Decreased expression of p63 in oral lichen planus and graft-vs.-host disease associated with oral inflammation

P63 and Ki-67 expression in radicular cyst

Objectives

The aim of the current study was to identify the expression of P63 and its relation to odontogenic epithelial cell proliferation, severity of the inflammatory infiltrate and size of radicular cysts (RCs).

Methods

In this retrospective cross-sectional study, 30 cases of paraffin-embedded RCs were randomly selected from the archive. P63 and Ki-67 expression was assessed by immunohistochemistry.

Results

Epithelial P63 expression was absent in four (13.3%), weak in 10 (33.3%), and moderate in 16 (53.3%) cases. In the connective tissue wall of RC, P63 expression was absent in two (6.7%) cases, weak in 24 (80.0%) cases, and moderate in four (13.3%) cases. Ki-67 was found to be weakly expressed in 12 (40.0%) cases, moderately expressed in 13 (43.3%), and strongly expressed in five (16.7%) cases. No correlation was found between Ki-67 expression in odontogenic epithelium and P63 expression in the odontogenic epithelium (rho = 0.110, p = .563) or fibrous capsule (rho = 0.160, p = .399). Nevertheless, we found a positive correlation between Ki-67 expression in the odontogenic epithelium and the size of the RC (rho = 0.450, p = .013). The inflammatory infiltrate was negatively correlated with P63 expression in the odontogenic epithelium (rho = -0.428, p = .018), and with the size of cysts (rho = -0.728, p < .001).

Conclusions

There is a high expression of P63 throughout the odontogenic epithelium and connective tissue capsule of the RC. P63 expression in the odontogenic epithelium is negatively correlated with the degree of the inflammatory infiltrate but not with epithelial cell proliferation or the size of the cyst.

Clinical Trials of Limbal Stem Cell Deficiency Treated with Oral Mucosal Epithelial Cells

The corneal surface is an essential organ necessary for vision, and its clarity must be maintained. The corneal epithelium is renewed by limbal stem cells, located in the limbus and in palisades of Vogt. Palisades of Vogt maintain the clearness of the corneal epithelium by blocking the growth of conjunctival epithelium and the invasion of blood vessels over the cornea. The limbal region can be damaged by chemical burns, physical damage (e.g., by contact lenses), congenital disease, chronic inflammation, or limbal surgeries. The degree of limbus damage is associated with the degree of limbal stem cells deficiency (partial or total). For a long time, the only treatment to restore vision was grafting part of the healthy cornea from the other eye of the patient or by transplanting a cornea from cadavers. The regenerative medicine and stem cell therapies have been applied to restore normal vision using different methodologies. The source of stem cells varies from embryonic stem cells, mesenchymal stem cells, to induced pluripotent stem cells. This review focuses on the use of oral mucosa epithelial stem cells and their use in engineering cell sheets to treat limbal stem cell deficient patients.

Alterations of p63 and p73 in human cancers

p53 and its related genes, p63 and p73 constitute the p53 gene family. While p53 is the most frequently mutated gene in human tumors, p63 and p73 are rarely mutated or deleted in cancers. Many studies have reported p63/p73 overexpression in human cancers while others showed that a loss of p63/p73 is associated with tumor progression and metastasis. Thus, whether p63 or p73 is a tumor suppressor gene or an oncogene has been a matter of debate. This controversy has been attributed to the existence of multiple splicing isoforms with distinct functions; the full-length TA isoform of p63 has structural and functional similarity to wild-type p53, whereas the ΔNp63 acts primarily in dominant-negative fashion against all family members of p53. Differential activities of TA and ΔN isoforms have been shown in vivo by creating isform-specific gene knockout mice. All p53, p63, p73 proteins bind to and activate target genes with p53-response elements; p63 also binds to distinct p63-response elements and regulate expression of specific target genes involved in skin, limb, and craniofacial development. Interestingly, several studies have shown that both p63 and p73 are involved in cellular response to cancer therapy and others have indicated that both of these molecules are required for p53-induced apoptosis, suggesting functional interplay among p53 family proteins. Consistent with these findings, aberrant splicing that result in ΔNp63 or ΔNp73 overexpression are frequently found in human cancers, and is associated with poor clinical outcomes of patients in the latter. Thus immunohistochemical staining of tumor specimen with ΔNp73-specific antibody might have diagnostic values in cancer clinics.

Autoantibodies and decreased expression of the transcription factor ELF-3 together with increased chemokine pathways support an autoimmune phenotype and altered differentiation in lichen planus located in oral mucosa

BACKGROUND

The pathogenesis of oral lichen planus (OLP), a chronic inflammatory disease, is not fully understood. It is known that OLP has autoimmune features, and it is suggested to be an autoimmune disease. ELF-3 is involved in differentiation of keratinocytes and deregulated in different tumours and inflammatory diseases. CXCR-3 and its ligands CXCL-10 and CXCL-11 are increased in autoimmune diseases and linked to Th-1 immune response.

OBJECTIVES

To analyse and compare expression of ELF-3, CXCR-3, CXCL-10 and CXCL-11 in OLP lesions and controls in whole and microdissected epithelium.

METHODS

Tissue biopsies from 20 patients clinically and histologically diagnosed with OLP and 20 healthy controls were studied using whole tissues or microdissected epithelium. By the use of qRT-PCR, mRNA levels of ELF-3, CXCR-3, CXCL-10 and CXCL-11 were studied. Western blot was used for analysis of ELF-3 protein expression. Sera from 19 OLP patients and 20 controls were analysed with ELISA in search for autoantibodies. Results  The upregulation of CXCR-3, CXCL-10 and CXCL-11 found in OLP is similar to previous findings showing an autoimmune phenotype in lichen planus (LP) and lichen sclerosus. Decreased expression of the differentiation-related transcription factor ELF-3 was also seen in OLP lesions, and we further demonstrate presence of circulating autoantibodies against the ELF-3 protein in sera from 3 of 19 (16%) LP patients tested.

CONCLUSIONS

On the basis of these findings, we confirm that OLP shows features of an autoimmune disease and suggest deregulated differentiation of keratinocytes to be one of the causes of the disease phenotype.

Oral lichen planus is a unique disease model for studying chronic inflammation and oral cancer

Oral lichen planus (OLP) is a chronic inflammatory disease, which has been defined by the World Health Organization as a potential precancerous condition, representing a generalized state associated with a significantly increased risk of oral cancer. We would like to put forward a hypothesis that inflammatory mediators such as cytokines and chemokines released from infiltrating T lymphocytes induce fundamental changes of proteins in oral epithelial cells, leading to the progression of OLP to oral squamous cell carcinoma (OSCC). These altered proteins can act as the key risk factors associated with the local microenvironment and development of OSCC. Identification of these proteins would add to our understanding of the connection between chronic inflammation and OSCC.

Oral lichen planus: controversies surrounding malignant transformation

Studies of the malignant potential of oral lichen planus (OLP) have been hampered by inconsistencies in the diagnostic criteria used for OLP, the criteria adopted to identify a true case of malignant transformation in OLP, the risk factors for malignant transformation and the optimum management of patients to ensure the early diagnosis of transformation. Consensus remains elusive, and leading workers in this field have recently published conflicting reports on the malignant potential of OLP and on the important question of the advisability of excluding patients with epithelial dysplasia or a tobacco habit from studies on this issue. The present review outlines these debates and proposes a possible a molecular basis for the malignant transformation in this disease.

Expression of novel p53 isoforms in oral lichen planus

Oral lichen planus (OLP) is a chronic inflammatory disease of unknown origin, showing little spontaneous regression. WHO classifies OLP as a premalignant condition, however, the underlying mechanisms initiating development of cancer in OLP lesions are not understood. The p53 tumour suppressor plays an important role in many tumours, and an increased expression of p53 protein has been seen in OLP lesions. Recently it was shown that the human TP53 gene encodes at least nine different isoforms. Another member of the p53 family, p63, comprises six different isoforms and plays a crucial role in the formation of oral mucosa, salivary glands, teeth and skin. It has also been suggested that p63 is involved in development of squamous cell carcinoma of the head and neck (SCCHN). In contrast to p53, a decreased expression of p63 protein has been seen in OLP lesions. In this study, we mapped the expression of five novel p53 isoforms at RNA and protein levels in OLP and matched normal controls. In the same samples we also measured levels of p63 isoforms using quantitative RT–PCR. Results showed p53 to be expressed in all OLP lesions and normal tissues. The p53β and Δ133p53 isoforms were expressed in the majority of samples whereas the remaining three novel isoforms analysed were expressed in only a few samples. Levels of p63 isoforms were lower in OLP lesions compared with normal tissue, however, changes were not statistically significant.

Detection of antibodies against p63 and p73 isoforms in sera from patients diagnosed with oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is a chronic inflammatory disease of oral mucosa. Despite numerous publications and intense research, the etiology of OLP is still unknown, however, autoimmunity as a possible causative factor has been discussed.

METHODS

In the present study sera from 20 patients clinically and histologically diagnosed with OLP were analyzed for antibodies directed toward p53, p63, and p73 using Western blot.

RESULTS

Sera from two patients reacted with all six p63 isoforms, and one also with p73. The strongest reaction was noted against the TAp63beta protein, which is the most potent transactivator of all p63 proteins and is implicated in the differentiation of stratified epithelia.

CONCLUSIONS

This is the first demonstration of antibodies directed against all p63 and some p73 isoforms in sera from patients diagnosed with OLP.