The unexplained survival of cells in oral cancer: what is the role of p53?

Expression of p53, p63, podoplanin and Ki-67 in recurring versus non-recurring oral leukoplakia

Oral leukoplakia (OL), a potentially malignant disorder, recurs in 40% of cases after surgical removal. Recurrence is a risk factor for malignant transformation. We aimed to examine the prognostic significance of four biomarkers related to cell proliferation: p53, p63, podoplanin (PDPN) and Ki-67 in predicting recurrence. Formalin-fixed-paraffin-embedded specimens from excised OL (n = 73, 33 recurrent; 40 non-recurrent) were collected in a prospective study. Immunohistochemistry was used to visualise expression of p53, p63, PDPN and Ki-67. Image analysis software was used for quantification of p53-, p63- and Ki-67-expressing cells, while PDPN was analysed visually. The expression of all four proteins were higher in recurrent compared with non-recurrent OL, only expression of p53 was statistically significant. In uni- and multivariable Cox regression analyses of individual markers, expression of p63 was significantly associated with higher recurrence risk (p = 0.047). OL with a combined high expression of both p53 and p63 had a significantly higher risk to recur [Log Rank, p = 0.036; multivariate Cox, HR: 2.48 (1.13–5.44; p = 0.024)]. Combination of p53 and p63 expression may be used as a prognostic biomarker for recurrence of OL.

Oral Potentially Malignant Disorders (OPMD): What is the clinical utility of dysplasia grade?

INTRODUCTION

Oral epithelial dysplasia is considered a potential histologic precursor of subsequent squamous cell cancer. As standard clinical practice, pathologists grade dysplasia to assess risk for progression to malignancy. Except for the most advanced grade, severe dysplasia, dysplasia grading has failed to correlate well with the risk to develop invasive cancer. The questions of what process dysplasia grading best represents and what clinical utility dysplasia grading may have are explored.

AREAS COVERED

This narrative review is based on PubMed search with emphasis on papers since 2010. Epithelial dysplasia as a precursor lesion of cancer and dysplasia grading as a risk assessment tool for progression to cancer are discussed. The close clinical association of dysplasia with known carcinogens, alcohol, and tobacco products is presented.

EXPERT OPINION

Oral epithelial dysplasia is often, associated with prolonged exposure to tobacco and alcohol products. With reduction of carcinogen exposure, dysplasia is known to regress in some cases. It is proposed that histologic dysplasia grade together with macroscopic images of dysplastic clinical lesions be used as an educational tool to incentivize patients to reduce their known carcinogen exposure. This strategy has the potential to reduce lesion progression thereby reducing the disease burden of oral cancer.

Cancerous lesions in the vicinity of dental implants: a systematic review

Introduction: The massive diffusion of dental implant treatments in the last decades leads to the appearance of complications, most of them inflammatory, although important complications have been described as malignant lesions in the vicinity of dental implants. The objective of this article is to describe the cases described in the literature of oral squamous cell carcinoma (OSCC) or clinical variants and metastases, in the vicinity of dental implants and to analyze the possible etiological agents involved. Material and methods: The criteria used were those described in the PRISMA® Declaration for performing systematic reviews. An electronic search was performed on MEDLINE (via PubMed) using the terms MeSH: “dental implants” AND “squamous cell carcinoma” OR “dental implant complications” AND “squamous cell carcinoma”. Results: Thirty-eight articles describing a total of 76 cases of OSCC or clinical variants, as well as metastasis in the vicinity of dental implants, were included. Conclusions: It is not possible to establish a cause-effect relationship between dental implants and the development of OSCC. Its clinical appearance can be confused with periimplantitis, so that, in cases of sudden onset, which do not respond to conventional treatment and/or have associated alterations in sensitivity, a biopsy should be performed.

Alterations in the expression of DNA damage response-related molecules in potentially preneoplastic oral epithelial lesions

OBJECTIVES

The aim of this study was to evaluate the expression levels of DNA damage response (DDR) markers in potentially preneoplastic oral epithelial lesions (PPOELs).

STUDY DESIGN

Immunohistochemical expression of DDR markers (γΗ2 ΑΧ, pChk2, 53 BP1, p53, and phosphorylated at Ser 15 p53) was assessed in 41 oral leukoplakias, ranging from hyperplasia (H) to dysplasia (D) and in comparison with oral squamous cell carcinoma (OSCC) and normal mucosa (NM). Statistical and receiver operating characteristic curve analysis were performed.

RESULTS

γH2 AX immunoexpression demonstrated a gradual increase and upper layer extension from NM to H to higher D degrees to OSCC. pChk2 expression was minimal in NM, relatively low in PPOELs, with an increasing tendency from H to D, and higher in OSCC. 53 BP1 demonstrated higher levels in OSCC than in NM, whereas its expression in PPOELs was heterogeneous, gradually increasing according to D. p53 demonstrated progressively higher levels and upper layer extension from H to D to OSCC. Phosphorylated p53 was absent in NM and relatively low in PPOELs and OSCC.

CONCLUSIONS

DDR markers' expression is variable in PPOELs, showing a tendency to increase along with dysplasia. Activated DDR mechanisms may play an important protective role at early stages of oral carcinogenesis, but probably suffer progressive deregulation, eventually failing to suppress malignant transformation.

P53 Protein Expression in Dental Follicle, Dentigerous Cyst, Odontogenic Keratocyst, and Inflammatory Subtypes of Cysts: An Immunohistochemical Study

OBJECTIVES

An odontogenic keratocyst (OKC) is a developmental odontogenic cyst with aggressive clinical behavior. This cyst shows a different growth mechanism from the more common dentigerous cyst and now has been renamed as a keratocystic odontogenic tumor (KCOT). Inflammation can assist tumor growth via different mechanisms including dysregulation of the p53 gene. This study aims to assess and compare the expression of tumor suppressor gene p53 in inflamed and non-inflamed types of OKC and dentigerous cyst.

METHODS

Immunohistochemical expression of p53 was assessed in 14 cases of dental follicle, 34 cases of OKC (including 18 inflamed OKCs), and 31 cases of dentigerous cyst (including 16 inflamed cysts).

RESULTS

The mean percentage of p53 positive cells was 0.7% in dental follicles, 5.4% in non-inflamed OKCs, 17.3% in inflamed OKCs, 1.2% in non-inflamed dentigerous cysts, and 2.2% in inflamed dentigerous cysts. The differences between the groups were statistically significant (p < 0.050) except for the difference between inflamed and non-inflamed dentigerous cysts, and between dental follicle and non-inflamed dentigerous cyst.

CONCLUSIONS

The difference in p53 expression in OKC and dentigerous cyst can explain their different growth mechanism and clinical behavior. Inflammation is responsible for the change in behavior of neoplastic epithelium of OKC via p53 overexpression.

Relationship among tobacco habits, human papilloma virus (HPV) infection, p53 polymorphism/mutation and the risk of oral squamous cell carcinoma

The prevalence of oral squamous cell carcinoma (OSCC) has significantly increased over decades in several countries and human papilloma virus (HPV) has been indicated as one of the underlying causes. This suggests that HPV plays a role in the early stages of carcinogenesis but is not a requisite for the maintenance and progression of malignant state. p53 is a tumor suppressor gene that checks the cell and promotes apoptosis and cell repair that can be deactivated by mutations and a viral interaction leading to cancer and individuals with particular polymorphic variant of p53 is more susceptible to HPV-induced carcinogenesis. The present study has been carried out to detect and correlate p53 polymorphism/mutation, HPV DNA in the biopsy samples of oral cancer patients who had tobacco habits.

Immunoprofiling of oral squamous cell carcinomas reveals high p63 and survivin expression

BACKGROUND

Cancer is a multifactorial disease composed of cells that show somatic mutations and epigenetic changes. The aim of this study was to investigate the expression of proteins involved in the development and maintenance of epithelia, cell cycle regulation, and apoptosis in human oral squamous cell carcinoma (OSCC) tissue samples.

METHODS

A tissue microarray containing 65 primary human OSCC specimens was immunolabeled for bcl-2, survivin, epidermal growth factor receptor (EGFR), p21, p53, p63, and cleaved caspase-3.

RESULTS

Samples were scored for percentage of positively stained tumor cells and staining intensity. A total immunostaining score was also calculated, using the product of percentage and intensity scores. All specimens showed high scores, > 75%, for p63 and survivin, and 75.4% of the specimens also presented high EGFR expression. All cases showed p53-positive cells. p21 showed a diffuse staining pattern. The percentage of cells positive for cleaved caspase-3 and bcl-2 was low.

CONCLUSIONS

The high frequency of tumor cells expressing p63 and survivin highlights the role of these proteins in the malignant transformation of oral epithelium. Collectively, our results suggest that p63 and survivin may constitute attractive targets for cancer therapy in patients with OSCC.

The hamster model of sequential oral oncogenesis

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

Expression of cell cycle regulatory proteins in epithelial components of dental follicles

Dental follicle is a component of tooth germs, which remain adjacent to the crown of unerupted or impacted teeth. Under the influence of pathologic changes, however, dental follicles that possess reduced epithelium can proliferate into stratified squamous epithelium as far as originate dental cysts. In order to clarify the role of apoptosis and cellular proliferation herein, expression of p53 and PCNA was examined in epithelial components of dental follicles associated with impacted third molars by means of immunohistochemistry. A total of 40 cases was included in this study being 22 cases with reduced epithelium and 18 cases with stratified epithelium. Expression of p53 expression was weak or not detected in dental follicles with reduced and stratified squamous epithelium. By contrast, PCNA positive cells were evidenced in basal and supra basal layers of the stratified squamous epithelium and in reduced epithelium of dental follicles, but without any significant statistically differences between them (P > 0.05). In conclusion, these data suggest that dental follicles possess proliferative activity as depicted by PCNA-positive nuclei in some epithelial cells. However, the biological behavior of dental follicles during the late stage of dental eruptive process may not be associated with deregulation of death and/or cell proliferation.

Firsthand cigarette smoke alters fibroblast migration and survival: implications for impaired healing

Although it is known that high levels of cigarette smoke lead to cell death, little is known about the effects of low-to-moderate levels of smoke components that are found in vivo, such as those experienced by cells in tissues. Clinical studies and experimental data show that smokers heal poorly and are more prone to develop fibrotic diseases. Here we show the effects of first-hand cigarette smoke on fibroblasts, cells that are critically involved in these processes. Using doses of smoke found in the tissues of smokers and a variety of cell and molecular approaches, we show that these doses of cigarette smoke do not cause cell death but rather stimulate fibroblasts to produce stress response and survival proteins such as interleukin-8, PKB/Akt, p53, and p21 that in turn contribute to an increase in cell survival. In addition, smoke-treated cells show a decrease in cell migration, which can be explained by the increased cell adhesion and alterations in cytoskeletal elements. We also show that these levels of smoke cause changes in mitochondrial morphology with a minimum loss of function and these changes are the result of exposure to reactive oxygen species. We conclude that the increase in cell survival may lead to a build-up of connective tissue in the area of a wound, potentially leading to delayed healing and/or fibrosis and that the alterations in the cytoskeleton and in cell adhesion result in inhibition of cell migration, a process that could lead to nonclosure of the wound for lack of proper fibroblast migration to form the healing tissue.

Effects of "second-hand" smoke on structure and function of fibroblasts, cells that are critical for tissue repair and remodeling

Background

It is known that "second-hand" cigarette smoke leads to abnormal tissue repair and remodelling but the cellular mechanisms involved in these adverse effects are not well understood. Fibroblasts play a major role in repair and remodelling. They orchestrate these processes by proliferating, migrating, and secreting proteins such as, cytokines, growth factors and extracellular matrix molecules. Therefore, we focus our studies on the effects of "second-hand" cigarette smoke on the structure and function of these cells.

Results

We used sidestream whole (SSW) smoke, a major component of "second-hand" smoke, primary embryonic fibroblasts, cells that behave very much like wound fibroblasts, and a variety of cellular and molecular approaches. We show that doses of smoke similar to those found in tissues cause cytoskeletal changes in the fibroblasts that may lead to a decrease in cell migration. In addition, we also show that these levels of cigarette smoke stimulate an increase in cell survival that is reflected in an increase and/or activation of stress/survival proteins such as cIL-8, grp78, PKB/Akt, p53, and p21. We further show that SSW affects the endomembrane system and that this effect is also accomplished by nicotine alone.

Conclusions

Taken together, our results suggest that: (i) SSW may delay wound repair because of the inability of the fibroblasts to migrate into the wounded area, leading to an accumulation of these cells at the edge of the wound, thus preventing the formation of the healing tissue; (ii) the increase in cell survival coupled to the decrease in cell migration can lead to a build-up of connective tissue, thereby causing fibrosis and excess scarring.

Análise da imunoexpressão do PCNA e p53 em carcinoma de células escamosas oral: correlação com a gradação histológica de malignidade e características clínicas

OBJETIVO: Analisar a imunoexpressão das proteínas PCNA e p53 em carcinoma de células escamosas oral (CCEO) vislumbrando verificar uma possível correlação entre o escore de malignidade e os dados clínicos dos pacientes. MÉTODOS: Selecionou-se 14 casos de CCEO e classificando-os de acordo com uma adaptação do sistema de gradação histológica de malignidade proposto por Anneroth, Batsakis, Luna, enquadrando-se 7 casos como baixo escore de malignidade (Grupo I) e 7 casos como alto escore (Grupo II). As informações dos pacientes foram coletadas através de fichas clínicas e os dados tabulados. Realizou-se, então, o estudo imuno-histoquímico utilizando anticorpos monoclonais anti-PCNA e anti-p53, obtendo-se o índice de positividade (IP) em cada caso. RESULTADOS: Identificou-se um IP médio ao PCNA de 56,0% no Grupo I e 83,8% no Grupo II. Com relação à p53 o IP médio no Grupo I e no Grupo II correspondeu, respectivamente, a 41,2% e 41,4%. A análise estatística demonstrou correlação significativa entre o índice de células PCNA positivas e o escore de malignidade. Nenhuma outra correlação foi observada. CONCLUSÕES: O maior número de células PCNA positivas correlacionou-se com elevado escore de malignidade em CCEOs, sugerindo maior atividade proliferativa nestas lesões, entretanto, tal correlação não se estabeleceu quando da análise da imunoexpressão da p53.