 labelling index (LI) was significantly higher in OLP compared with normal controls. A particularly large number of OLP lesions (64%) were p53 positive. No association was, however, found with p53 expression and the Ki67 LI. Atrophic and flat epithelia had a quantitatively higher LI, which did not significantly differ from acanthotic biopsies. Increased cell proliferation in OLP is likely to be a secondary phenomenon due to the damage inflicted on keratinocytes by infiltrating mononuclear cells in the submucosa.

Oral lichen planus has a high rate of TP53 mutations. A study of oral mucosa in icelanD

Oral squamous cell carcinoma (OSCC) is a world-wide health problem. In addition to external exposure (smoking and alcohol), certain oral lesions may increase the risk of oral cancer (e.g. leukoplakia, erythroplakia, and oral lichen planus). TP53 has been implicated in OSCC, but there are limited studies of mutations in premalignant oral lesions. In this study, 55 samples from OSCC, 47 from hyperkeratotic (HK) oral mucosa, clinically diagnosed as white patches, 48 samples from oral lichen planus (OLP), and 12 biopsies from normal oral mucosa were studied immunohistochemically for expression of TP53 protein. From all the carcinoma samples and selected non-malignant samples showing moderate or strong TP53 protein expression, malignant cells or TP53-positive nuclei were microdissected and screened for mutations in exons 5-8 by constant denaturation gel electrophoresis. Moderate to strong TP53 protein staining was seen in 56% of OSCC, 32% of OLP but only in 13% of HK. All OLP samples showed a characteristic pattern of positive nuclei confined to the basal layer, whereas TP53 staining was seen in suprabasal nuclei in HK. Mutation rate was 11 out of 52 for OSCC, three out of 20 tested for HK and, remarkably, nine out 27 tested for OLP. There was no correlation between TP53 protein staining and TP53 mutations. No associations were found with anatomical sites or disease progression. The unexpectedly high mutation rate of OLP might explain the premalignant potential of this lesion.

DNA content as a prognostic marker in patients with oral leukoplakia

BACKGROUND

Oral leukoplakia may develop into squamous-cell carcinoma, which has a poor prognosis. Risk factors for oral carcinoma have been identified, but there are no reliable predictors of the outcome in individual patients with oral leukoplakia.

METHODS

We identified 150 patients with oral leukoplakia that was classified as epithelial dysplasia and measured the nuclear DNA content (ploidy) of the lesions to determine whether DNA ploidy could be used to predict the clinical outcome. Biopsy specimens obtained at annual follow-up visits were graded histologically and classified with respect to DNA content in a blinded fashion. Disease-free survival was assessed in relation to DNA ploidy and the histologic grade. The mean duration of follow-up was 103 months (range, 4 to 165).

RESULTS

Among 150 patients with verified epithelial dysplasia, a carcinoma developed in 36 (24 percent). Of the 150 patients, 105 (70 percent) had diploid (normal) lesions, 20 (13 percent) had tetraploid (intermediate) lesions, and 25 (17 percent) had aneuploid (abnormal) lesions at the time of the initial diagnosis. A carcinoma developed in 3 of the 105 patients with diploid lesions (3 percent), as compared with 21 of the 25 patients with aneuploid lesions (84 percent), yielding a negative predictive value of 97 percent with respect to the diploid lesions and a positive predictive value of 84 percent with respect to the aneuploid lesions. Carcinoma developed in 12 of 20 patients with tetraploid lesions (60 percent). The mean time from the initial assessment of the DNA content to the development of a carcinoma was 35 months (range, 4 to 57) in the group with aneuploid lesions and 49 months (range, 8 to 78) in the group with tetraploid lesions (P=0.02). The cumulative disease-free survival rate was 97 percent among the group with diploid lesions, 40 percent among the group with tetraploid lesions, and 16 percent among the group with aneuploid lesions (P<0.001).

CONCLUSIONS

The DNA content in cells of oral leukoplakia can be used to predict the risk of oral carcinoma.

Overexpression of p53-related proteins predicts rapid growth rate of head and neck cancer

OBJECTIVES/HYPOTHESIS

The p53 tumor suppressor gene plays an important role for cell cycle regulation and is the most frequent mutated gene in head and neck cancer. Controversy remains regarding the biological and clinical value of immunohistochemical identification of the proteins accumulated in association with inactivation of the p53 gene and increased tumor growth. Therefore, the objective of the present study was to perform a cell kinetic analysis of cases with untreated squamous cell carcinoma and to compare the result with immunostaining for p53-related proteins in the tumor cells.

STUDY DESIGN

A prospective series of 32 patients presenting with various stages of untreated squamous cell carcinoma of the head and neck were included. Bromodeoxyuridine (BrdU) was injected as a tracer dose before tumor biopsy for cell kinetic analysis, and p53 protein accumulation was detected using two antibodies (DO7 and PAb 1801).

RESULTS

Antibody DO7 showed the highest and the optimal immunoreactivity. Diploid tumors were found in 27 cases (84%), and the mean potential doubling time (Tpot) was 55 +/- 7 hours for these tumors. Positivity of DO7 (>1%) was demonstrated in 85% of the cases. However, a discrimination level exceeding 20% was required to obtain a significant negative relationship (Spearman's rank correlation coefficient test, P < or = .03) between Tpot and DO7 positivity. At that level, 33% of the tumors remained DO7-positive. The corresponding Tpot was not significantly different from the overall mean. The rates of metastatic disease and survival were not dependent on DO7 immunoreactivity or cancer cell kinetics.

CONCLUSION

Accumulation of p53-related proteins is associated with an unrestrained growth of head and neck cancer.

Genetic aberrations in oral or head and neck squamous cell carcinoma 3: clinico-pathological applications

The molecular changes in malignant epithelium in the head and neck offer possibilities for the development of diagnostic, prognostic and other markers. This article reviews recent developments in this field.

Expression of p53 in oral squamous cell carcinoma is associated with the presence of IgG and IgA p53 autoantibodies in sera and saliva of the patients

Around 50% of head and neck cancers are known to have aberrations of the p53 gene. Overexpression of the mutant p53 protein can induce a specific humoral response in cancer patients. Matched saliva, serum, and tissue samples from 26 patients with histologically confirmed oral squamous and verrucous carcinoma were investigated. p53 protein expression was evaluated by immunohistochemistry and antibodies specific for 53 protein were analysed in sera and whole mouth saliva by ELISA, immunoprecipitation, and competition assays; 16/25 (64%) samples demonstrated the stabilized p53 protein in tissues and 7/26 (27%) had a high level of p53 antibody in serum. In samples where matching saliva was available, p53 antibody was also present in saliva. In some tumours, only IgA-type p53 antibody was detected. p53 antibodies were found only in the serum and saliva of patients who showed p53 overexpression in their tumour tissues. These results demonstrate that detection of p53 antibodies can offer a specific and non-invasive method for the detection of a subset of tumours with p53 aberrations.

p53 and P-glycoprotein expression are significant prognostic markers in advanced head and neck cancer treated with chemo/radiotherapy

The development of biological markers of response to chemo- and radiotherapy to judge benefit to risk ratios for toxic treatments is still at an experimental stage. Tumour cell death is largely by apoptosis and the p53 gene has a major influence on this. P-glycoprotein (P-gp) accumulation has been correlated with treatment failure in several types of cancer. p53 and P-gp expression were studied in 111 advanced head and neck cancers treated with radiotherapy and up to four courses of synchronous or sequential chemotherapy. The probability of survival at 5 years for patients in the trial as a whole was 27.7%, while the cohort used for this marker project was 29.4%. Among the subjects used for the marker study at the time of analysis, 13 remained disease-free and 18 were alive. Immunohistochemistry was used to assess p53 and P-gp expression; 27/111 (24%) head and neck cancers demonstrated p53/P-gp expression and 33/111 (30%) were both p53- and P-gp- negative. In univariate analysis, both p53 and P-gp expression were associated with reduced disease-free and overall survival. Multivariate analysis revealed tumour size, p53, and P-gp expression as the most powerful pretreatment prognosticators in the study cohort. Long-term follow-up results suggest that p53 and P-gp co-expression predicts the biological behaviour or the outcome following chemo/radiotherapy in advanced head and neck cancer.

p53 gene mutations in sequential oral epithelial dysplasias and squamous cell carcinomas

Previous studies of oral cancer have suggested that alterations of the p53 tumour suppressor gene occur early in the precancerous stage of development. However, these observations have been based on cross-sectional assessment of abnormal p53 protein staining by immunohistochemistry and may not necessarily reflect gene changes. The purpose of this longitudinal study was to examine the changes in the p53 gene in progressive, sequential epithelial dysplasias and carcinomas from the oral cavity. The study analysed 24 formalin-fixed, paraffin-embedded tissue biopsies from ten patients with two or more temporally distinct lesions from the same site in the oral cavity with the diagnosis of hyperkeratosis, epithelial dysplasia, carcinoma in situ or squamous cell carcinoma. Exons 5-8 of the p53 gene were amplified from genomic DNA using intronic primers and directly sequenced using fluorescent-labelled primers. Standard immunohistochemistry with the DO7 monoclonal antibody was used to detect mutant and wild-type p53 protein. Mutations of the p53 gene were identified in 9 of 24 samples. Eight were missense mutations and one occurred at a splice site. In six patients, mutations of the p53 gene occurred late after the transformation of epithelial dysplasia to carcinoma. In two patients with progressive dysplasia, but who had yet to develop invasive carcinoma, p53 missense mutations occurred at the carcinoma in situ stage in one case and in a moderate dysplasia in the other. There was an inconsistent relationship between gene mutations and the level of p53 protein staining by immunohistochemistry. It is concluded that during oral carcinogenesis, p53 gene mutations seem to occur relatively late and are associated with transformation to the invasive phenotype.

P53 and cyclin D1 staining patterns of malignant and premalignant oral lesions in age-dependent populations

OBJECTIVE

Recent epidemiologic studies have identified a trend of increasing cancer incidence in younger patients. The purpose of this study was to determine whether this might be reflected by different molecular mechanisms for tumor development.

STUDY DESIGN

Dysplastic and malignant oral lesions from age-distinct patient populations were immunohistochemically analyzed for expression of p53 and cyclin D1. Chi-square analysis was used to determine statistical significance.

RESULTS

Eighty-two percent of "older" and 75% of "younger" carcinomas stained positively with p53; 63% of carcinomas in the older population and 55% of carcinomas in the younger population showed cyclin D1 positivity. Dysplasias showed similar cyclin D1 staining in both groups. Interestingly, 100% of "younger" dysplasias stained positively for p53, whereas 35.3% of "older" dysplastic lesions showed immunoreactivity. Staining of carcinomas was not statistically significant, whereas p53 staining of dysplasias proved highly significant (P < .025).

CONCLUSIONS

p53 immunoreactivity is detectable at an earlier stage of carcinogenesis in younger patients than in the traditional risk population for oral cancer.

The upregulation of lysyl oxidase in oral submucous fibrosis and squamous cell carcinoma

Lysyl oxidase (LO) takes part in the initial steps of converting soluble monomers of collagen and elastin into insoluble fibres in the extracellular matrix. We have studied the immunolocalization of LO as a marker of fibrogenesis in oral submucous fibrosis (OSF). Oral biopsies from 13 subjects with OSF, 6 with histologically confirmed squamous cell carcinoma (SCC) arising in OSF and 10 SCC nonrelated to OSF, were examined. Strong positive staining was observed in 7/13 OSF samples in the cytoplasmic processes of fibroblasts and extracellularly in the upper third of the lamina propria. Furthermore, LO was found to co-localize in the areas stained strongly for collagen and elastin by histochemical stains. Examination of SCC tissues showed localization of LO adjacent to invading epithelial islands as evidence of a stromal reaction both in carcinomas arising from OSF and in SCC from non-OSF cases. These findings suggest that upregulation of LO may be an important factor in the pathogenesis of OSF and in the early stromal reaction of oral cancer.

p53 expression in oral precancer and cancer

Expression of the p53 tumour suppressor gene is a frequent finding in human malignancies, including oral cancer, and it has been detected in some potentially malignant lesions. The results of the present project showed that 35 of the 41 (85 per cent) oral mucosal lesions with histological evidence of epithelial dysplasia expressed p53, but the presence or absence of p53 staining could not be used to predict the outcome of potentially malignant oral mucosal lesions.

Loss of heterozygosity of p53 gene of oral cancer detected by exfoliative cytology

The p53 tumor suppressor gene is a 16-20-kb section of cellular DNA located on the short arm of human chromosome 17 at position 17 P 13.1. Allelic deletions and/or point mutations in p53 gene are now known to be associated with the development of carcinogenesis. A hallmark of p53 is that both alleles are generally altered during transformation, which usually represents a loss of heterozygosity (LOH). In this study 30 normal dental students and 22 oral cancer patients were collected from the affiliated hospital of Chung Shan Medical and Dental College, Taichung, Taiwan. Extractions of DNA from the buccal mucosa or cancer surface were sampled by cytology brush. The two polymorphic restriction sites exon 4 and intron 6 within the p53 gene were amplified with polymerase chain reactions followed by restriction fragment length polymorphism assay. In heterozygous individuals, 66% of oral cancers demonstrated loss of p53 gene heterozygosity at the exon 4 site, and 50% showed LOH at the intron 6 site. These results indicate that inactivation of p53 gene is associated with development and/or progression of oral cancer. The essential advantages of oral exfoliative cytology are the non-invasiveness, painlessness, rapidity, ease and cost-effectiveness of cell sampling and DNA extraction. Furthermore, this experimental assay might be useful for preliminary screening of carcinogenesis in human beings.

Prognostic value of p53 expression and histopathological parameters in squamous cell carcinoma of oral tongue

The TNM staging system is helpful but not enough to determine prognosis of the patients with squamous cell carcinoma of the oral tongue. T-stage alone is not suggestive for prediction of occult nodal metastases. For this reason, histopathological examination of 70 patients with squamous cell carcinoma of the oral tongue was done retrospectively. The histological differentiation, tumour thickness, perineural and lymphovascular space invasions, the amount of lymphocyte infiltration and pattern of tumour invasion were examined. Immunohistochemical examination was used to determine p53 immunoreactivity as well. The effect of these histopathological parameters and p53 immunoreactivity on nodal metastases and locoregional recurrence were analyzed using the chi-squared test. In terms of nodal metastases the only statistically significant difference between the two groups was tumour thickness, either < 9 mm or > 9 mm (p < 0.05, chi 2 = 17.182). Tumour thickness, perineural invasion, lymphovascular space invasion, the amount of lymphocyte infiltration all correlated statistically with locoregional recurrence (p < 0.05, chi 2 = 6.293 for tumour thickness; p < 0.06, p = 0.054 for perineural invasion; p < 0.05, chi 2 = 8.689 for lymphovascular space invasion; p < 0.05, chi 2 = 5.320 for lymphocyte infiltration). The immunoreactivity of p53 correlated significantly with larger primary tumour size (p < 0.05, chi 2 = 5.440, lymph node metastases (p < 0.05, chi 2 = 4.093) and with pathological tumour stage (p < 0.05, chi 2 = 5.713). These results reveal that the above-mentioned histological parameters and p53 determination could be used for handling a specimen from an anterior tongue squamous cell carcinoma.

New insights into p53 protein stabilisation in oral squamous cell carcinoma

p53 is a transcription factor which regulates cell proliferation and apoptosis to prevent division of potentially malignant cells. In many tumours mutation of the p53 gene leads to stabilisation of this protein which can be detected by immunohistochemistry (IHC). However, there are many reports describing detection of p53 by IHC in the absence of gene mutation, and in these cases other factors stabilise p53. To shed light on the mechanisms which permit detection of this protein in these mutation-negative cases we have examined 45 primary oral squamous cell carcinomas (SCCs) by IHC and gene sequencing for p53 (exons 4-8) and related the results to a FAL score (determined using microsatellite assay and expressing the number of loci showing allelic imbalance as a fraction of the total number of informative markers for each case). We also investigated the pattern of MDM2 expression in these tumours. High levels of p53 protein were detected in 24/45 cases and point mutations involving exons 4-9 were seen in 11 cases. A further four cases harboured deletions or a stop codon. For 6/48 cases there was concordance of AI within the p53 gene and mutation. However nine cases showed p53 mutation only and 5 AI without mutation, suggesting that oral tumours frequently retain one normal p53 allele. Detection of p53 by IHC correlated strongly with the FAL score. Thus whilst it is possible that some tumours harbour p53 mutations outside the open reading frames examined, or are missed due to sequencing a mixture of normal and tumour tissue, a subgroup of tumours may express high levels of wild-type p53 as a reflection of the high FAL score and ongoing genomic stress. Levels of MDM2 transcripts and protein were similar in all SCCs examined. However, MDM2 may be non-functional, or there may be defects affecting other important regulatory proteins in tumours which which express wild type p53 protein.

An immunohistochemical study of p53 and PCNA in inflammatory papillary hyperplasia of the palate: a dilemma of interpretation

OBJECTIVE

Inflammatory papillary hyperplasia of the palate (IPHP) or the granular type of denture stomatitis, is a non-neoplastic lesion characterized histologically by a significant epithelial hyperplasia and inflammatory infiltrate usually caused by trauma and Candida infection. p53 and proliferative cell nuclear antigen (PCNA) are cell-cycle regulators, that when overexpressed, are considered by many investigators as markers of malignant transformation. The objective of this study was to investigate the immunodetection of p53 and PCNA in IPHP, and to correlate these results with the degree of epithelial hyperplasia and inflammatory infiltrate.

MATERIALS AND METHODS

In 12 cases diagnosed clinically as IPHP, Candida was cultured from the denture base and the palatal mucosa. Lesions were biopsied and stained with H&E for histomorphometric analysis of the epithelial width and inflammatory infiltrate. PAS and Gram stains were used for screening of Candida. Sections were immunostained with DO-7 for p53 and PC-10 for PCNA. Fifteen palatal biopsies obtained from autopsies of edentulous subjects with normal palatal mucosa served as controls.

RESULTS

All cultures of swabs from both the palatal mucosa and denture base were positive for Candida. Candidal hyphae could not be identified in PAS stained sections. Small foci of Gram-positive organisms were found in two cases of IPHP. Epithelial width and inflammation were significantly higher in IPHP than in controls (P < 0.001). A three-fold increase in positively stained cells for p53 and a two-fold increase in positively stained cells for PCNA were seen in IPHP compared with controls (P < 0.001).

CONCLUSIONS

Although a significant increase in the immunodetection of p53 and PCNA may indicate a malignant potential, IPHP has never been reported to undergo malignant transformation nor is it associated with cytologic signs of dysplasia. The increase in the epithelial width and inflammation degree is probably associated with the colonization of the denture bases with Candida organisms. The increased detection of p53 and PCNA can be a secondary effect of cytokines originating from both the inflammatory cells and the keratinocytes. Thus, immunodetection of p53 and PCNA by current immunohistochemical methods on archival tissues is neither specific nor sensitive enough to be used as indicators for malignant potential in the absence of cytological dysplastic changes or genetic proof of mutated cell cycle genes.

Relationship of p53 overexpression to other cell cycle regulatory proteins in oral squamous cell carcinoma

Aberrations of the p53 gene and the overexpression of its protein are described in a variety of neoplasms, including oral and other head and neck cancers. Here we report the association of p53 (over)expression with a downstream cell cycle inhibitor p21/waf 1 in oral squamous cell carcinoma (SCC). The loss of expression of p16 and p27, two other cyclin-dependent kinase (cdk) inhibitors, was also examined. In this panel of tumours, 10/24 carcinomas were p53-immunopositive. Heterogeneous expression of p21 and p27 was seen in 10/24 SCC and 9/16 SCC, respectively, and this was not correlated to p53 status. The expression of p21 and p27 in these SCCs suggests the existence of mechanisms by which some growing tumour cells may tolerate these cell cycle inhibitors; eight SCCs lacked expression of both inhibitors but only two of these cancers overexpressed p53, suggesting that accumulation of p21/p27 can be independent of the functional status of the p53 gene. Data do not support a clear example of a phenotype that shows an overexpression of p53 with downregulation of p21 or p27 leading to cell cycle alterations. Furthermore, only three SCCs were p16-negative and p53-positive. This suggests that these two tumour suppressors may act in separate pathways.

Proliferative activity and loss of function of tumour suppressor genes as 'biomarkers' in diagnosis and prognosis of benign and preneoplastic oral lesions and oral squamous cell carcinoma

Oral cancer is a disease of the elderly and is closely connected with cigarette smoking and alcohol consumption. Since the successful introduction of multidisciplinary treatment, the survival rate has not changed. Because of the high mortality and potentially disfiguring treatment, today's efforts are aimed at eliminating risk factors, chemoprophylaxis, improvement in diagnostic procedures, and understanding of the genetic mechanisms of oral carcinogenesis. Immunohistochemical and molecular biology analysis of biopsy tissue and cell lines of preneoplastic and neoplastic lesions that originate from the oral mucosa have shown that alterations in tumour suppressor genes such as p53 and Rb gene may have an important role in oral carcinogenesis and may be potentially useful prognostic 'biomarkers' in oral carcinogenesis. Statistical analysis of immunohistochemical data from 216 patients did not identify significant or consistent differences of p53, MDM2, or RB expression with respect to stage of disease, malignant transformation, metastatic node involvement, recurrence, or survival. Nevertheless, p53 overexpression seems to correlate strongly with histological progression of the disease, which confirms the importance of p53 alterations in oral carcinogenesis. Overexpression of p53 is usually found in the less differentiated proliferating cells in benign and malignant oral lesions. Assessment of the proliferating activity is possible by immunohistochemical staining with monoclonal antibodies against proliferating nuclear antigen and Ki-67. Statistical analysis shows that overexpression of p53 combined with high proliferative activity predicts a less favourable course of disease in oral squamous cell carcinoma.

Epithelial p53 gene expression and mutational analysis, combined with growth fraction assessment, in oral lichen planus

The immunohistochemical detection of epithelial p53 protein expression in oral lichen planus (OLP) biopsies was supplemented with molecular analysis for mutations of the p53 gene using the polymerase chain reaction - single stranded conformational polymorphism (PCR-SSCP) technique. p53 protein expression, in the basal epithelial cell layer, as detected by the DO7 and 1801 antibodies, was significantly more frequent in OLP compared with other oral keratoses and normal mucosa, as was the growth fraction. The 10 OLP biopsies that had the most frequent p53 staining (plus a case of OLP found in continuity with a SCC) were screened by the PCR-SSCP technique, but no mutations were detected in the p53 gene (exons 5 9). The p53 overexpression in the OLP samples may be a physiological response to the hyper-proliferative state, as revealed by the growth fraction determination. This may usefully serve to protect against mutagenesis, and so be a factor in the low incidence of carcinoma associated with OLP.

Expression of p21WAF1/CIP1 is unrelated to p53 tumour suppressor gene status in oral squamous cell carcinomas

The p53 tumour suppressor gene is frequently mutated in oral squamous cell carcinomas. However, the downstream mechanism of p53 during oral carcinogenesis is not fully understood. The cyclin-dependent kinase inhibitor p21WAF1/CIP1 (p21), which can be induced by wild-type p53, functions as a downstream mediator of the antiproliferative and apoptosis-inducing actions of wild-type p53. To learn more about the roles of the p53 gene and its downstream mechanism, we evaluated p53 gene mutation and immunohistochemical expression of p53 and p21 in 20 cases of oral squamous cell carcinoma. p53 gene mutations were observed in 7 cases (35%). Overexpression of p53 was found in 4 of 13 cases with wild-type p53, and in 6 of 7 cases with p53 mutations. p21 expression was detected in 15 of 20 cases (75%). The expression of p21 correlated neither with mutated p53 mutation nor with p53 protein overexpression. p21 was expressed even in carcinomas in which molecular analysis revealed a nonsense mutation. In normal oral mucosa, p21 expression was limited in the differentiating spinous cell layer. However, dysplastic or hyperplastic epithelium adjacent to the tumour demonstrated the increased expression of p21 even in the proliferating basal cell layer. These molecular and immunohistochemical data did not show any correlation with various clinico-pathologic parameters. These results suggest that p53 gene mutations and altered expression of p21 are commonly involved in oral carcinogenesis, but do not correlate with each other or with the clinico-pathologic parameters. They also suggest that p21 expression in oral squamous cell carcinomas may be induced by a p53-independent pathway.

p53 expression in oral precancer as a marker for malignant potential

The potential of p53 protein expression as a marker for determining which oral precancerous lesions may transform to malignancy with time was assessed. We compared the p53 expression in archival formalin-fixed, paraffin-embedded tissues from 22 baseline biopsies of precancerous lesions that transformed to cancer in 4-25 years against that in 68 similar lesions that did not transform over the same time period. Twenty-nine percent of precancers that transformed were p53-positive at baseline, compared to 31% of the biopsies that did not transform to malignancy. When examined by immunohistochemical methods p53 expression failed to detect potential malignant status of oral precancer. Non-specificity of the assay may account for this result but overexpression of p53 due to DNA damage by tobacco/betel-quid in non-progressive lesions needs further study. Nine precancerous lesions became p53-immunoreactive from precancer to cancer. This may suggest p53 overexpression peaks close to the time of transition from precancer to cancer rather than early in the natural history of oral precancer.

Prevalence of human papillomavirus infection in premalignant and malignant lesions of the oral cavity in U.K. subjects: a novel method of detection

To evaluate the possible role of human papillomavirus (HPV) in oral neoplasms, 28 oral squamous cell carcinomas (SCC) and 12 potentially malignant lesions were analysed for the presence of HPV DNA. A nested polymerase chain reaction (PCR) approach, using two sets of HPV consensus primers to the L1 region, was used, which was able to detect a broad spectrum of HPV types. HPV DNA was detected in 14/28 (50%) carcinomas and 4/12 (33%) precancerous lesions. A novel approach based on labelling the PCR products with 32P and the separation of radioactively labelled products on an 8% polyacrylamide gel increased the sensitivity of the detection and enabled the identification of the HPV types. The typing of HPV was subsequently confirmed by direct DNA sequencing. HPV 6 and HPV 16 were the only HPV types detected and seven tumours harboured both types. Our results suggest that HPVs may be an important aetiological factor in the development of oral cancer. The detection procedure ensured sensitivity and consistency of the detection of low copy numbers of the virus DNA. The presence of HPV in 33% of premalignant tissues suggests that HPV infection may be an early event in the malignant transformation of oral SCC. There was no statistically significant association between viral infection and tumour grade or stage.

Characterization of an amorphous deposit in the lamina propria in oral snuff users in the Sudan as collagen

Histological and ultrastructural features of 25 oral snuff dipper's lesions with distinctive subepithelial hyaline deposits were investigated. Periodic acid-Schiff reaction with and without diastase digestion demonstrated the presence of glycogen and other carbohydrates, but histochemical stains for normal collagen, elastin and fibrin showed a weak variable reactivity of the deposit. Although in 7/25 cases the deposit was in close proximity to labial salivary glands and on occasions ducts were found within the deposit, the presence of mucin was not a consistent feature. Congo red staining and immunohistochemical investigation with an anti-amyloid antibody did not support the previous contention that such deposits were amyloid in nature. Immunohistochemically, collagen antibodies also provided negative results, but ultrastructural features of three biopsies studied suggest that the bulk of this deposit is made up of collagen, as typical cross-striated fibrils were found. The pathogenesis of this deposit could therefore be interpreted as over-production and/or reduced turnover of collagen by resident fibroblasts, which is further altered by the ingredients of toombak. The deposit does not appear to be a secretory product.

p53 aberrations in oral submucous fibrosis and oral squamous cell carcinoma detected by immunocytochemistry and PCR-SSCP

An archival series of oral biopsies from Karachi, Pakistan, consisting of 21 cases of oral submucous fibrosis (OSF) and 27 cases of squamous cell carcinoma (SCC), of which 6 had arisen from OSF, were used to examine the aberrations in the structure and expression of the p53 tumour suppressor gene. The PCR-SSCP method was used for mutation analysis of exons 2-9, and (over)expression of p53 protein was detected by immunocytochemistry using monoclonal antibody DO 7. Positive immunostaining was observed in 15/20 (75%) of OSF specimens, 3/6 (50%) of SCC arising from OSF and 14/21 (67%) of SCC not arising from OSF. Mobility shifts in SSCP indicative of a mutation in p53 or loss of heterozygosity (deletion of a band) were seen in 13/21 cases of OSF and 15/27 cases of SCC. There was concordance between immunocytochemistry and SSCP results in a majority (33/48) of samples. Though the number of analysed SCC cases arising from OSF was limited, the results suggest that p53 mutation/protein stabilisation may play a part in the pathogenesis of OSF and its progression to SCC.

Molecular assessment of p53 abnormalities at the invasive front of oral squamous cell carcinomas

BACKGROUND

The prognostic significance of the invasive tumor front in squamous cell carcinomas has recently been recognized. The aim of the present study was to investigate possible molecular mechanisms underlying the significance of this area in oral squamous cell carcinomas.

METHODS

We used immunohistochemical and molecular genetic techniques to investigate whether p53 alterations at the invasive tumor front could determine the aggressiveness of oral cancers.

RESULTS

p53 Overexpression was detected in 52% to 56% (four different p53 antibodies) of 100 carcinomas studied. The concordance rate between results of immunohistochemistry and genetic analysis was 60%. No correlation was found between p53 status of the tumors and clinicopathologic parameters analyzed statistically.

CONCLUSIONS

p53 Alterations have no prognostic impact in oral squamous cell carcinomas and apparently do not represent a molecular basis for the biologic significance of the invasive tumor front. The detection of discordant p53 aberrations between primary and second primary carcinomas in some patients provide evidence for their independent origin, with possible impact on prevention and therapy.

Antibodies to p53 may predict a high risk of treatment failure in head and neck cancer

Overexpression of p53 as well as the occurrence of serum p53 antibodieshave been correlated to shorter survival and relapse-free intervals in head and neck squamous cell carcinoma (HNSCC). The aim of this study was to reconsider the clinical implications of serum p53 antibodies in HNSCC. Two matched study groups (n=78 patients with HNSCC each), one group positive and one negative for serum p53 antibodies, were followed-up (median of 3 years) regarding the occurrence of relapses, second primaries and tumor related deaths. Tumor relapses (n= 27 vs. 12), second primaries (n= 76 vs. 4) and tumor related deaths (n=21 vs. 9) occurred more frequently in the seropositive group. The results of this study indicate that the presence of serum p53 antibodies in patients with HNSCC points out a group of patients, who have a high risk of treatment failure.

Human herpesvirus-6 (HHV-6) DNA and virus-encoded antigen in oral lesions

Archival oral tissues comprising 51 squamous cell carcinomas, 18 non-malignant lesions and 7 normal mucosa samples were investigated for human herpesvirus-6 (HHV-6)-encoded antigens and HHV-6 DNA. The virus-specific antigens were detected by an immunohistochemical method using monoclonal antibodies. Two further techniques used for HHV-6 DNA detection included the polymerase chain reaction (PCR) with virus-specific primers and in situ hybridization using digoxigenin-labelled oligonucleotides specific for HHV-6A and HHV-6B genotypes. A high proportion (79-80%) of the squamous cell carcinomas were positive for HHV-6 with the various detection methods. In cases of lichen planus and leukoplakia a high prevalence rate (67-100%) was noted with in situ hybridization and immunohistochemical techniques but a lower proportion (22-33%) was detected with the PCR method. All 7 normal tissues tested were negative for HHV-6. The HHV-6 variant B was found in 60% of the oral carcinoma tissues analysed. The study demonstrates the frequent presence of HHV-6 in neoplastic and non-malignant lesions of the oral cavity. While the role of HHV-6 in oral mucosal tissues remains to be determined, the in vitro tumorigenic potential of the virus suggests a possible role in the etiopathogenesis of oral lesions.

Overexpression of p53 in normal oral mucosa of oral cancer patients does not necessarily predict further malignant disease

Recent reports of p53 positivity in the normal mucosa of some head and neck cancer patients have been taken as evidence for field cancerization and hence a likelihood of the development of further tumours, yet few papers report the clinical significance of this finding through long-term follow-up. The immunohistochemical detection of p53 expression in clinically and histopathologically normal oral mucosa taken from the wound margin following excision of oral cancer was assessed using the polyclonal antibody CM1. Fresh frozen biopsies of normal oral mucosa and the corresponding tumour from 21 oral cancer patients and of normal mucosa from 25 non-cancer patients were assessed for p53 overexpression. The 'normal' mucosa was positive in 12 of the oral cancer patients and one of the non-cancer patients. Second malignant tumours were seen in patients from whom p53-positive 'normals' and p53-negative 'normals' were recorded. In five of the p53-positive 'normals', the corresponding cancer was p53-negative. In one case, where 'normal' mucosa was available from more than one site, one region was positive, whilst the other was negative. No obvious difference in age, tobacco use, or recurrence rate was seen between positive and negative cases. All patients who were still alive were reviewed for a minimum of 5 years. Using Fisher's exact test, no statistically significant difference was found for the rate of second malignant tumours occurring in patients with p53-positive compared with p53-negative normal mucosa. Thus, the detection of p53 in normal mucosa did not necessarily predict a further tumour.

Detection of HHV-6 genotypes by in situ hybridization with variant-specific oligonucleotide probes

Human herpesvirus-6 exists in two forms, HHV-6A which has not been clearly associated with any disease, and HHV-6B, the causative agent of exanthem subitum. The two variants have been distinguished by techniques such as dot blotting and restriction fragment length polymorphism of PCR products. This study aims to establish the prevalence of HHV-6A and HHV-6B in carcinoma tissues using variant-specific oligonucleotide probes. A total of 73 archived carcinoma biopsies from the oral, salivary gland, larynx, breast and cervix were obtained with seven histologically normal controls. In situ hybridization was carried out with nonradioactively labelled variant-specific probes. Samples that hybridized with both variant A and B probes were subjected further to nested PCR and digested with HindIII to distinguish the variants. A hybridization signal was observed in 76.2% of oral carcinoma tissue and 75.0% of salivary gland carcinoma tissue. In contrast, only 33.3% of cervical carcinoma tissue were positive for HHV-6 DNA. A hybridization signal was noted in all 4 laryngeal carcinoma tissues studied. However, the 10 breast carcinoma tissues studied were negative, as was the histologically normal tissue. The virus possesses tumourigenic potential and demonstrates virus transactivating properties. The frequency of HHV-6 variants in certain tumours suggest a cofactorial role in multistep carcinogenesis. While PCR amplifies selectively the predominant variant in a sample, this was not seen by in situ hybridization. The in situ hybridization technique allowed the localization of both HHV-6A and HHV-6B in the nuclei of transformed regions.

Expression of p53 in oral mucosal hyperplasia, dysplasia and squamous cell carcinoma

OBJECTIVE

To assess p53 expression in a range of oral mucosal lesions and to relate the results to the clinical outcome in patients with dysplastic oral mucosal lesions and oral squamous cell carcinomas (OSCC).

MATERIALS AND METHODS

Archival tissue was available for eight cases of normal oral mucosa, 50 cases of oral mucosal hyperplasia, 41 cases of oral mucosal dysplasia and 48 cases of OSCC. The monoclonal antibody DO-7, reactive to p53 protein, was applied to paraffin-embedded sections using microwave pretreatment and immunohistochemical techniques.

RESULTS

The results showed that normal oral mucosa did not express p53. Positive nuclear staining was found in 18/50 (36%) cases of hyperplasia, 35/41 (85%) cases of dysplasia and 45/48 (94%) cases of OSCC. None of the p53 negative dysplasias progressed, while 19% of p53 positive cases of dysplasia recurred following excision and 11% of the cases underwent neoplastic transformation. Five out of 10 (50%) cases of severe dysplasia which were p53 positive resolved.

CONCLUSION

The proportion of cases with positive p53 expression increased from hyperplasia to dysplasia to OSCC. These results may indicate an involvement of p53 in neoplastic transformation as well as in proliferative events although the presence or absence of p53 staining could not be used to predict the outcome of potentially malignant oral mucosal lesions.