p53 expression in oral precancer as a marker for malignant potential

Oral cancer prediction by noninvasive genetic screening

Oral squamous cell carcinomas (OSCCs) develop in genetically altered epithelium in the mucosal lining, also coined as fields, which are mostly not visible but occasionally present as white oral leukoplakia (OL) lesions. We developed a noninvasive genetic assay using next-generation sequencing (NGS) on brushed cells to detect the presence of genetically altered fields, including those that are not macroscopically visible. The assay demonstrated high accuracy in OL patients when brush samples were compared with biopsies as gold standard. In a cohort of Fanconi anemia patients, detection of mutations in prospectively collected oral brushes predicted oral cancer also when visible abnormalities were absent. We further provide insight in the molecular landscape of OL with frequent changes of TP53, FAT1 and NOTCH1. NGS analysis of noninvasively collected samples offers a highly accurate method to detect genetically altered fields in the oral cavity, and predicts development of OSCC in high-risk individuals. Noninvasive genetic screening can be employed to screen high-risk populations for cancer and precancer, map the extension of OL lesions beyond what is visible, map the oral cavity for precancerous changes even when visible abnormalities are absent, test accuracy of promising imaging modalities, monitor interventions and determine genetic progression as well as the natural history of the disease in the human patient.

Escape from Cellular Senescence Is Associated with Chromosomal Instability in Oral Pre-Malignancy

An escape from cellular senescence through the development of unlimited growth potential is one of the hallmarks of cancer, which is thought to be an early event in carcinogenesis. In this review, we propose that the molecular effectors of senescence, particularly the inactivation of TP53 and CDKN2A, together with telomere attrition and telomerase activation, all lead to aneuploidy in the keratinocytes from oral potentially malignant disorders (OPMD). Premalignant keratinocytes, therefore, not only become immortal but also develop genotypic and phenotypic cellular diversity. As a result of these changes, certain clonal cell populations likely gain the capacity to invade the underlying connective tissue. We review the clinical implications of these changes and highlight a new PCR-based assay to identify aneuploid cell in fluids such as saliva, a technique that is extremely sensitive and could facilitate the regular monitoring of OPMD without the need for surgical biopsies and may avoid potential biopsy sampling errors. We also draw attention to recent studies designed to eliminate aneuploid tumour cell populations that, potentially, is a new therapeutic approach to prevent malignant transformations in OPMD.

On the Cutting Edge of Oral Cancer Prevention: Finding Risk-Predictive Markers in Precancerous Lesions by Longitudinal Studies

Early identification and management of precancerous lesions at high risk of developing cancers is the most effective and economical way to reduce the incidence, mortality, and morbidity of cancers as well as minimizing treatment-related complications, including pain, impaired functions, and disfiguration. Reliable cancer-risk-predictive markers play an important role in enabling evidence-based decision making as well as providing mechanistic insight into the malignant conversion of precancerous lesions. The focus of this article is to review updates on markers that may predict the risk of oral premalignant lesions (OPLs) in developing into oral squamous cell carcinomas (OSCCs), which can logically be discovered only by prospective or retrospective longitudinal studies that analyze pre-progression OPL samples with long-term follow-up outcomes. These risk-predictive markers are different from those that prognosticate the survival outcome of cancers after they have been diagnosed and treated, or those that differentiate between different lesion types and stages. Up-to-date knowledge on cancer-risk-predictive markers discovered by longitudinally followed studies will be reviewed. The goal of this endeavor is to use this information as a starting point to address some key challenges limiting our progress in this area in the hope of achieving effective translation of research discoveries into new clinical interventions.

Targeting the genetic landscape of oral potentially malignant disorders has the potential as a preventative strategy in oral cancer

This study reviews the molecular landscape of oral potentially malignant disorders (OPMD). We examine the impact of tumour heterogeneity, the spectrum of driver mutations (TP53, CDKN2A, TERT, NOTCH1, AJUBA, PIK3CA, CASP8) and gene transcription on tumour progression. We comment on how some of these mutations impact cellular senescence, field cancerization and cancer stem cells. We propose that OPMD can be monitored more closely and more dynamically through the use of liquid biopsies using an appropriate biomarker of transformation. We describe new gene interactions through the use of a systems biology approach and we highlight some of the first studies to identify functional genes using CRISPR-Cas9 technology. We believe that this information has translational implications for the use of re-purposed existing drugs and/or new drug development. Further, we argue that the use of digital technology encompassing clinical and laboratory-based data will create relevant datasets for machine learning/artificial intelligence. We believe that therapeutic intervention at an early molecular premalignant stage should be an important preventative strategy to inhibit the development of oral squamous cell carcinoma and that this approach is applicable to other aerodigestive tract cancers.

Global Scenario of Research in Oral Cancer

INTRODUCTION

With 300,000 new cases diagnosed worldwide, oral cancer continues to be a major global public threat. In Indian subcontinent, oral cancer accounts for 30-40% of all cancer types.

METHODOLOGY

Early detection of oral cancer is still considered as the most effective way to improve survival. In this regard, early detection of oral premalignant lesions and conditions is quite important as it may help in prevention of oral cancer. Scientific evidence is available which clearly indicates that transition from normal epithelium to premalignancy to oral carcinoma is the result of accumulation of genetic and epigenetic alterations in a multi-step process.

CONCLUSION

Proper oral screening and understanding of the genetic and environmental factors involved in oral carcinogenesis will allow the emphasis of cancer medicine to shift from the therapy of established oral cancer to the prevention of oral carcinogenesis.

Oral epithelial dysplasia: Classifications and clinical relevance in risk assessment of oral potentially malignant disorders

After more than a decade, the World Health Organization (WHO) published the revised grading system for oral epithelial dysplasia in 2017. The revised classification has changes reflecting our evolution of understanding of the dysplastic process. Although the WHO 2017 three-tier grading system is the gold standard for histological diagnosis of oral potentially malignant disorders, it has certain limitations. Suggestions to overcome these limitations include the use of clinical determinants and molecular markers to supplement the grading system. It has also been suggested that a two-tier system may be more reproducible and clinically translatable for better management. These advances in the understanding of epithelial dysplasia are very important globally and for us in the Indian subcontinent, given the prevalence of habits (tobacco/areca nut) and burden of oral cancer in this part of the world. The following review traces the evolution of the grading system of dysplasia, its relevance and clinical utility.

Translational approach utilizing COX-2, p53, and MDM2 expressions in malignant transformation of oral submucous fibrosis

About 20% of the world's population uses some form of betel nut, which suggests that the incidence of oral submucous fibrosis (OSF) is higher than current estimates. OSF has the potential to undergo malignant transformation; thus, there is a need to identify relevant markers to assess its aggressiveness. We evaluated changes in COX-2, p53, and MDM2 expressions in progressive OSF. Expressions of COX-2, p53, and MDM2 increased with OSF progression. There was a strong association between COX-2 overexpression and recurrence of oral squamous cell carcinoma (P < 0.001) and a positive relation between increased MDM2 expression and failure of radiotherapy (P = 0.007). These findings suggest that COX-2 is an important marker of disease progression and that MDM2 expression is useful for treatment planning.

p53 and ki67 as biomarkers in determining response to chemoprevention for oral leukoplakia

BACKGROUND

We performed a randomized controlled chemoprevention trial of oral leukoplakia by administrating a low dose of beta-carotene and vitamin C supplements. 17% of subjects in the experimental arm (4/23) demonstrated clinical remission (complete or partial response) at completion of the trial. The objective of this study was to determine whether baseline expression of p53 and ki67 demonstrated any differences between those responding or not responding to our intervention. A secondary objective was to elucidate any relationship between dietary factors and clinical responses.

METHODS

For this biomarker study, we included all subjects in the experimental group (n = 23) who were non-smokers. Among 16 who completed the trial for 1 year of supplementation, there were four responders and 12 non-responders at 1-year follow-up. Following immuno-staining for p53 and ki67, the percentage of positive cell nuclei were analyzed as labeling index (LI).

RESULTS

Expression of p53 was greater in basal layers than in para-basal layers. Mean para-basal LI of p53 was higher in non-responding (26.0) than in responding subjects (11.2) (P = 0.028). ki67 LIs were not significantly different in the two groups.

CONCLUSIONS

Expression of p53 was inversely related to clinical response to the supplements. Other biomarkers that may recognize subject's responsiveness to chemoprevention require further study.

Identification of a combined biomarker for malignant transformation in oral submucous fibrosis

Background

Oral submucous fibrosis (OSF) is a chronic progressive disease of the oral cavity that is considered a common potentially malignant disorder in South Asia. Areca nut chewing is the main etiological factor, but its carcinogenic mechanism has yet to be proven. The purpose of this study was to identify the useful biomarkers in predicting high‐risk patients with OSF.

Methods

Thirty‐six cases of OSF and six cases of normal oral mucosa (NOM) were used for this study. Immunohistochemical staining was performed for Ki67, cyclin D1, p16, p53, β‐catenin, c‐Jun, c‐Met, and insulin‐like growth factor II mRNA‐binding protein 3 (IMP3). The expression patterns of NOM served as guidelines for the scoring system.

Results

The expression of Ki67, cyclin D1, c‐Met, IMP3, and β‐catenin showed a significant difference between OSF and NOM samples. The combined biomarkers of Ki67 and p16 showed significantly different expression between the transformation and non‐transformation groups. With discriminant analysis, we proposed a noble formula and cutoff value for predicting high‐risk patients with OSF.

Conclusion

The notable biomarkers in our present study were Ki67 and p16 showing significantly different expression levels between the transformation and non‐transformation groups. With the identification of high‐risk patients with OSF, we can expect to develop more intensive treatment modalities, leading to the reduction in cancer transformation rate from OSF.

Potentially malignant disorders of the oral cavity: current practice and future directions in the clinic and laboratory

Despite commendable progress in the prevention, detection, and treatment of a wide variety of solid tumor types, oral squamous cell carcinoma (OSCC) remains a significant health burden across the globe. OSCC carcinogenesis involves accumulation of genetic alterations that coincide with the multistep malignant transformation of normal oral epithelium. OSCC is often first diagnosed at late stages of the disease (advanced regional disease and/or metastasis). Delayed diagnosis precludes successful treatment and favorable outcomes. In clinical practice, opportunities exist to identify patients with oral potentially malignant disorders (OPMDs), which precede the development of cancer. This review addresses the current status of laboratory and clinical research on OPMDs, with emphasis on leukoplakia and erythroplakia. OSF is also presented, though there is a paucity of published studies on this disorder. We focus on findings that could translate into earlier diagnosis and more efficacious treatment of those lesions with significant malignant potential. We explore how markers of OPMD malignant transformation might be implemented into current diagnostic practice to help clinicians objectively stratify patients into treatment/follow-up groups according to relative risk. We provide an overview of recently concluded and ongoing OPMD chemoprevention trials. We describe laboratory OPMD models that can be used to not only to reveal the genetic and molecular intricacies of oral cancer but also to develop novel screening methods and therapeutic approaches. Finally, we call for targeted screening programs of at-risk populations in order to facilitate diagnosis and treatment of OPMD and early OSCC.

Can immunohistochemistry serve as an alternative to subjective histopathological diagnosis of oral epithelial dysplasia?

Many attempts have been made to identify objective molecular biomarkers to diagnose and prognosticate oral epithelial dysplasia (OED) because histopathological interpretation is subjective and lacks sensitivity. The majority of these efforts describe changes in gene expression at protein level in OED as determined by immunohistochemistry (IHC). However, the literature on these putative markers of oral cancer progression is vast and varied. The main purpose of this article is to review current knowledge on biomarkers of protein expression for OED by IHC approaches. We further discuss these findings in terms of the proposed essential hallmarks of cancer cells to better understand their role in oral oncogenesis.

Genetics/epigenetics of oral premalignancy: current status and future research

Squamous cell carcinoma (SCC) of the oral and oropharyngeal region is the sixth most common malignancy in the world today. Despite numerous advances in treatment, long-term survival from this disease remains poor. Early detection can decrease both morbidity and mortality associated with this neoplasm. However, screening for potentially malignant disease is typically confounded by difficulty in discriminating between reactive/inflammatory lesions vs those lesions that are premalignant in nature. Furthermore, the histologic diagnosis of dysplasia can be subjective and is thus prone to a considerable range of interpretation. Similarly, no definitive, validated criteria exist for predicting which dysplastic lesions are most likely to progress to cancer over time. Given this state of science, the presence of dysplasia can only be used to indicate that an oral lesion may have an increased risk of malignant transformation. Molecular biomarkers capable of identifying the subset of lesions likely to progress to cancer are required to eliminate this clinical diagnostic dilemma. The purpose of this review is to assess the current state of knowledge regarding genetic/epigenetic alterations observed in oral mucosal premalignancy. In addition, recommendations for future research studies directed at defining the predictive capacity of specific biomarkers in this modeling are presented.

Proliferation and apoptosis markers in oral submucous fibrosis

BACKGROUND

Premalignant/potentially malignant-oral lesions and conditions such as oral submucous fibrosis are known to transform into oral cancer. The malignant transformation is often associated with changes at the genetic level that in turn is reflected by the altered expression of proteins related to cell cycle, proliferation, and apoptosis.

AIM

To evaluate the expression of p53, Ki67 (MIB), bcl2, and bax in oral submucous fibrosis and oral squamous cell carcinoma.

MATERIALS AND METHODS

To assess the immunohistochemical expression of p53, Ki67 (MIB), bcl2, and bax in 50 cases of oral submucous fibrosis (OSF) and ten each of normal and oral squamous cell carcinoma (OSCC).

RESULTS

The labeling indices (LI) of OSF and OSCC were comparable for p53 and Ki67.The p53 LI ranged from 7.9 to 71.9 in OSF and 65.2 to 85.9 in OSCC, and for Ki67 it ranged from 4.39 to 43.23, 18.35 to 42.33, respectively.

CONCLUSION

The p53, Ki67, and bax profiles of OSF and OSCC were altered compared to the normal and these markers could be used as surrogate markers of malignant transformation in OSF.

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.

Management of oral epithelial dysplasia: a review

One of the goals of the fourth meeting of The World Workshop on Oral Medicine (WWOM IV) included a review of the pathophysiology and future directions for the clinical management of patients with oral epithelial dysplasia, excluding the lips and oropharynx. In the pathophysiology review of dysplasia since WWOM III (1998-2006), a wide range of molecular changes associated with progression of dysplasia to squamous cell carcinoma were found. These include loss of heterozygosity, dysregulation of apoptosis, aberrant DNA expression, and altered expression of numerous tissue markers. Based on the literature search, no single molecular pathway has been identified as the primary factor in progression of dysplasia to squamous cell carcinoma. A systematic review of medical (i.e., nonsurgical) management strategies for the treatment of dysplastic lesions has shown promising results in short-term resolution of dysplasia in the small number of studies that met eligibility criteria for review. However, because of the limited periods of follow-up reported in these studies, it remains unclear as whether resolution of dysplasia would actually be a long-term benefit of these interventions. This question is particularly germane when it is considered in the context of prevention of future development of squamous cell carcinoma. Because of the lack of randomized controlled trials that have shown effectiveness in the prevention of malignant transformation, no recommendations can be provided for specific surgical interventions of dysplastic oral lesions either.

Clinical, pathological, cellular and molecular lesions caused by oral smokeless tobacco - a review

While carcinogenicity of smokeless tobacco (ST) to humans is well established the oral lesions that precede development of cancer are less well characterized. The clinical appearances of ST-associated lesions are variable. Epidemiological studies show a strong significant association of risk with chronic daily use but population differences are noted because of various commercial products in use. Morphological features observed are some what different to oral lesions caused by smoking and oral dysplasia in ST-associated lesions is less common. Effects of ST on oral keratinocytes observed in vitro include alterations in cell proliferation, apoptosis and activation of inflammatory markers. Genetic aberrations caused by ST include activation of ras, uncommon in smokers but mutational hot spots in p53 encountered are similar to those in smokers.

The relationship of the histologic grade at the deep invasive front and the expression of Ki-67 antigen and p53 protein in oral squamous cell carcinoma

BACKGROUND

Although many histopathologic characteristics of oral squamous cell carcinoma (O-SCC) have been identified as prognostic factors, accurate, and unequivocal factors have not been clearly identified. The purpose of this study was to evaluate a potential association between the histologic grade of malignancy at the deep invasive front and the expression of Ki-67 antigen and p53 protein in O-SCC.

METHODS

The expression of Ki-67 antigen and p53 at the invasive tumor front area of O-SCC was examined by immunohistochemistry of archived tissue from 62 cases. The mean age of patients was 60.7 years (range: 37-89) and the male-female ratio was 1.6:1 (38 men, 24 women). There were 20, 17, 14, and 11 cases classified as stage I to stage IV, respectively. The correlation between the intensity of immunostaining for Ki-67 antigen and p53 and the histologic grade of malignancy at the deep invasive front (invasive front grade, IFG) was analyzed. The expression of Ki-67 antigen and p53 in normal oral epithelia (10 cases) was also investigated.

RESULTS

The mean Ki-67 labeling index (LI) in the O-SCC samples was 32.8 +/- 12.0% (n = 62). The mean total score of IFG (IFG score) was 9.1 +/- 2.7 points (n = 62). There was a significant linear correlation between the IFG score and the Ki-67 antigen (gamma = 0.651, R2 = 0.596, P < 0.0001). Of 50 tumors examined, 27 (54.0%) exhibited p53-positive nuclear immunostaining. The staining patterns for Ki-67 antigen and p53 were similar. Both Ki-67-LI and p53-positive status were significantly correlated with the IFG scores.

CONCLUSION

The findings of this study demonstrate that overexpression of Ki-67 antigen and p53 at the deep tumor invasive front of O-SCC is associated with histologic grade of malignancy.

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.

Alterations in expression of retinoid receptor beta and p53 in oral submucous fibrosis

OBJECTIVE

Knowledge of the molecular pathogenesis of oral submucous fibrosis (OSF), a potentially malignant condition with high risk of transition to oral cancer, is meagre. Alterations in the expression of retinoic acid receptor beta (RARbeta) and tumor suppressor gene, p53 are early events in oral tumorigenesis. The aim of this study was to investigate the alterations in the expression of RARbeta and p53 in OSF lesions and determine their association with disease pathogenesis.

METHODS

The expression of RARbeta and p53 proteins was analyzed by immunohistochemistry in 50 cases of OSF and 30 histologically normal oral tissues.

RESULTS

No detectable RARbeta expression was observed in 35 of 50 (70%) OSF cases. p53 protein accumulation was observed in 24 of 50 (48%) OSF cases analyzed. Thirty-six percent OSF lesions showed loss of RARbeta and p53 overexpression. Interestingly, 41 of 50 (82%) of OSF lesions showed altered expression of at least one of these two proteins.

CONCLUSION

Altered expression of either RARbeta or p53 in majority of OSF lesions suggests their association with disease pathogenesis and warrants follow-up to determine whether OSF lesions harboring concomitant alterations in RARbeta and p53 are at a high risk of transition to malignancy.

Habitual betel quid chewing and risk for hepatocellular carcinoma complicating cirrhosis

This case-control study aimed to assess the independent and interactive role of habitual betel quid chewing and known risk factors for hepatocellular carcinoma (HCC). Subjects enrolled included 210 pairs of sex- and age-matched cirrhotic patients with HCC, patients with cirrhosis alone, and healthy controls. Information on risk factors was obtained through serologic examination of hepatitis B surface antigen (HBsAg) and antibodies to hepatitis C virus (anti-HCV), and a standardized personal interview with a structured questionnaire. Multivariate analysis indicated that betel quid chewing (odds ratio [OR], 5.81; 95% confidence interval [CI], 2.26-14.94); HBsAg (OR, 37.98; 95% CI, 19.65-73.42); and anti-HCV (OR, 47.23; 95% CI, 18.86-118.25) were independent risk factors for HCC when HCC patients were compared with healthy controls. Using patients with cirrhosis alone as a reference group, multivariate analysis indicated that only betel quid chewing (OR, 1.69; 95% CI, 1.04-2.76) and HBsAg (OR, 1.54; 95% CI, l.01-2.37) were independent risk factors for HCC. There was an additive interaction between betel quid chewing and the presence of either HBsAg (synergy index, 5.22) or anti-HCV (synergy index, 1.35). Moreover, a higher risk of HCC was associated with a longer duration of betel quid chewing and a larger amount of betel quid consumed (each p(for trend) < 0.0001). In conclusion, betel quid chewing is an independent risk factor for cirrhotic HCC. There is an additive interaction between betel quid chewing and chronic hepatitis B and/or hepatitis C virus infection.

Alteration of the fragile histidine triad gene early in carcinogenesis: an update

An association between common chromosome fragile sites and frequent chromosomal deletions in cancer has been observed and led to the hypothesis that genes at fragile sites may play a role in tumor development. In 1996, the human fragile histidine triad gene, FHIT, was identified by positional cloning at 3p14.2, a chromosomal region spanning the carcinogen-sensitive, common fragile site FRA3B. FHIT gene is lost and inactivated in a large fraction of tumors and early in carcinogenesis. A group of ancestral cancerous cells that carry FHIT alterations, expanding in succeeding cell generations, exhibits a hallmark in carcinogenesis scenario.

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.

Prognostic relevance of molecular markers of oral cancer--a review

The aim of the present article was to review the current knowledge on the prognostic value of tumour marker in the treatment of oral squamous cell carcinoma (OSCC). The literature of the past 5 years (1997-August 2002) was screened. One hundred and sixty-nine articles were included in this review, twenty-nine molecular markers of relevance were identified. Tumour markers were allocated to four groups according to their function: (i) Enhancement of Tumour Growth: Cell cycle acceleration and proliferation, (ii) Tumour Suppression and Anti-Tumour Defence: Immune response and apoptosis, (iii) Angiogenesis, (iv) Tumour Invasion and Metastatic Potential: Adhesion molecules and matrix degradation. Data showed that the prognostic relevance of most tumour markers is still not quite clear. Only 12 of 23 reports on the prognostic relevance of markers for cell cycle acceleration and proliferation indicated a significant association with prognosis while 20 of 29 studies on markers for tumour suppression and anti-tumour response showed prognostic relevance. Markers of angiogenesis exhibited only minor importance for the prognosis and treatment of OSCC. Results on markers of tumour invasion and metastatic potential appeared to be too premature for a statement regarding their prognostic value. In general, the location of markers within the tumour and not their quantitative assessment as such is emphasized. Particularly, the analysis of the invasive front of the tumour with regard to the occurrence of molecular markers is supposed to be of great importance for prognostication.

The Ljubljana classification - its application to grading oral epithelial hyperplasia

INTRODUCTION

The diagnosis, prognosis and treatment of particular pathologic entities of the oral mucosa depend almost exclusively on the histologic changes in the epithelium. The basis for the classification of oral epithelial hyperplastic lesions should be their propensity to progress to invasive cancer.

MATERIAL AND METHODS

In a retrospective study, 135 biopsies of oral epithelial hyperplastic lesions from 115 patients were classified according to the Ljubljana classification, which has recently been introduced for the grading of laryngeal hyperplastic epithelial lesions.

RESULTS

Seventy nine cases (59%) showed simple, 42 (31%) abnormal and 11 (8%) atypical hyperplasia; carcinoma in situ was found in three cases (2%). During the follow-up, ranging from 3 months to 6 years (median 1 year), two cases of atypical hyperplasia progressed to invasive cancer, whereas none of the cases classified as simple or abnormal hyperplasia showed progression.

CONCLUSION

The present study suggests that the Ljubljana classification can be reliably applied for classifying oral epithelial hyperplastic lesions into different risk groups, which is essential for prognosis in order to plan therapy.

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.

Prevalence of p53, bcl-2, and Ki-67 immunoreactivity and of apoptosis in normal oral epithelium and in premalignant and malignant lesions of the oral cavity

PURPOSE

Loss of normal p53 is correlated to the progression of several preneoplastic lesions to neoplasms, and overexpression of bcl-2 determines an alteration of programmed cell death. There is an increased awareness of the importance of apoptosis in cancerogenesis, and a strong correlation of Ki-67 with high tumor grade has been reported.

MATERIALS AND METHODS

The aim of our study was to investigate immunohistochemically the expression and relationship of p53, bcl-2, MIB-1, and the apoptotic index (AI) in normal oral epithelium, leukoplakia, dysplasia, and oral squamous cell carcinoma.

RESULTS

A strong correlation was found between p53 overexpression and cell proliferation (MIB-1) and the AI. An inverse relationship was found between bcl-2 expression and MIB-1 and AI. A significant inverse relationship was found between p53 and bcl-2. A good positive correlation was present between AI and MIB-1 expression.

CONCLUSIONS

Apoptosis could be important to help to understand oral carcinogenesis.

Clinical implications of biomarkers in head and neck cancer

The term biomarker refers to a host of biologic factors found within a tumor or other clinical specimen that can be used to assess the tumor in some way. Biomarkers have many potential clinical applications. Before they are used in actual clinical settings, however, they must be carefully validated. The literature contains many reports of this ongoing work related to head and neck squamous cell carcinoma. Candidate biomarkers for this disease include the p53 gene and its protein; microsatellite regions throughout the genome; human papillomavirus; proteins involved in cellular proliferation, apoptosis, angiogenesis, and intracellular adhesion; epithelial growth factor receptor; and various measures of immune response to cancer. The best new evidence for the validity of each of these candidates is critiqued in this review.

Development of squamous cell carcinoma from pre-existent oral leukoplakia: with respect to treatment modality

The present study was undertaken in order to determine whether surgical treatment of oral leukoplakia reduces the risk of the subsequent development of carcinoma. This study included 142 patients with oral leukoplakia who received or did not receive surgical treatment. All subjects were followed-up for more than 6 months with a mean follow-up period of 4 years. Malignant transformation rate was lower among patients who received surgical excision (1/75) than among those who did not receive surgical treatments (4/51). However, the malignant transformation rates were high in patients who received cryosurgery (3/12) or cryosurgery plus surgical excision (1/4). There was no obvious relation between the grade of epithelial dysplasia and the rate of malignant transformation. Our results suggest that surgical excision of oral leukoplakia may reduce the risk of the subsequent development of carcinoma.

Cell-cycle control in cell-biomaterial interactions: expression of p53 and Ki67 in human umbilical vein endothelial cells in direct contact and extract testing of biomaterials

Current biocompatibility testing involves the demonstration of cell proliferation, which is usually interpreted as a sign of positive biocompatibility when the materials sustain cell proliferation. As the field of biomaterials research is rapidly moving toward tissue-engineered devices and hybrid organs, control of cell function has become a main topic. Cell function, which involves specific differentiation pathways, cannot be separated from cell-cycle control. The study of cell-cycle control is an important extension of routine proliferation assays and has extensive roots in developmental and tumor biology. We studied the expression of the tumour suppressor gene p53 and the proliferation-associated antigen Ki67 of endothelial cells in response to biomaterial contact. Cells were seeded in six- or 24-well plates, in which one or three 12-mm-diameter biomaterial disks were laid down. After 48- and 72-h incubation periods, cells were processed for flow cytometry, immunofluorescence, or Western blotting. The following materials were used: titanium, NiCr alloy, and CoCr alloy. Cells were also exposed to 24-h (ISO-norm) extracts in 25-cm(2) culture flasks (600, 000 cells) for 24 and 48 h. For extract testing, serially diluted Ni-ion suspensions were also used. Human umbilical vein endothelial cells adhered to metal surfaces and started forming a monolayer within 3 days. Ki67 expression was positive in more than 60% after 2 days and decreased markedly after 3 days of adhesion. During this time cells developed focal contacts and produced a fibronectin matrix. p53 expression could be demonstrated with Western blotting and flow cytometry, but not with immunofluorescence. Differences due to both culturing time and material were found in expression patterns with both methods. Inverse correlations between Ki67 and p53 expression were detected, which are probably based on culture kinetics. The results indicate that expression of p53 and also Ki67 is clearly influenced by biomaterials in direct contact testing, despite the absence of obvious morphological differences. The p53 marker can be used for defining cell function in more detail, although the correlation with specific physiological function has still to be clarified.

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.

Lack of molecular markers to predict malignant potential of oral precancer

Studies on the natural history of oral squamous cell carcinoma suggest a clinically detectable phase which precedes the development of cancer. Among the precancerous states, leukoplakia is the most commonly encountered clinical lesion. Although epithelial dysplasia is the most important predictive factor, non-dysplastic lesions in the oral cavity may transform with time. Early reports describing p53 overexpression in oral leukoplakia has resulted in many authors misinterpreting this result by concluding that p53 is an early marker of oncogenesis. Using sequential biopsies, few reports have critically examined the clinical significance of p53 as a risk marker. These studies suggest that p53 protein stabilization, or indeed the spectrum of mutations of p53, has no major relationship to the biological characteristics and outcome of oral leukoplakia. When used as a single marker, p53 is unsuitable for the prediction of tumour development in high-risk subjects and no other maker has yet emerged as useful. Despite the impact of molecular diagnostics on the diagnosis of tumours, assessing a patient's risk for development of cancer of the oral cavity remains limited to 'H&E' pathology.