Apoptosis, mitosis, PCNA and bcl-2 in normal, leukoplakic and malignant epithelia of the human oral cavity: prospective, in vivo study

Expressional variations of Kaiso: an association with pathological characteristics and field cancerization of OSCC

Background

A group of genetically altered cells that have not transformed into a clinical or histologically identifiable state of malignancy but contains a higher risk of transforming into one is known as the field of cancerization. Numerous molecules are being investigated for their significance in the development of this phenomenon. One such protein of this family is Kaiso also known as ZBTB33 (Zinc Finger and BTB Domain containing 33). This protein belongs to the POZ-ZF family of transcription factors and may have functional tasks similar to its other siblings such as the growth and development of vertebrates and the pathogenesis of neoplastic diseases. Nevertheless, its role in the pathogenesis, progression, epithelial mesenchyal transition and field cancerization in case of oral cancer still needs exploration. Hence, this study was designed to explore the expressional differences between the mucosa of controls and those diagnosed with oral squamous cell carcinoma (OSCC).

Methods

Soft tissue samples were obtained from the main tumor, tumor periphery and opposite buccal mucosa of 50 oral cancer patients, whereas normal mucosa was taken from 50 volunteers undergoing elective tooth removal. The acquired samples were subjected to Immunohistochemical exploration for expression of Kaiso and E-Cadherin. The expression was measured using Image-J IHC profiler and summed as Optical density. The Optical density values were then subjected to statistical analysis.

Results

Results revealed a significant differential expression of Kaiso between the mucosal tissues taken from oral cancer patients and controls (p-value: < 0.0001), showing almost 50% down-regulation of Kaiso in all three tissue samples taken from oral cancer patients as compared to normal mucosa.

Conclusion

Kaiso has a significant difference of expression in the mucosa of oral cancer patients as compared to the mucosa of normal patients, making it a probable contributor to disease pathogenesis and field cancerization.

Predicting transition from oral pre-malignancy to malignancy via Bcl-2 immuno-expression: Evidence and lacunae

Bcl-2 (B cell Lymphoma -2) family comprises of both anti-apoptotic and pro-apoptotic proteins whose altered expression or change in ratio inhibits apoptosis, and promotes tumor progression. The aim of this study is to assess the usefulness of Bcl-2 in distinguishing dysplastic or malignant epithelium from non-dysplastic or normal epithelium to aid in prediction of malignant transformation potential.

Material and method

Study group comprised of 30 cases of clinically diagnosed leukoplakia (OPMD), 15 cases of Oral Squamous Cell Carcinoma (OSCC) and 5 normal tissue samples. The labeling index of Bcl-2 was analyzed in immunohistochemically stained sections. Different statistical tools were used to analyze the data and to compare Bcl-2 expression qualitatively and quantitatively among all the groups.

Results

An increasing trend of Bcl-2 immunoexpression was observed from normal epithelium to non-dysplastic and from non-dysplastic to dysplastic lesions. In OSCC, the peripheral cells in the differentiating epithelial islands (within the connective tissue) showed Bcl-2 immuno-reactivity, which gradually decreased towards the center. In contrast, intense and diffuse Bcl-2 immuno-reactivity was seen in poorly differentiated carcinoma. But the overall Bcl-2 positivity was less in OSCC as compared to dysplastic lesions.

Conclusion

Increased expression of Bcl-2 oncoprotein in sequentially progressing epithelial dysplasia and down-regulation in differentiating carcinoma (well and moderately differentiating OSCC) unveils the clinical relevance of Bcl-2 in early stages of OSCC tumorigenesis. The heterogenous expression of Bcl-2 in carcinoma with different grades of differentiation renders them unable to be used as an independent tool for predicting transition from oral pre-malignancy to malignancy.

Analysis of images for detection of oral epithelial dysplasia: A review

This paper provides a review of various image analysis approaches that have been previously used for recognition of dysplasia in images of the epithelium of the oral cavity. This domain has become especially admissible with the uncovering of the importance of image analysis which can probably be an aid to subjective diagnosis by histopathologists. Oral malignancy is a rampant form of cancer found among people of the Indian subcontinent due to various deleterious habits like consumption of tobacco, areca nut, betel leaf etc. Oral Submucous Fibrosis, a precancer, whose pathological category falls between normal epithelium and epithelial dysplasia, is caused because of these habits and can ultimately lead to oral cancer. Hence early detection of this condition is necessary. Image analysis methods for this purpose have an enormous potential which can also reduce the heavy workload of pathologists and to refine the criterion of interpretation. This paper starts with a critique of statistics of oral carcinoma in India and distribution of cancer in intra-oral sites and moves on to its causes and diagnostic approaches including causative agents, problems in curative approach and importance of image analysis in cancer detection. The various image analysis methods to appraise the cytological and architectural changes accompanied by Oral Epithelial Dysplasia in the images of the oral epithelial region have been described in relation to 2005 WHO Classification System and it was found that in future, analysis of images based on the mentioned methods has the potential in better interpretation and diagnosis of oral carcinoma.

High MYC Levels Favour Multifocal Carcinogenesis

The term "field cancerisation" describes the formation of tissue sub-areas highly susceptible to multifocal tumourigenesis. In the earlier stages of cancer, cells may indeed display a series of molecular alterations that allow them to proliferate faster, eventually occupying discrete tissue regions with irrelevant morphological anomalies. This behaviour recalls cell competition, a process based on a reciprocal fitness comparison: when cells with a growth advantage arise in a tissue, they are able to commit wild-type neighbours to death and to proliferate at their expense. It is known that cells expressing high MYC levels behave as super-competitors, able to kill and replace less performant adjacent cells; given MYC upregulation in most human cancers, MYC-mediated cell competition is likely to pioneer field cancerisation. Here we show that MYC overexpression in a sub-territory of the larval wing epithelium of Drosophila is sufficient to trigger a number of cellular responses specific to mammalian pre-malignant tissues. Moreover, following induction of different second mutations, high MYC-expressing epithelia were found to be susceptible to multifocal growth, a hallmark of mammalian pre-cancerous fields. In summary, our study identified an early molecular alteration implicated in field cancerisation and established a genetically amenable model which may help study the molecular basis of early carcinogenesis.

Image analysis assisted study of mitotic figures in oral epithelial dysplasia and squamous cell carcinoma using differential stains

BACKGROUND

Mitosis is a process of cell division resulting in two genetically equivalent daughter cells. Excessive proliferation of cells due to mitosis is the hallmark in pre cancer and cancer.

AIMS

This study was conducted to count the number of mitotic figures in normal oral mucosa, oral epithelial dysplasia and squamous cell carcinoma in both Hematoxylin and Eosin (H&E) and Crystal Violet stained sections. Also the overall number of mitotic figures with both stains were compared along with the evaluation of staining efficacy of both the stains.

METHODS AND MATERIAL

The present study was conducted on 20 specimens each of the three categories. These were further divided into two groups for staining with H&E and with 1% Crystal Violet respectively. Images were captured and analyzed using image analysis software Dewinter Biowizard 4.1.

RESULTS

Comparison of mitotic figure count in three categories in sections stained with both stains showed statistically significant difference (p < 0.001). The mean number of mitotic figures seen in Crystal Violet reagent were significantly higher as seen in H&E stain (p < 0.001). The overall diagnostic efficacy of Crystal Violet was 87.6%. Crystal Violet scored over H&E stain and also helped to better appreciate metaphases in Squamous cell carcinoma and telophases in dysplasia.

CONCLUSION

Number of mitotic figures progressively increase with the advancement of the pathology. Use of 1% Crystal Violet provides better appreciation of mitotic figures and can be employed as a selective stain in routine histopathology.

Clinicopathological correlation of Bcl-2 oncoprotein expression in oral precancer and cancer

Oral squamous cell carcinoma is the most common malignant tumor of the oral cavity. Normally the death of cell and the growth are active processes and depend not only on external factors but also on the expression of genes such as Bcl-2, which activate and inhibit apoptosis. The term Bcl-2 is an acronym for B-cell lymphoma/leukemia-2 genes. It has been reported that there is deregulation of Bcl-2 expression during progression from oral epithelial dysplasia to squamous cell carcinoma. Expression of this oncoprotein can be detected by immunohistochemistry.

AIMS AND OBJECTIVES

An attempt was made to evaluate Bcl-2 oncoprotein expression in patients with oral precancer and cancer.

MATERIALS AND METHODS

A selective prospective clinical and immunohistochemical study. Clinicopathological examination was correlated with immunohistochemical findings. The immunolocalization of Bcl-2 protein was performed using the labeled streptavidin biotin method. To visualize the reaction, 3,3-diaminobenzidine was used.

RESULTS

Bcl-2 expression was positive in 11 [36.66%, low Bcl-2 expression 3 (10.00%), moderate Bcl-2 expression 7 (23.33%), and high Bcl-2 expression 1 (3.33%)] oral cancer cases and 14 [87.50%, low expression 8 (50%), moderate expression 6 (37.50%)] precancer cases.

CONCLUSION

On the basis of the results of our study, we conclude that positive Bcl-2 expression may be an indicator of poor prognosis in oral cancer and precancer.

Oral field cancerization: an update on current concepts

There always exists a field with genetically altered cells with a high risk of developing premalignant and malignant lesions. It may often happen that an individual stem cell is genetically altered and can cause the formation of a clone or a patch which is likely to turn into a tumor. This explains the higher recurrence rates following tumor resections. It is essential to identify and to treat this field in order to have greater chances to prevent cancer and achieve a better outcome. This article reports concepts, theories and markers for the assessment of field cancerization.

Oral field cancerization: current evidence and future perspectives

INTRODUCTION

Oral field cancerization implies that oral cancer does not arise as an isolated cellular phenomenon but rather as an anaplastic tendency involving many cells at once and results in the multifocal development of cancer at various rates within the entire field in response to a carcinogen especially tobacco. This concept has been frequently used to explain the occurrence of multiple primary cancers and recurrences following complete excision of oral cancer.

DISCUSSION

This review deals in detail with the origin, principle, various theories used to explain this effect and molecular, genetic, as well as cytogenetic findings related to oral field cancerization. Further, the clinical implications and future research directives are also discussed.

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.

PCNA and p53 expression in oral leukoplakia with different degrees of keratinization

Leukoplakias are oral lesions that may have many clinical and histological aspects and they are usually associated with malignancy when dysplastic alterations are shown. However, these transformations may occur in non-dysplastic lesions that show harmless clinical aspect. For this reason, the proposal was to study the p53 and PCNA immunohistochemical expression in non-dysplastic leukoplakias, trying to correlate the results only with the epithelial keratinization degree. For this, 24 leukoplakias degrees I, II and III of Grinspan were used, all of them located in oral mucosa. Most of the leukoplakias showed p53 and PCNA expression in their different keratinization degrees. The p53 marking was confined to the basal and parabasal layers, while the PCNA marking occurred in practically all epithelial layers. The expression pattern of these markers was histologically and statistically similar between the lesions with these keratinization variations. It was evident that non-dysplastic epithelium of leukoplakias showed submicroscopical signs of alterations that lead to malignant transformation, and that the keratinization degree did not correlate to a greater risk of this event.

Bcl-2 Expression in Oral Squamous Cell Carcinoma

Apoptosis is a genetically regulated process involved in tissue size regulation, morphogenesis, and elimination of genetically damaged cells. A pallet of genes is involved in the control of apoptosis, such as bcl-2 family whose oncogenic potential has been demonstrated in oral tumorigenesis. Different members of bcl-2 family may promote or inhibit apoptosis by synthesizing anti- and proapoptotic proteins. One of antiapoptotic proteins, bcl-2, with a crucial role in apoptosis regulation was the object of our study. By means of immunohistochemistry we estimated the level of overexpression of bcl-2 proteins in a series of the 26 formalin fixed, paraffin-embedded samples of oral squamous cell carcinoma (OSCC). Analyzed tumors originated from different sites of oral cavity; 7/26 belonged to stage II, 14/26 to stage III, and 5/26 to stage IV. Immunoreactivity was scored according to the percentage and intensity of positive cytoplasmic bcl-2 staining. All tumors had low percentage of positively stained bcl-2 cells, with mean values for lower/higher intensity of 8.3 +/- 2.5/34.4 +/- 7, 7.5 +/- 1.1/31.9 +/- 4.3, and 8.4 +/- 5.8/31.5 +/- 5.8 within stages II, III, and IV, respectively. Low level of bcl-2 expression in our sample seems to be associated with higher survival rate: 77% for the 5-year follow-up period. Comparing clinicopathologic and risk factors data within each and between three groups of analyzed tumors (lip-tongue P = 0.58, tongue-floor of the mouth, P = 0.21, lip-floor of the mouth, P = 0.50) there was no significant difference. However, our results suggest that the level of bcl-2 expression could be a valuable predictor of tumor behavior and disease outcome.

Use of fuzzy neural networks in modeling relationships of HPV infection with apoptotic and proliferation markers in potentially malignant oral lesions

To evaluate in oral leukoplakia the relationship between HPV infection and markers of apoptosis (bcl-2, survivin) and proliferation (PCNA), also conditionally to age, gender, smoking and drinking habits of patients, by means of Fuzzy neural networks (FNN) system 21 cases of oral leukopakia, clinically and histologically diagnosed, were examined for HPV DNA presence, bcl-2, survivin and PCNA expression. HPV DNA was investigated in exfoliated oral mucosa cells by nested PCR (nPCR: MY09-MY11/GP5-GP6), and the HPV genotype determined by direct DNA sequencing. All markers were investigated by means of standardised immunohistochemistry procedure. Data were analysed by chi-square test, crude OR and the 95% CI; in blindness, FNN was applied. HPV DNA was found in 8/21 OL (38.1%); survivin, PCNA, and tobacco smoking were associated in univariate analysis (p = 0.04) with HPV DNA status. HPV-18 was the most frequently detected genotype (6/8), followed by HPV-16 (2/8). FNN revealed that survivin and PCNA, both being expressed in all of OL HPV+ve, were associated with HPV infection. In conclusion, the FNN allowed to hypothesise a model of specific variables associated to HPV infection in OL. The relevance of survivin and PCNA suggest that they may be involved in HPV-mediated deregulation of epithelial maturation and, conversely, that HPV may have a role in the expression level of these two markers. FNN system seems to be an effective tool in the analysis of correlates of OL and HPV infection.

Molecularly targeted agents: Their promise as cancer chemopreventive interventions

Molecular medicine has fully entered in to the oncology arena. The development of targeted therapies is one of the major ongoing efforts in cancer treatment. Targeted therapy refers to treatment strategies directed against molecular targets considered to be involved in neoplastic transformation. Such molecularly targeted agents (MTA) are currently under study in all treatment settings including that of chemoprevention, defined as the use of natural or synthetic agents to interrupt the carcinogenic process, to nip tumours in the bud. This review article aims to provide a general overview of the potential use of some of these MTA in the chemoprevention setting.

Two-phase appearance of oral epithelial dysplasia resulting from focal proliferation of parabasal cells and apoptosis of prickle cells

BACKGROUND

One of the histologic characteristics of epithelial dysplasias of the oral mucosa is droplet-shaped rete processes resulting from a solid proliferation of basaloid cells. These basaloid cells are suddenly changed into an overlay of parakeratotic cells. However, it is unknown how this characteristic two-phase appearance is generated.

METHODS

Formalin-fixed paraffin sections of the oral mucosal specimens with normal, hyperplastic, dysplastic epithelia and squamous cell carcinomas were examined for apoptosis by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) method and for lymphoid cells by immunohistochemistry.

RESULTS

Apoptotic cells were only located in the keratinized layer of normal/hyperplastic epithelia. However, in epithelial dysplasias, apoptotic cells were scattered in the middle or even in the lower parts of the epithelial layer with frequent vacuolation changes of epithelial cells. Within the epithelial layer of dysplasias, there were increased number of lymphocytes, which were immunopositive for CD45RO, CD8, and CD57- and CD68-immunopositive (+), S-100 protein-positive and major histocompatibility complex (MHC) class II-positive monocytic lineages. They increased in number with the severity of dysplastic degrees, and they were often located in the vicinity of apoptotic epithelial cells, but decreased in carcinomas in situ and invasive carcinomas, which contained fewer numbers of apoptotic figures.

CONCLUSION

The findings indicate that intraepithelial infiltrations of both cytotoxic T cells and natural killer cells are closely related to the apoptotic phenomena of prickle cells, which may result in the characteristic 'two-phase appearance' of epithelial dysplasia.

The dl1520 virus is found preferentially in tumor tissue after direct intratumoral injection in oral carcinoma

PURPOSE

dl1520 (also known as Onyx-015) is an E1B-deleted adenovirus designed to selectively lyse p53-deficient cancer cells. Clinical trials involving patients with recurrent squamous cell carcinoma of the head and neck have shown clinical efficacy, but no direct evidence as to the tumor or p53 selectivity of the virus was demonstrated. We wanted to determine whether dl1520 is selective for survival and replication within tumor tissue after direct injection and whether this is determined by p53 status of the tissues. We also wanted to ascertain whether the virus has any macroscopic effect on normal tissue.

EXPERIMENTAL DESIGN

An open-label Phase II trial was devised in which a fixed dose of the virus was administered to 15 patients via a direct intertumoral injection before surgery for untreated oral squamous cell carcinoma. The agent was also delivered into an area of adjacent normal buccal mucosa. Specimens of the excised tumor and of biopsies of the injected normal tissue were assessed for viral presence and p53 status.

RESULTS

We demonstrated that the virus replicates selectively in tumor as opposed to normal tissue after this direct injection. It was not possible to determine whether this selectivity was p53 related. It was found that dl1520 triggers an early rise in apoptosis levels in injected normal tissues. No adverse effects of viral injection were noted.

CONCLUSIONS

This is the first report of injection of dl1520 into previously untreated squamous cell cancer. The data support the concept that dl1520 is replication deficient in normal, compared with cancerous, tissues and has potential as a selective anticancer agent against tumor tissues.

Detection of apoptotic cells in whole saliva of patients with oral premalignant and malignant lesions: A preliminary study

OBJECTIVE

The purpose of this study was to identify and measure apoptotic cells in whole saliva of patients with oral premalignant and malignant lesions and explore its utility as a prognostic indicator.

STUDY DESIGN

A fluorescent TUNEL technique (APO-BrdU TUNEL) modified by our lab was applied to unstimulated whole saliva from 8 healthy volunteers, 16 patients with oral leukoplakia and/or lichen planus, 10 untreated and 5 treated cases with oral malignant lesion.

RESULTS

The apoptotic cells in whole saliva were detected in 4 groups of study subjects. The apoptotic cells demonstrated morphology similar to normal exfoliated epithelial cells of oral mucosa. The fraction of apoptotic cell in treated malignant patients (18.18+/-12.65) was significantly higher than that in healthy volunteers (6.99+/-6.52), premalignant patients (4.43+/-5.52), and untreated malignant patients (3.40+/-5.14) (P<.05).

CONCLUSION

Detection of apoptotic epithelial cells in whole saliva appears to have some clinical potential in monitoring reaction to chemoradiotherapy and may reveal some insight into the mechanism of oral carcinogenesis.

Análise da imunoexpressão do PCNA e p53 em carcinoma de células escamosas oral: correlação com a gradação histológica de malignidade e características clínicas

OBJETIVO: Analisar a imunoexpressão das proteínas PCNA e p53 em carcinoma de células escamosas oral (CCEO) vislumbrando verificar uma possível correlação entre o escore de malignidade e os dados clínicos dos pacientes. MÉTODOS: Selecionou-se 14 casos de CCEO e classificando-os de acordo com uma adaptação do sistema de gradação histológica de malignidade proposto por Anneroth, Batsakis, Luna, enquadrando-se 7 casos como baixo escore de malignidade (Grupo I) e 7 casos como alto escore (Grupo II). As informações dos pacientes foram coletadas através de fichas clínicas e os dados tabulados. Realizou-se, então, o estudo imuno-histoquímico utilizando anticorpos monoclonais anti-PCNA e anti-p53, obtendo-se o índice de positividade (IP) em cada caso. RESULTADOS: Identificou-se um IP médio ao PCNA de 56,0% no Grupo I e 83,8% no Grupo II. Com relação à p53 o IP médio no Grupo I e no Grupo II correspondeu, respectivamente, a 41,2% e 41,4%. A análise estatística demonstrou correlação significativa entre o índice de células PCNA positivas e o escore de malignidade. Nenhuma outra correlação foi observada. CONCLUSÕES: O maior número de células PCNA positivas correlacionou-se com elevado escore de malignidade em CCEOs, sugerindo maior atividade proliferativa nestas lesões, entretanto, tal correlação não se estabeleceu quando da análise da imunoexpressão da p53.

Cell death regulation in oral squamous cell carcinoma: methodological considerations and clinical significance

In the last three decades, more work has been done on apoptosis and its role in the pathogenesis of many diseases including cancer. In almost all instances of cancer, dysregulation of cell death (apoptosis) and cell proliferation have been found to play a major role in tumourigenesis. A lot of progress has been made on understanding the molecular basis of apoptosis and its regulatory mechanisms. This review focuses on current knowledge on the regulation of apoptosis in oral squamous cell carcinoma, current methodologies and methodological consideration in estimation of cell death in tissue sections and the clinical significance of apoptosis related molecules in progression of oral squamous cell carcinoma.

Analysis of proliferation, apoptosis and keratin expression in cultured normal and immortalized human buccal keratinocytes

The current study was undertaken to analyse growth and differentiation-related functions of normal keratinocytes (NOK) and an SV40T-immortalized keratinocyte line (SVpgC2a) from buccal mucosa, viewing the latter cell line as a model of a dysplastic epithelium. Morphological and immunohistochemical assessments of organotypic epithelia generated from 10 or 17 d of culture showed three- to five-fold higher apoptotic and proliferative activity in SVpgC2a relative to NOK. Conditions with or without serum (up to 10%) did not significantly influence these parameters in NOK whereas serum supported proliferation of SVpgC2a. Both cell types showed basal expression of collagen IV and laminin 1, indicating basal lamina, as well as vimentin, indicating an activated, proliferative state. Reduced expression of keratin, including the non-keratinizing marker K13, was seen in SVpgC2a. Assessment of proliferative monolayer cultures by microarray showed that NOK transcribed tissue-specific keratins, but also the epidermal keratin K2a, several simple epithelial keratins and low levels of hair keratins. SVpgC2a transcribed keratins seen in epithelial dysplasia, and K2a and hair keratins, albeit at low level. Overall, the results implied aberrant apoptosis, proliferation and keratin expression in the immortalized state of SVpgC2a. Comparison of NOK and SVpgC2a under identical culture conditions may serve to model the progression from a normal to a pre-neoplastic state of buccal epithelium.

Rothmund-Thomson syndrome: a case report

Rothmund-Thomson syndrome (RTS) is an extremely rare genetic disorder characterized by poikilodermatous skin changes, photosensitivity, and an increased risk of developing skin and bone malignancies. In this case report, the dental and periodontal features of RTS in a 16-year-old female patient are presented. The transmission electron microscopy performed on a gingival biopsy specimen showed structural defects of connective tissue. If the unusual ultrastructural findings of this case are confirmed as being consistent with other RTS patients, it is our opinion that this syndrome can be considered among the systemic diseases associated with early-onset periodontitis.

Investigation of environmental factors for diagnosing malignant potential in oral epithelial dysplasia

A study was conducted in rats with early tongue carcinoma induced by 4-nitroquinoline 1-oxide (4NQO), in order to investigate the early diagnosis of malignant potential of epithelial dysplasia. The rat tongue lesions were classified by their severity into three groups corresponding to early cancer, dysplasia and no change. The grade of epithelial changes was determined according to 13 items of WHO Epithelial Dysplasia Criteria. The expression levels of p53 and Bcl-2 proteins were detected immunohistochemically, and apoptotic cells were detected using the TUNEL method. In addition, a p53 mutation by lesions was detected. The expression ratio of p53 protein was high in dysplasia, and the ratio of Bcl-2 protein was high in early cancer and dysplasia. The TUNEL-positive cells were observed primarily in the granular layers of the no change cells, and their numbers decreased as the cells shifted to the early cancer stage. The p53 mutation was detected using a microdissection method in dysplasia, where it was found in three out of nine lesions. All the mutations in dysplasia detected were on the same codon that was found to be mutated in the early cancer. These results indicate that the association between the p53 mutation and histological changes in carcinogenesis epithelial dysplasia is strong, and that both the identification of p53- and Bcl-2-positive epithelium, and decrease in the TUNEL positive ratio, were useful for the diagnosis of the malignant potential of precancerous lesions.

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.

Apoptosis, proliferation and p12(doc-1) profiles in normal, dysplastic and malignant squamous epithelium of the Syrian hamster cheek pouch model

Disruption of the homeostatic balance between proliferation and apoptosis is widely believed to contribute to human oral carcinogenesis. Using the Syrian hamster oral cancer model, we examined normal, hyperplastic, dysplastic and malignant oral epithelium for the fraction of apoptotic, proliferating and p12(doc-1) expressing keratinocytes using the TUNEL assay, as well as PCNA and p12(doc-1) immunostaining, respectively. The percentage of TUNEL positive cells progressively increased from normal to dysplastic epithelium (P<0.0019), but returned to normal keratinocyte levels in the malignant epithelium (P<0.20). However, PCNA positive cells increased progressively through hamster oral malignant progression (P<0.0012). The overall ratio of apoptotic to proliferating keratinocytes remains similar until the transition between dysplastic and malignant epithelium, where the ratio is markedly reduced (P<0.05). p12(doc-1) labeling demonstrated a similar expression pattern (P<0.008). This study demonstrates that apoptosis, proliferation and the expression of p12(doc-1) reflects alterations reported during human oral carcinogenesis and supports the use of the Syrian hamster model for the further examination of these pathways.

Expression of bcl-2 and bax in chewing tobacco-induced oral cancers and oral lesions from India

Deregulation of oncogenes and tumor suppressor genes involved in apoptosis has been associated with tumor development and progression. To investigate the involvement of apoptosis regulating proteins in oral cancer in Indian patients, primarily associated with chewing tobacco habits, immunohistochemical expression of bcl-2 and bax was examined in 63 oral squamous cell carcinomas, and 31 putative premalignant lesions. Our studies revealed overexpression of tumor specific cytoplasmic bcl-2 in 56% and bax in 43% oral cancers. The oral cancers in the Indian patients are preceded by premalignant oral lesions; hence oral lesions were examined for bcl-2 and bax expression. We observed aberrant expression of bcl-2 in 16% oral lesions comprising leukoplakias and SMF and bax in 55% oral lesions. We have already reported, p53 expression in these oral cancers and lesions. It was noteworthy that 30% oral cancers demonstrated a p53+bcl2+ pattern, and 14% samples exhibited p53+bcl2+bax+ pattern. However, none of the oral lesions showed concurrent deregulation of p53 and bcl-2 or all the three genes. Interestingly 45% oral lesions were p53-bax+ as compared to 18% oral cancers; while 39% oral lesions were bcl2-bax+ as compared to 14% oral cancers, indicating overexpression of bax in oral lesions, in the absence of p53 and bcl-2 proteins. Significant correlation was observed between positive nodal status and bcl2+ (p=0.047) and p53+bcl-2+ (p=0.01) in oral cancers. Kaplan Meier survival analysis showed significantly (p=0.059) higher survival in patients with p53- oral tumors than with p53+ tumors. Our studies thus indicate frequent overexpression of apoptosis regulators bcl-2, bax and p53 proteins in oral cancers, and a subset of oral lesions, representing early events in oral car-cinogenesis. The aberrant bcl-2 expression and loss of p53 function observed, may play an important role in the tumorigenesis of oral cancers by allowing escape from apoptosis and enabling additional genetic alterations to accrue.

bcl-2 expression in head and neck cancer: an enigmatic prognostic marker

PURPOSE

The role of bcl-2 overexpression in cancer presents a paradox. In some tumor types, it is associated with favorable outcome, whereas in others the reverse is true. The purpose of this study was to explore the influence of bcl-2 in a large series of head and neck cancer patients treated in the CHART randomized trial.

METHODS AND MATERIALS

Histologic material was obtained from 400 patients; bcl-2 expression was assessed by immunohistochemistry as either positive or negative cytoplasmic staining.

RESULTS

Positivity of bcl-2 was recorded in 12.8% (9.5-16.5%, 95% confidence limits) of tumors. There were significant differences in positive tumors within different sites with nasopharynx showing the highest incidence (46.2%). A multivariate logistic regression analysis showed that bcl-2 was strongly associated with histologic dedifferentiation, as well as increasing N stage and female gender. In univariate analyses, bcl-2 positive patients had a lower locoregional relapse rate (RR 0.57, p = 0.02) and improved survival (RR 0.49, p = 0.004) compared to bcl-2 negative patients; this became more significant in multivariate analysis.

CONCLUSION

These data demonstrate that bcl-2 overexpression is a marker of what is considered to be more advanced and aggressive disease yet it is associated with a more favorable outcome irrespective of the treatment schedule.

Bcl-2 expression in sequential biopsies of potentially malignant oral mucosal lesions assessed by immunocytochemistry

OBJECTIVE

To examine, for the first time Bcl-2 expression in sequential (autogenous) oral mucosal biopsies taken from the same sites in a gender, risk-factor matched, Caucasoid sample, over a 21-year period.

DESIGN

Retrospective immunocytochemical longitudinal study of archival serial biopsies.

MATERIALS AND METHODS

Computer records were used to identify biopsy specimens derived from 12 patients. These were divided into four groups: (1) Histologically innocuous lesions which remained histologically innocuous. (2) Dysplastic lesions which remained dysplastic. (3) Histologically innocuous lesions which later progressed to squamous cell carcinoma (SCC). (4) Dysplastic lesions which later progressed to SCC. This represented 65 biopsies in total. Bcl-2 expression was studied using mouse antihuman BCL-2 oncoprotein clone 124 (Dako, Denmark).

RESULTS

Generally, there was a lack of Bcl-2 immunoreactivity in the epithelium, with one exception in dysplastic epithelium from a group (3) patient.

CONCLUSION

These findings suggest that in our series, Bcl-2 is not expressed early in oral premalignant lesions and appears to contradict previous reports. Possible explanations for this disparity are considered.

Overexpression of cyclin-D1, bcl-2, and bax proteins, proliferating cell nuclear antigen (PCNA), and DNA-ploidy in squamous cell carcinoma of the oral cavity

The prognostic role of the expression of bcl-1, bcl-2, bax, PCNA, and DNA-ploidy in a series of 25 oral squamous cell carcinoma (SCC) was investigated. The average age of the patients was 62.04 years (range, 27 to 81 years), with a sex ratio (M/F) of 23:2. The follow-up mean time was 2.24 years (range, 8 months to 8 years from surgery). Immunohistochemistry for PCNA, bcl-2, bcl-1, and bax proteins was carried out on 5-microm serial sections from formalin-fixed, paraffin-embedded tissue. The findings were compared with clinicopathologic data and with follow-up. The statistical evaluation of the results of the current study suggests that the low positivity for PCNA with a high positivity for bcl-2 protein are related to a better clinical behavior of the tumors. By converse, a high expression of PCNA, bax, and bcl-1 appears to correlate with a worse prognosis. All of our cases of SCC showed the presence of aneuploid populations, which was not correlated with the clinicopathologic parameters or with the overexpression of bcl-1, bcl-2, bax, and PCNA. Therefore, the aneuploidy per se did not predict the clinical evolution for the single cases of cancers. Nevertheless, once the parameters considered for the evaluation of DNA were examined in detail, it appeared that some of them, individually or combined with each other or with the expression of bcl-1, bcl-2, and bax, gained statistical significance in predicting the clinical evolution of SCC of our series. Particularly, high values of 2cDI and DNA-MG and the absence or reduction of the euploid population were associated with a short interval between surgery and recurrence or death, and this significance persisted when the simultaneous presence of overexpression of bcl-1 was considered.

Expression of proliferating cell nuclear antigen in ameloblastomas and odontogenic cysts

The identification of the proliferative activity in tumours may be useful to predict the biological behaviour of different lesions. Proliferating cell nuclear antigen (PCNA) has been used for the evaluation of the proliferative ability of many lesions. In this study 22 ameloblastomas (4 follicular, 5 plexiform, 4 acanthomatous, 5 unicystic, 4 recurrent), 12 odontogenic keratocysts (OKC), 8 dentigerous cysts (DC), and 12 radicular cysts (RC) were analysed. PCNA+ cells were present in all cyst types but the OKC contained the highest number of PCNA+ cells. In OKC the location of PCNA+ cells was mainly suprabasal. In ameloblastoma PCNA+ cells were located mainly in the peripheral portion of the tumour islands. Statistical analysis showed that ameloblastoma had higher PCNA+ cell counts than OKC (P < 0.0001); OKC had higher values than DC and RC (P < 0.0001). Recurrent ameloblastoma presented higher PCNA+ cell counts than other types of ameloblastoma, while unicystic ameloblastoma showed lower values than acanthomatous, plexiform and follicular ameloblastomas (in this latter case the difference was not statistically significant). These data could help to explain the different biological behaviour of these lesions.