The importance of BRAF-V600E mutation to ameloblastoma metabolism.

BACKGROUND: Ameloblastoma is a locally infiltrative, aggressive epithelial odontogenic neoplasm. BRAF-V600E mutation is frequently found in this tumor and has a pivotal role in its pathogenesis, but the consequences of this alteration need to be addressed. An untargeted metabolomics approach was applied to verify whether metabolic disturbances are related to tumor biology and whether BRAF-V600E mutation contributes to these alterations. METHODS: Formalin-fixed and paraffin-embedded tissue specimens from thirteen ameloblastoma and six dental follicles were included in this study. BRAF mutational status was determined by competitive allele-specific real-time PCR. Metabolite extracts were analyzed using gas chromatography coupled to mass spectrometry. Univariate and multivariate statistical methods were employed to compare the metabolic profiles of the samples. RESULTS: The abundance of eleven metabolites was significantly higher in ameloblastoma in relation to dental follicles, including amino acids, fatty acids, carbohydrates, inorganic acids, and organoheterocyclic compounds. The presence of BRAF-V600E mutations in ameloblastoma was related to decreased levels of glycerol in comparison with tumors carrying only wild-type alleles of this gene. No metabolic differences were observed between recurrent and primary manifestations of ameloblastoma. CONCLUSIONS: Ameloblastoma exhibits a distinct metabolic profile from normal odontogenic epithelium. BRAF-V600E may contribute to metabolic alterations in ameloblastoma. Collectively, our findings suggest that metabolic alterations might play a role in tumor pathogenesis.

Evaluation of tumor-infiltrating lymphocytes in osteosarcomas of the jaws: a multicenter study.

The aim of the present study was to investigate the profile of tumor-infiltrating lymphocytes (TIL) in osteosarcomas of the jaws (OSJ). A total of 21 OSJ samples were analyzed in a retrospective and cross-sectional multicenter study. Immunohistochemistry was performed to determine the recognition of TIL such as CD4+, CD8+, granzyme B+ (GrB), programmed cell death protein+ (PD-1), and cytotoxic T lymphocyte-associated antigen 4+ (CTLA-4) in intratumoral and peripheral (stromal) regions. Positivity was determined based on the percentage and density of TIL+ per square millimeter [1 = absent (< 25 cells/mm2), 2 = low (25 to 130 cells/mm2), and 3 = high (> 130 cells/mm2)]. The association of TIL density with clinicopathologic data was determined by the Mann-Whitney test (p < 0.05). OSJ were positive for CD8+ cells in 45% (n = 9) of cases, for CD4+ cells in 30% (n = 6) of cases, and for CTLA-4+ in 4.8% (n = 1) of cases, with a score of 2 (low TIL) in all cases. All cases were negative for GrB and PD-1 (score 1). No association was observed between immune infiltrate and clinicopathologic findings. OSJ showed a microenvironment with low TIL, including failure of effectiveness of the antitumor immune response (absence of GrB+ cells), and few cells exhibited immunotherapeutic targets, such as CTLA-4 and PD-1.