Differential expression of p53, p63 and p73 proteins in human buccal squamous-cell carcinomas

Clinical implications of the deregulated TP73 isoforms expression in cancer

TP73 is a member of the TP53 family whose expression has been observed altered in most human cancers and associated with the prognosis. TP73 translates into a complex number of isoforms with both oncogenic and tumour-suppressor functions and presents a complex cross-talk with other members of the family (TP53 and TP63). In this revision, we focus on the evidence that may support TP73 variants as prognostic markers in cancer. Nowadays, most publications in this topic highlight the association between overexpression of the oncogenic variants and failure to respond to chemotherapy and/or shorter survival. In addition, we comment on the putative possibilities that the detection through a liquid biopsy of TP73 variants may provide, and finally, the significance of determining the value of the combined alteration of the TP53 family members in the clinical setting.

Immunohistochemical expression of p53 and its clinicopathological correlation with modified Anneroth's histological grading system

Introduction and Objectives:

Oral squamous cell carcinoma (OSCC) is an epithelial neoplasm generally beginning as focal overgrowth of altered stem cells near the basement membrane, moving upward and laterally, replacing the normal epithelium. Histopathological grading has been used for many decades in an attempt to predict the clinical behavior of oral squamous cell carcinoma. In the present study, Forty biopsies were studied for histological grading and p53 expression. The p53 expression was studied in relation to clinical parameters such as age, sex of patient and site of tumors. Relation between histological grade of malignancy and p53 protein expression was analysed. All cases were classified according to Anneroth's histological malignancy grading system (1987).

Materials and Methods:

40 cases of OSCC were assessed for clinical parameters, Anneroth's histological grading and immunohistochemically stained with p53 protien.

Statistical Analysis:

The results obtained were analyzed using Spearman's Co-relation.

Observations and Results:

The positive expression of p53 was found in 62% of carcinomas studied. Positivity of p53 showed correlation with histological grade of malignancy and with individual parameters like degree of keratinization, nuclear polymorphism, number of mitoses and lymphoplasmacytic infiltration while showed a negative correlation with pattern of invasion.

Conclusion:

Our study showed a significant correlation between parameters of tumor cell population, lymphoplasmacytic infiltration and p53 expression. A significant association between high grade of malignancy and p53 overexpression and insignificant correlation of p53 with age, sex of the patient and site of the tumor was found.

The TP73 complex network: ready for clinical translation in cancer?

TP73 is a member of the TP53 family, whose deregulated expression has been reported in a wide variety of cancers and linked to patients' outcome. The fact that TP73 encodes a complex number of isoforms (TAp73 and ΔTAp73) with opposing functions and the cross-talk with other members of the family (TP53 and TP63) make it difficult to determine its clinical relevance. Here, we review the molecular mechanisms driving TAp73 and ΔTAp73 expression and how these variants inhibit or promote carcinogenesis. We also highlight the intricate interplay between TP53 family members. In addition, we comment on current pharmacological approaches targeting the TP73 pathway and those affecting the TAp73/ΔTAp73 ratio. Finally, we discuss the current data available in the literature that provide evidence on the role of TP73 variants in predicting prognosis. To date, most of the studies that evaluate the status levels of TP73 isoforms have been based on limited-size series. Despite this limitation, these publications highlight the correlation between high levels of the oncogenic forms and failure to respond to chemotherapy and/or shorter survival. Finally, we emphasize the need for studies to evaluate the significance of combining the deregulation of various members of the TP53 family in order to define patient outcome or their responsiveness to specific therapies.

Oral cancer prognosis based on clinicopathologic and genomic markers using a hybrid of feature selection and machine learning methods

Background

Machine learning techniques are becoming useful as an alternative approach to conventional medical diagnosis or prognosis as they are good for handling noisy and incomplete data, and significant results can be attained despite a small sample size. Traditionally, clinicians make prognostic decisions based on clinicopathologic markers. However, it is not easy for the most skilful clinician to come out with an accurate prognosis by using these markers alone. Thus, there is a need to use genomic markers to improve the accuracy of prognosis. The main aim of this research is to apply a hybrid of feature selection and machine learning methods in oral cancer prognosis based on the parameters of the correlation of clinicopathologic and genomic markers.

Results

In the first stage of this research, five feature selection methods have been proposed and experimented on the oral cancer prognosis dataset. In the second stage, the model with the features selected from each feature selection methods are tested on the proposed classifiers. Four types of classifiers are chosen; these are namely, ANFIS, artificial neural network, support vector machine and logistic regression. A k-fold cross-validation is implemented on all types of classifiers due to the small sample size. The hybrid model of ReliefF-GA-ANFIS with 3-input features of drink, invasion and p63 achieved the best accuracy (accuracy = 93.81%; AUC = 0.90) for the oral cancer prognosis.

Conclusions

The results revealed that the prognosis is superior with the presence of both clinicopathologic and genomic markers. The selected features can be investigated further to validate the potential of becoming as significant prognostic signature in the oral cancer studies.

Diagnostic utility of p63 (Ab-1) and (Ab-4) tumor markers in the squamous cell carcinomas of head and neck

P63 is a gene product required in cell cycle regulation which plays vital roles in tumor differentiation. Aims of the present study were to assess the frequency, pattern, sensitivity and specificity of two p63 protein clones P63 4A4 and P63 4A4+Y4A3 in squamous cell carcinomas (SCCs). Thirty cases of head and neck region SCC diagnosed on the basis of HandE staining were examined along with 60 cases of head and neck region biopsies other than squamous cell carcinoma, negative on HandE staining, were taken as control. Immunostaining was performed on slides according to the Thermo Scientific UltraVision LP detection System. P63 4A4+Y4A3 clone is more sensitive 96.6% in comparison to 86% in P63 4A4 with having greater NPV of 98.3%. The results signify the importance of P63 4A4+Y4A3 marker over the old markers and may be used as a confirmatory marker of squamous cell carcinoma.

Analysis of the intracellular localization of p73 N-terminal protein isoforms TAp73 and ∆Np73 in medulloblastoma cell lines

The protein homologous to the tumor suppressor p53, p73, has essential roles in development and tumorigenesis. This protein exists in a wide range of isoforms with different, even antagonistic, functions. However, there are virtually no detailed morphological studies analyzing the endogenous expression of p73 isoforms at the cellular level in cancer cells. In this study, we investigated the expression and subcellular distribution of two N-terminal isoforms, TAp73 and ΔNp73, in medulloblastoma cells using immunofluorescence microscopy. Both proteins were observed in all cell lines examined, but differences were noted in their intracellular localization between the reference Daoy cell line and four newly established medulloblastoma cell lines (MBL-03, MBL-06, MBL-07 and MBL-10). In the new cell lines, TAp73 and ΔNp73 were located predominantly in cell nuclei. However, there was heterogeneity in TAp73 distribution in the cells of all MBL cell lines, with the protein located in the nucleus and also in a limited non-random area in the cytoplasm. In a small percentage of cells, we detected cytoplasmic localization of TAp73 only, i.e., nuclear exclusion was observed. Our results provide a basis for future studies on the causes and function of distinct intracellular localization of p73 protein isoforms with respect to different protein-protein interactions in medulloblastoma cells.

p53 and the pathogenesis of skin cancer

The p53 tumor suppressor gene and gene product are among the most diverse and complex molecules involved in cellular functions. Genetic alterations within the p53 gene have been shown to have a direct correlation with cancer development and have been shown to occur in nearly 50% of all cancers. p53 mutations are particularly common in skin cancers and UV irradiation has been shown to be a primary cause of specific 'signature' mutations that can result in oncogenic transformation. There are certain 'hot-spots' in the p53 gene where mutations are commonly found that result in a mutated dipyrimidine site. This review discusses the role of p53 from normal function and its dysfunction in pre-cancerous lesions and non-melanoma skin cancers. Additionally, special situations are explored, such as Li-Fraumeni syndrome in which there is an inherited p53 mutation, and the consequences of immune suppression on p53 mutations and the resulting increase in non-melanoma skin cancer in these patients.

Clinicopathological significances of P73 and P53 protein expression in gastric carcinomas with tissue microarray technique

AIM: To investigate the expression of P73 and mutant P53 (mP53) gene coding proteins and their significances in gastric carcinoma.

METHODS: Two tissue microarray blocks containing 104 cases of gastric cancer and precancerous lesions (1.0 mm each in diameter) was constructed. SABC immunohistochemical stainning was used to detect the expression of P73 and mP53 proteins and the correlation between their roles and the pathological behavior of gastric carcinoma was investigated.

RESULTS: The positive rate of P73 protein was significantly higher in gastric cancer, intestinal metaplasia and atypical hyperplasia than that in the normal tissues (90.1%, 44.0%, 80.0% vs 17.9%, P < 0.01). The expression of P73 protein was also markedly higher in gastric carcinoma of Borrman Ⅲ/Ⅳ types than that of Borrman Ⅱ type (92.9%/100% vs 57.1%, P < 0.05). Moreover, the expression P73 protein was markedly increased in gastric cancer with lymph node metastasis, liver metastasis and ovarian metastasis as compared with that in non-metastatic cancer (94.4%, 100%, 100% vs 76.2%, P < 0.01). There was a positive correlation between P73 and mP53 expression (χ² = 9.6736, P < 0.01).

CONCLUSION: P73 expression is correlated with the malignant behaviors of gastric cancer. Although P73 protein has a similar construction to P53 protein, its expression shows a positive correlation with that of mP53 protein. This finding indicates that P73 may play a role in the carcinogenesis of gastric cancer as a mimic mutant of P53.

Binary state pattern clustering: a digital paradigm for class and biomarker discovery in gene microarray studies of cancer

Class and biomarker discovery continue to be among the preeminent goals in gene microarray studies of cancer. We have developed a new data mining technique, which we call Binary State Pattern Clustering (BSPC) that is specifically adapted for these purposes, with cancer and other categorical datasets. BSPC is capable of uncovering statistically significant sample subclasses and associated marker genes in a completely unsupervised manner. This is accomplished through the application of a digital paradigm, where the expression level of each potential marker gene is treated as being representative of its discrete functional state. Multiple genes that divide samples into states along the same boundaries form a kind of gene-cluster that has an associated sample-cluster. BSPC is an extremely fast deterministic algorithm that scales well to large datasets. Here we describe results of its application to three publicly available oligonucleotide microarray datasets. Using an alpha-level of 0.05, clusters reproducing many of the known sample classifications were identified along with associated biomarkers. In addition, a number of simulations were conducted using shuffled versions of each of the original datasets, noise-added datasets, as well as completely artificial datasets. The robustness of BSPC was compared to that of three other publicly available clustering methods: ISIS, CTWC and SAMBA. The simulations demonstrate BSPC's substantially greater noise tolerance and confirm the accuracy of our calculations of statistical significance.

p63 expression in odontogenic cysts

A total of 123 cases of odontogenic cysts, distributed as follows: 30 follicular (FC), 35 radicular (RC), 53 keratocysts, 1 glandular odontogenic and 4 calcifying odontogenic cysts, were analysed by immunohistochemistry for expression of p63, a component of p53 protein family. In RCs p63 positivity was not only in basal and parabasal layers but also in the intermediate layer and about 1/3 of cases displayed a percentage of stained cells comprised between 0 and <5%, and about 2/3 between >5% and <50%. In FCs positivity was confined to basal and parabasal layers of the epithelium and in the majority of FCs the stained cells were comprised between 0 and <5%. OKCs displayed the most intense and diffuse p63 labeling. In conclusion, these data suggest that p63 expression may be useful to identify cysts type with more aggressive and invasive phenotype supporting the hypothesis of a suprabasal proliferative compartment in OKCs.

p63 overexpression associates with poor prognosis in head and neck squamous cell carcinoma

p63 belongs to a protein family that includes 2 structurally related proteins, p53 and p73. The aim of this study was to investigate the biologic role of p63 in oral tumorigenesis and its possible role as prognostic marker in oral cancer. Ninety-four cases of oral squamous cell carcinoma and 10 cases of normal mucosa were analyzed for p63 expression by immunohistochemistry. Normal oral mucosa showed a basal and parabasal expression of p63. Five (5.3%) cases of oral cancer showed less than 10% of positive tumor cells; in 33 (35.1%) cases the positive tumor cells comprised between 10% and less than 30%, in 36 (38.3%) cases the positive tumor cells comprised between 30% and less than 50%, and in 20 (21.3%) cases the positive tumor cells were more than 50%. There was also a statistically significant correlation between p63 expression and tumor differentiation: p63 expression was amplified in poorly differentiated tumors (P < .05). When analyzed for prognostic significance, patients with perineural infiltration had poorer survival rates than the group with no perineural infiltration (P < .05) and patients with increased p63 expression had poorer survival rates than the group with reduced p63 expression (P < .05). The statistical analysis showed no significant correlation between p63 expression, sex, age, tumor size, staging, recurrence, and metastasis. Cases with diffuse p63 expression were more aggressive and poorly differentiated and related to a poorer prognosis. These data suggest that p63 expression may be useful to identify cases of oral squamous cell carcinoma with more aggressive and invasive phenotype providing novel diagnostic and prognostic information on individual patient survival with oral cancers.

Expression of p63 protein and mRNA in oral epithelial dysplasia

BACKGROUND

Abnormalities in the TP53 are regarded as the most consistent findings in oral squamous cell carcinoma. Two related members of the TP53 family, p73 and p63, have shown remarkable structural similarity to TP53, indicating possible functional and biological interactions. The aim of the present study was to investigate the expression of p63 protein and mRNA in oral epithelial dysplasia.

METHODS

Immunohistochemical p63 staining was compared for samples from 90 male patients with buccal epithelial dysplasias and 15 healthy individuals with normal buccal mucosa and 15 subjects with reactive epithelial hyperplasia of the oral mucosa secondary to traumatic insult. The buccal lesions consisted of mild, moderate and severe epithelial dysplasias (30 samples in each category). The mRNA expression using reverse transcription polymerase chain reaction (RT-PCR) was also included for a subset of available fresh tissue specimens (four samples in each category of mild and moderate epithelial dysplasia; five samples in severe epithelial dysplasia; five samples in each of normal and reactive epithelial hyperplasia).

RESULTS

Nuclear p63 staining was demonstrated predominantly in the basal layers of the epithelium of the normal buccal mucosa and reactive epithelial hyperplasia specimens. For epithelial dysplasia lesions, however, staining was not restricted to the basal layers, extending to the middle spinous layer for samples in the mild category, with p63 immunoexpression observed across almost the full thickness of the dysplastic epithelium for analogous moderate and severe specimens. Compared with normal/reactive hyperplastic mucosa, p63 staining in the dysplastic mucosa was significantly increased. The severity of dysplasia was increased with the increase of p63 staining. Furthermore, Delta Np63mRNA was identified in all of the fresh tissue samples whereas expression of transactivation (TA) isotype was not detected. A subset of moderate epithelial dysplasia and severe variant showing p63-positive staining has undergone malignant transformation to squamous cell carcinomas in about 5 years follow-up.

CONCLUSION

Our results indicate that impaired p63 immunoexpression (predominantly Delta N isoform) is associated with the severity of oral epithelial dysplasias and up-regulation of p63 may play a role in the early stage of human oral tumorigenesis.

Tumor predisposition in mice mutant for p63 and p73: evidence for broader tumor suppressor functions for the p53 family

p63 and p73 are functionally and structurally related to the tumor suppressor p53. However, their own role in tumor suppression is unclear. Given the p53-like properties of p63 and p73, we tested whether they are involved in tumor suppression by aging mice heterozygous for mutations in all p53 family genes and scored for spontaneous tumors. We show here that p63+/-;p73+/- mice develop spontaneous tumors. Loss of p63 and p73 can also cooperate with loss of p53 in tumor development. Mice heterozygous for mutations in both p53 and p63 or p53 and p73 displayed higher tumor burden and metastasis compared to p53+/- mice. These findings provide evidence for a broader role for the p53 family than has been previously reported.

Assessment of p63 expression in oral squamous cell carcinomas and dysplasias

OBJECTIVES

p63, a p53 homologue, may be associated with tumorigenesis in epithelial tissues through its inhibition of p53 transactivation functions. We sought to determine the pattern and levels of p63 expression in oral dysplasias and carcinomas using standard immunohistochemical staining. We also assessed and compared expression of p53 and a cell proliferation marker in these lesions.

STUDY DESIGN

This retrospective cross-sectional survey (n=67) included hyperkeratosis (10), mild dysplasia (9), moderate dysplasia (11), severe dysplasia/in situ carcinoma (10), squamous cell carcinoma (SCC) (22 [9 well differentiated, 7 moderately differentiated, 6 poor differentiated]), and normal mucosa (5). Serial sections were stained immunohistochemically with antibodies to p63 (4A4 recognizing all p63 isotypes), p53 (DO-7), and Ki-67 (MIB-1) proteins. In preinvasive lesions, both the percentage of positive cells and staining patterns (negative, basal, suprabasal) were assessed. In oral SCCs, the percentage of positive cells was assessed. Statistical analysis was done using the Tukey-Kramer multiple comparisons test.

RESULTS

A suprabasal p63 staining pattern was evident in keratinocyte nuclei in the entire range of noninvasive lesions studied, including normal mucosa. Most nuclei in invasive SCCs stained positive. When all grades of dysplasia were combined, the percent of p63 positive cells was significantly greater than hyperkeratosis (P < .01), and well-differentiated SCC (P < .001). Moderately differentiated SCC had statistically significant more positive cells than well-differentiated SSC (P < .01). Comparison of serial sections showed different p63 staining patterns compared to p53 or Ki-67 staining patterns.

CONCLUSIONS

We conclude that p63 is expressed in oral carcinomas and dysplasias, as determined by immunohistochemical staining with a primary antibody to all isotypes. Neither staining pattern nor percentage of stained cells could be used to differentiate the lesions studied. The statistically significant differences found between some groups are not likely to be of diagnostic value. p63 is not coexpressed with p53 expression or Ki-67 suggesting functional independence. When antibodies to the p63 isotypes become available, oral dysplasias and carcinomas should be reassessed.

Differential expression of p53, p63 and p73 protein and mRNA for DMBA-induced hamster buccal-pouch squamous-cell carcinomas

Abnormalities in the p53 gene are regarded as the most consistent of the genetic abnormalities associated with oral squamous-cell carcinoma. Two related members of the p53 gene family, p73 and p63, have shown remarkable structural similarity to p53, suggesting possible functional and biological interactions. The purpose of this study was to investigate the differential expression of p73, p63 and p53 genes for DMBA-induced hamster buccal-pouch squamous-cell carcinoma. Immunohistochemical analysis for protein expression and reverse transcriptase-polymerase chain reaction (RT-PCR) for mRNA expression were performed for 40 samples of hamster buccal pouches, the total being separated into one experimental group (15-week DMBA-treated; 20 animals) and two control groups (untreated and mineral oil-treated; 10 animals each). Using immunohistochemical techniques, nuclear staining of p53 and p73 proteins was detected in a subset of hamster buccal-pouch tissue specimens treated with DMBA for a period of 15 weeks, whereas p63 proteins were noted for all of the 20 hamster buccal-pouch tissue specimens treated with DMBA for 15 weeks as well as for all of the untreated and mineral oil-treated hamster buccal-pouch tissue specimens. Differential expression of p63, p73 and p53 protein for the experimental group was as follows: p63+/p73+/p53+ (n = 14; 70%); p63+/p73+/p53- (n = 2; 10%); p63+/p73-/p53- (n = 4; 20%) and p63+/p73-/p53- (untreated [n = 10] and mineral oil-treated mucosa [n = 10]; 100% each). Upon RT-PCR, DeltaNp63mRNA was detected within all of the 20 hamster buccal-pouch tissue specimens treated with DMBA for 15 weeks, whereas expression of TAp63 was not detected. Furthermore, p73 mRNA was identified for 16 of the hamster buccal-pouch tissue specimens treated with DMBA for 15 weeks, whereas p53 mRNA was noted for 14 15-week DMBA-treated pouches. The proportional (percentage) expression of DeltaNp63, p73 and p53 mRNA for the hamster buccal-pouch tissue specimens treated with DMBA for 15 weeks was noted to be consistent with the findings using immunohistochemical techniques. A significant correlation between p53, p63 and p73 expression (protein and mRNA) was demonstrated for the hamster buccal-pouch carcinoma samples. Our results indicate that both p73 and p63 may be involved in the development of chemically induced hamster buccal-pouch carcinomas, perhaps in concert with p53.