Oral submucous fibrosis. A review

A bstract — Oral submucous fibrosis (OSF) affects an estimated 2.5 million people, mostly in the Indian subcontinent. Limitation of oral opening resulting in difficulty in eating is the main presenting feature. Although nutritional deficiencies and immunological processes may play a part in the pathogenesis, the available epidemiological evidence indicates that chewing betel quid (containing areca nut, tobacco, slaked lime or other spices) is an important risk factor for OSF. Genetically determined susceptibility could explain why only a small fraction of those using betel quid develop the disease. In OSF there is an incidence of oral cancer of 7.6 per cent for a median 10 year follow-up period. Risk markers for malignant transformation in OSF include epithelial dysplasia, silver binding nucleolar organizer region counts, and sister-chromatid exchange frequencies; p53 tumour suppressor gene mutations may be involved in these potentially malignant changes.     

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

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

p53 expression in oral precancer and cancer

Expression of the p53 tumour suppressor gene is a frequent finding in human malignancies, including oral cancer, and it has been detected in some potentially malignant lesions. The results of the present project showed that 35 of the 41 (85 per cent) oral mucosal lesions with histological evidence of epithelial dysplasia expressed p53, but the presence or absence of p53 staining could not be used to predict the outcome of potentially malignant oral mucosal lesions.     

p53,PCNA在口腔粘膜癌前病变中的表达及其临床意义

目的观察ｐ５３和ＰＣＮＡ在口腔粘膜癌前病变中的表达特征,进一步探讨其临床意义。方法对５０例临床疑为癌前病变的患者行局部组织活检、光镜检查,作出病理诊断;同时采用免疫组织化学方法进行ｐ５３和ＰＣＮＡ的标记,并将两者结果做比较。结果在癌前病变中,随着上皮细胞的异常增生从基底层向角化层发展,ｐ５３和ＰＣＮＡ阳性表达细胞也随着同步发展。病变伴不同程度异常增生的各病例阳性表达程度之间有显著差异（Ｐ＜０．０１）。结论ｐ５３和ＰＣＮＡ在口腔粘膜癌前病变中的表达呈同步性。且与病变细胞的异常增生程度呈正相关;ｐ５３在癌前病变中的阳性表达可能是其发生癌变的早发事件;癌变的发生可在上皮异常增生的较早期。故ｐ５３和ＰＣＮＡ的检测有利于临床上早期发现有异常增生倾向的病变。     

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.     

Upregulation of heme oxygenase-1 in oral epithelial dysplasias

The expression of heme oxygenase-1 (HO-1), stress-related enzyme, is induced in leukaemia and some cancer tissues, but relatively little is known about the differential pattern of HO-1 expression and proliferation in premalignant lesions of the epithelial oral mucosa. The purpose of this study was to evaluate whether HO-1 expression and proliferation were increased in preneoplastic lesions compared to normal and oral cancer tissues. Immunohistochemical staining was used to examine the expression patterns of HO-1 and proliferating cell nuclear antigen (PCNA) in a series of normal mucosa and mild-to-severe cases of oral epithelial dysplasia (OED) and oral squamous cell carcinoma. Both HO-1 and PCNA are expressed in the basal cells of normal oral mucosa. In patients with OED and carcinoma in situ, immunostaining for PCNA and HO-1 was more intense, and gradually extended into the superficial layers of the mucosa. HO-1 and PCNA expression was correlated with the degree of epithelial dysplasia. Oral squamous cell carcinoma also showed elevated expression of HO-1, but this level was not higher than in severe OED or carcinoma in situ. These results suggest that the up-regulation of HO-1 in premalignant oral lesions is part of an early cytoprotection mechanism against carcinogenesis in the oral mucosa.     

Epithelial p53 gene expression and mutational analysis, combined with growth fraction assessment, in oral lichen planus

The immunohistochemical detection of epithelial p53 protein expression in oral lichen planus (OLP) biopsies was supplemented with molecular analysis for mutations of the p53 gene using the polymerase chain reaction - single stranded conformational polymorphism (PCR-SSCP) technique. p53 protein expression, in the basal epithelial cell layer, as detected by the DO7 and 1801 antibodies, was significantly more frequent in OLP compared with other oral keratoses and normal mucosa, as was the growth fraction. The 10 OLP biopsies that had the most frequent p53 staining (plus a case of OLP found in continuity with a SCC) were screened by the PCR-SSCP technique, but no mutations were detected in the p53 gene (exons 5–9). The p53 overexpression in the OLP samples may be a physiological response to the hyper-proliferative state, as revealed by the growth fraction determination. This may usefully serve to protect against mutagenesis, and so be a factor in the low incidence of carcinoma associated with OLP.     

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

OBJECTIVE: Knowledge of the molecular pathogenesis of oral submucous fibrosis (OSF), a potentially malignant condition with high risk of transition to oral cancer, is meagre. Alterations in the expression of retinoic acid receptor beta (RARbeta) and tumor suppressor gene, p53 are early events in oral tumorigenesis. The aim of this study was to investigate the alterations in the expression of RARbeta and p53 in OSF lesions and determine their association with disease pathogenesis. METHODS: The expression of RARbeta and p53 proteins was analyzed by immunohistochemistry in 50 cases of OSF and 30 histologically normal oral tissues. RESULTS: No detectable RARbeta expression was observed in 35 of 50 (70%) OSF cases. p53 protein accumulation was observed in 24 of 50 (48%) OSF cases analyzed. Thirty-six percent OSF lesions showed loss of RARbeta and p53 overexpression. Interestingly, 41 of 50 (82%) of OSF lesions showed altered expression of at least one of these two proteins. CONCLUSION: Altered expression of either RARbeta or p53 in majority of OSF lesions suggests their association with disease pathogenesis and warrants follow-up to determine whether OSF lesions harboring concomitant alterations in RARbeta and p53 are at a high risk of transition to malignancy.     

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.     

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.     

Nuclear and cytoplasmic expression of Met in oral squamous cell carcinoma and in an organotypic oral cancer model

Brusevold IJ, Søland TM, Khuu C, Christoffersen T, Bryne M. Nuclear and cytoplasmic expression of Met in oral squamous cell carcinoma and in an organotypic oral cancer model. Eur J Oral Sci 2010; 118: 342–349. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci Met, the hepatocyte growth factor receptor, is important in transducing signals for tumour growth and metastasis. The aim of this study was to examine the pattern of Met expression and its value as a prognostic factor in oral squamous cell carcinomas (OSCCs). The material consisted of 53 OSCCs and five healthy controls from normal oral mucosa supplied with cell lines, 10 organotypic models supplied with oral cancer cells, and three organotypic models supplied with normal keratinocytes. Met protein expression was assessed by immunohistochemistry and western blotting. Met expression was scarce and limited to the basal layer in normal oral mucosa, but was more extensive in the tumours. Cytoplasmic expression of Met was found in the majority of the tumours, and nuclear expression was found in 72%, including a high fraction of the cells located at the invasive front. Organotypic models with normal or malignant oral cells yielded principally similar results as in the mucosa and the cancers, respectively. A smaller amount of Met immunoreactivity was detected, by western blotting, in the nuclear fraction of cultured oral cancer cells. In conclusion, Met was upregulated in OSCCs and was also found in the nucleus. However, Met was not a marker for prognosis in this study.     

口腔粘膜上皮癌前及癌变中PCNA和P53的表达

目的：检测口腔粘膜上皮癌前及癌变组织中ＰＣＮＡ和ｐ５３的表达，探讨口腔癌变的机理。方法：采用免疫组化的方法检测８０例口腔粘膜病变组织中ＰＣＮＡ和ｐ５３的表达。结果：正常口腔粘膜基底层有少数ＰＣＮＡ阳性细胞，随着粘膜异常增生程度的加重到鳞癌，ＰＣＡＮ表达的阳性分级升高，ＰＣＮＡ的相对含量也升高。Ｐ５３的阳性表达仅见于重度异常增生及鳞癌组织中。结论：对ＰＣＮＡ和ｐ５３的研究有助于探讨口腔粘膜癌变多阶段发生过程的机理，并可为监测癌变提供生物学指标。     

Higher expressions of p53 and proliferating cell nuclear antigen (PCNA) in atrophic oral lichen planus and patients with areca quid chewing

OBJECTIVE: The aim of the study was to examine the expressions of p53 and proliferating cell nuclear antigen (PCNA) in oral lichen planus (OLP) in relation to its clinical behavior and the patients' oral habits. STUDY DESIGN: Immunohistochemical study was carried out to investigate the expressions of p53 and PCNA in 56 OLP specimens. The results were correlated with the clinical behavior of the disease and the patients' oral habits. The expression rates were further compared with those of normal oral mucosa (NOM), epithelial hyperkeratosis (EH), epithelial dysplasia (ED), and squamous cell carcinoma (SCC). RESULTS: The staining rate of p53 (28.6%) and PCNA labeling index (LI) (27.6 +/- 8.8%) in OLP were similar to those in EH ( P = .868, .074, respectively), but higher than those of NOM and lower than those of ED and SCC (all P < .05). In OLP, no significant correlations were found between p53 or PCNA expression and the patients' age, gender, lesion duration, location, size, number of site, presence of pain, presence of local irritant, and the habits of alcohol drinking and cigarette smoking (all P > .05). In addition, the mean PCNA LI of p53+ cases was close to that of p53- cases (P = .38). However, the staining rate of p53 in OLP was higher in areca quid (AQ) chewers compared to abstainers (P = .001), and the mean PCNA LI in atrophic cases was higher than that in hypertrophic cases (P = .029). Interestingly, the staining rate of p53 and mean PCNA LI were significantly increased in AQ chewers with atrophic OLP (100%, 36.7% +/- 9.0%, respectively), which were similar to those in ED and SCC (all P > .05). CONCLUSIONS: Although this study could not confirm the precancerous nature of OLP by the relatively low p53 and PCNA expression, the results do suggest that atrophic form OLP and patients with AQ chewing habit may have a higher disease activity in view of higher expression rates of p53 and PCNA in the lesions.     

TP53 mutations in clinically normal mucosa adjacent to oral carcinomas

J Oral Pathol Med (2010) 39 : 662–666 Background: The tumour‐suppressor protein p53 often accumulates in histologically normal epithelium adjacent to oral squamous cell carcinomas (OSCC). We investigated whether this was associated with mutations in TP53, the gene for p53, and might implicate impending malignancy. Methods: Specimens from 18 human squamous cell carcinomas were stained with monoclonal p53 antibodies. Positive cells were microdissected with laser‐captured microscopy from the tumour and adjacent normal and dysplastic epithelium. DNA was extracted, and exons 5–9 of the TP53 gene were amplified by PCR. Amplified products were separated by denatured gradient gel electrophoresis. Fragments with a deviant DGEE pattern were sequenced. Results: TP53 mutations were found in six of 18 tumours. Fourteen specimens contained histologically normal mucosa adjacent to the tumour; 13 of these showed small clusters of p53 positive cells. Seven specimens contained both histological normal and dysplastic epithelial tissues adjacent to the tumour. A TP53 mutation was found in only one specimen; this mutation appeared in the normal mucosa, the adjacent tumour, and the epithelial dysplasia. Conclusion: We found that upregulation of p53 was a frequent event in histological normal mucosa adjacent to OSCC; however, it was rarely associated with a mutation in the TP53 gene.     

PCNA,p53在口腔粘膜癌前病变及鳞癌中表达的免疫组化研究

应用免疫组化方法对３９例口腔粘膜癌前病变和癌中的增殖细胞核抗原，突变型ｐ５３的表达进行检测。结果表明：从ＬＰ，ＬＫ到ＩＳＣ，其ＰＣＮＡ和Ｐ５３的阳性表达均呈递增趋势。提示ＰＣＮＡ，Ｐ５３表达程度与细胞增殖程度和分化程度关系密切。     

Expression form of p53 and PCNA at the invasive front in oral squamous cell carcinoma: correlation with clinicopathological features and prognosis

J Oral Pathol Med (2011) 40 : 693–698 Background: Abnormalities in cell‐cycle‐controlling genes are important in the malignant transformation and proliferation of tumors. Among these genes, the tumor suppressor gene p53 is the most notable, and its mutations provide an indicator of tumor progression and prognosis. Proliferating cell nuclear antigen (PCNA) is a highly conserved nuclear protein that is expressed during cell replication and DNA repair. This study examined the expression of p53 and PCNA at the invasive front of oral squamous cell carcinomas (OSCC) by immunohistochemical staining, and investigated the relationship of these proteins to clinicopathological findings and prognosis. Methods: Fifty‐nine biopsy cases of OSCC were examined by immunohistochemical staining. Clinicopathological data were gathered and patient survival was analyzed. Results: The p53 labeling index (p53‐LI) and PCNA labeling index (PCNA‐LI) were examined at the invasive front of the tumors. A high p53‐LI (p53+) was observed in 17 of the 59 cases (28.8%) and a high PCNA‐LI (PCNA+) was observed in 28 of the 59 cases (47.5%). Among the modes of cancer invasion, many of the p53+/PCNA+ cases could be confirmed as highly invasive cancer (P < 0.05). In addition, the p53+/PCNA+ cases showed a high risk of tumor recurrence compared with the other expression forms, and patients with p53+/PCNA+ had a worse prognosis than those with the other expression forms. High labeling indices of p53 and PCNA are associated with poor prognosis in patients with OSCC. Conclusion: We suggest that it is important to investigate the expression of p53 and PCNA at the invasive front of OSCC.     

人成釉细胞瘤中端粒酶活性与细胞周期素A的表达

目的　研究端粒酶hTERT基因在人成釉细胞瘤 (ameloblastoma,AB)中的表达及其与细胞周期素A (cyclinA)和相关因子 p53蛋白、增殖细胞核抗原 (proliferationcellnuclearantigen ,PCNA)的关系 ,探讨其临床生物学意义。方法　用免疫组化 (SP法 )和原位杂交技术分别检测了AB中细胞周期素A、p53蛋白和PCNA ,hTERTmRNA的表达 ,同时以正常口腔粘膜和牙源性角化囊肿(odontogenickeratocyst,OKC)为对照。 结果　在正常口腔粘膜中只有 1例hTERT阳性 (1 / 7) ,cyclinA、p53蛋白、PCNA三者之间表达有着相似共性。OKC中表达在基底或副基底层细胞核中 ,有1 4例hTERT阳性 (1 4 / 1 6) ,4例cyclinA阳性 (4/ 32 )、1 1例p53蛋白阳性 (1 1 / 2 5) ,5例PCNA阳性(5/ 9)。hTERTmRNA在AB中表达率为 94 4% (51 / 54) ,cyclinA为 66 7% (40 / 60 ) ,p53蛋白为85 7% (42 / 4 9) ,PCNA为 78 1 % (2 5/ 32 ) ,hTERT与cyclinA、p53蛋白、PCNA之间经Kendall相关分析 ,rs 分别为 0 91 4、0 848、0 80 4 ,P <0 0 5。结论　随着组织学分级增高 ,hTERTmRNA与cyclinA、p53蛋白、PCNA阳性率及信号强度均增高。在AB中端粒酶的活性表达与p53蛋白的蓄积有关 ,与细胞的增殖、分化有关 ,并受cyclinA调节 ,在S期中有较高表达     

P53 expression and clinical significance in oral squamous cell carcinoma]

P53 protein expression was investigated in oral squamous cell carcinomas and oral premalignant lesions by monoclonal antibody Do-1 and immunohistochemistry technique. 4 of 12 (33.3%) samples of severe epithelial dysplasia and 25 of 44 (56.8%) samples of squamous cell carcinoma expressed P53 protein while all the normal mucosa, mild and moderate epithelial dysplasia were negative. The P53 expression in carcinomas was associated with differentiation, lymph node metastasis and tumour stage. This result indicated that P53 genic mutation might be an early event in oral mucosa carcinogenesis and related to oral tumor progression. Detection of P53 protein probably has clinical significance in identifying the premalignant lesions of oral mucosa and predicting the prognosis of oral carcinomas.     

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。