Comparison of Immunohistochemistry and DNA Sequencing for BRAF V600E Mutation Detection in Mandibular Ameloblastomas

Deciphering the Role of BRAFV600E Immunohistochemistry in Breast Lesions: A Comprehensive Review

The BRAFV600E mutation has been extensively studied in various cancers, but its role in breast lesions remains less understood. Immunohistochemistry (IHC) has emerged as a valuable tool for detecting BRAFV600E expression in breast tissue, aiding in diagnosis and prognosis. This comprehensive review examines the significance of BRAFV600E IHC in breast lesions, encompassing its frequency, association with clinicopathological features, and potential clinical implications. We summarize key findings, emphasizing their utility in diagnosis, prognosis prediction, and treatment response assessment. Additionally, we discuss implications for clinical practice, highlighting the need for integrating BRAFV600E IHC into diagnostic algorithms. Recommendations for future research include larger-scale studies to validate findings, optimize detection techniques, and explore therapeutic interventions targeting BRAFV600E in breast cancer. This review contributes to understanding the molecular landscape of breast lesions and informs clinical decision-making in their management.

Exploring protein profiles and hub genes in ameloblastoma

Ameloblastoma (AM) is a prominent benign odontogenic tumor characterized by aggressiveness, likely originating from tooth-generating tissue or the dental follicle (DF). However, proteomic distinctions between AM and DF remain unclear. In the present study, the aim was to identify the distinction between AM and DF in terms of their proteome and to determine the associated hub genes. Shotgun proteomics was used to compare the proteomes of seven fresh-frozen AM tissues and five DF tissues. Differentially expressed proteins (DEPs) were quantified and subsequently analyzed through Gene Ontology-based functional analysis, protein-protein interaction (PPI) analysis and hub gene identification. Among 7,550 DEPs, 520 and 216 were exclusive to AM and DF, respectively. Significant biological pathways included histone H2A monoubiquitination and actin filament-based movement in AM, as well as pro-B cell differentiation in DF. According to PPI analysis, the top-ranked upregulated hub genes were ubiquitin C (UBC), breast cancer gene 1 (BRCA1), lymphocyte cell-specific protein-tyrosine kinase (LCK), Janus kinase 1 and ATR serine/threonine kinase, whereas the top-ranked downregulated hub genes were UBC, protein kinase, DNA-activated, catalytic subunit (PRKDC), V-Myc avian myelocytomatosis viral oncogene homolog (MYC), tumor protein P53 and P21 (RAC1) activated kinase 1. When combining upregulated and downregulated genes, UBC exhibited the highest degree and betweenness values, followed by MYC, BRCA1, PRKDC, embryonic lethal, abnormal vision, Drosophila, homolog-like 1, myosin heavy chain 9, amyloid beta precursor protein, telomeric repeat binding factor 2, LCK and filamin A. In summary, these findings contributed to the knowledge on AM protein profiles, potentially aiding future research regarding AM etiopathogenesis and leading to AM prevention and treatment.

Comparison of diagnostic methods for detection of BRAFV600E mutation in ameloblastoma

BACKGROUND

Ameloblastoma is an aggressively growing, highly recurrent odontogenic jaw tumor. Its association with BRAFV600E mutation is an indication for BRAFV00E-inhibitor therapy The study objective was to identify a sensitive low-cost test for BRAFV600E-positive ameloblastoma. We hypothesized that immunohistochemical staining of formalin-fixed paraffin-embedded tissues for BRAFV600E mutation is a low-cost surrogate for BRAFV600E gene sequencing when laboratory resources are inadequate for molecular testing.

METHODS

Tissues from 40 ameloblastoma samples were retrieved from either formalin-fixed paraffin-embedded blocks, RNAlater™ stabilization solution or samples inadvertently pre-fixed in formalin before transfer to RNAlater™. BRAFV600E mutation was assessed by Direct Sanger sequencing, Amplification Refractory Mutation System-PCR and immunohistochemistry (IHC).

RESULTS

BRAFV600E mutation was detected by IHC, Amplification Refractory Mutation System-PCR and Direct Sanger sequencing in 93.33%, 52.5% and 30% of samples respectively. Considering Direct Sanger sequencing as standard BRAFV600E detection method, there was significant difference between the three detection methods (𝜒2 (2) = 31.34, p < 0.0001). Sensitivity and specificity of IHC were 0.8 (95% CI: 0.64-0.90) and 0.9 (95% CI: 0.75-0.99) respectively, while positive predictive value and negative predictive value (NPV) were 0.9 and 0.8 (Fischer's test, p < 0.0001) respectively. Sensitivity and specificity of Amplification Refractory Mutation System-PCR detection method were 0.7 (95% CI: 0.53-0.80) and 0.9 (95% CI = 0.67-0.98) respectively, while PPV and NPV were 0.9 and 0.6 respectively (Fischer's test, p < 0.0001).

CONCLUSION

Low-cost and less vulnerability of IHC to tissue quality make it a viable surrogate test for BRAFV600E detection in ameloblastoma. Sequential dual IHC and molecular testing for BRAFV600E will reduce equivocal results that could exclude some patients from BRAFV600E-inhibitor therapies.

Differential expression of PEA3 in odontogenic cysts and tumors

BACKGROUND

PEA3 transcription factor has been identified as a downstream target of the MAPK and PI3K pathways, and PEA3 overexpression has been observed in a variety of tumor types. We aimed to evaluate PEA3 expression in odontogenic cysts and tumors and compare the expression among odontogenic lesions. In addition, the correlations between PEA3 expression and clinicopathological characteristics of conventional ameloblastoma and unicystic ameloblastoma were investigated.

METHODS

This study was performed on 165 samples of odontogenic cysts and tumors including 20 dentigerous cysts, 20 odontogenic keratocysts, 16 adenomatoid odontogenic tumors, 5 ameloblastic fibromas, 45 unicystic ameloblastomas, and 59 conventional ameloblastomas. The sections were immunohistochemically stained with mouse monoclonal anti-PEA3 antibody and PEA3 expression was evaluated as the immunoreactive score.

RESULTS

PEA3 expression was absent in all dentigerous cysts (DCs) and odontogenic keratocysts, while all adenomatoid odontogenic tumors showed either no (75%) or low (25%) expression of PEA3. Most of the ameloblastic fibromas (60%) displayed no PEA3 expression. A high expression of PEA3 was observed in a substantial number of unicystic ameloblastomas (48.9%) and conventional ameloblastomas (49.2%) in our study. PEA3 expression in DCs, odontogenic keratocysts and adenomatoid odontogenic tumors were significantly different from that in conventional ameloblastomas and that in unicystic ameloblastomas (p < 0.05). The expression of PEA3 was significantly different in the age groups of unicystic ameloblastomas and histological subtypes of conventional ameloblastomas (p < 0.05).

CONCLUSION

PEA3 overexpression is predominant in unicystic ameloblastomas and conventional ameloblastomas compared to other odontogenic lesions, indicating a pivotal role of PEA3 as a downstream effector of MAPK pathway in these two odontogenic lesions.

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.

Factors affecting the accuracy of anti-BRAF V600E immunohistochemistry results in ameloblastomas

BACKGROUND

There are still some controversies about the results of anti-BRAF V600E-specific antibody immunohistochemistry in ameloblastomas. This study aimed to examine the accuracy of V600E-specific antibody immunohistochemistry in detection of BRAF V600E mutation in ameloblastoma tissue sections of different ages.

METHODS

The BRAF V600E status of 64 ameloblastoma specimens was assessed using both Sanger sequencing and V600E-specific antibody immunohistochemistry, and the sensitivity, specificity, positive predictive value, and negative predictive value were calculated. The difference in V600E-specific antibody immunohistochemistry staining intensity among the three groups of ameloblastoma tissue blocks of different ages was evaluated by chi-square test. The consistency between V600E-specific antibody immunohistochemistry and DNA sequencing results and the V600E-specific antibody immunohistochemistry staining intensity of 15 paired newly-cut and 3-month storage sections of the same 15 ameloblastomas were also compared.

RESULTS

For detection of BRAF V600E mutation, the V600E-specific antibody immunohistochemistry had high sensitivity (98.21% 55/56), specificity (87.5% 7/8), positive predictive value (98.21% 55/56), and negative predictive value (87.5% 7/8). Heterogeneity of the staining intensity was observed in the same tissue section, but all or none expression pattern was noticed in the solid tumor nests. The storage time of paraffin tissue blocks ranging from 2 to 14 years did not affect the V600E-specific antibody-positive staining intensity. However, the three-month storage sections showed a significant diminishment of V600E-specific antibody-positive staining signals.

CONCLUSIONS

The BRAF V600E-specific antibody immunohistochemistry is suitable for routine detection of BRAF V600E mutation in ameloblastomas. The all or none expression pattern suggests the BRAF V600E mutation may be an early event in the pathogenesis of ameloblastoma.

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 diagnostic utility of BRAF VE1 mutation-specific immunohistochemistry in ameloblastoma

Ameloblastoma is a benign, locally aggressive odontogenic neoplasm with variable solid and cystic morphology. On account of its histologic variety, diagnostically challenging cases can bear resemblance to odontogenic keratocyst/keratocystic odontogenic tumor (KCOT) or dentigerous cyst (DC). BRAF^V600E mutation has been reported to be specific for and frequent in ameloblastoma, and this study evaluated the usefulness of immunohistochemistry (IHC) using the BRAF VE1 mutant-specific antibody as a diagnostic adjunct in this setting. We investigated 46 ameloblastomas, 30 KCOTs, and 30 DCs. BRAF VE1 IHC was performed on all cases and allele-specific polymerase chain reaction (AS-PCR) for BRAF^V600E mutation was performed on 30 ameloblastomas and any IHC-positive KCOT/DC. BRAF VE1 IHC was positive in 31/37 (83.8%) mandibular ameloblastomas but not in any maxillary ameloblastomas (0/9), KCOT (0/30), or DC (0/30). Equivocal staining was seen in 1/37 (3.3%) mandibular ameloblastomas. Of the 30 ameloblastomas subjected to AS-PCR, BRAF^V600E mutation was identified in 19/23 (82.6%) mandibular ameloblastomas and 0/7 (0.0%) maxillary ameloblastomas. BRAF^V600E mutant ameloblastomas were positive by IHC in 18/19 (94.7%) cases and equivocal in 1/19 (5.3%) cases. All 11 (100.0%) BRAF-wild type ameloblastomas were negative by IHC. BRAF VE1 is an excellent tool for the diagnosis of mandibular ameloblastoma but of limited utility in the maxilla, where it less commonly occurs and where BRAF^V600E mutation is considerably less frequent.

Diagnostic accuracy of immunohistochemistry compared with molecular tests for detection of BRAF V600E mutation in ameloblastomas: systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review with meta-analysis was to critically evaluate the available data on sensitivity and specificity of IHC compared with molecular tests in the detection of BRAF V600E mutation in ameloblastomas.

MATERIALS AND METHODS

This systematic review was performed based on the PRISMA statement and registered in Prospero (CRD42021259117). PubMed, Web of Science, Scopus and Cochrane Library databases were searched for observational studies to answer the question "What is the diagnostic accuracy of immunohistochemistry compared with molecular tests for the diagnosis of BRAF V600E mutation in ameloblastomas?". Methodological quality and risk of bias assessment of the selected studies were based on the QUADAS-2. Meta-analysis based on hierarchical SROC curve model and summary measures for sensitivity and specificity were computed.

RESULTS

A total of 226 records were found, but only 05 articles met the inclusion criteria, with 277 FFPE specimens of ameloblastoma included in the quantitative analysis. The sensitivity of the IHC compared to molecular tests ranged from 0.71 to 1.00, while all of the included studies showed perfect specificity (1.00). Pooled measures for sensitivity and specificity were 0.95 [95% CI 0.89, 1.00] and 1.00 [95% CI 0.95, 1.00], respectively. The Diagnostic Odds Ratio was 4.05 and the AUC for SROC curve was calculated as 0.979.

CONCLUSIONS

BRAF V600E-specific IHC using VE1 antibody showed extremely high sensitivity and specificity when compared with molecular tests in the detection of the mutation in ameloblastomas.

Genetic Study of BRAF V600E and SMO L412F Mutations in Japanese Patients with Ameloblastoma

Background and aim: Ameloblastoma is a benign, intraosseous, progressively growing, epithelial, odontogenic neoplasm. BRAF and SMO mutations have been reported in ameloblastoma. In this study, we evaluated BRAF V600E and SMO L412F mutations; and assessed the relationship between BRAF V600E mutant expression and the clinicopathological features in Japanese patients with ameloblastoma. Methods: We examined 24 formalin-fixed paraffin-embedded samples. All specimens were from patients with mandibular ameloblastoma: 20 were conventional ameloblastoma and 4 were unicystic ameloblastoma. The BRAF V600E mutation was assessed by Sanger sequencing and immunohistochemistry, and the SMO L412F mutation was assessed only by Sanger sequencing. Results: Twenty of the 24 (83%) ameloblastoma samples carried the BRAF V600E mutation; 22 of the 24 (92%) samples were immunohistochemically positive for BRAF V600E. However, the SMO L412F mutation was not detected in any of them. The BRAF V600E mutation status did not correlate with the clinicopathological features, such as age, sex, location, method, recurrence, and subtype. Conclusion: BRAF inhibitors could be a potential treatment option for Japanese patients with ameloblastoma, harboring the BRAF V600E mutation.

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.