p53 GENE ALTERATIONS AND p53 PROTEIN IN ORAL EPITHELIAL DYSPLASIA AND SQUAMOUS CELL CARCINOMA

To examine the expression of p53 protein and gene alterations in oral epithelial lesions including epithelial dysplasias and primary squamous cell carcinomas, immunohistochemical and temperature gradient gel electrophoresis (TGGE) methods were applied to formalin-fixed and paraffin-embedded tissues. Morphologically normal mucosal epithelium stained negatively for p53 protein. Three out of 11 (27·3 per cent) epithelial dysplasias and 19 out of 57 (33·3 per cent) primary squamous cell carcinomas stained positively for p53 protein. Although more than half of the cases were positive for p53 protein in stage I, the positive cancer cases were found at other stages with variable frequency. Immunoreactive products were localized in the nucleus, especially in the basal and suprabasal layers. The analysis by TGGE revealed gene alterations in exons 5–8 in 3 out of 3 epithelial dysplasias and 17 out of 19 (89·5 per cent) primary squamous cell carcinomas which were immunohistochemically positive for p53 protein. These results suggest that p53 gene mutation may be involved in carcinogenesis in the oral squamous epithelium even in the early stage of the dysplasia–carcinoma sequence.     

Concurrent p53 expression in bronchial dysplasias and squamous cell lung carcinomas.

We analyzed the p53 protein immunohistochemically in bronchial dysplasias or squamous cell carcinomas in situ and in squamous cell lung carcinomas occurring in the same patients. The polyclonal antibody used (CM-1) is directed against the wild-type p53 protein, but also recognizes the mutated p53 in formalin-fixed and paraffin-embedded sections. To study the integrity of basement membranes (BMs) and the possible invasion of the dysplastic epithelium, immunostainings for the BM proteins laminin and type IV collagen were used. Nine of the 17 dysplasias showed p53 protein expression (53%); it was significantly more often seen in severe dysplasias and carcinomas in situ than in mild or moderate dysplasias (P = 0.04). The p53 antigenicity was generally located in the basal part of the epithelium. The BMs beneath mildly dysplastic epithelia were continuous. In contrast, those under moderately or severely dysplastic epithelia showed occasional disruptions. p53 protein expression was also found in dysplastic epithelium above a continuous BM suggesting an ominous process before signs of invasion. Twelve of the 17 squamous cell carcinomas showed p53 protein expression (71%). There was a significant concurrent p53 expression in bronchial dysplasias and their related squamous cell carcinomas (P = 0.009), so that all nine cases of p53 positive bronchial dysplasia also showed p53 positivity in the associated squamous cell carcinomas. These findings indicate that p53 protein expression is possible in premalignant bronchial lesions, and suggests that the p53 expression could, at least in some cases, be an early event in the development of a squamous cell carcinoma of the lung.     

Markers for dysplasia of the upper aerodigestive tract. Suprabasal expression of PCNA, p53, and CK19 in alcohol-fixed, embedded tissue.

Recognition of premalignant lesions in the oral epithelium has the potential to increase survival rates for squamous cell carcinoma of the oral cavity. It has previously been reported that cytokeratin 19 (CK19), a 40-kd epithelial cytoskeletal protein within the suprabasal squamous epithelium, is a specific marker of moderate-to-severe dysplasia and carcinoma in situ in oral cavity squamous epithelium. In contrast, normal epithelium and hyperplastic lesions reportedly express CK19 only in the basal layer if at all. The authors chose to test and extend this hypothesis by studying suprabasal CK19 expression and dysplasia of the oral cavity and upper aerodigestive tract in paraffin-embedded specimens that had been fixed in alcohol, a superior fixative for the preservation of cytokeratins. The authors examined 56 alcohol-fixed, paraffin-embedded specimens including 37 from the oral cavity, using two antibodies specific for CK19 (Ks19.1 and 4.62), an antibody to the nuclear proliferation marker, proliferating cell nuclear antigen (PCNA) (19A2), and an antibody to the putative tumor suppressor gene, p53 (pAb1801). The lesions were classified as normal, hyperplasia, mild dysplasia, moderate dysplasia, severe dysplasia/carcinoma in situ, or invasive squamous cell carcinoma, following standard histologic criteria. Immunocytochemically stained sections were scored for the presence or absence of suprabasal CK19, suprabasal PCNA, and p53 positivity, regardless of location. The immunostaining patterns of the two anti-CK19 antibodies were essentially equivalent. Except for one laryngeal specimen, normal epithelium, when positive, showed CK19 expression only in scattered cells throughout the basal layer. Proliferating cell nuclear antigen-positive nuclei were found exclusively in the basal layer. In areas of hyperplasia, CK19 immunostaining was absent or confined to the basal layer in 20 of 38 specimens and was expressed in suprabasal cells in 18 of 38 hyperplastic specimens. Proliferating cell nuclear antigen immunostaining in all cases of hyperplasia was limited to the basal layer. Severe dysplasia and carcinoma in situ showed suprabasal CK19 staining in six of nine specimens and no CK19 staining in three of nine specimens. In contrast, suprabasal PCNA immunostaining was found in all dysplasia and carcinoma in situ cases. p53 expression was detected in three of nine severe dysplasia/CIS specimens and was immunocytochemically undetectable in all normal, hyperplasia, and mild to moderate dysplasia specimens. The authors conclude that suprabasal CK19 expression is neither a sensitive nor a specific marker of premalignancy in oral epithelium and cannot be used to distinguish hyperplasia from dysplasia. In contrast, a strong correlation between suprabasal expression of PCNA, a marker for proliferating cells, and dysplasia/carcinoma in situ was evident.(ABSTRACT TRUNCATED AT 400 WORDS)     

p53 immunoexpression in non-malignant oral mucosa adjacent to oral squamous cell carcinoma: potential consequences for clinical management

p53 is a tumour suppressor gene encoding a protein whose function is impaired in a very large proportion of human cancers. The objectives of this study were to determine the natural history of p53 alterations during stages of oral carcinogenesis, by comparing p53 immunoexpression in oral squamous cell carcinomas (OSCCs), their non-malignant adjacent mucosa, and respective metastases; and to define the potential practical consequences for clinical management of p53 staining in the non-malignant adjacent mucosa. Forty-two samples of non-malignant mucosa adjacent to OSCCs, the respective carcinomas, and six lymph node metastases derived from six of the OSCCs were investigated for p53 protein expression by immunohistochemistry. Seven out of 42 (17%) non-malignant mucosal samples immediately adjacent to OSCC showed suprabasal p53 staining and this was significantly associated with moderate/severe dysplasia (p=0.02). In six of these cases (86%), the respective carcinoma showed p53 immunoexpression in more than 50% of the neoplastic cells and in the remaining case, p53 immunoexpression was found in more than 25% of the neoplastic cells. In all p53-negative carcinomas that showed p53 immunoexpression in the non-malignant adjacent mucosa, p53 staining was never detected above the basal cell layer. Lymph node metastases showed the same patterns of p53 immunoexpression as the carcinomas from which they were derived. When suprabasal p53 staining is present in non-malignant mucosa immediately adjacent to OSCCs, this suggests stable p53 alterations which are maintained upon progression to overt malignancy. The immunostaining in non-malignant mucosa of the resection margins of OSCCs might be a valuable predictor for local recurrences and may therefore have implications for the management of patients who have received surgical treatment for OSCC.     

p53 Immunoreactivity in inflammatory and neoplastic diseases of the uterine cervix

Immunoreactivity for the tumour suppressor gene product p53 is commonly found in many different human malignancies and few premalignant lesions. Data on cervical neoplasms, however, are still lacking. We retrospectively investigated p53 immunoreactivity in 92 lesions of the uterine cervix, including 44 cases of chronic cervicitis, 29 squamous intraepithelial lesions (SILs), and 19 invasive carcinomas. p53 immunoreactivity confined to the basal cell layer, was detected in 74 per cent of cases showing chronic cervicitis and in all cases with low-grade SILs. Conversely, suprabasal and/or diffuse p53 immunoreactivity was exclusively demonstrated in 25 per cent of high-grade SILs and in 74 per cent of invasive carcinomas. The results of this investigation document a high prevalence of p53-immunoreactive malignant tumours of the uterine cervix. In high-grade SILs, p53-immunoreactive cells paralleled the height of involvement by dysplastic changes within the squamous epithelium. A prolonged half-life of the protein is the most likely explanation for the occurrence of p53 immunoreactivity in neoplastic cells. The unexpected finding of p53-immunoreactive cells in inflammatory lesions, though possibly related to an increased proliferation rate of the basal cell compartment, requires further study and underlines the need for a careful approach to p53 immunocytochemistry.     

Molecular analysis of oral lichen planus. A premalignant lesion?

Oral lichen planus (OLP) is a common mucosal condition that is considered premalignant by some, although others argue that only lichenoid lesions with dysplasia are precancerous. To address the question of whether OLP without dysplasia is premalignant, we used microsatellite analysis to examine 33 cases of OLP for allelic loss at nine loci located on chromosomes 3p, 9p, and 17p. Loss of heterozygosity (LOH) on these three arms occurs frequently in oral tumors, and the presence of these alterations in premalignant lesions suggests that they may play an important role in tumor progression. Results were compared with those observed in oral dysplasias (10 mild, 11 moderate, 16 severe/carcinoma in situ), 22 oral squamous cell carcinomas, and 29 reactive lesions. LOH was present in 6% of OLP, 14% of reactive lesions, 40% of mild dysplasia, 46% of moderate dysplasia, 81% of severe dysplasia/carcinoma in situ, and 91% of squamous cell carcinomas. LOH was detected on only a single arm in OLP and reactive lesions but occurred on more than one chromosome in dysplasia and cancer, and the frequency of this multiple loss correlated significantly with increasing degrees of dysplasia and progression into squamous cell carcinoma (P = 0.0028). Although these findings do not support OLP as a lesion at risk for malignant transformation, such results need to be confirmed by use of other genetic markers as OLP may undergo malignant transformation through genetic pathways different from those of oral dysplasia.     

Immunocytochemical analysis of AE1/AE3, CK 14, Ki-67 and p53 expression in benign, premalignant and malignant oral tissue to establish putative markers for progression of oral carcinoma

Squamous cell carcinoma (SCC) is the most common form of oral malignancy and is often preceded by premalignant lesions, some of which are more likely to progress to carcinoma than others. In this study, a panel of monoclonal antibodies (AE1/AE3, cytokeratin [CK] 14, Ki-67 and p53) is applied to 10 cases of human oral tissue in each of six categories to establish staining patterns indicative of which lesions are more likely to progress to malignancy. The six tissue categories are normal tissue; abnormal benign lesions; mild, moderate and severe dysplasia; and SCC. A statistical analysis of Ki-67 and p53 immunoexpression is performed. The results showed that AE1/AE3 and CK 14 expression was reduced as a late event in oral carcinogenesis, particularly in poorly differentiated SCC. Expression of Ki-67 and p53 proved to be a weak but statistically significant predictor of malignant progression in oral tissue.     

Expression pattern of p63 in oral epithelial lesions and submucous fibrosis associated with betel-quid chewing in Sri Lanka

Betel-quid chewing, which is closely related to the high incidence of oral cancer, is prevalent in Sri Lanka. p63 has a remarkable structural similarity to p53, suggesting an aberrant expression in oral cancer. Using anti-p63 antibody and immunohistochemistry, the present study investigated the expression pattern of p63 in oral epithelial lesions, including different types of squamous cell carcinoma (SCC), different grades of epithelial dysplasia, and submucosal fibrosis associated with betel-quid chewing. Nuclear immunoreactivity for p63 was detected in all the cases, including normal oral epithelium and epithelial lesions. In normal oral epithelium, nuclear positivity for p63 was observed in some of the basal cell layers and focally in the parabasal layer. Nuclear positivity increased in the epithelial lesions. The percentage of positive nuclei in the epithelial lesions was significantly higher than in normal epithelium (P < 0.01) and was also significantly higher in oral submucosal fibrosis than in epithelial dysplasia (P < 0.05). The results indicate that the overexpression of p63 in oral precancerous lesions and SCC in betel-quid chewers in Sri Lanka may be a useful marker for oral precancerous lesions.     

p53 gene mutations in sequential oral epithelial dysplasias and squamous cell carcinomas

Previous studies of oral cancer have suggested that alterations of the p53 tumour suppressor gene occur early in the precancerous stage of development. However, these observations have been based on cross-sectional assessment of abnormal p53 protein staining by immunohistochemistry and may not necessarily reflect gene changes. The purpose of this longitudinal study was to examine the changes in the p53 gene in progressive, sequential epithelial dysplasias and carcinomas from the oral cavity. The study analysed 24 formalin-fixed, paraffin-embedded tissue biopsies from ten patients with two or more temporally distinct lesions from the same site in the oral cavity with the diagnosis of hyperkeratosis, epithelial dysplasia, carcinoma in situ or squamous cell carcinoma. Exons 5-8 of the p53 gene were amplified from genomic DNA using intronic primers and directly sequenced using fluorescent-labelled primers. Standard immunohistochemistry with the DO7 monoclonal antibody was used to detect mutant and wild-type p53 protein. Mutations of the p53 gene were identified in 9 of 24 samples. Eight were missense mutations and one occurred at a splice site. In six patients, mutations of the p53 gene occurred late after the transformation of epithelial dysplasia to carcinoma. In two patients with progressive dysplasia, but who had yet to develop invasive carcinoma, p53 missense mutations occurred at the carcinoma in situ stage in one case and in a moderate dysplasia in the other. There was an inconsistent relationship between gene mutations and the level of p53 protein staining by immunohistochemistry. It is concluded that during oral carcinogenesis, p53 gene mutations seem to occur relatively late and are associated with transformation to the invasive phenotype.     

Assessment of p53 protein expression in normal, benign, and malignant oral mucosa.

Recent studies have shown the accumulation of high levels of p53 protein to be associated with malignant disease, within a range of tissues. This paper assesses p53 expression in oral mucosal disease. Biopsies were obtained from a range of oral disorders which included normal, benign, premalignant, and malignant oral tissue. In addition, oral smears were obtained from a limited number of patients with biopsy-proven oral cancer. Expression of the p53 protein was assessed using the polyclonal antibody CM1, together with a standard immunoperoxidase technique. A total of 37 oral cancers were assessed, of which 20 were found to express the p53 protein (54 per cent of cases). The p53 protein was not identified in normal, benign, or premalignant oral mucosa (54 cases). The identification of p53 within biopsies of oral mucosal lesions would appear to correlate with oral malignancy.     

Suprabasal p53 immunoexpression is strongly associated with high grade dysplasia and risk for malignant transformation in potentially malignant oral lesions from Northern Ireland

AIMS: No good predictive marker for the malignant transformation of potentially malignant oral lesions (PMOLs) is currently available. This study re-evaluated the value of p53 immunoexpression to predict malignant transformation of PMOLs after discounting possible confounding factors. METHODS: PMOLs from 18 patients who showed progression to carcinoma, 16 of the respective carcinomas, and PMOLs from 18 matched controls were evaluated by immunohistochemistry (IHC) for p53 expression. A mouse monoclonal antibody that detects wild-type and mutant forms of human p53 was used. The p53 immunostaining pattern was also correlated with the degree of dysplasia. RESULTS: Suprabasal p53 staining was significantly associated with high grades of dysplasia (p < 0.01). The specificity and positive predictive value (PPV) for malignant transformation of suprabasal p53 staining were superior to the assessment of dysplasia, but sensitivity was inferior. All carcinomas derived from PMOLs with suprabasal p53 showed strong p53 immunostaining. However, the absence of suprabasal p53 staining and/or dysplastic changes did not preclude malignant transformation in a considerable proportion of PMOLs. CONCLUSIONS: This study confirms and extends previous findings that suprabasal p53 immunoexpression has a high PPV for malignant transformation of PMOLs and can be used as a specific marker for lesions that are at high risk for malignant transformation. The absence of suprabasal p53 staining (that is, absence of, or basal, p53 staining) is non-informative for prognostic purposes. Because of its limited sensitivity, p53 IHC is not a substitute for the assessment of dysplasia in the evaluation of PMOLs. Instead, p53 IHC emerges as a clinically useful supplement of histopathological assessment in the prognosis of PMOLs.     

p53蛋白表达与上颌窦鳞状细胞癌发生的关系

用免疫组化技术对８例上颌窦正常粘膜、１６例乳头状瘤及癌变、５０例鳞状细胞癌及１４例癌旁粘膜（包括癌旁正常粘膜、单纯增生及不典型增生）ｐ５３蛋白的表达进行了检测。结果显示，上颌窦癌ｐ５３阳性率为６２％（３１／５０）。ｐ５３表达与患者性别、年龄及肿瘤分化程度无关。上颌窦正常粘膜、单纯增生及乳头状瘤ｐ５３表达阴性。不典型增生ｐ５３表达为４／６，其表达与相应鳞癌存在一致性，不典型增生ｐ５３阳性者，相应癌组织亦为阳性，反之亦然。４例乳头状瘤癌变中，３例ｐ５３阳性。研究结果表明，ｐ５３表达是人上颌窦癌发生的早期事件，而与其恶性程度无关，ｐ５３表达发生于不典型增生或乳头状瘤癌变阶段，显示ｐ５３基因突变与上颌窦癌的发生密切相关。研究结果还表明，检测ｐ５３蛋白有助于上颌窦良，恶性病变的鉴别及早期发现上颌窦癌。     

Suprabasal 40 kd keratin (K19) expression as an immunohistologic marker of premalignancy in oral epithelium.

The authors have studied the expression of keratin 19 in normal oral mucosa and in oral lesions exhibiting a range of histopathologic changes that are thought to precede squamous cell carcinoma. Formalin-fixed, paraffin-embedded sections were pretreated with pronase and stained with a K19-specific antibody by the avidin-biotin immunoperoxidase method. In nonkeratinized mucosa, whether normal or benign hyperplastic, K19 was detectable in the basal cell layer. In keratinized mucosa, whether normal or benign hyperplastic, there was no detectable K19. All lesions from any oral site that exhibited atypia diagnosed from hematoxylin and eosin stained sections as moderate-to-severe dysplasia or carcinoma in situ, whether hyperkeratotic or not, stained strongly for K19 in the basal and suprabasal cell layers. The number of cell layers that were K19-positive correlated with the level in the epithelium to which dysplasia persisted. Suprabasal K19 staining tended to occur in regions of the epithelium in which expression of the terminal differentiation protein involucrin was delayed or absent. Thus, K19 expression may be linked to the retention of stem cell character or a state otherwise uncommitted to terminal squamous differentiation. Suprabasal K19 staining is clearly correlated with premalignant change in oral epithelium and therefore promises to be a useful tool in oral histopathologic diagnosis.     

Immunohistochemical analysis of oral dysplasia: diagnostic assessment by fascin and podoplanin expression

The aim of this study was to investigate fascin and podoplanin expression in oral dysplasia and carcinoma in situ (CIS) immunohistochemically, and to evaluate their relationship to histopathological diagnosis based on architectural and cytological features. Fascin and podoplanin expression patterns were analyzed immunohistologically in 26 specimens of oral lesions, including benign disease (hyperplasia, papilloma, and others), intraepithelial neoplasia/borderline disease (dysplasia), and malignant disease (CIS, invasive squamous cell carcinoma). Fascin expression was scored into four original categories, and podoplanin expression was scored into five previously established categories. The relationship between the immunohistochemically determined scores of fascin and podoplanin expression and the architectural and cytological features in the hematoxylin-eosin-stained slides was analyzed statistically. The immunostaining scores for fascin and podoplanin were significantly higher in dysplasia and CIS than in benign disease (p=0.0011, p=0.00036), and they were significantly higher in dysplasia than in benign disease (p=0.0087, p=0.0032). In all cases of invasive SCC, fascin was expressed mainly in the cytoplasm of the tumor cells and fascin expression extended from the destruction of the basal layer of the epithelium to the upper layer of the epithelium and podoplanin was expressed in the cytoplasm and membrane of the tumor cells. This was the first report of up-regulation of fascin in oral dysplasia. Our results suggest that it would be helpful for improving the diagnostic accuracy of oral dysplasia and CIS to assess the expression of fascin and podoplanin immunohistochemically.     

Premalignant and malignant oral lesions are associated with changes in the glycosylation pattern of carbohydrates related to ABH blood group antigens

The distribution of carbohydrate structures related to the ABO(H) blood group antigen system was studied in biopsies from eight squamous cell carcinomas, and eight erythroplakias with epithelial dysplasia. Twenty oral lesions without histological evidence of malignancy (13 lichen planus lesions and 7 homogeneous leukoplakias) were also examined. The distribution of Lex, Ley, H type 2 chain, and N-acetyllactosamine, all type 2 chain carbohydrate structures, was investigated by immunohistological staining using monoclonal antibodies with selected specificity. The histological pattern of expression of these antigens in the benign lesions was similar to that of normal oral mucosa, i.e. expression of: N-acetyllactosamine on basal cells, H antigen on parabasal cells, and Lex and Ley on spinous cells. However, lesions with epithelial dysplasia showed H antigen on all spinous cells, and often also on basal cells, with expression of Lex and Ley restricted to the most superficial part of the epithelium above the H-positive cell layers. In carcinomas most cells were negative for H antigen but were positive for Ley and Lex in 5 out of 8 cases.     

p53 protein accumulation in oesophageal squamous cell carcinomas and precancerous lesions.

AIMS--To investigate the immunohistochemical expression of p53 protein in oesophageal squamous cell carcinomas and in dysplastic areas of the oesophageal mucosa surrounding the tumours. METHODS--Biopsy samples were obtained from 20 patients with an oesophageal squamous cell carcinoma. Blocks of the tumours and of the surrounding mucosa were immunostained with the monoclonal antibody DO-7. RESULTS--Fourteen of the 20 carcinomas were positive for p53 (70%). The frequency of p53 overexpression increased with the differentiation of the tumour. Nine out of 13 dysplastic specimens were positive for p53 (69%): eight cases with severe dysplasia and one case with moderate dysplasia. No p53 immunostaining was detected in normal oesophageal epithelium. All p53 positive dysplastic specimens were taken from the mucosa adjacent to tumours that were also immunostained. In moderate dysplastic mucosa the p53 positive cells were located in the proliferative basal zone, whereas in severe dysplasia the immunostained cells increased in number and spread to upper cell layers of the epithelium. CONCLUSION--This study supports the hypothesis that TP53 gene is frequently involved in the development of oesophageal squamous cell carcinoma and that p53 protein accumulation is an early event in human oesophageal carcinogenesis.     

p53 expression in normal,dysplastic, and neoplastic laryngeal epithelium. Absence of a correlation with prognostic factors

p53 expression has been examined in 89 squamous cell carcinomas of the larynx (34 glottic, 28 supraglottic, 18 transglottic, 8 pyriform sinus, and 1 subglottic) obtained from 88 patients surgically treated in our centre. In addition, 59 laryngeal samples including normal respiratory epithelium and non-invasive squamous cell lesions were also tested. Frozen sections were immunostained with PAb 1801 and the results were correlated with pathological features, DNA ploidy and S-phase of the tumours, disease-free interval, and survival of the patients. p53 immunoreactivity was observed in 57 (64 per cent) carcinomas. None of the eight samples of normal respiratory epithelium was positive. p53-positive cells were seen in 8 of 23 (35 per cent) squamous cell metaplasias, 6 of 19 (32 per cent) low-grade dysplasias and 5 of 10 (50 per cent) high-grade dysplasias. No correlation was found between p53 expression in carcinomas and their clinical and pathological characteristics, DNA ploidy, or proliferative activity. Neither disease-free nor overall survival showed differences between p53-positive and p53-negative cases. These findings indicate that p53 may play a role in an early stage of malignant transformation of a subset of squamous cell carcinomas of the larynx, but seems not to be associated with further progression of the tumours.     

Immunohistochemical expression of metallothionein in benign premalignant and malignant epithelium of the larynx: correlation with p53 and proliferative cell nuclear antigen

In this study we evaluated the immunohistochemical expression of metallothionein (MT) in 44 squamous cell carcinomas, 14 cases of in situ carcinoma, 47 with epithelial dysplasia, 11 papillomas and 21 cases of keratosis. The MT expression was studied in correlation with p53 protein expression and the proliferative cell nuclear antigen (PCNA). The monoclonal antibodies E9 (anti-MT), DO-7 (which reacts with a denaturation-resistant epitope in wild-type and mutant p53) and PC10 (anti-PCNA) on formalin-fixed, paraffin-embedded tissue were used employing the immunoperoxidase (ABC) method. The immunohistochemical localization of MT has shown its rather ubiquitous presence in the cytoplasm and nucleus of both benign and malignant epithelial cells. In most cases the adjacent "normal" epithelium showed low positivity in the basal portion. The mean value of metallothionein expression was 35.73 in squamous cell carcinomas, 32.21 in in situ carcinomas, 11.86 in dysplastic epithelium, 5.10 in papillomas and 3.5 in keratosis. In carcinomas, low MT expression (< 10% of neoplastic cells) was observed in 20.5% of the cases, moderate (10%-50% of neoplastic cells) in 54.5% and extensive expression (> 50% of neoplastic cells) in 25% of the cases. We did not find any statistically significant difference of MT expression between in situ and infiltrating carcinomas, while we did observe a significant difference between carcinomas and the other groups. There was a statistically significant difference in the PCNA values in both benign and malignant lesions, while no statistically significant difference was observed in p53 protein expression in the above groups. A positive correlation between MT expression and the PCNA value (p < 0.0001) in the benign and malignant groups was detected. The PCNA value was also correlated with the p53 protein expression (p = 0.001). No correlation was found between MT and p53 protein expression. In conclusion, these results suggest that the MT expression may play a role in the development of malignant disease of the larynx, from the early phase of laryngeal carcinogenesis, independently from the p53 expression. It is also possible to contribute to tumour cell growth, as determined by the PCNA score.     

In oral squamous cell carcinoma, high FAK expression is correlated with low P53 expression

Focal adhesion kinase (FAK) and p53 have been associated with metastatic activity and a poor prognosis in oral squamous cell carcinoma (OSCC). Recently, a feedback mechanism in which FAK regulates p53 has been proposed. The present study aims to determine the role of p53 in FAK regulation in these tumors. FAK and p53 expression was examined by immunohistochemistry in normal oral mucosa and in 67 oral squamous cell carcinomas. p16(INK4a) was also studied in view of its association with human papillomavirus infection. The association between FAK and p53 was subsequently analyzed. FAK expression in OSCCs was heterogeneous: 22 (33?%) cases showed weak expression, 16 (24?%) showed moderate expression, and 22 (33?%) cases showed high expression. Regarding p53, 31 of 67 (46?%) available tumor specimens showed negative staining, and 36 of 67 (54?%) showed positive nuclear staining for p53. FAK expression was inversely correlated with p53 expression (Fisher's exact test, p?=?0.005). There was no association between p16(INK4a) and p53 or FAK expression. In conclusion, our results support the hypothesis that FAK activity might be involved in the down-regulation of p53 expression in OSCC.