BRAF V600E expression in ameloblastomas-A 36-patient cohort from Helsinki University Hospital

A multi-center cross-sectional investigation of BRAF V600E mutation in Ameloblastoma

Background

B-Raf proto-oncogene, serine/threonine kinase (BRAF) V600E mutation stands as a pivotal genetic alteration strongly associated with several neoplasms and contributes significantly to their pathogenesis as well as potential targeted treatment strategies.

Objective

This cross-sectional study aimed to determine the frequency of BRAF V600E mutation in ameloblastoma in a multi-center of Thailand.

Method

Anti-BRAF V600E (clone VE1) immunohistochemistry was performed on 227 conventional ameloblastoma (AM) and 113 unicystic ameloblastoma (UA) samples collected from four major dental schools located in the Central, North, South, and Northeast regions of Thailand. Tumor cells from randomly chosen AM cases were also micro-dissected from the FFPE sections and subjected to DNA sequencing to confirm the immunohistochemical results.

Results

BRAF V600E mutation was detected in 71.8% of the AM samples, while 65.5% of samples with UAs demonstrated BRAF V600E positivity. The BRAF V600E mutation was significantly different in the histological subtypes of AMs in the four centers (p = 0.012) and the location of UA in three centers (p = 0.013). There was no significant association between the BRAF V600E mutation and the location of ameloblastoma in the overall prevalence of our multi-center study; nonetheless, a statistically significant association was found between the BRAF V600E mutation and the mandible location of AMs from the Central Faculty of Dentistry, Mahidol University (MU) center (p = 0.033), as well as with the histological subtypes of AMs from the Southern Faculty of Dentistry, Prince of Songkla University (PSU) center (p = 0.009). No statistical association was observed between the BRAF V600E mutation and AM and UA recurrence (p = 0.920 and p = 0.312), respectively. The results of DNA sequencing performed in randomly selected 40 BRAF V600E-positive and 20 BRAF V600E-negative ameloblastoma tissues were in accordance with the immunohistochemical findings.

Conclusion

As a result of a notable prevalence of BRAF V600E in Thai individuals diagnosed with ameloblastoma, they may benefit from the utilization of adjunctive anti-BRAF targeted therapy for treatment.

Unicystic ameloblastoma: A retrospective study on recurrent factors from a single institute database

OBJECTIVE

Unicystic ameloblastomas are a variant of ameloblastoma with a definite recurrence rate because of the biological behaviours of the tumour. The risk factors associated with disease recurrence were analysed in this retrospective study.

METHODS

A total of 132 patients with primary unicystic ameloblastoma reported in a tertiary hospital from 2005 to 2015 were analysed to identify the clinic-pathological and radiological factors associated with recurrence using univariate and multivariate Cox regression analyses.

RESULTS

The mean volume was 30.54cm3 ± 12.55 cm3, and this value differed significantly according to recurrence (p < 0.001). Root resorption and bone cortex/soft tissue invasion were also significantly associated with recurrence among unicystic ameloblastoma patients (p = 0.017 vs. p < 0.001, respectively). A new stage classification system was developed to predict disease recurrence of patients. The multivariate Cox regression analysis revealed that the new stage classification system was the only predictor of disease recurrence in unicystic ameloblastoma patients (p < 0.001), regardless of root resorption, position and site characteristics.

CONCLUSIONS

Volume, root resorption and bone cortex/soft tissue invasion were risk factors for disease recurrence among unicystic ameloblastoma patients. The new stage classification was an independent predictor of disease recurrence in patients with unicystic ameloblastoma.

Does BRAF V600E mutation affect recurrence rate of ameloblastomas? Systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review with meta-analysis was to critically evaluate the available data on the association of the BRAF V600E mutation and recurrence rate of ameloblastomas.

MATERIALS AND METHODS

This systematic review was registered in Prospero (CRD42020183645) and performed based on the PRISMA statement. A comprehensive search in PubMed, Web of Science, Scopus and Cochrane Library databases was performed in order to answer the question "Does BRAF V600E mutation affect recurrence rate of ameloblastomas?" Methodological quality and risk of bias of the selected studies were assessed with JBI Critical Appraise Tool. Meta-analysis of quantitative data was conducted with RevMan 5.3 and Jamovi 2.3.

RESULTS

The initial search identified 302 articles, and 21 met the inclusion criteria. A total of 855 subjects with ameloblastoma were included in the analysis. The pooled measures for frequency of BRAF V600E mutation was 65.30% (95% CI: 0.56-0.75; p < .001; I2  = 90.85%; τ = 0.205; p < .001), and the pooled recurrence rate was 25.30% (95% CI: 0.19-0.31; p < .001; I2  = 79.44%; τ = 0.118; p < .001). No differences in recurrence rate were observed between the BRAF V600E and wild type BRAF ameloblastomas, with a pooled Odds Ratio of 0.93 (95% CI: 0.56-1.54; p = .78; I2  = 31%; p = .09).

CONCLUSIONS

BRAF V600E mutation is a frequent event in ameloblastomas, but does not increase nor reduce its recurrence rate, and thus have a limited value in predicting its prognosis.

BRAF V600E Mutation in Ameloblastoma: A Systematic Review and Meta-Analysis

The discovery that ameloblastoma has a high mutation incidence of BRAF V600E may enable a better investigation of pathophysiology. However, there is inconsistent evidence regarding this mutation occurrence and its association with clinical information. This systematic review and meta-analysis aim to pool the overall mutation prevalence of BRAF V600E in reported ameloblastoma cases and to determine its association with patient demographic and clinicopathological features. Following the PRISMA guidelines, a comprehensive article search was conducted through four databases (Scopus, Google Scholar, PubMed, and Web of Science). Seventeen articles between 2014 and 2022 met the inclusion criteria with 833 ameloblastoma cases. For each included study, the significance of BRAF V600E on the outcome parameters was determined using odd ratios and 95% confidence intervals. Meta-analysis prevalence of BRAF V600E in ameloblastoma was 70.49%, and a significant meta-analysis association was reported for those younger than 54 years old and in the mandible. On the contrary, other factors, such as sex, histological variants, and recurrence, were insignificant. As a result of the significant outcome of BRAF V600E mutation in ameloblastoma pathogenesis, targeted therapy formulation can be developed with this handful of evidence.

The Molecular Pathology of Odontogenic Tumors: Expanding the Spectrum of MAPK Pathway Driven Tumors

Odontogenic tumors comprise a heterogeneous group of lesions that arise from the odontogenic apparatus and their remnants. Although the etiopathogenesis of most odontogenic tumors remains unclear, there have been some advances, recently, in the understanding of the genetic basis of specific odontogenic tumors. The mitogen-activated protein kinases/extracellular signal-regulated kinases (MAPK/ERK) pathway is intimately involved in the regulation of important cellular functions, and it is commonly deregulated in several human neoplasms. Molecular analysis performed by different techniques, including direct sequencing, next-generation sequencing, and allele-specific qPCR, have uncovered mutations in genes related to the oncogenic MAPK/ERK signaling pathway in odontogenic tumors. Genetic mutations in this pathway genes have been reported in epithelial and mixed odontogenic tumors, in addition to odontogenic carcinomas and sarcomas. Notably, B-Raf proto-oncogene serine/threonine kinase (BRAF) and KRAS proto-oncogene GTPase (KRAS) pathogenic mutations have been reported in a high proportion of ameloblastomas and adenomatoid odontogenic tumors, respectively. In line with the reports about other neoplasms that harbor a malignant counterpart, the frequency of BRAF p.V600E mutation is higher in ameloblastoma (64% in conventional, 81% in unicystic, and 63% in peripheral) than in ameloblastic carcinoma (35%). The objective of this study was to review MAPK/ERK genetic mutations in benign and malignant odontogenic tumors. Additionally, such genetic alterations were discussed in the context of tumorigenesis, clinical behavior, classification, and future perspectives regarding therapeutic approaches.

Analysis of BRAF V600E expression and disease-free survival in patients with ameloblastoma

The correlation between BRAF mutation and the aggressiveness of ameloblastoma remains controversial. The aim of this study was to investigate the association of BRAF V600E expression with clinicopathological features and disease-free survival (DFS) in patients with ameloblastoma. Seventy-four conventional ameloblastoma samples were collected. Immunohistochemistry using anti-BRAF V600E antibody was performed on formalin-fixed, paraffin-embedded tissue sections. Clinicopathological characteristics and treatment outcomes were retrieved from the patient medical records. BRAF V600E immunoreactivity was detected in 50/74 cases (67.6%); 39 were strongly positive and 11 weakly. There was a significant difference in BRAF V600E expression between ameloblastoma and dental follicle (P = 0.034). However, there was no significant association of BRAF V600E expression with any clinicopathological features, including sex, age, location, duration, tumour size, radiographic appearance, cortical perforation, recurrence, and histological subtype. DFS analysis revealed that patients with BRAF-mutated ameloblastoma had a shorter median survival time (84 months vs 168 months) and lower 5-year survival rate (59% vs 67%) compared to the BRAF wild-type group; however, this was not statistically significant (P = 0.169). Moreover, logistic regression analysis revealed that treatment with enucleation was an independent risk factor for tumour recurrence (odds ratio 9.236; P = 0.028). This study demonstrated that the BRAF V600E mutation was not associated with any clinicopathological features of ameloblastoma. A trend towards earlier recurrence in tumours with BRAF mutation was observed, but this requires further investigation. Furthermore, the findings suggest that the treatment modality is an important factor in determining recurrence in ameloblastoma despite genetic alterations.

SAMD9 Is Relating With M2 Macrophage and Remarkable Malignancy Characters in Low-Grade Glioma

Immunoreactions regulated by TAMs (Tumor-associated macrophages) play a pivotal role in tumorigenesis and metastasis. In recent decades, treatments based on immune regulation have achieved revolutionary breakthroughs in cancer targeted therapies. The phenotypes of TAMs in gliomas are more heterogeneous and inherently complex than can be simply defined by classification into the M1 and M2 polarized states. The detailed mechanisms surrounding infiltrating macrophage phenotype and glioma characteristics remain undefined. SAMD9 (Sterile Alpha Motif Domain-Containing Protein 9) was found to be highly expressed in glioma and closely related to histological and genetic features in CGGA and TCGA databases. Simultaneously, we present evidence to show that there was a positive association between SAMD9 and malignancy characters in LGG. Univariable and Multivariate proportional hazard Cox analysis showed that SAMD9 was an independent prognostic factor for LGG. Surprisingly, Gene Ontology (GO) analysis showed SAMD9 expression level was remarkably well correlated with immunological responses and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis supported the connection with immune responses and tumorigenesis. Immune infiltration analysis demonstrated that high SAMD9 expression resulted in an accumulation of macrophages by CIBERSORT and TIMER databases, especially positively related to macrophage total marker gene AIF1 and Macrophage M2 marker gene CD163. IHC staining further indicated a high correlation of SAMD9 with those specific macrophage markers in the immune response. Human THP-1 cells were induced into M2 macrophages, which were then co-cultured with LN229 cells. Silencing of SAMD9 by shRNA in LN229 cells attenuated the infiltration abilities of M2 macrophage. SAMD9 explored immune response via relating of M2 macrophage in vitro. Our results revealed SAMD9 acted as the malignancy characters in LGG, enrichment with M2 macrophage.

BRAF p.V600E status in epithelial areas of ameloblastoma with different histological aspects: Implications to the clinical practice

BACKGROUND

BRAF p.V600E is reported in up to 80% of ameloblastomas. Despite the high frequency, the presence of this mutation in different histopathological areas of the tumour has not been investigated. This information has an important role in the use of BRAF p.V600E assessment as an auxiliary tool in the differential diagnosis between unicystic ameloblastoma and other odontogenic cystic lesions, especially when only incisional biopsies are available. Therefore, the purpose of the present study was to investigate BRAF p.V600E heterogeneity in unicystic ameloblastoma.

METHODS

Five cases of ameloblastoma and two dentigerous cysts were analysed. The regions exhibiting different microscopic characteristics were selected from each ameloblastoma case and manually dissected. TaqMan allele-specific qPCR or Sanger sequencing was performed to determine BRAF p.V600E status.

RESULTS

We screened the mutation in a small cohort of UA and no molecular heterogeneity was found. Four cases of ameloblastoma (80%) exhibited BRAF p.V600E in all different areas evaluated. One case did not harbour the mutation in any microscopic region analysed. The BRAF mutation was absent in the dentigerous cysts.

CONCLUSION

Ameloblastomas appear to exhibit a homogeneous profile regarding the BRAF p.V600E no matter what histological feature is observed under light microscopy, suggesting that this molecular test may contribute to establish the correct diagnosis in cases microscopically resembling other odontogenic lesions.

BRAF V600E mutation-specific immunohistochemical analysis in ameloblastomas: a 44-patient cohort study from a single institution

PURPOSE

The aim of this study is to investigate the presence and prevalence of BRAF V600E mutation in ameloblastomas using anti-BRAF V600E monoclonal antibody (VE1 clone) and to identify any clinicopathologic correlation with BRAF V600E mutation in ameloblastoma.

MATERIALS AND METHODS

The pathology files of the Department of Oral Pathology and Oral Medicine, Faculty of Dentistry, Lagos State University College of Medicine, Lagos, Nigeria, were searched for the diagnosis of ameloblastoma from 2016 to 2020. Archived non-decalcified formalin-fixed paraffin-embedded tissue underwent immunohistochemistry using anti-BRAF V600E antibody at the University of Pittsburgh, Pennsylvania. Clinicopathologic data such as age at diagnosis, gender, jaw bone involved (mandible or maxilla), tumor location (anterior or posterior) and histologic subtype were collected. The clinicopathologic parameters were analyzed using Chi-square test and Fisher's exact test according to the BRAF status.

RESULTS

Forty-four cases of ameloblastoma were retrieved. The male to female ratio was 1.32:1. The average age of patients at diagnosis was 33.3 years. Thirty-nine cases were located in the mandible and 5 cases in the maxilla. Only cases in the mandible were positive for anti-BRAF V600E antibody (n = 15/39; 38.5%). There was a significant correlation between BRAF V600E expression in mandibular tumors and histologic subtype (p = 0.02); however, no significance was observed for gender, age and tumor location.

CONCLUSION

BRAF V600E mutation preferentially occurs in mandibular ameloblastomas, especially in non-plexiform ameloblastomas. These patients may benefit therapeutically from the use of BRAF inhibitors.

Frequency of BRAF V600E mutation in a group of Thai patients with ameloblastomas

OBJECTIVE

BRAF V600E mutation has recently been reported in a high proportion of ameloblastomas. This study was conducted to investigate the frequency of this mutation in ameloblastoma and unicystic ameloblastoma. The correlation between clinicopathologic data and BRAF V600E mutation was also analyzed.

STUDY DESIGN

A total of 51 archival samples of ameloblastomas and 22 cases of unicystic ameloblastomas were examined for BRAF V600E mutation by using anti-BRAF V600E (clone VE1) immunohistochemistry.

RESULTS

Positivity for anti-BRAF V600E antibody was detected in 72.5% (37 of 51) of ameloblastomas, but the mutation showed no significant correlation with the clinicopathologic parameters. With regard to unicystic ameloblastoma, 95.5% (21) of the 22 cases exhibited positive immunostaining for BRAF V600E, whereas only 1 case showed the mural subtype of wild-type BRAF.

CONCLUSIONS

A high frequency of BRAF V600E mutation was detected in a group of Thai patients with ameloblastomas, suggesting the future use of BRAF-targeted therapy in patients with BRAF-mutated ameloblastoma. However, no significant association between BRAF V600E mutation and the clinicopathologic characteristics of ameloblastomas was found in our study.

Homeobox B8 Targets Sterile Alpha Motif Domain-Containing Protein 9 and Drives Glioma Progression

Gliomas are the most commonly occurring tumors of the central nervous system. Glioblastoma multiforme (GBM) is the most malignant and aggressive brain cancer in adults. Further understanding of the mechanisms underlying the aggressive nature of GBM is urgently needed. Here we identified homeobox B8 (HOXB8), a member of the homeobox family, as a crucial contributor to the aggressiveness of GBM. Data mining of publicly accessible RNA sequence datasets and our patient cohorts confirmed a higher expression of HOXB8 in the tumor tissue of GBM patients, and a strong positive correlation between the expression level and pathological grading of tumors and a negative correlation between the expression level and the overall survival rate. We next showed that HOXB8 promotes the proliferation and migration of glioblastoma cells and is crucial for the activation of the PI3K/AKT pathway and expression of epithelial-mesenchymal transition-related genes, possibly through direct binding to the promoter of SAMD9 (Sterile Alpha Motif Domain-Containing Protein 9) and activating its transcription. Collectively, we identified HOXB8 as a critical contributor to the aggressiveness of GBM, which provides insights into a potential therapeutic target for GBM and opens new avenues for improving its treatment outcome.