PTCH1 mutation and local aggressiveness of odontogenic keratocystic tumors in children: is there a relationship?

In Silico Analysis of Genes Associated with the Pathogenesis of Odontogenic Keratocyst

Odontogenic keratocyst (OK) is a benign intraosseous cystic lesion characterized by a parakeratinized stratified squamous epithelial lining with palisade basal cells. It represents 10-12% of odontogenic cysts. The changes in its classification as a tumor or cyst have increased interest in its pathogenesis.

OBJECTIVE

Identify key genes in the pathogenesis of sporadic OK through in silico analysis.

MATERIALS AND METHODS

The GSE38494 technical sheet on OK was analyzed using GEOR2. Their functional and canonical signaling pathways were enriched in the NIH-DAVID bioinformatic platform. The protein-protein interaction network was constructed by STRING and analyzed with Cytoscape-MCODE software v 3.8.2 (score > 4). Post-enrichment analysis was performed by Cytoscape-ClueGO.

RESULTS

A total of 768 differentially expressed genes (DEG) with a fold change (FC) greater than 2 and 469 DEG with an FC less than 2 were identified. In the post-enrichment analysis of upregulated genes, significance was observed in criteria related to the organization of the extracellular matrix, collagen fibers, and endodermal differentiation, while the downregulated genes were related to defensive response mechanisms against viruses and interferon-gamma activation.

CONCLUSIONS

Our in silico analysis showed a significant relationship with mechanisms of extracellular matrix organization, interferon-gamma activation, and response to viral infections, which must be validated through molecular assays.

The Role of Smoothened-Dependent and -Independent Hedgehog Signaling Pathway in Tumorigenesis

The Hedgehog (Hh)-glioma-associated oncogene homolog (GLI) signaling pathway is highly conserved among mammals, with crucial roles in regulating embryonic development as well as in cancer initiation and progression. The GLI transcription factors (GLI1, GLI2, and GLI3) are effectors of the Hh pathway and are regulated via Smoothened (SMO)-dependent and SMO-independent mechanisms. The SMO-dependent route involves the common Hh-PTCH-SMO axis, and mutations or transcriptional and epigenetic dysregulation at these levels lead to the constitutive activation of GLI transcription factors. Conversely, the SMO-independent route involves the SMO bypass regulation of GLI transcription factors by external signaling pathways and their interacting proteins or by epigenetic and transcriptional regulation of GLI transcription factors expression. Both routes of GLI activation, when dysregulated, have been heavily implicated in tumorigenesis of many known cancers, making them important targets for cancer treatment. Hence, this review describes the various SMO-dependent and SMO-independent routes of GLI regulation in the tumorigenesis of multiple cancers in order to provide a holistic view of the paradigms of hedgehog signaling networks involving GLI regulation. An in-depth understanding of the complex interplay between GLI and various signaling elements could help inspire new therapeutic breakthroughs for the treatment of Hh-GLI-dependent cancers in the future. Lastly, we have presented an up-to-date summary of the latest findings concerning the use of Hh inhibitors in clinical developmental studies and discussed the challenges, perspectives, and possible directions regarding the use of SMO/GLI inhibitors in clinical settings.

Dental and orthodontic follow-up in nevoid basal cell carcinoma syndrome patient with odontogenic keratocystic tumors

OBJECTIVES

Nevoid Basal Cell Carcinoma Syndrome (NBCS) is a rare genetic condition affecting multiple organs including the maxillofacial and dental region. The surgical removal of the odontogenic keratocystic tumors (OKT), the high rate of recurrence leads to a iatrogenic tooth loss requiring dental care. The aim of this study is therefore to describe the dental and orthodontic management, and to assess the impact of surgery on facial growth and oral development.

METHODS

A retrospective study including 14 patients with GGS, followed at the Necker Enfants Malades Hospital. The study was carried out on the medical files and photographic records RESULTS: Patients developed on average 5.5 OKT (range: 1 to 11) and 1.7 recurrences (range:0 to 9) during the follow-up. The mean age at diagnosis of first OKT was 11.23 years (range: 6.75 to 16). KOTs were more frequently localized at the mandibular (30.9%) and maxillary molar level (25.1%). Forty-seven impacted teeth were extracted during the OKT removal. Eight patients out of 12 presented a class III skeletal relationship. The remaining ones had a skeletal class II associated with a hyperdivergent typology. Almost all patients had dental impactions with ectopic positions of the succedaneums tooth. At the inter-arch level, all patients needed orthodontic care, 3 patients did not begin their orthodontics. Orthodontic treatments began with an orthopedic phase followed by braces for the majority in 8 patients. Two patients had to undergo orthognathic surgery. Impacted teeth were treated by traction or extraction with further rehabilitation.

CONCLUSION

The objective is not to simply compensate the iatrogenic hypodontia generated by the surgical procedure but to take into consideration the maxillofacial phenotype, skeletal characteristics and numerous intra- and inter-arch dental anomalies for a healthy oral management.

The immunohistochemical profile of basal cell nevus syndrome-associated and sporadic odontogenic keratocysts: a systematic review and meta-analysis

OBJECTIVES

To provide a systematic review of the literature on studies comparing the immunoprofile of nevoid basal cell carcinoma syndrome (BCNS)-associated and sporadic odontogenic keratocysts (OKCs), in order to identify markers that could accurately distinguish the two OKC subtypes.

MATERIALS AND METHODS

We searched MEDLINE/Pubmed, Web of Science, EMBASE via OVID, and grey literature for publications until December 28th, 2019, that compared the immunohistochemical expression of the two OKC subtypes. The studies were qualitatively assessed using the Critical Appraisal Tool for Case Series (Joana Briggs Institute). Sensitivity and specificity, positive and negative likelihood ratio, diagnostic odds ratio and area under the curve, and pooled estimates were calculated, using a random-effects model.

RESULTS

Seventy-one studies were qualitatively analyzed; 61 markers were evaluated in one study and 32 in ≥ 2 studies. Twenty-five studies reported differential expression of 29 markers in the form of higher number of positive cells or greater staining intensity usually in BCNS-associated OKCs. Meta-analysis for bcl-2, Cyclin D1, CD56, CK18, p53, and PCNA showed that none of those markers is distinguishable between BCNS-associated and sporadic OKCs, in a 95% confidence interval. The risk of bias was high in 34 studies, moderate in 22, and low in 15.

CONCLUSIONS

The present systematic review and meta-analysis uncovered that, although several immunohistochemical markers might characterize the OKC phenotype, they cannot discriminate between the BCNS-associated and sporadic OKCs.

CLINICAL RELEVANCE

This study highlighted the requirement for additional screening for markers by immunohistochemistry, preferentially coupled to alternative diagnostic applications such as genomics technologies.

Transcriptome Variability in Keratocystic Odontogenic Tumor Suggests Distinct Molecular Subtypes

Keratocystic Odontogenic Tumor (KCOT) is a locally aggressive developmental cystic neoplasm thought to arise from the odontogenic epithelium. A high recurrence rate of up to 30% has been found following conservative treatment. Aggressive tumor resection can lead to the need for extensive reconstructive surgery, resulting in significant morbidity and impacting quality of life. Most research has focused on candidate-genes with a handful of studies employing whole transcriptome approaches. There is also the question of which reference tissue is most biologically-relevant. This study characterizes the transcriptome of KCOT using whole genome microarray and compare it with gene expression of different odontogenic tissues (“dentome”). Laser capture microdissection was used to isolate the neoplastic epithelial tissue in 20 cases. KCOT gene expression was compared with the “dentome” and relevant pathways were examined. Cluster analysis revealed 2 distinct molecular subtypes of KCOT. Several inflammatory pathways were activated in both subtypes. The AKT pathway was activated in one subtype while MAP kinase pathway was activated in the other. Additionally, PTCH1 expression was downregulated in both clusters suggesting involvement in KCOT tumorigenesis. In conclusion, this study provides new insights into the transcriptome of KCOT and highlights pathways that could be of diagnostic and prognostic value.