Immunohistochemical evaluation of bcl-2 oncoprotein in oral dysplasia and carcinoma

Immunohistochemical Characterization of Bcl-2 in Oral Potentially Malignant Disorders

Bcl-2 is a group of apoptotic proteins that play a key role in cellular homeostasis. Overexpression of Bcl-2 has been associated with the poor prognosis of oral squamous cell carcinoma (OSCC). The aim of this study is to analyze the immunohistochemical expression of Bcl-2 in healthy oral mucosa, different oral potentially malignant disorders and OSCC, and to determine its diagnostic value. A retrospective observational study was carried out in the Oral Medicine Unit of the University of Santiago de Compostela. All the clinicopathologic data were collected and paraffin-embedded blocks were available to perform the immunohistochemistry study with Bcl-2. We studied 18 fibromas, 15 OSCC, 29 oral leukoplakia lesions (OL), 59 oral lichen planus (OLP) cases, and 16 healthy controls. OL with epithelial dysplasia (31.2%) showed the highest expression of Bcl-2 and OLP (1.9%) showed the lowest expression of Bcl-2 (P=0.025). Receiver operating characteristics curves showed that the detection of Bcl-2 enables discrimination between OL and OLPs (sensitivity: 58.6%, specificity of 99.32%). Bcl-2 negative expression in the OLP diagnosis obtained an odds ratio of 13.750 (95% confidence interval: 3.354-56.369; P<0.0001) and the positive expression in the OL 4.468 (95% confidence interval: 1.889-10.565; P=0.001). Bcl-2 could be used as a diagnostic biomarker to study their malignant transformation.

Evaluation of the chemopreventive effects of Hypericum perforatum L on DMBA-applied rat oral mucosa

OBJECTIVE

Hypericum perforatum L also known as St. John's wort is known to have many beneficial properties for the organism including its antioxidant and anticancer activities. It is also known to have shown antiproliferative and cytotoxic effects against various cancer cell lines. The purpose of this study was to investigate the effects of Hypericum perforatum L on 7,12-dimethylbenz(a)anthracene-induced rat oral squamous cell carcinoma model.

DESIGN

The in vitro antioxidant properties of Hypericum perforatum L was determined and an extract was prepared. Thirty Wistar male rats were divided randomly into 4 groups (Control group, DMBA group, HP + DMBA group, HP group). The antioxidant defense mechanisms in tissue and blood samples were evaluated biochemically and immunohistochemically, the carcinomatous changes in connective tissue were investigated immunohistochemically and epithelial changes in the tissue samples were evaluated histopathologically.

RESULTS

The extract revealed inhibitory effects on some antioxidant enzymes (catalase, glutathione peroxidase). Immunohistochemical evaluations revealed no invasive changes in the connective tissue. Hypericum perforatum L demonstrated chemopreventive effects although it did not prevent carcinomatous changes altogether.

CONCLUSIONS

Hypericum perforatum L is a promising chemopreventive agent and further studies are needed in order to evaluate the full potential of this plant.

Changes in Cellular Regulatory Factors before and after Decompression of Odontogenic Keratocysts

Decompression followed by enucleation, which is one of the treatments used for odontogenic keratocysts (OKCs), is frequently used in OKC lesions of large sizes. This method offers the advantage of minimizing the possibility of sensory impairment without creating a wide-range bone defect; moreover, the recurrence rate can be significantly lower than following simple enucleation. This study aimed to assess the changes in histology and expression of proliferation markers in OKCs before and after decompression treatment. A total of 38 OKC tissue samples from 19 patients who had undergone decompression therapy were examined morphologically and immunohistochemically to observe changes in proliferative activity before and after decompression. The markers used for immunohistochemistry (IHC) staining were Bcl-2, epidermal growth factor receptor (EGFR), Ki-67, P53, PCNA, and SMO. The immunohistochemistry positivity of the 6 markers was scored by using software ImageJ, version 1.49, by quantifying the intensity and internal density of IHC-stained epithelium. The values of Bcl-2, Ki-67, P53, proliferating cell nuclear antigen (PCNA), and SMO in OKCs before and after decompression showed no significant change. No correlation between clinical shrinkage and morphologic changes or expression of proliferation and growth markers could be found. There was no statistical evidence that decompression treatment reduces potentially aggressive behavior of OKC within the epithelial cyst lining itself. This might indicate that decompression does not change the biological behavior of the epithelial cyst lining or the recurrence rate.

Comparative evaluation of survivin expression in leukoplakia, lichen planus, and oral squamous cell carcinoma: An immunohistochemical study

Background

Screening for oral squamous cell carcinomas (OSCCs) and oral premalignant lesions may decrease the devastating morbidity and mortality associated with the disease. This has led to widespread research for the identification of molecular-based biomarkers. Among them, survivin is a recently characterized protein which is a member of the inhibitor of apoptosis family. The aim of this study is evaluating the expression of survivin in oral leukoplakia, oral lichen planus, and OSCC compared with normal mucosa.

Materials and Methods

The retrospective study consisted of twenty cases of oral leukoplakia, oral lichen planus, and OSCC in the age group of 20-70 years. Twenty cases of normal mucosa made up the control group. Immunohistochemical staining was performed with the use of survivin polyclonal antibody. Grades of expression of survivin were evaluated. Kruskal-Wallis test was used for statistical analysis.

Results

The expression of survivin was higher in OSCC (80%) when compared to oral leukoplakia (70%), oral lichen planus (45%), and normal mucosa (35%). The variation in the expression of survivin between the samples was statistically significant with P = 0.015 (Kruskal-Wallis test significant at 0.01 level).

Conclusion

It is concluded that survivin can be identified as a useful tool for the identification of potentially malignant disorders at higher risk for progression into invasive carcinoma.

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.

Bcl-2 expression in reactive oral lesions with atypical epithelium and in oral epithelial dysplasia associated with carcinogen exposure

Background:

Reactive lesions of the oral cavity are nonneoplastic proliferations with very similar appearance to benign neoplastic lesions and are associated with chronic local irritation or trauma. Although these lesions are uncommonly associated with carcinogen exposure, at times, they present histopathologically with dysplastic epithelium, thus making it difficult to differentiate it from true potentially malignant disorders. Hence, the present study was conducted to evaluate the expression of Bcl-2 protein, an antiapoptotic marker, in reactive lesions with and without atypical epithelium and in true epithelial dysplasia, which clinically presents as premalignant disorders.

Materials and Methods:

The samples included 15 cases each of normal oral mucosa (NOM), reactive lesions with and without dysplasia and oral epithelial dysplasia (OED) associated with carcinogen exposure. All the samples were subjected to immunohistochemical staining using Bcl-2 antibody. The total number of cells in the basal and parabasal layers in each field and total number of cells expressing Bcl-2 among them and the staining intensity were assessed.

Statistical Analysis:

Kruskal–Wallis ANOVA test was used to compare the number of positive cells among the four groups. The comparison of average percentage of positive cells between the study groups was done using Mann–Whitney U-test.

Results:

The immunohistochemical staining for Bcl-2 protein was identified in few cells in the basal layers of NOM, reactive lesions without atypical epithelium and in the basal and parabasal layers in reactive lesions with atypical epithelium and OED, as a granular cytoplasmic staining and as an accentuation around the nuclear membrane. There was a gradual increase in the expression and intensity of staining from Group I to IV.

Interpretation and Conclusion:

The altered or increased expression of Bcl-2 oncoprotein in reactive lesions with atypical epithelium and in OED with carcinogen exposure may lead to prolonged cell survival and can be considered as an early molecular event in carcinogenesis, helping us in understanding the nature of dysplasia in reactive lesions, which was not considered during the histopathology reporting.

Bcl-2 and c-Myc expression in oral dysplasia and oral squamous cell carcinoma: An immunohistochemical study to assess tumor progression

Introduction

Oral cancer is a multistep process involving foul play of proto-oncogenes that induce cell proliferation, inactivation of tumor suppressor gene and cessation of programmed cell death. Among various proto-oncogenes, the nature and behavior of Bcl-2 and c-Myc in oral precancerous/cancerous lesions were obscured which require further assessment for better understanding of etiology, treatment and prognosis.

Aim

The aim of the study is to assess the expression of Bcl-2 and c-Myc in oral epithelial dysplasia and oral squamous cell carcinoma (OSCC).

Materials and Methods

This retrospective study of 70 (oral dysplasia [30], OSCC [30] and normal gingiva [10]) is immunohistochemically assessed for Bcl-2 and c-Myc for distribution, intensity, percentage of positive cells, localization and immunoreactive scores using ImageJ software.

Results

Bcl-2 showed 60% and 37% positivity within dysplasia and OSCC, respectively (P = 0.03); c-Myc showed 87% and 90% positivity within dysplasia and OSCC, respectively. In OSCC, c-Myc showed moderate intensity (P = 0.04). Average percentage of positive cells expressing c-Myc and Bcl-2 increased proportionally within grades of dysplasia (P = 0.000 and P = 0.008, respectively), whereas in OSCC, only c-Myc showed significant expression (P = 0.021). Localization of c-Myc was seen in the nucleus among OSCC (P = 0.01). c-Myc and Bcl-2 showed moderate immunoreactivity in dysplasia (P = 0.005 and P = 0.013, respectively), whereas in OSCC, moderate immunoreactivity of c-Myc (P = 0.05) was observed.

Conclusion

Variable expression of c-Myc and Bcl-2 reveals that these proteins act in synergism in early phases of carcinogenesis, whereas in later stages, due to the diminished activity of Bcl-2, c-Myc interacts incoordination with other oncogenes contributing to tumor progression.

Possible Role of Bcl-2 Expression in Metastatic and Non Metastatic Oral Squamous Cell Carcinoma

Introduction

Oral carcinoma is a global health problem. India accounts for one-third of world burden with high prevalence rate of 2.5 million and mortality rate of 5.5 lacs per year. Oral carcinogenesis is a multistage process that frequently involves invasion and metastasis that needs early detection and treatment to improve the overall quality of life. The ability of Oral Squamous Cell Carcinoma (OSCC) to metastasize to lymph nodes does not always show a relationship with clinical staging. A spectrum of molecular mechanisms is involved in carcinogenesis, where defect in the regulation of apoptosis is assumed to contribute to the pathogenesis and progression of cancer. Apoptosis regulatory genes include the antiapoptotic protein such as B-cell lymphoma-2 (Bcl-2) gene that might be used as a molecular marker to evaluate the biological behaviour of oral cancer.

Aim

To evaluate and correlate the Bcl-2 expression in OSCC patients with lymphnode metastasis and without metastasis.

Materials and Methods

The study comprised of 30 samples, 15 cases of metastatic and 15 non-metastatic primary OSCC. All the cases were stained for routine Hematoxylin and Eosin (H&E), and Bcl-2 antibody by immunohistochemistry. The H&E stained sections were evaluated for Lymphocytic Infiltrate (LI) and Pattern Of Invasion (POI). Bcl-2 stained sections were evaluated for staining intensity and distribution. The differences between the groups were statistically analysed using chi-square test.

Results

The histopathological parameters, LI and POI did not show any statistical difference between the study groups. Expression of Bcl-2 in OSCC was 33.3% among the study groups, where metastatic group showed a positive expression of 13.3% and 20% in non-metastatic OSCC that did not show statistically significance among the study groups.

Conclusion

There was no significant difference in the expression of Bcl-2 between the study groups. Apoptosis is regulated by interaction among the Bcl-2 gene family. Hence, evaluation of Bcl-2 along with other apoptotic regulating proteins could define the role in pathogenesis and prognosis of metastatic and non-metastatic OSCC.

The prognostic implication of the expression of EGFR, p53, cyclin D1, Bcl-2 and p16 in primary locally advanced oral squamous cell carcinoma cases: a tissue microarray study

Oral squamous cell carcinomas comprise a heterogeneous tumor cell population with varied molecular characteristics, which makes prognostication of these tumors a complex and challenging issue. Thus, molecular profiling of these tumors is advantageous for an accurate prognostication and treatment planning. This is a retrospective study on a cohort of primary locally advanced oral squamous cell carcinomas (n = 178) of an Indian rural population. The expression of EGFR, p53, cyclin D1, Bcl-2 and p16 in a cohort of primary locally advanced oral squamous cell carcinomas was evaluated. A potential biomarker that can predict the tumor response to treatment was identified. Formalin-fixed paraffin-embedded tumor blocks of (n = 178) of histopathologically diagnosed cases of locally advanced oral squamous cell carcinomas were selected. Tissue microarray blocks were constructed with 2 cores of 2 mm diameter from each tumor block. Four-micron-thick sections were cut from these tissue microarray blocks. These tissue microarray sections were immunohistochemically stained for EGFR, p53, Bcl-2, cyclin D1 and p16. In this cohort, EGFR was the most frequently expressed 150/178 (84%) biomarker of the cases. Kaplan-Meier analysis showed a significant association (p = 0.038) between expression of p53 and a poor prognosis. A Poisson regression analysis showed that tumors that expressed p53 had a two times greater chance of recurrence (unadjusted IRR-95% CI 2.08 (1.03, 4.5), adjusted IRR-2.29 (1.08, 4.8) compared with the tumors that did not express this biomarker. Molecular profiling of oral squamous cell carcinomas will enable us to categorize our patients into more realistic risk groups. With biologically guided tumor characterization, personalized treatment protocols can be designed for individual patients, which will improve the quality of life of these patients.

Investigation of the association between miR‑181b, Bcl‑2 and LRIG1 in oral verrucous carcinoma

Abnormal expression of microRNAs (miRNAs) is involved in the development of and anti-apoptotic effects in various types of human cancer. However, miRNA-mediated regulation of oral verrucous carcinoma (OVC) remains to be elucidated. The present study aimed to investigate the expression of miR-181b in OVC and oral squamous cell carcinoma (OSCC). The expression levels of miR-181b were determined using reverse transcription-quantitative polymerase chain reaction. The expression levels of B-cell lymphoma 2 (Bcl-2) and leucine rich repeats and immunoglobulin like domains 1 (LRIG1), were evaluated using immunohistochemical staining. The correlation between Bcl-2 and LRIG1 expression was determined using a Pearson correlation analysis. The expression levels of miR-181b and Bcl-2 in OVC were significantly higher compared with normal mucosal tissue (NM); however, lower compared with the OSCC. The key target of miR-181b was LRIG1 and it was significantly lower in OVC tissues compared with NM tissue; however this was higher when compared with OSCC tissue. The expression levels of Bcl-2 were correlated with expression levels of LRIG1 in OVC tissues. Therefore, LRIG1 may be associated with anti-apoptotic function in OVC tissues.

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.

Myeloid cell leukemia-1 is a molecular indicator for malignant transformation of oral lichen planus

Oral lichen planus (OLP), characterized by a chronic mucocutaneous inflammatory condition, is a common disease of the oral cavity. Retrospective and prospective epidemiological data suggest that OLP is considered to have malignant potential. However, it is unclear as to which types of molecules may cause malignant transformation of OLP. In the present study, the presence of myeloid cell leukemia-1 (Mcl-1) and B-cell lymphoma-2 (Bcl-2) was studied by western blot analysis in 11 OLP and three normal oral mucosa (NOM) samples and in two human oral cancer cell lines. The functional role of Mcl-1 in oral cancer cells was analyzed using a trypan blue exclusion assay and soft agar assay. Mcl-1 was strongly expressed in the OLP and the two oral cancer cell lines compared with NOM, whereas Bcl-2 was not. Sorafenib and mithramycin A decreased cell viability in MC-3 and HSC-3 oral cancer cells and at same concentration they reduced the expression level of Mcl-1 in the two cell lines. The two chemicals affected Mcl-1 protein and significantly inhibited neoplastic cell transformation in the two cell lines. We suggest that the malignant potential of OLP may be associated with the expression of Mcl-1, and that downregulation of Mcl-1 may prevent malignant transformation of OLP to oral cancer.

Expression of Bcl-2 and epithelial growth factor receptor proteins in keratocystic odontogenic tumor in comparison with dentigerous cyst and ameloblastoma

Background:

Keratocystic odontogenic tumor (KCOT) is a developmental odontogenic cyst on which various investigations have been focused due to its biological activities, high tendency to recur and different growth mechanisms in comparison with other cystic lesions. Previous studies have shown different biological and proliferative activities for the lining epithelium of KCOT. The aim of this study was immunohistochemical evaluation of Bcl-2 and epidermal growth factor receptor (EGFR) expression in KCOT compared with dentigerous cyst and ameloblastoma.

Materials and Methods:

Formalin-fixed and paraffin-embedded tissue sections of 16 cases of KCOT, 16 cases of dentigerous cyst and 16 cases of ameloblastoma were immunohistochemically analyzed to determine Bcl-2 and EGFR proteins’ expression. Biotin-Stereotavidin method was used. It was observed by two oral pathologists separately, and the data were analyzed by Mann–Whitney and Kruskul–Wallis. P < 0.05 was considered as significant.

Results:

Regardless of staining intensity, all cases of ameloblastoma and KCOT except dentigerous cases were positively stained for Bcl-2. Expression of Bcl-2 was higher in the peripheral layer of ameloblastoma and basal layer of KCOT. Furthermore, all cases of ameloblastoma and dentigerous cysts except KCOT samples were positively stained for EGFR. Expression of EGFR was higher in the peripheral layer of ameloblastoma and basal layer of dentigerous cysts.

Conclusion:

According to the expression of — Bcl-2 in ameloblastoma and KCOT, and no expression of EGFR in KCOT, it can be concluded that the biological activity and growth mechanisms of KCOT are different compared with other cystic lesions. However, the aggressive potential of KCOT is not as severe as that of a neoplasm such as ameloblastoma.

Study of immunohistochemical demonstration of Bcl-2 protein in ameloblastoma and keratocystic odontogenic tumor

Background:

The Bcl-2 (B-cell lymphoma) gene product also known as apoptotic inhibitor is expressed in many normal and tumor tissues. This Bcl-2 gene protects the cell by blocking postmitotic differentiation from apoptosis, thus maintaining the stem cell pool.

Objective:

To study the expression of Bcl-2 protein in ameloblastoma and keratocystic odontogenic tumor (KCOT) to determine their apoptotic behaviors and to analyze biological nature of KCOT, which has higher proliferative potential and aggressive clinical behavior like odontogenic tumors.

Materials and Methods:

Formalin-fixed paraffin sections of ameloblastoma (n = 20) and KCOT (n = 20) are considered for immunohistochemical analysis using monoclonal antibody against antihuman Bcl-2 oncoprotein. Lymphomas (n = 3) were used as controls.

Statistical Analysis:

The statistical analysis was performed using software package of social science version 16. The data were analyzed using Chi-square test and Student's t test. In all the above tests, P < 0.05 was accepted as statistically significant.

Results:

The positive ratio of Bcl-2 was 85% (17/20) in ameloblastoma, 85% (17/20) in KCOT and 100% (3/3) in lymphomas. Bcl-2 was expressed in peripheral cells and few scattered cells of stellate reticulum in ameloblastoma. KCOT showed strong positivity for Bcl-2 mainly in the basal layer.

Interpretation and Conclusion:

The present study demonstrates the aggressive nature of KCOT and intrinsic growth potential of its lining epithelium. This study clearly demonstrates that KCOT like ameloblastoma demonstrates aggressive clinical and noticeable invasive behavior. Therefore, it is now considered as no longer a developmental cyst but as odontogenic tumor.

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.

Bax expression measured by AQUAnalysis is an independent prognostic marker in oral squamous cell carcinoma

Background

Resistance to apoptosis is a hallmark of cancer and proteins regulating apoptosis have been proposed as prognostic markers in several malignancies. However, the prognostic impact of apoptotic markers has not been consistently demonstrated in oral squamous cell carcinoma (OSCC). This inconsistency in reported associations between apoptotic proteins and prognosis can be partly attributed to the intrinsic low resolution and misclassification associated with manual, semi-quantitative methods of biomarker expression measurement. The aim of this study was to examine the association between apoptosis-regulating proteins and clinical outcomes in oral squamous cell carcinoma (OSCC) using the quantitative fluorescence immunohistochemistry (IHC) based AQUAnalysis technique.

Methods

Sixty-nine OSCC patients diagnosed between 1998–2005 in Calgary, Alberta, Canada were included in the study. Clinical data were obtained from the Alberta Cancer Registry and chart review. Tissue microarrays (TMAs) were assembled from triplicate cores of formalin-fixed paraffin embedded pre-treatment tumour tissue. Bax, Bcl-2 and Bcl-XL protein expression was quantified using fluorescent IHC and AQUA technology in normal oral cavity squamous epithelium (OCSE) and OSCC tumour samples. Survival was analyzed using Kaplan-Meier plots and the Cox proportional hazard model.

Results

Bax expression was predominantly nuclear in OCSE and almost exclusively cytoplasmic in OSCC. No similar differences in localization were observed for Bcl-2 or Bcl-XL. Only Bax expression associated with disease-specific survival (DSS), with 5-year survival estimates of 85.7% for high Bax versus 50.3% for low Bax (p = 0.006), in univariate analysis. High Bax expression was also significantly associated with elevated Ki67 expression, indicating that increased proliferation might lead to an improved response to radiotherapy in patients with elevated Bax expression. In multivariate analyses, Bax protein expression remained an independent predictor of DSS in OSCC [HR 0.241 (0.078-0.745), p = 0.013].

Conclusions

The AQUA technique used in our study eliminates observer bias and provides reliable and reproducible estimates for biomarker expression. AQUA also provides essential measures of quality control that cannot be achieved with manual biomarker scoring techniques. Our results support the use of Bax protein expression as a prognostic marker in conjunction with other clinico-pathological variables when designing personalized treatment strategies for OSCC patients.

p16 overexpression in malignant and premalignant lesions of the oral and esophageal mucosa following allogeneic hematopoietic stem cell transplantation

Objectives

Secondary malignancy in the oral mucosa is recognized as one of the most serious complications in patients who received allogenic hematopoietic stem cell transplantation (HSCT). However, potential risk factors associated with carcinogenesis after HSCT that have been reported remain elusive. We experienced a rare case of secondary malignancies of the oral and esophageal mucosa and analyzed the expression of tumor suppressor gene product p16.

Case report

A 35-year-old male had malignant lesions of the oral and esophageal mucosa two years after HSCT. Partial maxillectomy and endoscopic submucosal dissection were performed. Immunohistochemical analyses revealed that the tumor cells of malignant and premalignant lesions of the oral cavity and esophagus but not keratosis were positive for p16.

Conclusions

Pathological examinations with p16 immunohistochemistry may contribute to an early diagnosis of secondary malignancy after HSCT.

Expression of p14(ARF), p15(INK4b), p16(INK4a) and skp2 increases during esophageal squamous cell cancer progression

Esophageal carcinoma is the sixth most common cause of cancer-related mortality in the world. Senescence and apoptosis are assumed to be two main mechanisms that inhibit age-related carcinogenesis. p14(ARF), p15(INK4b) and p16(INK4a), which are known to induce senescence by regulating G(1) cell cycle arrest, have been identified as senescence markers. However, the mechanism by which senescence and apoptosis causes neoplasia in esophageal squamous cell carcinoma (ESCC) has not been identified. In this study, 20 cases of normal esophageal tissues, 11 cases of esophageal intraepithelial dysplasia (EID) and 60 cases of ESCC were obtained and pathologically diagnosed. Immunohistochemical staining was performed to assess the expression of p14(ARF), p15(INK4b), p16(INK4a), skp2, bcl-2 and ki-67. The senescence markers p14(ARF) and p16(INK4a) were found to be expressed in 15 and 10% of the normal tissues, 82 and 73% of the EID cases and 100 and 88% of the ESCC cases, respectively. The expression of p15(INK4b) was low in normal tissues, while 92% of the ESCC specimens were diffusely and markedly stained, involving the basal, middle and upper portion of the epithelium. The nuclear expression markers ki-67 and skp2 were highly expressed in ESCC tissues (100 and 72%, respectively). bcl-2 was expressed weakly in normal tissues (10%) and demonstrated various staining patterns in carcinoma specimens (strong in 60%, negative in 40%). MI was 0.09% in normal tissues and 0.95% in the ESCC specimens. Apart from the increased proliferation in esophageal carcinogenesis, as indicated in the ki-67 and skp2 indices, there was an increased expression of senescence-associated molecular markers in the ESCC specimens, which indicates that the senescence pathway may be activated and become a part of cancer development. Of greatest interest to us was that, when compared with clinical information, the expression of the senescence markers was markedly high in the poorly differentiated specimens with lymph node metastasis, indicating that senescence markers may have diagnostic potential in clinical settings.

Biomarkers of oral premalignant epithelial lesions for clinical application

Oral cancer is the sixth most common form of cancer worldwide, and the majority of cases occur in India and Southeast Asia. Its major risk factors in the western world include smoking and drinking alcohol, whereas in Asia, it is primarily caused by tobacco/areca nut/betel leaf chewing and/or human papillomavirus (HPV) infections. Little is known about this type of cancer despite recent advances in cancer biology. The generally asymptomatic nature of the early oral lesions causes them to remain undetected in many cases. Thus, the disease progresses substantially before the patients seek treatment and is a major contributing factor to the severity of this disease. Therefore, there is a great need to create awareness for its prevention and early diagnosis. The application of advanced molecular biological and biochemical methodologies to elucidate its biomarkers may aid in early detection; however, much more work must be done for this information to be effectively applied in the clinical setting. This review focuses on the need for systematic diagnoses in the early detection of oral cancer using molecular and biochemical approaches, thereby reducing the number of advanced cases in the chewing tobacco-dominated oral cancer population.

Expression of Bcl-2 family proteins and association with clinicopathological characteristics of oral squamous cell carcinoma

AIMS

To characterize the expression of proteins that inhibit (Bcl-2, Bcl-x, Bcl-xL, Bcl-2-related protein A1, BAG-1) or promote (Bak, Bax, Bim/Bod, Bim-Long, Bad, Bid, PUMA) apoptosis and determine possible correlations between the expression of these proteins and clinicopathological features of oral squamous cell carcinoma (OSCC).

METHODS AND RESULTS

Two-hundred and twenty-nine cases of OSCC, arranged in a tissue microarray, were immunohistochemically analysed. The results demonstrated that the absence of vascular invasion was associated with increased expression of Bak, Bax, Bcl-xL, Bcl-2-related protein and PUMA. Increased expression of Bim/Bod and BAG-1 was associated with the presence of perineural infiltration. An increase in Bid and Bim-Long expression was associated with moderately to well-differentiated tumours. Increased expression of the Bcl-2-related protein and PUMA was associated with tumours occurring in the floor of mouth and increased expression of PUMA was also associated with recurrence of the tumour. Multivariate Cox analysis demonstrated that PUMA and Bim-Long were independent factors in prognosis of OSCC.

CONCLUSIONS

Our results showed the involvement of the Bcl-2 family of proteins in OSCC tumorigenesis and suggest that the expression of apoptotic molecules might be used as a prognostic indicator for OSCC.

Activation of MAP kinase signaling through ERK5 but not ERK1 expression is associated with lymph node metastases in oral squamous cell carcinoma (OSCC)

In an attempt to further elucidate the pathomechanisms in oral squamous cell carcinoma (OSCC), gene expression profiling was performed using a whole-transcriptome chip that contains 35,035 gene-specific 70 mere oligonucleotides (Human OligoSet 4.0; Operon, Cologne, Germany) to a set of 35 primary OSCCs. Altogether, 7390 genes were found differentially expressed between OSCC tumor samples and oral mucosa. To characterize the major biologic processes in this tumor collection, MAPPFinder, a component of GenMAPP version 2.1, was applied to this data set to generate a statistically ranked list of molecular signaling pathways. Among others, cancer-related pathways, such as mitogen-activated protein (MAP) kinase signaling (z score = 4.6, P < .001), transforming growth factor-beta signaling (z score = 3.0, P = .015), and signaling pathways involved in apoptosis (z score = 2.1, P = .037), were found deregulated in the OSCC collection analyzed. Focusing on the MAP kinase signaling pathway, subsequent tissue microarray analyses by immunohistochemistry revealed an increase in protein expression of MAP kinase-related proteins ERK1 in 22.8% (48 of 209) and ERK5 in 27.4% (76 of 277), respectively. An association of high ERK5 but not of high ERK1 expression with advanced tumor stage and the presence of lymph node metastases was found (P = .008 and P = .016, respectively). Our analysis demonstrates the reliability of the combined approach of gene expression profiling, signaling pathway analyses, and tissue microarray analysis to detect novel distinct molecular aberrations in OSCC.

Study of antiapoptotic gene of oral carcinoma by using Bcl-2 oncogene

The present study was addressed to find out the expression of Bcl-2 proto-oncogene in tumor tissue derived from 24 patients with malignant oral carcinoma and oral mucosa from the same patients served as control and showed a cytoplasmic pattern of Bcl-2 immunoreactivity in basal cell layer. Fourteen of 24 (58.3%) of oral carcinoma and four adenocystic carcinoma expressed positive Bcl-2 oncogene. Well-differentiated squamous cell carcinoma showed absence of immunoreactivity. No statistically significant correlation could be demonstrated between Bcl-2 immunoreactivity and the age or sex of the patients, tumor size, and lymph node metastasis. A direct correlation between Bcl-2 immunoreactivity in G2 and G3 was statistically significant (P < 0.05). Patients with absence of or low (scores 0 or 1) Bcl-2 immunoreactive tumors manifested poorer overall survival rate in comparison with patients with moderate or high (scores 2 and 3) Bcl-2 expression, but the difference was not statistically significant. Tumors exhibited three different expressions of Bcl-2 (weak, moderate, and strong positive), compared to the mucosa of some patients affected by these tumors. No correlation was found between the histopathology of the tumors, mucosal expression, and degree of Bcl-2 expression. We propose from this study that overexpression of Bcl-2 proto-oncogene acts as a strong antiapoptotic in both squamous cells and adenocystic carcinoma may be an important molecular event on oral carcinoma to make these tumors resistant to radiotherapy and chemotherapy.

The hamster model of sequential oral oncogenesis

Oral squamous cell carcinoma (OSCC) is a common cancer characterised by low survival rate and poor prognosis. The multistep process of oral carcinogenesis is affected by multiple genetic events such as alterations of oncogenes and tumour suppressor genes. The use of appropriate experimental animal models that accurately represent the cellular and molecular changes which are associated with the initiation and progression of human oral cancer is of crucial importance. The Syrian golden hamster cheek pouch oral carcinogenesis model is the best known animal system that closely correlates events involved in the development of premalignant and malignant human oral cancers. Therefore, we established an experimental system of chemically induced oral carcinogenesis in hamsters, in order to study different stages of tumour formation: normal mucosa, hyperkeratosis, hyperplasia, dysplasia, early invasion, well differentiated OSCC and moderately differentiated OSCC. We investigated the expression of oncogenes EGFR, erbB2, erbB3, FGFR-2, FGFR-3, c-myc, N-ras, ets-1, H-ras, c-fos and c-jun, apoptosis markers Bax and Bcl-2, tumour suppressor genes p53 and p16, and cell proliferation marker Ki-67 in the sequential stages of hamster oral oncogenesis. Here, we describe the findings of the experimental model in regard to the involvement of signal transduction pathways in every stage of cancer development. Increased apoptosis and cell proliferation were observed in early stages of oral oncogenesis. Furthermore, the increased expression of transmembrane receptors (EGFR, erbB2, FGFR-2 and FGFR-3) as well as the increased expression of nuclear transcriptional factors in early stages of oral cancer indicates that these molecules may be used as early prognostic factors for the progression of OSCC. Since the expression of both H-ras and N-ras do not seem to affect signal transduction during oral oncogenesis, it can be assumed that a different signalling pathway, such as the PI3K and/or PLCgamma pathway, may be implicated in the pathogenesis of OSCC.

4-nitroquinoline-1-oxide induced experimental oral carcinogenesis

Human oral cancer is the sixth largest group of malignancies worldwide and single largest group of malignancies in the Indian subcontinent. Seventy percent of premalignant cancers appear from premalignant lesions. Only 8-10% of these lesions finally turn into malignancy. The appearance of these premalignant lesions is one distinct feature of human oral cancer. At present there is dearth of biomarkers to identify which of these lesions will turn into malignancy. Regional lymph node metastasis and locoregional recurrence are the major factors responsible for the limited survival of patients with oral cancer. Paucity of early diagnostic and prognostic markers is one of the contributory factors for higher mortality rates. Cancer is a multistep process and because of constrain in availability of human tissues from multiple stages of oral carcinogenesis including normal tissues, animal models are being widely used, aiming for the development of diagnostic and prognostic markers. A number of chemical carcinogens like coal tar, 20 methyl cholanthrene (20MC), 9,10-dimethyl-1,2-benzanthracene (DMBA) and 4-nitroquinoline-1-oxide (4NQO) have been used in experimental oral carcinogenesis. However, 4NQO is the preferred carcinogen apart from DMBA in the development of experimental oral carcinogenesis. 4NQO is a water soluble carcinogen, which induces tumors predominantly in the oral cavity. It produces all the stages of oral carcinogenesis and several lines of evidences suggest that similar histological as well as molecular changes are observed in the human system. In the present review an attempt has been made to collate the information available on mechanisms of action of 4NQO, studies carried out for the development of biomarkers and chemopreventives agents using 4NQO animal models.

Cell proliferation and apoptosis culminate in early stages of oral oncogenesis

Markers of cell proliferation (Ki-67 antigen) and apoptosis (Bax, Bcl-2) were studied in an experimental system of induced oral carcinogenesis in Syrian golden hamsters. Thirty-seven animals were divided into one control group and three experimental groups, which were treated with a carcinogen and sacrificed at 10, 14 and 19 weeks after treatment. The histological status of the lesions in the three experimental groups corresponded well with tumour advancement (from oral mucosal dysplasia to moderately differentiated squamous cell carcinoma). Tumour sections were studied using monoclonal antibodies against Bax, Bcl-2 and Ki-67 proteins. Pro-apoptotic Bax expression maintained high levels during all stages of oral carcinogenesis. Anti-apoptotic Bcl-2 expression decreased significantly in dysplastic and early invasion lesions and consequently increased almost to normal tissue level in consequent stages. Finally, Ki-67 expression increased sharply in initial stages of oral carcinogenesis, but significantly decreased in later stages.

Expression of Bcl-2 but not Bax has a prognostic significance in tongue carcinoma

BACKGROUND

Among the molecular mechanisms involved in carcinogenesis, defects in the regulation of programmed cell death (apoptosis) make important contributions to the pathogenesis and progression of cancer. Apoptosis regulatory genes include the antiapoptotic bcl-2 gene and the proapoptotic bax gene. The aim of this study was to determine the spectrum of Bax and Bcl-2 expression, and to correlate these findings with clinicopathologic variables and prognosis.

METHODS

In this study we have evaluated the immunohistochemical expression of Bcl-2 and Bax proteins in a series of 35 squamous cell carcinomas of the tongue.

RESULTS

Immunoreactivity for Bax was detected in 37.1% and for Bcl-2 in 8.6% of cells, and for both proteins the staining was cytoplasmic and granular. Bcl-2 and Bax expression was mainly seen in peripheral cells of epithelial tumor islands with decreasing immunoreactivity toward the center of the neoplastic nests. Bax immunoexpression was significantly correlated with histologic grading (P=0.05), but not with the remaining clinicopathologic variables. Bcl-2 immunoreactivity was significantly correlated with N-stage (P=0.01) and survival. Patients with Bcl-2-negative tumors [mean survival: 73.97 months; 95% confidence interval (CI): 59-88] vs. Bcl-2-positive ones (mean survival: 17.67 months; 95% CI: 6-29) had a longer survival (P=0.01; odds ratio=6.9).

CONCLUSIONS

Bcl-2 is associated with aggressive disease, neck lymph node metastasis, and poor prognosis. Whereas Bax is related with histologic grade.

Abnormal expression of bcl-2 and bax in rat tongue mucosa during the development of squamous cell carcinoma induced by 4-nitroquinoline 1-oxide

4-Nitroquinoline 1-oxide (4NQO)-induced rat tongue carcinogenesis is a useful model for studying oral squamous cell carcinoma. The aim of this study was to investigate the expression of bcl-2 and bax during tongue carcinogenesis induced by 4NQO. Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution through their drinking water for 4, 12 or 20 weeks. Ten animals were used as negative control. Although no histological changes were induced in the epithelium after 4 weeks of carcinogen exposure, bcl-2 and bax were over-expressed (P < 0.01) in all layers of the 'normal' epithelium. The expression levels were the same in all layers of epithelium for both the antibodies used (bcl-2 or bax). In dysplastic lesions at 12 weeks following carcinogen administration, the levels of bcl-2 and bax expression did not increase when compared to negative control with the immunoreactivity for bcl-2 being restricted to the superficial layer of epithelium. In well-differentiated squamous cell carcinoma induced after 20 weeks of treatment with 4NQO, bcl-2 was expressed in some cells of tumour islands. On the other hand, immunostaining for bax was widely observed at the tumour nests. The labelling index for bcl-2 and bax showed an increase (P < 0.05) after only 4 weeks of 4NQO administration. In conclusion, our results suggest that abnormalities in the apoptosis pathways are associated with the development of persistent clones of mutated-epithelial cells in the oral mucosa. Bcl-2 and bax expression appears to be associated with a risk factor in the progression of oral cancer.

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.

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.

p53, bcl-2 and Ki-67 expression in adenoid cystic carcinoma of the palate. A clinico-pathologic study of 21 cases with long-term follow-up

Adenoid cystic carcinoma (ACC) is an indolent tumor that pursues a protracted clinical course with recurrences and late metastases. The aim of this study was to investigate immunohistochemically the expression of p53, bcl-2 protein, and Ki-67 in 21 cases of ACC of the palate, all with a minimum of 10 years and a maximum of 22 years of clinical follow-up. These results were also analyzed with regard to different clinical prognoses of the histologic subtypes of ACC. High expression of p53 and bcl-2 was noted in 19 out of 21 ACC cases (90%), in which most tumor cells (from 66% to 99%) proved to be immunopositive. A relation to the histologic types, clinical staging, and survival was not found. Therefore, the high immunoreactivity against these oncoproteins in the same tumor cells suggests that these two oncogenes may be involved since the early stage of carcinogenesis. Loss of function of the p53 protein combined with bcl-2 upregulation might give the tumor cells a double growth advantage, because uncontrolled proliferation is combined with a reduced cell death rate. The interaction with other oncogenes may then trigger a multistep process able to promote tumor progression. The low labeling index Ki-67 was detected in nine out of 21 cases (42%), with a low percentage of tumor cells (from 3% to 15%) being positive, whereas the remaining 12 cases were negative. We found no relation to the histologic types, clinical staging, and survival; however, the low proliferation rate could explain the natural course of tumor.

Expression of MIB-1 and bcl-2 in hepatocellular carcinoma and paracarcinomatous tissues

AIM: To investigate the effects of MIB-1 and bcl-2 proteins expression in the primary hepatocellular carcinoma(HCC) and their paracarcinomatous tissues.

METHODS: The expression of MIB-1 and bcl-2 proteins was evaluated in paraffin-embedded tissue by immunohistochemical techniques (S-P) in 40 cases of hepatocellular carcinoma.

RESULTS: The positive expression of MIB-1 was located in nucleus. The mean MIB-1 positive rate in HCCs was 27.61±13.26%, while MIB-1 positive cells in paracarcinomatous tissues were 1.24±1.67% (P < 0.001). The expression of MIB-1 in HCCs was related to the cancer grading, the lower the differentiation of HCCs, the higher the MIB-1 proliferation index (P < 0.01). As for the paracarcinomatous tissues the MIB-1 proliferation index of small liver cell dysplasia (LCD) was higher than that of its adjacent liver tissue. However, in larger cell LCD, the MIB-1 index had no significant difference compared with that of its adjacent tissue. The positive rates of bcl-2 in cancer and paracarcinomatous tissues were 17.5% (7/40) and 77.5% (31/40) respectively. The bcl-2 expression was located in cytoplasm and its positive signals were strong and cluster-like in paracarcinomatous tissues, while the number of the bcl-2 positive cell was sporadic and the signals were weak and "piece-meal like" in HCCs.

CONCLUSION: This study shows that the MIB-1 proliferation index reflects the proliferation speed and the degree of anaplasia in HCCs. The higher expression of MIB-1 in small cell LCD suggests that its proliferation is faster than that of large cell LCD and their adjacent liver tissues, so the small cell LCD is more approximate to HCCs. The study also shows that bcl-2 may not directly play a role in liver cell proliferation during the processes of liver cell carcinogenesis, but it may take part in liver cell apoptosis regulated by the reduction of bcl-2 protein level.

The role of apoptosis in oral disease: mechanisms; aberrations in neoplastic, autoimmune, infectious, hematologic, and developmental diseases; and therapeutic opportunities

Apoptosis is a genetically programmed form of cell death, which primarily functions to eliminate senescent or altered cells that are useless or harmful for the multicellular organism. Contrary to necrosis, apoptosis represents a physiologic cellular mechanism, normal function and control of which are critical for the development and homeostasis of multicellular organisms. In contrast, aberrations of the apoptotic mechanisms that cause excessive or deficient programmed cell death have been linked to a wide array of pathologic conditions. This review briefly summarizes the major apoptotic pathways and molecules and presents the most important oral diseases that are related to dysregulation of apoptosis. Knowledge of the association between aberrations in apoptotic mechanisms and human pathology hopefully will be implemented for the design of improved diagnostic and prognostic assays and the development of novel, more efficient, therapeutic strategies.

Immunohistochemical analysis of Bcl-2 and Bax oncoproteins in rabbit craniomandibular joint

The purpose of this study was to elucidate the expression of proto-oncogene Bcl-2 (anti-apoptotic) and Bax (pro-apoptotic) in fibrocartilage of the disc and hyaline cartilage of the condyle in the rabbit craniomandibular joint (CMJ). Ten New Zealand white rabbit heads were used. Sections were processed by the immunohistochemical techniques using mouse anti-Bcl-2 and anti-Bax antibodies. Intensity levels of immunostaining in condylar cartilage were quantified by a computer-image system. Immunoreactivity for Bcl-2 was mainly observed in the cytoplasm of the reserve cell and chondrocytic cell layers. A mild heterogeneous Bax expression was detected in the cytoplasm of chondrocytes of the upper hypertrophic layer and a few cells of the chondrocytic layer. The cytoplasm of chondrocytes in the disc exhibited a high intensity for Bcl-2, while Bax activity was only sporadically observed. We have shown that Bcl-2 and Bax proteins are present in CMJ cartilage and their expression patterns suggest that these oncoproteins are involved in chondrocyte survival or death via apoptotic pathways.

Survivin, a potential early predictor of tumor progression in the oral mucosa

Survivin is a recently described apoptosis inhibitor selectively over-expressed in most tumors. Immunohistochemistry was used to investigate a potential role of survivin as an early predictor of malignant transformation in precancerous and cancerous lesions of the oral cavity. Survivin was present in 10/30 cases (33%) of oral precancerous lesions without malignant progression, and in 15/16 cases (94%) of oral precancerous lesions evolved into full-blown squamous cell carcinoma. Tumors that progressed from these precancerous lesions retained widespread survivin positivity (100%). Variations among group means were highly statistically significant (p < 0.001). No significant correlation was found between survivin expression and the degree of dysplasia. High expression of cytoplasmic/nuclear survivin is an early event during oral carcinogenesis and may provide a useful tool for the identification of precancerous lesions at higher risk of progression into invasive carcinoma.

[Genic alterations in oral and head and neck squamous cell carcinomas: analysis of international literature]

The development of oral and head and neck squamous cell carcinomas occurs in relation with multiple events including mainly: loss of cycle cell control, evasion from apoptosis, telomerase reactivation. Complex interactions between a set of molecules, cell cycle proteins, tumour suppressor genes, oncogenes and the telomerase, occur in the multiple step process of carcinogenesis. The 2 main ways of control of the cell cycle rely on 2 tumour suppressor genes: the P53 gene and the retinoblastoma gene or RB gene. One of the regulation pathways or the 2 regulation pathways are disabled during the development of oral and head and neck squamous cell carcinomas. Most of the time, the inactivation of the P53 pathway results from a loss of function of the p53 protein, secondary to mutation and/or deletion of the P53 gene; It may also result of the amplification of the MDM2 gene and of the inactivation of the arf protein. The RB pathway leads to cell proliferation by loss of the p16 protein, by amplification of the cyclin D1 gene and less frequently by mutation of the RB gene or loss of the retinoblastoma protein. In India and South-East Asia, the activation of RAS and MYC oncogenes appears to be related with the presence of specific carcinogens in snuff and tobacco. By blocking apoptosis, the Bcl2 protein seems to increase the resistance of tumours to radiotherapy and chemotherapy.

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.

Head and neck cancer: gene therapy approaches. Part II: genes delivered

In Part I, the review summarised the safety of adenoviral vectors and provided insight into approaches being undertaken to improve the specificity, durability and potency of adenoviral delivery vehicles. In Part II, brief discussions are held regarding results of preclinical and clinical trials with a variety of different genes, which have demonstrated antitumour activity in squamous cell carcinoma of the head and neck region (HNSCC). Studies have been performed with a variety of immune modulatory genes. Preliminary results demonstrate activity with several cytokine genes, tumour antigen genes and co-stimulatory molecule genes. Despite only preliminary results, thus far, a theoretical attractive feature for the use of gene therapy for the enhancement of immune modulation is that local injection of the gene product appears to be well tolerated. It is also successful in inducing systemic immune response, potentially providing effect to metastatic sites distal from the injected site. Animal studies have confirmed efficacy in the use of specific targeting of molecules regulating cancer growth (EGF receptor [EGFR], super oxide dismutase [SOD], cyclin D1, E1A and Bcl-2). These approaches are discussed. However, the most significant clinical advances for the use of gene therapy in advanced HNSCC involves two agents: Adp53 and ONYX-015. Preliminary Phase I and II results suggest evidence of efficacy and justify accrual Phase III trials, which are currently ongoing.

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.