Update on current trends in oral and maxillofacial pathology

Reduction of NrF2 as coadjuvant during the development of persistent periapical lesions

BACKGROUND

Persistent periapical lesions (PPL) are the result of pulpar necrosis induced by bacterial infection resulting in bone degradation and culminating with the loss of dental piece. Pathological changes in the peripapice are associated with the presence of free radicals. The transcription factor Nrf2 is the main regulator of the endogenous antioxidant response against oxidative stress and has been implicated in the regulation of osteoclastogenesis.The aim is to determine the oxidative condition in samples from patients with Persistent Periapical Injuries as a detonating factor of tissue damage.

MATERIAL AND METHODS

An observational, descriptive, cross-sectional study was carried out in samples with PPL (cases) and samples by removal of third molars (controls) obtained in the clinic of the specialty in endodontics, University of Guadalajara. Samples were submitted to histological staining with Hematoxylin-Eosin, lipoperoxide analysis, Superoxide Dismutase (SOD), Glutathione-Peroxidase (GPx) and Catalase (CAT) activities were determined by immunoenzymatic assays and NrF2 by Western Blot analysis.

RESULTS

Samples from PPL patients histologically showed an increased presence of lymphocytes, plasma cells, and eosinophils, as well as a decrease in extracellular matrix proteins and fibroblast cells. There was a rise in lipid peroxidation, GPx and SOD activities, but an important decline (36%) in Catalase activity was observed (p<0.005); finally, NrF2-protein was diminished at 10.41%. All comparisons were between cases vs controls.

CONCLUSIONS

The alterations in antioxidants endogenous NrF2-controlled are related to osseous destruction in patients with PPL.

MARCH1 silencing suppresses growth of oral squamous cell carcinoma through regulation of PHLPP2

PURPOSE

Oral squamous cell carcinoma (OSCC) is the most frequent type of oral cancer and is associated with high mortality. Membrane-associated ring-CH type finger 1 (MARCH1) is an E3 ubiquitin ligase with roles in immune regulation and cancer development. Whether MARCH1 has a specific role in OSCC, and if so through what mechanism, has not been explored.

METHODS

Immunohistochemistry was performed to examine MARCH1 expression in OSCC clinical samples and adjacent paracancerous tissues. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and Western blot were conducted to determine mRNA expression and protein levels, respectively. Knockdown and overexpression experiments were carried out to evaluate the effects of MARCH1 on proliferation and apoptosis. To test protein-protein interaction, co-immunoprecipitation assay was performed. Finally, tumor cell grafting was utilized to test the function of MARCH in vivo.

RESULTS

High MARCH1 expression in OSCC clinical samples correlated with poor patient prognosis. Functionally, MARCH1 knockdown in OSCC cells suppressed proliferation and promoted apoptosis, while MARCH1 overexpression displayed the opposite effects. We identified PH Domain And Leucine Rich Repeat Protein Phosphatase (PHLPP) 2 as an important target of MARCH1. Mechanistically, MARCH1 interacted with PHLPP2 and promoted PHLPP2 ubiquitination. Lastly, MARCH1 knockdown suppressed OSCC tumorigenicity in vivo and increased PHLPP2 protein level.

CONCLUSION

Our study uncovered a function of MARCH1 in OSCC and identified PHLPP2 as an important target of MARCH1 to modulate OSCC cell proliferation and apoptosis.

Trichosanthin cooperates with Granzyme B to restrain tumor formation in tongue squamous cell carcinoma

BACKGROUND

Tongue squamous cell carcinoma (TSCC) is a common type of oral cancer, with a relatively poor prognosis and low post-treatment survival rate. Various strategies and novel drugs to treat TSCC are emerging and under investigation. Trichosanthin (TCS), extracted from the root tubers of Tian-Hua-Fen, has been found to have multiple biological and pharmacological functions, including inhibiting the growth of cancer cells. Granzyme B (GrzB) is a common toxic protein secreted by natural killer cells and cytotoxic T cells. Our group has reported that TCS combined with GrzB might be a superior approach to inhibit liver tumor progression, but data relating to the use of this combination to treat TSCC remain limited. The aim of this study was to examine the effectiveness of TCS on TSCC processes and underlying mechanisms.

METHODS

First, we screened the potential antitumor activity of TCS using two types of SCC cell lines. Subsequently, a subcutaneous squamous cell carcinoma xenograft model in nude mice was established. These model mice were randomly divided into four groups and treated as follows: control group, TCS treatment group, GrzB treatment group, and TCS/GrzB combination treatment group. Various tumorigenesis parameters, such as Ki67, PCNA, caspase-3, Bcl-2 and VEGFA, et al., were performed to determine the effects of these treatments on tumor development.

RESULTS

Screening confirmed that the SCC25 line exhibited greater sensitivity than the SCC15 line to TCS in vitro studies. TCS or GrzB treatment significantly inhibited tumor growth compared with the inhibition seen in the control group. The TCS/GrzB combination inhibited tumor growth more than either drug alone. TCS treatment inhibited tumor proliferation by downregulating Ki67 and Bcl2 protein expression while accelerating tumor apoptosis. In the TCS/GrzB-treated group, expression of Ki67 was further downregulated, while the level of activated caspase-3 was increased, compared with their expression in either of the single drug treatment groups.

CONCLUSION

These results suggest that the TCS/GrzB combination could represent an effective immunotherapy for TSCC.

Molecular and Cellular Modelling of Salivary Gland Tumors Open New Landscapes in Diagnosis and Treatment

Salivary gland tumors are neoplasms affecting the major and minor salivary glands of the oral cavity. Their complex pathological appearance and overlapping morphological features between subtypes, pose major challenges in the identification, classification, and staging of the tumor. Recently developed techniques of three-dimensional culture and organotypic modelling provide useful platforms for the clinical and biological characterization of these malignancies. Additionally, new advances in genetic and molecular screenings allow precise diagnosis and monitoring of tumor progression. Finally, novel therapeutic tools with increased efficiency and accuracy are emerging. In this review, we summarize the most common salivary gland neoplasms and provide an overview of the state-of-the-art tools to model, diagnose, and treat salivary gland tumors.

Comparative evaluation of autofluorescence imaging and histopathological investigation for oral potentially malignant disorders in Taiwan

OBJECTIVES

Autofluorescence imaging is gaining popularity as an adjunctive test for oral potentially malignant disorders (OPMD). This study evaluated the efficacy of autofluorescence imaging based on the current standard oral mucosal disorder checklist in Taiwan.

MATERIALS AND METHODS

In total, 126 patients suspected to have mucosal disorders at the Division of Oral and Maxillofacial Surgery, Tri-Service General Hospital, Taipei, Taiwan, were enrolled. Following a conventional oral examination by using the oral mucosal disorder checklist and an autofluorescence imaging examination, all participants underwent histopathological examination to access epithelial dysplasia.

RESULTS

Among 126 patients, 68 patients were diagnosis as having an OPMD and 63 having epithelial dysplasia. Autofluorescence imaging exhibited a sensitivity, specificity, positivity predictive value (PPV), negative predictive value (NPV), and accuracy of 77.94%, 35.42%, 63.10%, 53.13%, and 60.34%, respectively, for OPMD and of 88.89%, 43.86%, 63.64%, 78.13%, and 67.50%, respectively, for epithelial dysplasia. After the exclusion of 48 non-OPMD cases according to the checklist, the sensitivity, specificity, PPV, NPV, and accuracy of autofluorescence imaging became 87.50%, 72.73%, 94.23%, 53.33%, and 85.07%, respectively, for epithelial dysplasia.

CONCLUSION

The efficacy of epithelial dysplasia identification and OPMD risk assessment can be increased after the exclusion of the non-OPMD cases through autofluorescence imaging.

CLINICAL RELEVANCE

Autofluorescence imaging is a useful adjunct that can assist specialists in assessing OPMD patients prone to dysplasia without compromising patient care.

An Extrafollicular Adenomatoid Odontogenic Tumor Mimicking a Periapical Cyst

Adenomatoid odontogenic tumor (AOT) is a rare noninvasive odontogenic tumor that occurs mostly in the second decade of life. Based on its tooth association, AOT can be classified into three categories of follicular, extrafollicular, and peripheral types; the follicular classification is considered as the most common type of AOT. This study reported a large extrafollicular case of AOT in a 40-year-old female. She was asymptomatic and tumor was detected accidentally by her dental practitioner. Since the panoramic radiograph showed a well-defined unilocular radiolucent lesion, we observed radiopaque spots within the lesion by using cone beam computed tomography. The extrafollicular type can mimic a periapical radiolucent lesion.

Adenomatoid odontogenic tumor associated with an unerupted mandibular lateral incisor: a case report

Adenomatoid odontogenic tumor (AOT) is a rare, benign odontogenic tumor that predominantly appears in the second decade of life in female patients. Most AOTs occur in the anterior part of the maxilla and are usually associated with impacted anterior teeth. There are three types of AOT, follicular, extrafollicular, and peripheral, which are classified based on the location of the lesion and its association with the impacted tooth. We report a rare case of AOT associated with an impacted right mandibular lateral incisor in an 11-year-old female patient.

Odontogenic keratocyst: What is in the name?

The classification of odontogenic cysts is complicated and can create confusion for both clinicians and pathologists. The odontogenic keratocyst (OKC) is an enigmatic developmental cyst that deserves special attention. It has characteristic histopathological and clinical features; but, what makes this cyst special is its aggressive behavior and high recurrence rate. Despite of many classifications and nomenclature, unfortunately the clinicians still have to face difficulties in the management of this commonly found jaw lesion. This article is an effort to provide an overview of various aspects of OKC with emphasis on nomenclature, recurrence, molecular aspects, and management of OKC.