p53 mutations, protein expression and cell proliferation in squamous cell carcinomas of the head and neck

Oral Lichen Planus and Mutated TP53-A Road to Cancer?

The malignant potential of oral lichen planus (OLP) has been discussed and disputed for decades. The lesions are often characterized by strong expression of the TP53 protein in the basal layer of the mucosa. In 2002, we reported the presence of TP53 mutations in nine out of 27 OLP lesions tested. At follow-up in 2009, one case of oral squamous cell cancer (OSCC) had occurred in a different site six years later. In contrast, in another case, TP53 mutation persisted for years without malignant transformation. In a longitudinal study of eight selected patients with OSCC or different pre-malignant lesions, it was concluded that TP53 mutations could occur early or late in the development of OSCC. A follow-up in the present, almost 20 years later, revealed that one further case of OSCC had occurred in a TP53-mutated case of OLP, 21 years after the first sample was taken, again in a different site. With this second case, this small study now points towards a risk of developing OSCC in TP53-mutated OLP lesions. A review of recent literature indicates a growing consensus that OLP should be regarded as a potentially pre-malignant lesion. Several protein markers have been studied, but none proved useful for prediction of malignant progression. The great majority of published studies are retrospective, and it has been suggested that multi-centre prospective studies will be needed to reach a definitive answer on the malignant potential of OLP, and particularly, to identify contributing factors. Screening for TP53 mutations could help to identify the subgroup of OLP patients that is truly at risk of developing oral cancer.

Prognostic Value of Epithelial Cell Adhesion Molecules in T1-2N0M0 Glottic Cancer

OBJECTIVE

This is an ancillary study of a multi-institutional randomized non-inferiority phase III trial of accelerated fractionation (AF) versus standard fractionation (SF) radiation therapy for T1-2N0M0 glottic cancer (JCOG0701). Biopsy specimens of tumors from the patients enrolled in the JCOG0701 are collected and the association between clinical outcomes and histopathologic features such as expression of epithelial cell adhesion molecule (EpCAM), p53, and p16 were investigated.

METHODS

Five slices of undyed slides from biopsy specimens were sent to the National Cancer Center Hospital and all the specimens were assessed for the expression of EpCAM, p53, and p16. The primary objective was to investigate the association between 3-year progression-free survival (PFS) and expression of EpCAM, p53, and p16.

RESULTS

A total of 88 out of 370 patients were enrolled in this ancillary study. The 3-year PFS for tumors with strong expression of EpCAM was 70.6% (95% CI 43.1%-86.6%), while that of tumors without strong expression of EpCAM was 77.5% (95% CI 65.9%-85.5%) with no remarkable difference between groups (P = .67). Likewise, there was no significant difference in 3-year PFS between tumors regardless of p53 or p16 status. However, in a subgroup analysis for 17 patients with a strong expression of EpCAM, AF showed better 3-year PFS than SF (100% vs 54.5%, P = .07).

CONCLUSIONS

From the current study, it could not be concluded that EpCAM, p16, and p53 were prognostic factors for early-stage glottic cancer after primary radiation therapy. AF might be an appropriate fractionation for tumors with a strong expression of EpCAM.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:1522-1527, 2021.

Prognostic value of the expression of epithelial cell adhesion molecules in head and neck squamous cell carcinoma treated by definitive radiotherapy

A reliable biomarker can contribute to appropriate treatment selection in the management of head and neck squamous cell carcinoma (HNSCC). Recently, epithelial cell adhesion molecule (EpCAM) was shown to have prognostic features in several malignancies. However, it remains to be elucidated whether EpCAM predicts prognosis of HNSCC after radiotherapy. Therefore, the prognostic potential of EpCAM in HNSCC patients treated by radiotherapy was investigated in this study. All HNSCCs patients examined between January 2013 and December 2015 were analyzed for the expression of EpCAM. One hundred HNSCC patients were identified who were treated by primary radiotherapy. Intense expression of EpCAM was found in 29 HNSCC patients. Two-year overall survival (OS) for patients with intense EpCAM expression was 62.2%, whereas it was 87.9% for those without (P = 0.011). In multivariate analysis, intense EpCAM expression was found to be an independent prognostic factors for OS (P = 0.036). Overall, EpCAM was found to be an independent prognostic factor for HNSCC.

Expression of P53, BAX, and BCL-2 in human malignant melanoma and squamous cell carcinoma cells after tea tree oil treatment in vitro

Tea tree oil (TTO) is an essential oil obtained by steam distillation from the leaves of Melaleuca alternifolia (Myrtaceae). This oil has traditionally been used for the treatment of various skin infections. The present study aimed to investigate the cytotoxic effects of TTO against two representative types of human skin cancer, namely malignant melanoma (A-375) and squamous cell carcinoma (HEp-2).To outline the basic molecular mechanism involved in apoptosis induction in A-375 and HEp-2 cell lines, Annexin V/PI staining for apoptosis detection, cell cycle analysis were monitored using flow cytometry and mRNA expression levels of the apoptosis-regulatory genes P53, BAX, and BCL-2 were determined by real-time PCR and western blot after treatment with TTO. Results showed that TTO exhibited a strong cytotoxicity towards A-375 and HEp-2 cell lines, with IC50 values of 0.038% (v/v) and 0.024% (v/v) respectively. This cytotoxicity resulted from TTO induced apoptosis in both A-375 and HEp-2 cell lines as evidenced by morphological features of apoptosis and Annexin V/PI staining results in addition to the activation of caspase-3/7 and -9, upregulation of pro-apoptotic genes (P53 and BAX) and downregulation of the anti-apoptotic gene BCL-2. Additionally, cell cycle analysis showed that TTO caused cell cycle arrest mainly at G2/M phase. Taken together, the results of this study reveal that TTO is an effective apoptosis inducer in A-375 and HEp-2 cancer cell lines, indicating that it could be a promising chemopreventive candidate to be used in topical formulations against melanoma and squamous cell cancers; however, further in vivo studies may be warranted.

P53 Protein Expression in Dental Follicle, Dentigerous Cyst, Odontogenic Keratocyst, and Inflammatory Subtypes of Cysts: An Immunohistochemical Study

OBJECTIVES

An odontogenic keratocyst (OKC) is a developmental odontogenic cyst with aggressive clinical behavior. This cyst shows a different growth mechanism from the more common dentigerous cyst and now has been renamed as a keratocystic odontogenic tumor (KCOT). Inflammation can assist tumor growth via different mechanisms including dysregulation of the p53 gene. This study aims to assess and compare the expression of tumor suppressor gene p53 in inflamed and non-inflamed types of OKC and dentigerous cyst.

METHODS

Immunohistochemical expression of p53 was assessed in 14 cases of dental follicle, 34 cases of OKC (including 18 inflamed OKCs), and 31 cases of dentigerous cyst (including 16 inflamed cysts).

RESULTS

The mean percentage of p53 positive cells was 0.7% in dental follicles, 5.4% in non-inflamed OKCs, 17.3% in inflamed OKCs, 1.2% in non-inflamed dentigerous cysts, and 2.2% in inflamed dentigerous cysts. The differences between the groups were statistically significant (p < 0.050) except for the difference between inflamed and non-inflamed dentigerous cysts, and between dental follicle and non-inflamed dentigerous cyst.

CONCLUSIONS

The difference in p53 expression in OKC and dentigerous cyst can explain their different growth mechanism and clinical behavior. Inflammation is responsible for the change in behavior of neoplastic epithelium of OKC via p53 overexpression.

Impact of EGFR and p53 expressions on survival and quality of life in locally advanced oral squamous cell carcinoma patients treated with chemoradiation

EGFR and p53 are molecular markers which play important role in tumor progression and development. The objective of this study was to assess the association between EGFR and p53 expression and survival, and to determine whether EGFR and p53 expression levels were associated with differences quality of life in OSCC patients undergoing chemoradiation. A total of 120 OSCC patients aged 20-67 y and stage III/IV were recruited. Treatment response was assessed according to W.H.O. (1979). EGFR and p53 expression in tumor tissue was estimated by immunohistochemical (IHC) method and quantified as percentage positive nuclei. Molecular marker expressions of both EGFR and p53 were found significantly (P < 0.01 or P < 0.001) associated with overall response, survivals and quality of life. Neither EGFR nor p53 expression was associated with hematologic or non-hematologic toxicity. EGFR and p53 molecular marker expressions may have significant association with survival and QOL in OSCC patients undergoing chemoradiation.

Correlation between expressions of Cyclin-D1, EGFR and p53 with chemoradiation response in patients of locally advanced oral squamous cell carcinoma

Introduction

Cyclin-D1, p53 and EGFR are molecular markers that regulate the cell cycle and play an important role in tumor progression and development. The present study evaluates the prognostic significance of these markers with chemoradiation response in patients of locally advanced oral squamous cell carcinoma (OSCC).

Material and method

A total of 97 OSCC patients (females = 19 and males = 78), aged 20–67 years and stage III/IV were recruited. Treatment response was assessed according to WHO criteria. Cyclin-D1, p53 and EGFR expressions in tumor tissue was estimated by immunohistochemical (IHC) method and quantified as percentage positive nuclei.

Results

The positive expression rates of molecular markers were 86.6% for Cyclin-D1, 92.8% for EGFR and 85.6% for p53. The strong positive expressions of both Cyclin-D1 and p53 showed significant association with poor response. The Cox multivariate regression analysis showed coexpressions of Cyclin-D1 and p53 a significant and independent predictor of overall survival (OR = 1.90, 95% CI = 1.45–4.82, p = 0.046) after adjusting the demographic, clinicopathological and radiological response. The strong positive expressions of Cyclin-D1 and p53 and coexpressions of Cyclin-D1, EGFR and p53 showed significant (p < 0.05 or p < 0.01 or p < 0.001) and lower survival as compared to negative or moderate positive expressions and coexpressions, respectively.

Conclusion

Expressions and coexpressions of Cyclin-D1 and p53 may serve as a prognostic marker in OSCC patients.

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Cyclin-D1, p53 and EGFR are molecular markers that regulate the cell cycle.

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Coexpressions of Cyclin-D1, EGFR & p53 serve as prognostic marker in advanced OSCC.

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p53 alone may serve as prognostic marker in patients of locally advanced OSCC.

P53 nuclear stabilization is associated with FHIT loss and younger age of onset in squamous cell carcinoma of oral tongue

BACKGROUND

Squamous cell carcinoma of tongue (SCCT) is expected to harbor unique clinico-pathological and molecular genetic features since a significant proportion of patients are young and exhibit no association with tobacco or alcohol.

METHODS

We determined P53, epidermal growth factor receptor, microsatellite instability, human papilloma virus infection and loss of heterozygosity status at several tumor suppressor loci in one hundred and twenty one oral SCCT (SSCOT) samples and analyzed their association with clinico-pathological features and patient survival.

RESULTS

Our results revealed a significantly higher incidence of p53 nuclear stabilization in early (as against late) onset SCCOT. FHIT loss was significantly associated with p53 nuclear stabilization and the association was stronger in patients with no history of tobacco use. Samples harboring mutation in p53 DNA binding domain or exhibiting p53 nuclear stabilization, were significantly associated with poor survival.

CONCLUSION

Our study has therefore identified distinct features in SCCOT tumorigenesis with respect to age and tobacco exposure and revealed possible prognostic utility of p53.

Expression of EpCAM and prognosis in early-stage glottic cancer treated by radiotherapy

OBJECTIVES/HYPOTHESIS

Treatment of head and neck squamous cell carcinoma (HNSCC) often requires radiotherapy, but relapse can occur. There is, therefore, an urgent need for the identification of a predictive novel biomarker for radiosensitivity. The epithelial cell adhesion molecule (EpCAM) has been shown to promote the transformation of malignant tumors, and EpCAM may have prognostic significance, but it is not known if EpCAM determines prognosis, especially with respect to radiotherapy. Therefore, we determined the incidence of the expression of EpCAM in HNSCC and analyzed the prognostic value in patients with early-stage glottic cancer treated with radiotherapy.

STUDY DESIGN

Retrospective analysis.

METHODS

All patients with HNSCCs examined in our hospital between January 2012 and February 2013 were analyzed prospectively for the expression of EpCAM. T1-2N0 glottic cancer patients who were primarily treated by radiation therapy between 1995 and 2008 were retrospectively investigated. Patients with or without local recurrence after radical radiation therapy were extracted. The relationship between local recurrence and histopathologic EpCAM expression was compared within these two groups.

RESULTS

One hundred eighteen patients with HNSCCs from the nasopharynx, oropharynx, hypopharynx, larynx, oral cavity, paranasal cavity, unknown primary, and other sites were analyzed. Positive expression of EpCAM was noted in the oropharynx, hypopharynx, and larynx (72%, 90%, and 58%, respectively). Seventeen and 22 patients with or without local recurrence were extracted, respectively. There was no difference between two groups, with the exception of EpCAM expression.

CONCLUSIONS

The expression of EpCAM in HNSCC was investigated. Patients with strong EpCAM expression were associated with local recurrence after primary radiation therapy.

LEVEL OF EVIDENCE

NA

Prognostic impact of p16 and p53 expression in oropharyngeal squamous cell carcinomas

BACKGROUNDS

A p16 protein is known to be overexpressed in human papillomavirus-positive head and neck squamous cell carcinoma specimens. p53 is a tumor suppressor protein detectable by immunohistochemistry in carcinogen-associated head and neck squamous cell carcinoma as a result of gene mutations. The purpose of this study is to investigate the prognostic impact of p16 and p53 expression in oropharyngeal squamous cell carcinomas.

METHODS

We retrospectively examined the relationship between prognosis, and p16 and p53 expression levels of oropharyngeal squamous cell carcinoma specimens in 53 patients using immunohistochemistry.

RESULTS

Overall, 55% of patients were p16 positive and 45% p16 negative, while 28% were p53 positive and 72% p53 negative. The p16 status showed an inverse relationship with the p53 status. A survival analysis by p16 status, p53 status, Union for International Cancer Control stage and main treatment modality demonstrated that only p16 status was related to better prognosis in terms of overall survival and disease-specific survival (3-year overall survival, 87 vs. 62%, P = 0.02; 3-year disease-specific survival, 90 vs. 62%, P = 0.02). To evaluate the practical prognostic factors in oropharyngeal squamous cell carcinoma patients, we classified patients as either p16-positive or p53-negative oropharyngeal squamous cell carcinomas, representing human papillomavirus-related oropharyngeal squamous cell carcinoma with wild-type p53 or the remaining patients with p16-negative or p53-positive OPSCCs, respectively. The former group showed survival advantages in terms of overall survival and disease-specific survival by log-tank test compared with the latter group (3-year overall survival, 96 vs. 58%, P = 0.005; 3-year disease-specific survival, 96 vs. 63%, P = 0.02).

CONCLUSIONS

A group of patients who were p16 positive/p53 negative had better prognoses in terms of overall survival and disease-specific survival than that who were p16-positive alone.

[Analysis of mutations within the TP53 gene in patients with squamous cell carcinoma of the head and neck]

Head and neck cancer is the sixth most common type of cancer. Tobacco and alcohol consumption are implicated in 75% of all SCCHN and have a multiplicative combined effect. It is considered to be the main risk factor for the cancer development. The identification of a number of these genetic alterations, for example mutations in the p53 tumour suppressor gene, paved the way for their use as molecular markers. Mutations in the TP53 gene frequently occur in many cancers and are present in 50-60% of head and neck cancers, p53 plays a sentinel role in the pathways that prevent development of cancer by inducing apoptosis, DNA repair and cell cycle arrest in response to different types of cellular stress The aim of the study, was the assessment of the TP53 mutations prevalence in the head and neck cancer patients and it's relation with the clinical data and course of the disease. The material comprised of peripheral blood and tumour tissue obtained from 50 HNSCC patients with a primary tumour in the oral cavity, oropharynx or larynx, who were scheduled for surgical treatment. The mutations in TP53, were detected with use of PCR-SSCP technique. In total 8 patients (16%), showed TP53 mutation in primary tumour. The significant correlation between tobacco and alcohol consumption and the mutation incidence has been observed. The site of the tumour and histopathological grading were also related to the prevalence of mutations, however without reaching the level of statistical significance. There was no correlation between mutations and the T and N stage of the disease.

C-deletion mutation of the p53 gene at exon 4 of codon 63 in the saliva of oral squamous cell carcinoma in central India: a preliminary study

AIM

The purpose of this study was to detect the C-deletion mutation of the p53 gene at exon 4 of codon 63 in the saliva of oral squamous cell carcinoma in central India.

METHODS

The study was carried out in 30 oral squamous cell carcinoma cases and five healthy controls with no habit of betel nut and tobacco chewing. The C-deletion mutation of the p53 gene at exon 4 of codon 63 was detected in the saliva samples by using polymerase chain reaction.

RESULTS

In this study, C-deletion at exon 4 of codon 63 was detected in 28 of 30 oral squamous cell carcinoma cases (93.33%), but was negative in all five healthy controls and two oral squamous cell carcinoma cases.

CONCLUSIONS

The results indicated that C-deletion mutation at exon 4 of codon 63 of the p53 gene in the saliva might be a plausible molecular marker for oral squamous cell carcinoma patients with a habit of betel nut and tobacco lime quid chewing. The results further emphasize the presence of p53 gene mutation in patients with oral squamous cell carcinoma, which can be detected in the saliva through polymerase chain reaction.

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.

Role of TP53 in the progression of pre-malignant and malignant oral mucosal lesions. A follow-up study of 144 patients

BACKGROUND

Prediction of progression from pre-malignant oral mucosal lesions to malignancy, or recurrence of an existing oral squamous cell carcinoma (OSCC), is an important clinical problem in oral medicine.

METHODS

This study presents a follow-up of a study published in 2002. Samples from 54 patients with OSCC, 45 with oral lichen planus (OLP) and 45 with hyperkeratosis (clinically leukoplakia), diagnosed between 1987 and 1996, were analysed for TP53 protein expression and TP53 mutation. Follow-up was 11-17 years for OSCC (mean 13.3), 12-22 years for OLP (mean 15.9) and 12-17 years for hyperkeratosis (mean 14.5).

RESULTS

Of the 54 OSCC patients, 28 experienced recurrent disease, 21 died of OSCC, 22 died of other causes. Of the 14 OSCC patients with mutated TP53 (n = 11), the cancer recurred in eight (57%) and in 20/39 (51%) without mutation. Expression of TP53 protein was significantly associated with reduced overall survival. Among OLP patients, nine were TP53-mutated out of 31 tested. One TP53-mutated OLP patient developed OSCC in a different site. Of the hyperkeratosis patients, three were mutated of 22 tested. One hyperkeratosis patient (non-mutated) developed OSCC in the same site.

CONCLUSION

TP53 mutations can exist in benign oral mucosal lesions for many years without progression to malignancy. No association was found between TP53 protein expression or TP53 mutation and recurrence of OSCC or disease-related survival. Overall survival was reduced in patients with positive TP53 protein expression.

Genetic expression profiles and biologic pathway alterations in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is associated with considerable mortality and morbidity and is a major public health concern worldwide. To date, > 20 studies incorporating DNA microarray analyses have examined genomewide genetic expression changes associated with the development of HNSCC. The authors identified published reports of genetic expression profiles of HNSCC by Medline database search. They performed a review of the reports to identify genes that have been found repeatedly to exhibit substantially altered expression in HNSCC. Genes with altered expression were subsequently examined in the context of defined biologic systems with the use of GenMapp 2.0 pathway analysis software. Genes most commonly found to exhibit altered expression were those encoding for cytoskeletal and extracellular matrix proteins, inflammatory mediators, proteins involved in epidermal differentiation, and cell adhesion molecules. Results of GenMapp 2.0 analysis suggested global down-regulation of genes that encode for ribosomal proteins and enzymes in the cholesterol biosynthesis pathway; and up-regulation of genes that encode for matrix metalloproteinases and genes that bear on the inflammatory response. The review indicated that there are several genes and pathways that exhibit substantially altered expression in cancerous versus noncancerous states across studies. Further investigation into the genomic, proteomic, and functional consequences of these gene expression alterations may provide insight into the pathophysiology of HNSCC.

Cell proliferation, apoptosis and apoptosis-related factors in odontogenic keratocysts and in dentigerous cysts

BACKGROUND

The purpose of this study was to elucidate why odontogenic keratocysts (OKC) can form cystic lesions but not tumor masses, notwithstanding their prominent proliferative activity.

METHODS

We investigated cellular proliferation, cell death, and expression of apoptosis-related proteins in the lining cells of OKCs and of dentigerous cysts (DGCs).

RESULTS

TdT-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells were observed in the surface layers of OKCs and of DGCs. However, no TUNEL-positive cells were seen in the basal or intermediate layers of both cysts. Ki67-positive ratio in the intermediate layer was the highest in OKCs. The p53-positive ratio of the intermediate layer was highest in OKCs. Bcl-2-positive cells were discernible exclusively in the basal layer of OKCs.

CONCLUSIONS

These results suggest that cellular proliferation and death is regulated in association with apoptosis-related proteins in the lining epithelia of OKCs, and subsequently those cysts are seen as cystic lesions but not as tumor masses.

Prognostic value of apoptosis and apoptosis-associated proteins in salivary gland adenoid cystic carcinoma

The purpose of the present study was to investigate the level of apoptosis and expressions of p53, mdm2 and bcl-2 proteins in salivary gland adenoid cystic carcinoma (ACC) to determine potential relationships among apoptosis, apoptosis-associated proteins and clinical cumulative survival. Thirty-nine formalin-fixed, paraffin-embedded cases, cribriform (17), tubular (13) and solid (9), were studied by immunohistochemistry. Apoptosis detection and analysis were determined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL). There was an inverse significance between the apoptotic index (AI) and bcl-2 expression (P = 0.018), whereas no correlation was found between the AI and either p53 or mdm2 expression (P = 0.416 and P = 0.456). Co-expression of p53 and mdm2 was found in 22 cases (P = 0.037). Patients with p53-positive tumors had a worse prognosis than those with p53-negative tumors (P = 0.014). Patients with a high AI had a better cumulative survival than patients with a low AI (P = 0.038). The present study suggests that p53 expression and AI can be useful as prognostic values; bcl-2 protein plays a role in the down-regulation of apoptosis and is also potentially useful as a prognostic parameter in salivary gland ACC.

Prognostic and predictive factors in oral squamous cell cancer: important tools for planning individual therapy?

An escalation in the incidence of oral cancer and its attributable mortality has been observed in recent decades in Europe; oral cancer is expected to become a public health problem in the foreseeable future. However, survival rates have remained at a disappointingly stable level despite significant development in the multimodality treatment of the disease. Additionally, due to the limited prognostic value of conventional prognostic factors and the uniformity of treatment strategies, several patients are still over- or under-treated with significant personal and socio-economical impact. Here we review some promising prognostic and predictive markers that can help the clinician to improve prognostic accuracy and define the most appropriate management for the individual patient with oral cancer.

Cell proliferation and tumour suppressor gene expression in iodine unstained area surrounding oral squamous cell carcinoma

The purpose of this study was to investigate the relationship between epithelial dysplasia unstained with iodine and the expression of proliferating cell nuclear antigen (PCNA) and/or tumour suppressor gene (p53) and the existence of glycogen. Thirty cases of squamous cell carcinomas arising from the buccal mucosa and floor of the mouth were examined. Iodine unstained areas were diagnosed histopathologically as mild, moderate or severe epithelial dysplasia. Normal oral mucosa stained with iodine was used as a control group. There was no histochemical difference in the distribution or ratio of PAS-positive cells between the control and the mild epithelial dysplasia groups, however PAS stained areas of the moderate and the severe dysplasia groups were significantly decreased. Ultrastructurally, glycogen granules were not recognized in the moderate or severe dysplastic epithelia. Immunoreactive ratios of PCNA and p53 in the moderate and severe dysplastic groups were significantly higher than those of the control and the mild dysplasia groups. The positive ratio of PCNA was higher than that of p53, although the immunostaining patterns of PCNA- and p53-positive cells were quite similar. These results suggest that mild dysplastic epithelia that are stained with iodine may be in the category of normal epithelia, whereas both moderate and severe dysplasia that are un-stained with iodine may be suspected of malignant lesions.

Activation of p53 signalling in acetylsalicylic acid-induced apoptosis in OC2 human oral cancer cells

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as acetylsalicylic acid (ASA, aspirin) are well known chemotherapeutic agents of cancers; however, the signalling molecules involved remain unclear. The aim of this study was to investigate the possible existence of a putative p53-dependent pathway underlying the ASA-induced apoptosis in OC2 cells, a human oral cancer cell line.

MATERIALS AND METHODS

The methyl tetrazolium (MTT) assay was employed to quantify differences in cell viability. DNA ladder formation on agarose electrophoresis was used as apoptosis assay. The expression levels of several master regulatory molecules controlling various signal pathways were monitored using the immunoblotting techniques. Flow cytometry was used to confirm the effect of ASA on cell cycle. Patterns of changes in expression were scanned and analyzed using the NIH image 1.56 software (NIH, Bethesda, MD, USA). All the data were analyzed by ANOVA.

RESULTS

Acetylsalicylic acid reduced cell viability and presence of internucleosomal DNA fragmentation. In the meanwhile, phosphorylation of p53 at serine 15, accumulation of p53 and increased the expression of its downstream target genes, p21 and Bax induced by ASA. The expression of cyclooxygenase-2 was suppressed. Disruption of p53-murine double minute-2 (MDM2) complex formation resulted in increasing the expression of MDM2 60-kDa cleavage fragment. Inhibited the activation of p42/p44 mitogen-activated protein kinase (MAPK) by PD98059, a specific inhibitor of extracellular regulatory kinase (ERK), significantly decreased cell viability and enhanced the expression of p53 induced by ASA. The result of the cell-cycle analysis showed that ASA and PD98059 induced the cell cycle arrested at the G0/G1 phase and resulted in apoptosis.

CONCLUSION

Nonsteroidal anti-inflammatory drug-inhibited cyclooxygenase is not the only or even the most important mechanism of inhibition. Our study presents evidences that activation of p53 signalling involved in apoptosis induced by ASA. Furthermore, the apoptotic effect was enhanced by blocking the activation of p42/p44 MAPK in response to treatment with ASA, thus indicating a negative role for p42/p44 MAPK.

p53 Expression and keratinocyte hyperproliferation in middle ear cholesteatoma

Keratinocytes in middle ear cholesteatoma have hyperproliferative properties. There is controversy regarding the role of p53 and its effect on cellular proliferation in cholesteatoma. This study was instituted to examine this. Cholesteatoma and deep meatal skin control specimens were analysed for MIB-1 (n = 7, controls = 7), a marker of cellular proliferation, and p53 (n = 17, controls = 17) expression by immunocytochemistry. Expression of p53 was minimal or absent in both cholesteatoma and controls (P = 0.2). MIB-1 expression was higher, but not significantly so, in cholesteatoma than in controls (P = 0.09). Our study has shown no significant p53 expression in cholesteatoma epithelium. This suggests that there is no dysfunction in the p53-mediated cell cycle control mechanisms in cholesteatoma.

p53, mdm2, and p21 expression in oral squamous cell carcinomas: relationship with clinicopathologic factors

OBJECTIVE

The purpose of this study was to clarify the correlation of expression of cell cycle-associated gene proteins with clinicopathologic factors in oral squamous cell carcinoma (SCC).

STUDY DESIGN

Formalin-fixed paraffin-embedded tissues from 69 oral SCC cases and 10 normal mucosa cases were stained by immunohistochemistry (IHC) for p53, mdm 2, and p21 proteins.

RESULTS

We found p53, mdm 2, and p21 expression in 44 of 69 (63.8%), 25 of 69 (36.2%), and 37 of 69 (53.6%) oral SCCs, respectively. Ki-67-labeling index of combined p53(+)/mdm 2(+) expression cases was significantly higher than those that lacked combined expression (P =.004). Combined p53(+)/p21(+) expression showed a significant association with lymph node metastasis (P =.019). In survival analysis, combined p53(+)/p21(+) and p53(+)/mdm 2(+)/p21(+) expression was associated with poor clinical outcome (P =.018 and.012, respectively).

CONCLUSION

Combined p53/mdm 2 expression was associated with tumor proliferation in oral SCC. Combined p53/p21 and p53/mdm 2/p21 expression may be a predictive factor in lymph node metastasis.

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.

Prognostic value of p53 mutations, bax, and spontaneous apoptosis in maxillary sinus squamous cell carcinoma

BACKGROUND

Many researchers have attempted to correlate p53 mutation and spontaneous apoptosis with the effectiveness of radiochemotherapy and with prognosis in several malignancies.

METHODS

The current study group consisted of 70 Japanese patients with maxillary sinus squamous cell carcinoma (SCC). Fifty seven patients were treated with radiochemotherapy followed by total or partial maxillectomy, and the remaining 13 patients were treated with radiotherapy alone. Tumor biopsy specimens at pretreatment status were examined for apoptosis-related proteins such as p53 protein, Fas, bax, bcl-x, and apoptosis using immunohistologic methods. The proportion of apoptotic cells labeled by single stranded DNA antibody was expressed as an apoptotic index (AI). p53 mutations at exons 5 through 8 were analyzed by direct sequence on polymerase chain reaction amplified products obtained from laser microdissected tissues. The effectiveness of radiochemotherapy was investigated histologically on surgically dissected specimens.

RESULTS

p53 mutations were identified in 20 (29%) of 70 patients. p53 protein was overexpressed in 39 patients (56%), Fas in 20 patients (29%), bax in 40 patients (57%), and bcl-x in 33 patients (47%). Overexpression of bax was associated with negativity of bcl-x (P = 0.015) and with high AI (P = 0.024). Low AI and/or p53 mutation in the pretreatment tissues correlated with low histologic effectiveness of radiochemotherapy (P = 0.048, P = 0.019, respectively). Kaplan-Meier analysis as well as univariate analysis using the Cox proportional hazards model showed that low histologic effectiveness of radiochemotherapy (P = 0.0281, P = 0.0284, respectively), p53 mutations (P = 0.0095, P = 0.0187, respectively), negativity of bax (P = 0.0069, P = 0.0191, respectively), and low AI (P = 0.0134, P = 0.0407, respectively) were significantly related to worse disease-free survival. Multivariate analysis showed AI as an independent factor predicting for disease-free survival (P = 0.0455).

CONCLUSIONS

The p53 mutations, expression of bax, and levels of spontaneous apoptosis have prognostic value in maxillary sinus SCC; AI especially is an independent factor for disease-free survival. A high level of spontaneous apoptosis induced by overexpression of bax may increase sensitivity of radiochemotherapy resulting in good prognosis, while p53 mutation may lead to resistance against radiochemotherapy, resulting in poor prognosis.

Comparison of HPV infection, p53 mutation and allelic losses in post-transplant and non-posttransplant oral squamous cell carcinomas

BACKGROUND

Oral squamous cell carcinoma (SCC) is increasingly found in transplant recipients, although little is known of the natural history of the disease or the mechanism underlying this increase.

METHODS

In this article we describe the history of development of 5 oral post-transplant SCCs (PSCCs) and compare their genetic profiles to 34 non-posttransplant SCCs (NPSCCs).

RESULTS

Of the five patients with PSCCs, 3 had bone marrow transplants and two, kidney. All three PSCCs from bone marrow recipients were preceded locally by graft-vs.-host disease (GVHD). Two of the GVHD were biopsied and demonstrated dysplasia. Similar frequencies of loss of heterozygosity (LOH) occurred in PSCCs and NPSCCs at 3p, 9p, 17p and 8p, with lower frequencies in PSCCs at 4q (39% vs. 0%), 11q (53% vs. 20%) and 13q (45% vs. 20%), although the latter were not significantly different. Only 1 PSCC had a p53 mutation, compared to historical values of 40-60% for NPSCC. Interestingly, human papillomavirus (HPV) DNA was detected in 3 (60%) PSCCs, in comparison to only 4 (12%) of the 34 NPSCCs (P = 0.0346).

CONCLUSIONS

Dysplasia in oral GVHD may be a strong indicator of cancer risk and should not be regarded as reactive changes to lichenoid mucosites. The low level of p53 mutation and increased HPV infection support the involvement of HPV in the development of PSCC, while the similarity in LOH patterns suggests that other aspects of carcinogenesis may be comparable in these two types of SCCs.

Splicing mutations in TP53 in human squamous cell carcinoma lines influence immunohistochemical detection

The mutational status of the tumor suppressor gene TP53 is often examined by immunohistochemistry. We compared the incidence of TP53 mutations in 12 permanent squamous cell carcinoma lines of the head and neck with the immunohistochemical staining obtained with two different antibodies. The mutational status of the TP53 gene was assessed by sequencing the complete coding frame of the TP53 mRNA. All 12 tumor cell lines had TP53 mutations. Six of them showed missense mutations and five had premature stop codons caused either by splicing mutations or nonsense mutations or by exon skipping. One tumor cell line was heterozygous, with a truncating splicing mutation and an additional missense mutation located on different alleles. In one case, an in-frame insertion of 23 extra codons was found. All missense mutations were positive in immunhistochemistry and Western blotting. The truncated p53 was not immunohistochemically detected in three cases with the DO-7 antibody and in five cases with the G59-12 antibody, giving false-negative results in 25% or 40%, respectively, of all tumor cell lines examined. We conclude that splicing mutations are common in squamous cell carcinoma lines and that the incidence of p53 inactiviation by erroneous splicing is higher than yet reported. Sequencing of only the exons of TP53 may miss intronic mutations leading to missplicing and may therefore systematically underestimate the TP53 mutation frequency.

P53 and Ki-67 as outcome predictors for advanced squamous cell cancers of the head and neck treated with chemoradiotherapy

HYPOTHESIS

P53 and Ki-67 status will predict response to treatment, organ preservation, and survival in patients with advanced squamous cell cancers of the head and neck treated with chemoradiotherapy (CRT).

STUDY DESIGN

Retrospective analysis of p53 and Ki-67 status from the CRT arm of a randomized, controlled trial (n = 50) and from patients receiving the same treatment but not enrolled in the trial (n = 55).

METHODS

P53 and Ki-67 status were established from archived tissue samples using immunohistochemical (IHC) staining. Tumors were positive for p53 (p53+) when more than 2% of cells stained for p53 and were positive for Ki-67 (Ki-67+) when any cell stained for Ki-67. End points were tumor response, tumor recurrence, survival status, and organ preservation at last follow-up, and time to events. Predictive models were calculated for each outcome.

RESULTS

Neither marker predicted tumor response to treatment. P53+ status was associated with tumor recurrence (P =.003) and locoregional recurrence (P =.003). Adjusting for time to event, p53+ status was significantly related to a lower recurrence-free survival (P =.004), lower disease-specific survival (P =.04), lower overall survival with primary site preservation (P =.03), and lower disease-specific survival with primary site preservation (P =.003). Multivariate analysis revealed that p53+ status was significantly related to a lower recurrence-free survival (P =.01, risk ratio [RR] = 3.65) and lower disease-specific survival with organ preservation (P =.02, RR = 3.41). Ki-67+ status was not related to any variables. However, multivariate analysis revealed that Ki-67+ was significantly related to a lower overall survival (P =.05, RR = 2.03). The combination of both markers negative (p53-/Ki-67-) was associated with a lower incidence of tumor recurrence (P =.02), lower locoregional recurrence (P =.01), and fewer second primary lesions (P =.04). Adjusting for time to event, p53-/Ki-67- status was significantly related to a higher recurrence-free survival (P =.02), higher disease-specific survival with primary site preservation (P =.02), and higher overall survival with primary site preservation (P =.02). Multivariate analysis revealed that p53-/Ki-67- status was significantly related to a higher overall survival with site preservation (P =.01, RR = 2.78).

CONCLUSIONS

P53 and Ki-67 status appear to be related to the various survival end points considered in this study. However, this relation does not seem to be sufficient to warrant treatment modifications. Closer follow-up may be justified in both p53+ and Ki67+ patients to detect recurrence or a second primary at an earlier stage, possibly improving survival.

Malignancy: Tumor Suppressor Gene Aberrations in Acute Myelogenous Leukemia

Acute myelogenous leukemia is a heterogeneous disease that appears to evade the normal regulatory controls of tumor suppressor genes. Studies in AML have documented mutations in both p53 and Retinoblastoma (Rb) genes, but these mutations are relatively uncommon, especially compared to their mutational frequency in solid tumors. In addition, expression abnormalities have now been documented in several tumor suppressor genes or related genes including MDM2, p73, Rb, p14(ARF), p15(INK4B), and p16(INK4A). We review the current literature regarding tumor suppressor genes in AML and suggest how these genes may be involved in the development of the disease.

MIB-1 and p53 expression in radiotherapy-resistant T1aN0M0 glottic squamous cell carcinoma

Radiotherapy of T1aN0M0 glottic carcinoma results in a local control rate of 80-94%. This homogenous group, which is the earliest recognisable invasive malignancy in the head and neck region, provides a 'unique model' for studying possible biological markers of radiosensitivity. p53 and MIB-1 were investigated as possible markers of radiosensitivity in such a group. In all, 107 patients with T1aN0M0 glottic squamous cell carcinoma treated with radiotherapy were identified. Cases not responsive to radiotherapy were compared with matched radiosensitive controls by immunohistochemistry using monoclonal primary antibodies to MIB-1 (n = 18; controls = 10) and p53 (n = 6; controls = 11). No significant difference in p53 expression was noted between the two groups (P = 0.73). A greater MIB-1 expression was found in the radiosensitive group but only a trend towards significance was observed (P = 0.06). MIB-1 is a potential marker of radiosensitivity. A larger multicentre study is required for a more definitive answer.

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.

Malignant craniopharyngioma

Craniopharyngiomas are histologically and cytologically benign epithelial tumors of the central nervous system that may be locally aggressive and tend to recur after excision. Malignant change in craniopharyngiomas is extremely rare; we found only 4 such reports in the literature. In this report, we describe a case of squamous cell carcinoma arising in a previously benign craniopharyngioma in a 42-year-old woman. The patient was diagnosed with craniopharyngioma in 1982; during the subsequent 15 years she experienced 7 tumor recurrences, for which surgical resections and 3 courses of radiotherapy were performed. In 1998, the tumor recurred with involvement of the nasal cavity and sphenoid and ethmoid sinuses. Histologic evaluation revealed foci of typical adamantinomatous craniopharyngioma associated with a moderately differentiated squamous cell carcinoma. The transition of typical craniopharyngioma to squamous cell carcinoma was well demonstrated, suggesting that carcinoma arose from the underlying craniopharyngioma. Radiation may have been a contributing factor to carcinogenesis in this case.

Potentially malignant and malignant lesions of the lip. Role of silver staining nucleolar organizer regions, proliferating cell nuclear antigen, p53, and c-myc in differentiation and prognosis

The cellular changes leading to carcinoma of the lip are still not completely understood. This study was carried out on 44 malignant and potentially malignant lesions of the lower lip [30 squamous cell carcinomas (SCC), 7 actinic cheilitis, 3 leukoplakias, and 4 nodal metastases from lower lip SCC]. Silver-stained nucleolar organizer regions (AgNORs) and the immunohistochemical expression of proliferating cell nuclear antigen (PCNA), p53, and c-myc were evaluated on formalin-fixed, paraffin-embedded sections. The results indicate that the size and numbers of AgNORs and the percentage of PCNA-positive cells are sensitive parameters for discriminating between potentially malignant lesions and SCC, and for the prognostic sub-typing of lower lip SCC. Furthermore, while p53 positivity was found more frequently in high-grade carcinomas, p53-positive cellular clones were also found in some potentially malignant lesions, a finding probably related to ultraviolet-related cellular damage. These p53-positive lesions could be considered at higher risk of progression to malignancy than the p53-negative ones, although there is no evidence for this as yet. c-myc positivity was found only in some high-grade carcinomas and metastases, and appeared correlated with the later phases of lip carcinogenesis. The combined evaluation of the proliferation status, together with the changes in p53 and c-myc oncoproteins, might constitute useful markers for the prognostic evaluation of potentially malignant, as well as malignant, lesions of the lip.

Expression of p21/waf1 in oral squamous cell carcinomas--correlation with p53 and mdm2 and cellular proliferation index

The cyclin-dependent kinase inhibitor p21/waf1 is regulated by p53-dependent and p53-independent pathways. In addition, mdm2 is an oncogene which forms an auto-regulatory loop with the normal p53 protein and its role has been implicated in oncogenesis. To determine whether a correlation exists between the expression of these gene products, tumor differentiation, tumor staging and radiation therapy, we investigated the expression of p21, p53 and mdm2, and cellular proliferation by Ki-67 (MIB1) labeling index using immunohistochemistry in 88 human oral squamous cell carcinoma (SCC) samples from 56 patients. Tumor expression of all nuclear proteins was scored according to the percentage of positive cancer nuclei, both with the cancer tissue as a whole as well as in different epithelial compartments of differentiation. Positive p21, p53, mdm2 and MIB1 staining was present in 82.4, 67.8, 25.9 and 98.8% of the SCC samples. The staining in different epithelial compartments of differentiation varied: those of p21 and mdm2 present predominantly in suprabasal and upper regions of the tumors: those of p53 and MIB1 in basal and suprabasal regions. Higher levels of p21 expression were seen in actively proliferating tumors (P = 0.025). p21 expression positively correlated with mdm2 expression but not with p53 expression. Moreover, the level of p21 expression was higher in older patients (P = 0.024) and female patients (P = 0.008). There was no significant association among p53, mdm2 and MIB1. Expression of p53 was higher in tumors with poorer cellular differentiation and in younger patients (P = 0.038 and 0.028). There was no association between tumor stage by TNM classification and the expression of any of these gene products or proliferation index. Radiation therapy did not alter the expression of any of these. To conclude, p21 protein was overexpressed in oral SCCs, and this overexpression was related to cell proliferation index and mdm2 expression but independent of p53 protein alteration. Overexpression of p21 alone appeared to be insufficient to suppress tumor progression.

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.

Nuclear DNA content and p53 overexpression in stage I squamous cell carcinoma of the tongue compared with advanced tongue carcinomas

AIMS

To evaluate the predictive value of the nuclear DNA content (image cytometry) and p53 overexpression (immuno-histochemistry using antibody CM-1) in uniformly treated stage I carcinomas of the mobile tongue. Also, to compare stage I carcinomas with advanced tongue carcinomas (stages II-IV).

METHODS

Archival formalin fixed, paraffin wax embedded tumour specimens from 54 patients with stage I squamous cell carcinoma and 37 patients with advanced squamous cell carcinoma were analysed. Mean follow up time of the stage I carcinomas was 71 months (median, 62.5; range, 6-175).

RESULTS

Twenty three patients (stage I) had recurring disease: 10 had local recurrence (in the tongue) and 13 had regional recurrence (cervical metastases). Locally recurring stage I carcinomas had a more pronounced DNA deviation than the other stage I carcinomas and this degree of deviation was comparable with the DNA content of advanced carcinomas. Stage I carcinomas that developed regional recurrences overexpressed p53 more frequently. In Cox multivariate regression analysis of time to recurrence, DNA deviation was a significant parameter in tumours that recurred locally (p = 0.032). p53 overexpression was the only parameter close to significance for regional recurrence (p = 0.065).

CONCLUSIONS

Nuclear DNA content and p53 immunostaining are of value for the prediction of recurrence of stage I squamous cell carcinomas of the mobile tongue. Stage I tongue carcinomas that are prone to local recurrence show the same DNA content as do advanced tongue carcinomas.

p53 mutation, but not p53 overexpression, correlates with survival in head and neck squamous cell carcinoma

Survival in squamous cell carcinoma of the head and neck (HNSCC) was compared with overexpression and mutation of the p53 gene. Archival tissue from 77 tumours was analysed for protein expression using immunohistochemistry (IHC) with the monoclonal antibody Do-7, and for the presence of mutation in exons 5-8 using single-stranded conformation polymorphism (SSCP), followed by DNA sequencing in SSCP-positive cases. p53 expression was scored as high (>70% nuclei stained) in 25 (32%) tumours, as intermediate (10-70% nuclei stained) in 19 (25%) tumours and as low (<10% nuclei stained) in 33 (43%) tumours. Twelve (18%) tumours exhibited gene mutation (ten missense and two nonsense mutations) and an additional five tumours contained changes that could not result in amino acid substitution or protein truncation. There was no correlation between gene expression and mutation, mutations being equally frequent in tumours with either high (4/25), intermediate (4/19) or low protein expression (4/33). Fifty-eight patients were eligible for survival analysis. There was a strong correlation between p53 mutation and cause-specific survival; median survival among mutated cases was 12.5 months compared with >160 months among non-mutated patients (P < 0.005). There was no correlation between p53 overexpression and survival. The results suggest that p53 mutation status is an important prognostic factor in HNSCC, and that IHC analysis of protein overexpression is an inadequate measure of gene mutation in these tumours.

Expression of P-glycoprotein, a multidrug-resistance gene product, is induced by radiotherapy in patients with oral squamous cell carcinoma

BACKGROUND

It has been observed that patients who have previously undergone radiotherapy have a lower rate of response to chemotherapy.

METHODS

The authors investigated the effects of radiation on the expression of P-glycoprotein (Pgp), a multidrug-resistance gene product, in 56 patients with primary oral cancer. No patients received prior or concurrent chemotherapy. The 56 patients consisted of 3 groups: 1) 20 patients with preradiation or pretreatment specimens only, 2) 18 patients with both pre- and postradiation specimens, and 3) 18 patients with postradiation specimens only. Pgp expression was determined by immunohistochemistry with two monoclonal antibodies, C219 and C494.

RESULTS

Among patients in Groups 1 and 2, only 1 (2.6%) and 2 (5.3%) patients had Pgp expression in their tumors before treatment with C219 and C494, respectively. For Group 2 patients, 66.7% and 72.2% had tumors that expressed Pgp with the two antibodies, respectively, only after and not prior to radiation. When patients in Groups 2 and 3 were combined, 63.9% and 72.2% had Pgp expression with the two antibodies, respectively, after radiation. Pgp expression was significantly induced after radiation compared with expression before treatment (P < 0.001). Overexpression of p53 protein, detected by immunohistochemistry with DO-7 antibody, was seen in the tumors of 40 patients (71.4%), and the status was quite consistent throughout radiotherapy. Pgp expression had no significant association with p53 protein expression.

CONCLUSIONS

Pgp expression was significantly induced by radiation in human oral cancers. This induction of Pgp expression likely confers multidrug resistance to the cancer cells and may affect the efficacy of subsequent or concurrent chemotherapy. It may explain the lower rate of response to chemotherapy among patients who have previously had radiotherapy.

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.

Molecular analysis of the p53 gene in pancreatic adenocarcinoma

Mutations in the p53 tumor suppressor gene are the most common genetic alterations found in human cancer. Most mutations are accompanied by stabilization of the protein, which renders the mutations detectable through immunohistochemical techniques. The immunoreactivity of p53, however, might not correlate with the result of p53 DNA sequencing. In order to explain the discrepancy, we studied the p53 expressions, mutations, and changes of the three-dimensional protein structure of mutant p53 in a series of 61 pancreatic adenocarcinoma specimens using immunohistochemistry, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), DNA sequencing, and computerized protein modeling. PCR-SSCP followed by DNA sequencing of the p53 gene showed mutations in 31.2% (19 of 61) of the pancreatic adenocarcinomas. Eight of 19 cases showed p53 immunopositivity. These mutations were located on the surface of the three-dimensional structure or formed unfolded proteins, which were easily recognized by the antibody. Among other mutations in which p53 was immunonegative, five cases with deletions and insertion caused frameshift and formation of severely truncated p53 protein structures unreactive with the antibody used. In three cases with point mutations, the mutant amino acids were located in the core of the tightly packed beta sandwich inaccessible to the antibody. Three silent mutations were immunonegative, corresponding with the absence of amino acid changes. These results strongly suggest that the analysis of a computer-generated p53 three-dimensional model based on DNA sequencing data can assist in evaluating the significance of p53 immunostaining and mutations for clinical applications.

p53 expression and p53 gene mutation in oral cancer and dysplasia

BACKGROUND

The aim of the current study was to examine the possible association of the p53 tumor suppressor gene with the development of oral cancer. We examined biopsy material from patients with oral squamous cell carcinoma for p53 protein expression and p53 mutations.

METHODS

Eighteen samples were analyzed. These comprised oral squamous cell carcinoma biopsy samples and oral dysplastic biopsy material taken from nine patients. An immunohistochemical technique was used to determine p53 protein expression. A direct sequencing technique was used to detect mutations in the p53 gene itself.

RESULTS

Overall seven of nine (77%) oral squamous cell carcinomas and seven of nine (77%) oral dysplastic lesions analyzed showed evidence of p53 protein over-expression. Mutations in exons 5 and 6 of the p53 gene were detected in five of nine (55%) oral squamous cell carcinomas and four of nine (44%) dysplastic lesions analyzed.

CONCLUSIONS

Both p53 protein over-expression and p53 mutations were noted in dysplastic oral lesions. Over-expression of the p53 protein and p53 gene mutations were not always coexistent, however, suggesting that gene mutation may be only one of the mechanisms responsible for stabilization of the p53 protein.