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

Trivedy C, Warnakulasuriya KAAS, Tavassoli M, Steingrimsdottir H, Penhallow J, Maher R, Johnson NW: p53 aberrations in oral submucous fibrosis and oral squamous cell carcinoma detected by immunocytochemistry and PCR-SSCP. J Oral Pathol Med 1998; 27: 72–7. © Munksgaard, 1998.
An archival series of oral biopsies from Karachi, Pakistan, consisting of 21 cases of oral submucous fibrosis (OSF) and 27 cases of squamous cell carcinoma (SCC), of which 6 had arisen from OSF, were used to examine the aberrations in the structure and expression of the p53 tumour suppressor gene. The PCR-SSCP method was used for mutation analysis of exons 2–9, and (over)expression of p53 protein was detected by immunocytochemistry using monoclonal antibody DO 7. Positive immunostaining was observed in 15/20 (75%) of OSF specimens, 3/6 (50%) of SCC arising from OSF and 14/21 (67%) of SCC not arising from OSF. Mobility shifts in SSCP indicative of a mutation in p53 or loss of heterozygosity (deletion of a band) were seen in 13/21 cases of OSF and 15/27 cases of SCC. There was concordance between immunocytochemistry and SSCP results in a majority (33/48) of samples. Though the number of analysed SCC cases arising from OSF was limited, the results suggest that p53 mutation/protein stabilisation may play a part in the pathogenesis of OSF and its progression to SCC.     

Epithelial growth fraction and expression of p53 tumour suppressor gene in oral submucous fibrosis

The incidence of squamous cell carcinoma in patients with oral submucous fibrosis (OSF) exceeds 7 per cent. The proliferative cell nuclear antigen (PCNA) is a convenient marker of epithelial cell proliferation and p53 tumour suppressor gene mutations or deletions are frequent in oral cancer. The present study estimated the basal epithelial cell growth fraction using a standard immunohistological method for the detection of nuclear PCNA from 20 Nepalese patients with OSF as 31.8 per cent compared with 7.6 per cent for oral mucosa from 43 normal subjects (p<0.001) and 39.4 per cent for 44 patients with oral cancer. The PCNA growth fraction correlated significantly with that derived by Ki-67 labelling. There was no correlation between the growth fraction and the severity of epithelial dysplasia found is OSF.
Abnormal expression of p53 protein identified by immunohistochemistry with a panel of antibodies was found in 70 per cent of the OSF specimens, and 21 per cent of mucosal specimens from subjects with clinically normal mouths. PCNA-positive cells and p53 expression were restricted to the basal epithelial layer in OSF. The unexpected finding of p53 protein in clinically healthy mucosa was confined to subjects aged over 40 years who smoked tobacco, a known risk factor for oral cancer. There was no association between p53 expression and epithelial atypia scores in OSF.
It is concluded that the proportion of actively cycling epithelial cells is increased in OSF and that p53 tumour suppressor gene mutations or deletions may be prevalent. Confirmation by molecular biology techniques of this genetic damage is now needed.     

Adenomatous polyposis coli gene mutation and decreased wild-type p53 protein expression in oral submucous fibrosis: a preliminary investigation

OBJECTIVE: The purpose of this study was to identify the adenomatous polyposis coli (APC) tumor suppressor gene mutation and level of wild-type p53 protein expression in patients with oral submucous fibrosis (OSF). STUDY DESIGN: Cells from OSF and control subjects were cultured in Dulbecco modified Eagle medium with 10% fetal bovine serum at 37 degrees C. Genomic DNA was extracted from cultured cells and used as a template for polymerase chain reaction amplification of the APC tumor suppressor gene. The presence of wild-type p53 protein in cell lysates of cultured cells was analyzed by Western blot. Data were analyzed by the sign test for nonparametric samples and by analysis of variance. RESULTS: The results showed that the APC gene of explant cultured cells from OSF patients (8/8) had a CGA-to-GGA transition mutation at codon 498 that resulted in an Arg-to-Gly missense mutation (P <.01). All (8/8) normal HGF cultures revealed expression of the wild-type APC protein. Cells cultured from 7 of 8 OSF patients were also found to have a single nucleotide deletion at nucleotide 1494 that resulted in creating a stop codon (TGA) at codon 504 (P <.01). This created a premature signal for the endpoint of translation and thus resulted in the generation of a truncated protein product that encodes a polypeptide of 503 amino acid residue. It was found that wild- type p53 protein in human gingival fibroblast cell cultures was significantly higher than in OSF cells (P <.01). CONCLUSION: Alterations of the APC and wild-type p53 tumor suppressor genes in OSF may imply a risk for progression to oral cancer.     

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

OBJECTIVE: To assess p53 expression in a range of oral mucosal lesions and to relate the results to the clinical outcome in patients with dysplastic oral mucosal lesions and oral squamous cell carcinomas (OSCC).
MATERIALS AND METHODS: Archival tissue was available for eight cases of normal oral mucosa, 50 cases of oral mucosal hyperplasia, 41 cases of oral mucosal dysplasia and 48 cases of OSCC. The monoclonal antibody DO-7, reactive to p53 protein, was applied to paraffin-embedded sections using microwave pretreatment and immu-nohistochemical techniques.
RESULTS: The results showed that normal oral mucosa did not express p53.Positive nuclear staining was found in 18/50 (36%) cases of hyperplasia, 35/41 (85%) cases of dysplasia and 45/48 (94%) cases of OSCC.None of the p53 negative dysplasias progressed, while 19% of p53 positive cases of dysplasia recurred following excision and 11% of the cases underwent neoplastic transformation. Five out of 10 (50%) cases of severe dysplasia which were p53 positive resolved.
CONCLUSION: The proportion of cases with positive p53 expression increased from hyperplasia to dysplasia to OSCC. These results may indicate an involvement of p53 in neoplastic transformation as well as in proliferative events although the presence or absence of p53 staining could not be used to predict the outcome of potentially malignant oral mucosal lesions.     

The effects of chewing areca/betel quid with and without cigarette smoking on oral submucous fibrosis and oral mucosal lesions

OBJECTIVES: The purpose of this study was to investigate the risk of areca/betel quid chewing with or without cigarette smoking on oral submucous fibrosis (OSF) and other oral mucosal lesions. METHODS: A stratified case-control study was designed. There were in total 102 patients with oral mucosal lesions or OSF (confirmed pathologically) in the case group. OSF (n = 62) and oral mucosal lesions (n = 62) in 102 subjects were separately analyzed for men and women investigating their risks. RESULTS: For OSF, people with both smoking and chewing habits had a statistically significant odds ratio (OR) 8.68 (95% CI = 1.87, 40.23). For the group of people with chewing habit only and without any lifetime cigarette smoking habit, the OR was 4.51 (95% CI = 1.20, 16.94). For other oral mucosal lesions, people with mixed habits and chewing only had also significant risks (OR = 8.37 and 3.95, respectively). For both OSF and other oral lesions, the ORs of mixed habits and chewing only were both higher in women than in men. Conclusions: The areca/betel quid used in Taiwan does not contain any tobacco product. The only way of areca/betel quid could synergize with any tobacco product is through cigarette smoking. A statistically significant association with oral mucosal lesions and OSF was still found in the group of areca/betel quid chewing only.     

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

OBJECTIVE: The purpose of this study was to clarify the correlation of expression of cell cycle-associated gene proteins with clinicopathologic factors in oral squamous cell carcinoma (SCC). STUDY DESIGN: Formalin-fixed paraffin-embedded tissues from 69 oral SCC cases and 10 normal mucosa cases were stained by immunohistochemistry (IHC) for p53, mdm 2, and p21 proteins. RESULTS: We found p53, mdm 2, and p21 expression in 44 of 69 (63.8%), 25 of 69 (36.2%), and 37 of 69 (53.6%) oral SCCs, respectively. Ki-67-labeling index of combined p53(+)/mdm 2(+) expression cases was significantly higher than those that lacked combined expression (P =.004). Combined p53(+)/p21(+) expression showed a significant association with lymph node metastasis (P =.019). In survival analysis, combined p53(+)/p21(+) and p53(+)/mdm 2(+)/p21(+) expression was associated with poor clinical outcome (P =.018 and.012, respectively). CONCLUSION: Combined p53/mdm 2 expression was associated with tumor proliferation in oral SCC. Combined p53/p21 and p53/mdm 2/p21 expression may be a predictive factor in lymph node metastasis.     

口腔黏膜下纤维性变及其癌变组织中端粒酶逆转录酶表达

目的:探讨人端粒酶逆转录酶(hTERT)在口腔黏膜下纤维性变(OSF)癌变过程中的作用。方法:用免疫组织化学SP法检测10例正常口腔黏膜组织,46例OSF组织,14例OSF癌变组织以及10例相邻非癌变OSF组织中hTERT表达情况。结果:正常口腔黏膜组织上皮中无hTERT阳性表达,OSF癌变组织中hTERT阳性表达率(12/14)明显高于OSF组(7/46)(P<0.005),相邻非癌变OSF组织中hTERT阳性表达率(7/10)明显高于普通OSF组(7/46)(P<0.005)。结论:hTERT蛋白过度表达在OSF癌变过程中具有重要作用。     

Expression of apoptotic signaling proteins in leukoplakia and oral lichen planus: quantitative and topographical studies

Although the pathogenesis of leukoplakia has been unclear, carcinogenic transformation is postulated to result from alterations of apoptotic signal transduction proteins in epithelial cells. The pathogenesis of oral lichen planus (OLP) has also been unclear, but apoptotic changes of the epithelial cells in OLP have been reported. In the present study, we used a histochemical approach to describe human keratinocyte-expression of several apoptotic signaling proteins in leukoplakia, in OLP, and in normal oral mucosa as a control. Mucosal biopsies from patients with leukoplakia (n=13), OLP (n=10), and normal oral mucosa (n=9) were frozen, sectioned and immunostained with monoclonal antibodies to wild-type (wt) tumor suppressive protein p53, cyclin-dependent kinase inhibitor p21WAF1/CIP1 and the oncoproteins MDM2, and Bcl-2. Apoptosis was assessed in all cases by the TUNEL method. MDM2 and Bcl-2 expression in keratinocytes were quantitatively greater in leukoplakia than in OLP. Wt-p53 and p21WAF1/CIP1 expression was quantitatively greater in keratinocytes in OLP than in leukoplakia. Keratinocyte maturation appeared histologically normal in OLP, even though wt-p53 and p21WAF1/CIP1 were expressed in these cells. Altered keratinocyte maturation was seen in leukoplakia lesions expressing MDM2 and Bcl-2. No significant difference for the number of apoptotic epithelial cells was observed between leukoplakia and OLP, in spite of the divergent outcomes of the apoptotic signaling proteins.     

Aberrant expression of p53, p16INK4a and Ki‐67 as basic biomarker for malignant progression of oral leukoplakias

J Oral Pathol Med (2011) 40 : 629–635 Background: The risk of malignant progression of oral leukoplakia with and without dysplasia is unpredictable. Materials and methods: Leukoplakias without dysplasia of 35 patients, leukoplakias with dysplasia of 4 patients, and similar lesions obtained from tumor patients were retrospectively examined by immunohistochemistry for the expression of the proteins pRb, p53, p16^INK4a, Cyclin D1 and Ki‐67. The predictive power of combined aberrant expression patterns for the progression of leukoplakias without dysplasia was examined. Results: Increased expression of p53, Ki‐67 and Cyclin D1, and loss of p16^INK4a occurred in 45.9%, 38.9%, 29.4% and 32.4% of the leukoplakias without dysplasia, respectively. All alterations increased with progression but had poor positive predictive value. However, the combined p53/p16^INK4a/Ki‐67 aberration occurred in only three (9%) cases, of which two patients (66.7%) experienced progression to dysplasia and carcinoma in situ. The combined p53/p16^INK4a/Ki‐67 alteration had a negative predictive value (NPV) and sensitivity of 100%, specificity of 97% and positive predictive value (PPV) of 67%. By contrast, the combined p53/p16^INK4a/Cyclin D1 alteration had 97% NPV and sensitivity of 50%, specificity of 90% and only 25% PPV. Loss of pRb and concomitant overexpression of p16^INK4a were not observed arguing against an involvement of HPV in oral leukoplakia. Conclusions: We propose the combined p53/p16^INK4a/Ki‐67 alteration as a basic marker to define high risk leukoplakia patients. Lesions not showing this alteration appear to be harmless. Future studies should validate these findings and search for proteins which can further improve the PPV of the proposed basic marker.     

Association of aberrant p53 and p21WAF1 immunoreactivity with the outcome of oral verrucous leukoplakia in Taiwan

The expression of p53 and p21WAF1 in 53 oral verrucous leukoplakias (OVLs), mostly non-dysplastic lesions, was investigated to ascertain the role of such events in malignant conversion. Immunohistochemical analysis revealed aberrant p53 and p21WAF1 immunoreactivity in 51% (27 cases) and 75% (40 cases), respectively. After an average follow-up period of three and a half years, histopathological examination revealed that 22 (42%) cases had developed oral squamous cell carcinoma (OSCC), 14 (26%) cases had undergone recurrence, and 17 (32%) cases were free of disease. The oncogenic potential of this subset of premalignant lesions warrants attention. A significant difference in the frequency of OSCC progression/recurrence was noted in lesions bearing aberrant immunoreactivity of either p53 (93% vs 42%; P=0.00008) or p21WAF1 (80% vs 32%; P=0.002) in comparison with lesions without immunoreactivity. This study suggested that the aberrant immunoreactivity of p53 and p21WAF1 may represent important alterations of OVL and could affect the outcome of this lesion.     

口腔黏膜下纤维化癌变过程中G2、M期细胞周期蛋白与存活素磷酸化的研究

目的 探讨细胞周期G2、M期重要分子细胞周期蛋白B1(Cyclin B1)、细胞分裂周期蛋白2(cell division cycle 2,p34cdc2)和存活素磷酸化在口腔黏膜下纤维化(oral submucosa fibrosis,OSF)癌变过程中的作用与意义.方法 应用Western blotting检测10例正常口腔黏膜上皮组织、40例OSF上皮组织及42例OSF癌变组织中Cyclin B1、p34cdc2和存活素磷酸化的表达情况,免疫共沉淀实验分析p34cdc2激酶与存活素的相关性.结果 Cyclin B1、p34cdc2、磷酸化p34cdc(p-p34cdc2)和存活素磷酸化在OSF组织中表达显著高于正常口腔黏膜(P＜0.05);在OSF癌变组织中的表达显著高于OSF组织(P＜0.05);但在OSF早、中、晚期3组间差异无统计学意义(P＞0.05).免疫共沉淀实验证实了p34cdc与存活素的结合.结论 细胞周期G2、M期重要分子Cyclin B1、p34cdc2及存活素磷酸化在OSF细胞分裂增殖过程中起促进作用,对OSF癌变的早期诊断和治疗具有重要的临床意义.     

Oral precancerous disorders associated with areca quid chewing, smoking, and alcohol drinking in southern Taiwan

OBJECTIVE: To investigate the prevalence and the associated risk factors of oral precancerous disorders in southern Taiwan. METHODS: We conducted a cross-sectional community survey interviewing 1075 adult subjects, 15 years of age and over, gathered from randomly selected 591 households, and spanning five villages in southern Taiwan. The study protocol included a visual oral soft tissue examination and a questionnaire-based interview. The chi-square test was used to test the differences in prevalence of oral precancerous lesions and conditions by different "life styles" relating to current risk habits of current areca quid chewing, smoking, and alcohol drinking. To control for possible confounding, a logistic regression model was used to estimate the Odds Ratios (OR) for leukoplakia and oral submucous fibrosis (OSF). RESULTS: 136 precancerous lesions and conditions were detected among 1075 subjects (12.7%). The analysis of the spectrum of oral precancerous disorders detected, leukoplakia (n = 80), OSF (n = 17) and verrucous lesions (n = 9), demonstrated an association with gender (P < 0.001). There were statistically significant associations among leukoplakia (P < 0.01), OSF (P < 0.0001), and verrucous lesions (P < 0.0001) and the life style of current areca quid chewing, smoking, and alcohol drinking. The synergistic effect of smoking and areca quid chewing habit on leukoplakia and OSF was demonstrated. CONCLUSION: This study reinforces the association of current areca quid chewing without tobacco, cigarette smoking, and alcohol drinking to leukoplakia, OSF, and verrucous lesions in Taiwan.     

Cell cycle regulating mechanisms in oral lichen planus: molecular bases in epithelium predisposed to malignant transformation

OBJECTIVE: Expression of p53, p21, ki-67, Bcl-2 and caspase-3 proteins in oral lichen planus (OLP) was studied to investigate cell cycle regulation mechanisms in this disease. MATERIAL AND METHODS: Oral biopsies were obtained from 51 patients with OLP and 26 controls for immunohistochemical analysis (peroxidase antiperoxidase) to quantify expression of the proteins under study (-: 0%, +: <10%, ++: 10-25%, +++: 26-50%, ++++: >50% positive cells). RESULTS: Basal expression of caspase-3 was negative in 22 cases (46.8%) and positive in <10% of basal cells in 22 cases (46.8%); caspase-3 expression in inflammatory infiltrate was negative in 22 cases (46.8%) and positive in <10% of lymphocytes in 20 cases (42.5%). Basal expression of Bcl-2 was negative in 35 cases (74.5%); Bcl-2 was expressed in inflammatory infiltrate in 34 cases (72.3%) and was positive in <25% of lymphocytes in 14 of these (29.7%). Basal expression of p53 and p21 was positive in 32 (67.9%) and 23 (48.8%) cases, respectively. Basal expression of ki-67 was positive in 45 cases (95.7%), of which 20 (42.5%) showed positivity in >25% of cells; ki-67 was expressed in inflammatory infiltrate in 23 cases (48.9%). Significant associations were found between basal expressions of p53 and ki-67 (p<0.001) and between Bcl-2 expression in infiltrate and basal expression of ki-67 (p<0.001). No association was observed between basal expressions of p53 and caspase-3 (p=0.08). Bcl-2 expression in infiltrate and basal expression of ki-67 were independently associated with presence of OLP. CONCLUSIONS: Epithelial cells in OLP do not preferentially develop apoptosis but rather cycle arrest or an increased proliferation rate, which may create a suitable substrate for malignant transformation.     

Evaluation of p53, Caspase-3, Bcl-2, and Ki-67 markers in oral squamous cell carcinoma and premalignant epithelium in a sample from Alava Province (Spain)

Objectives: The objective of this study was to determine whether alterations in the expression of p53, caspase-3 Bcl-2, and ki-67 appear early in premalignant oral epithelium and show clonal behavior. Study Design: Samples from 41 tumors with their adjacent non-tumor epithelia were immunohistochemically analyzed using monoclonal antibodies that recognize p53, caspase-3, Bcl-2, and Ki-67 Results: A statistically significant association was found between the expression in tumor and adjacent epithelium of p53, caspase-3, and Bcl-2 but not of k-67. A significant association was observed between the expression of ki-67 and p53 in both localizations. In non-tumor (premalignant) epithelium samples, there was a significant inverse relationship between the expressions of p53 and caspase-3 and a significant direct relationship between the expressions of p53 and Bcl-2. Conclusions: Alterations in these proteins appear to operate in combination with premalignant epithelia to create hyperproliferative cell states that favor the acquisition of summative oncogenic errors that confer invasive capacity. Key words:Cell cycle, apoptosis, p53, caspase-3, Bcl-2, Ki-67.     

转化生长因子β1在口腔粘膜下纤维性变角朊细胞中的表达

为探讨转化生长因子β１在口腔粘膜下纤维性变发病机理中的作用，作者应用原位杂交方法，对２５例口腔粘膜下纤维性变（ｏｒａｌｓｕｂｍｕｃｏｕｓｆｉｂｒｏｓｉｓ，ＯＳＦ）、５例正常口腔粘膜（ＮＯＲ）及１０例口腔扁平苔藓（ｏｒａｌｌｉｃｈｅｎｐｌａｎｕｓ，ＯＬＰ）组织角朊细胞中转化生长因子β１（ｔｒａｎｓｆｏｒｍｉｎｇｇｒｏｗｔｈｆａｃｔｏｒβ１，ＴＧＦβ１）ｍＲＮＡ进行了检测。结果：１５例（６０％）ＯＳＦ组织角朊细胞中有ＴＧＦβ１ｍＲＮＡ表达，阳性表达主要分布于早、中期ＯＳＦ组织角朊细胞中；５例ＮＯＲ及１０例ＯＬＰ组织角朊细胞表达呈阴性。结果提示：ＯＳＦ组织角朊细胞可合成分泌ＴＧＦβ１，ＴＧＦβ１在ＯＳＦ的发病机理中可能起重要作用，可能作为一中间介质参与了ＯＳＦ的发病过程。     

核受体共激活因子7在槟榔碱诱导的上皮间充质转化中的生物学功能

目的研究核受体共激活因子7(nuclear receptor coactivator 7,NCOA7)在口腔黏膜下纤维性变(OSF)中的表达及意义,并探讨其在人口腔角质细胞株HOKs间充质转化过程中的作用。方法收集OSF组织30例及正常口腔黏膜组织15例,采用免疫印迹法检测NCOA7、上皮间充质转化相关标记物在OSF组织及正常黏膜组织中蛋白水平的表达情况;以Western blot法检测槟榔碱刺激后HOKs中NCOA7、上皮及间充质标记物的蛋白水平变化。结果 NCOA7在30例OSF组织高表达(P<0.05);同时在细胞基底层出现间充质标记物的阳性表达。NCOA7在槟榔碱刺激的HOKs中高表达,且具有槟榔碱浓度依赖性(P=0.004 3);随着槟榔碱浓度的升高,上皮标志物表达逐渐下调,间充质标记物表达逐渐升高。结论口腔黏膜下纤维性变组织中高表达的NCOA7,可能参与调控上皮细胞间充质转化过程,进一步促进纤维化进程。     

口腔黏膜下纤维化中VEGF和TSP表达及相关性的研究

目的:研究血管内皮生长因子(vascular endothelial growth factor,VEGF)和血小板反应蛋白(thrombo-spondin,TSP)在口腔黏膜下纤维化(oral submucous fibrosis,OSF)中的表达,探讨两者的相关性及在OSF发病中的作用.方法:选取30 例OSF患者,其中早、中、晚期各10 例, 5 例健康志愿者作为对照组.取每例研究对象口腔颊黏膜,采用免疫组化SP法检测VEGF和TSP的蛋白表达. 结果:VEGF在OSF早期较正常口腔黏膜中表达增高,中、晚期逐渐下降,其中早期组与正常组、中期组、晚期组比较均有显著性差异(P<0.05).TSP在OSF早、中期表达持续增高,晚期稍下降,各组间差异无显著性(P>0.05).病变组织黏膜下层中VEGF与TSP呈负相关(r=-0.620,P<0.05).结论:VEGF和TSP的异常表达可能是OSF微血管病变的重要发病机制之一.