Nuclear Localization of BRAFV600E Is Associated with HMOX-1 Upregulation and Aggressive Behavior of Melanoma Cells

Acemannan-containing bioactive resin modified glass ionomer demonstrates satisfactory physical and biological properties

Background/purpose

Resin-modified glass ionomers (RMGIs) have been recommended as liner and cement to provide the teeth with mechanical support, a chemical barrier, and thermal insulation. Acemannan, the main polysaccharide extracted from Aloe vera, is a promising inductive material in vitro and in vivo. This study aimed to develop acemannan-containing bioactive resin-modified glass ionomers (RMGIs).

Materials and methods

Acemannan (3%, 5%, and 10%) was added to the three types of RMGIs (RU-HBM1/Fuji II LC/Vitrebond) to generate 3%, 5%, and 10% aceRMGIs (aceRU/aceFuji/aceVB). The materials were evaluated for depth of cure/flexural strength/cumulative fluoride ion release. Cell viability and vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) secretion were determined using MTT/apoptosis/necrosis assays, and ELISA kits, respectively. RMGI without acemannan were used as controls.

Results

The aceRMGIs met the ISO requirements for depth of cure and flexural strength. Adding 10% acemannan increased the cumulative fluoride release in the RU and FJ groups, but slightly decreased it in the VB group (P < 0.05). The MTT assay revealed 10% aceRU and all aceFJ groups significantly increased cell viability compared with each control group (P < 0.05). Apoptosis/necrosis assay showed the biocompatibility of all aceRMGIs. Adding acemannan to RMGIs significantly induced VEGF expression in a dose dependent manner while 5% and 10% aceRU significantly induced BMP-2 expression compared with RU group (P < 0.05).

Conclusion

We conclude that 5-10% acemannan in RMGI is the optimal concentration based on its physical properties and ability to induce pulp cell proliferation and growth factor secretion.

BRAF Mutations in Melanoma: Biological Aspects, Therapeutic Implications, and Circulating Biomarkers

Melanoma is an aggressive form of skin cancer resulting from the malignant transformation of melanocytes. Recent therapeutic approaches, including targeted therapy and immunotherapy, have improved the prognosis and outcome of melanoma patients. BRAF is one of the most frequently mutated oncogenes recognised in melanoma. The most frequent oncogenic BRAF mutations consist of a single point mutation at codon 600 (mostly V600E) that leads to constitutive activation of the BRAF/MEK/ERK (MAPK) signalling pathway. Therefore, mutated BRAF has become a useful target for molecular therapy and the use of BRAF kinase inhibitors has shown promising results. However, several resistance mechanisms invariably develop leading to therapeutic failure. The aim of this manuscript is to review the role of BRAF mutational status in the pathogenesis of melanoma and its impact on differentiation and inflammation. Moreover, this review focuses on the mechanisms responsible for resistance to targeted therapies in BRAF-mutated melanoma and provides an overview of circulating biomarkers including circulating tumour cells, circulating tumour DNA, and non-coding RNAs.

A Predictive Model of Adaptive Resistance to BRAF/MEK Inhibitors in Melanoma

The adaptive acquisition of resistance to BRAF and MEK inhibitor-based therapy is a common feature of melanoma cells and contributes to poor patient treatment outcomes. Leveraging insights from a proteomic study and publicly available transcriptomic data, we evaluated the predictive capacity of a gene panel corresponding to proteins differentially abundant between treatment-sensitive and treatment-resistant cell lines, deciphering predictors of treatment resistance and potential resistance mechanisms to BRAF/MEK inhibitor therapy in patient biopsy samples. From our analysis, a 13-gene signature panel, in both test and validation datasets, could identify treatment-resistant or progressed melanoma cases with an accuracy and sensitivity of over 70%. The dysregulation of HMOX1, ICAM, MMP2, and SPARC defined a BRAF/MEK treatment-resistant landscape, with resistant cases showing a >2-fold risk of expression of these genes. Furthermore, we utilized a combination of functional enrichment- and gene expression-derived scores to model and identify pathways, such as HMOX1-mediated mitochondrial stress response, as potential key drivers of the emergence of a BRAF/MEK inhibitor-resistant state in melanoma cells. Overall, our results highlight the utility of these genes in predicting treatment outcomes and the underlying mechanisms that can be targeted to reduce the development of resistance to BRAF/MEK targeted therapy.