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The Current State of Molecular Testing in the BRAF-Mutated Melanoma Landscape.

ABSTRACT: The incidence of melanoma, among the most lethal cancers, is widespread and increasing. Metastatic melanoma has a poor prognosis, representing about 90% of skin cancer mortality. The increased knowledge of tumor biology and the greater understanding of the immune system role in the anti-tumor response has allowed us to develop a more rational approach to systemic therapies. The discovery of activating BRAF mutations in half of all melanomas has led to the development of molecularly targeted therapy with BRAF and MEK inhibitors, which dramatically improved outcomes of patients with stage IV BRAF-mutant melanoma. More recently, the results of clinical phase III studies conducted in the adjuvant setting led to the combined administration of BRAF and MEK inhibitors also in patients with resected high-risk melanoma (stage III). Therefore, BRAF mutation testing has become a priority to determine the oncologist's choice and course of therapy. In this review, we will report the molecular biology-based strategies used for BRAF mutation detection with the main advantages and disadvantages of the most commonly used diagnostic strategies. The timing of such molecular assessment in patients with cutaneous melanoma will be discussed, and we will also examine considerations and approaches for accurate and effective BRAF testing.

SUBMITTER: Vanni I

PROVIDER: S-EPMC7338720 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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The Current State of Molecular Testing in the BRAF-Mutated Melanoma Landscape.

Vanni Irene I Tanda Enrica Teresa ET Spagnolo Francesco F Andreotti Virginia V Bruno William W Ghiorzo Paola P

Frontiers in molecular biosciences 20200630

The incidence of melanoma, among the most lethal cancers, is widespread and increasing. Metastatic melanoma has a poor prognosis, representing about 90% of skin cancer mortality. The increased knowledge of tumor biology and the greater understanding of the immune system role in the anti-tumor response has allowed us to develop a more rational approach to systemic therapies. The discovery of activating <i>BRAF</i> mutations in half of all melanomas has led to the development of molecularly target ...[more]

PMID: 32695793

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Project description:BackgroundMost mutations in melanoma affect one critical amino acid on BRAF gene, resulting in the V600E substitution. Patient management is often based on the use of specific inhibitors targeting this mutation.MethodsDNA and RNA mutation status was assessed in 15 melanoma cell lines by Sanger sequencing and RNA-seq. We tested the cell lines responsiveness to BRAF inhibitors (vemurafenib and PLX4720, BRAF-specific and sorafenib, BRAF non-specific). Cell proliferation was assessed by MTT colorimetric assay. BRAF V600E RNA expression was assessed by qPCR. Expression level of phosphorylated-ERK protein was assessed by Western Blotting as marker of BRAF activation.ResultsThree cell lines were discordant in the mutation detection (BRAF V600E at DNA level/Sanger sequencing and BRAF WT on RNA-seq). We initially postulated that those cell lines may express only the WT allele at the RNA level although mutated at the DNA level. A more careful analysis showed that they express low level of BRAF RNA and the expression may be in favor of the WT allele. We tested whether the discordant cell lines responded differently to BRAF-specific inhibitors. Their proliferation rate decreased after treatment with vemurafenib and PLX4720 but was not affected by sorafenib, suggesting a BRAF V600E biological behavior. Yet, responsiveness to the BRAF specific inhibitors was lower as compared to the control. Western Blot analysis revealed a decreased expression of p-ERK protein in the BRAF V600E control cell line and in the discordant cell lines upon treatment with BRAF-specific inhibitors. The discordant cell lines showed a lower responsiveness to BRAF inhibitors when compared to the BRAF V600E control cell line. The results obtained from the inhibition experiment and molecular analyses were also confirmed in three additional cell lines.ConclusionCell lines carrying V600E mutation at the DNA level may respond differently to BRAF targeted treatment potentially due to a lower V600E RNA expression.

Project description:β-Galactosylceramidase (GALC) is a lysosomal enzyme involved in sphingolipid metabolism by removing β-galactosyl moieties from β-galactosylceramide and β-galactosylsphingosine. Previous observations have shown that GALC may exert pro-oncogenic functions in melanoma and Galc silencing, leading to decreased oncogenic activity in murine B16 melanoma cells. The tumor-driving BRAF(V600E) mutation is present in approximately 50% of human melanomas and represents a major therapeutic target. However, such mutation is missing in melanoma B16 cells. Thus, to assess the impact of GALC in human melanoma in a more relevant BRAF-mutated background, we investigated the effect of GALC overexpression on the proteomic landscape of A2058 and A375 human melanoma cells harboring the BRAF(V600E) mutation. The results obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) demonstrate that significant differences exist in the protein landscape expressed under identical cell culture conditions by A2058 and A375 human melanoma cells, both harboring the same BRAF(V600E)-activating mutation. GALC overexpression resulted in a stronger impact on the proteomic profile of A375 cells when compared to A2058 cells (261 upregulated and 184 downregulated proteins versus 36 and 14 proteins for the two cell types, respectively). Among them, 25 proteins appeared to be upregulated in both A2058-upGALC and A375-upGALC cells, whereas two proteins were significantly downregulated in both GALC-overexpressing cell types. These proteins appear to be involved in melanoma biology, tumor invasion and metastatic dissemination, tumor immune escape, mitochondrial antioxidant activity, endoplasmic reticulum stress responses, autophagy, and/or apoptosis. Notably, analysis of the expression of the corresponding genes in human skin cutaneous melanoma samples (TCGA, Firehose Legacy) using the cBioPortal for Cancer Genomics platform demonstrated a positive correlation between GALC expression and the expression levels of 14 out of the 27 genes investigated, thus supporting the proteomic findings. Overall, these data indicate for the first time that the expression of the lysosomal sphingolipid-metabolizing enzyme GALC may exert a pro-oncogenic impact on the proteomic landscape in BRAF-mutated human melanoma.

Project description:BACKGROUND:Approximately one third of women who develop melanoma at childbearing age are diagnosed during gestation or the postpartum period, facing pregnancy-associated melanoma (PAM). However, only some retrospective studies with heterogeneous data have analyzed the impact of pregnancy on melanoma development, and no evidence exists about the behavior and the management of BRAF-mutated disease. SUBJECTS, MATERIALS, AND METHODS:In order to better describe the evolution of BRAF V600E-mutated PAM, we present here all consecutive cases diagnosed in our site during the last 7?years, recording oncological, obstetrical, and perinatal parameters, as well as the therapeutic decisions for both melanoma and gestation. Based on our institutional experience, we weigh the current published evidence and discuss upcoming clinical considerations about the prognosis of PAM, the role of BRAF status, and the possible treatment options during pregnancy in localized or advanced/metastatic disease. Five women were diagnosed with newly metastatic or relapsed BRAF V600E-mutated PAM (four during gestation and one in the 1st year postpartum) between 2012 and 2019. All of them developed extensive metastatic disease with multiple organ involvement, and four developed brain metastases. All cases experienced melanoma progression in less than 6 months under targeted therapy and died soon independently of the followed sequence of treatments. All the neonates were delivered alive and healthy, but one developed melanoma earlier than the second year of life. RESULTS:Reviewing the literature to confirm our unfavorable outcomes, no specific data on BRAF-mutated PAM were retrieved and current evidence still supports that the prognosis of PAM should be guided by the established risk factors, whereas the management of advanced/metastatic PAM should be evaluated on a case-by-case basis. CONCLUSION:More data are required to ascertain whether BRAF-mutated profile adversely affects PAM outcome, although the clinicians should be aware to detect any potential melanoma lesion during pregnancy as soon as possible, treating it locally, regardless of its BRAF status. IMPLICATIONS FOR PRACTICE:The prognosis and management of pregnancy-associated melanoma whether BRAF-mutated or wild type, is currently guided by the same parameters as in the nonpregnant condition. In this special nontrial subpopulation, BRAF-mutated status seems to have a detrimental effect on disease outcome, independently of the following treatments. In early stage melanoma, wide local excision with or without sentinel lymph node dissection may be curative at any trimester of gestation, while in advanced/metastatic setting, therapeutic strategy including immune-checkpoint or BRAF/MEK inhibitors, is more challenging, regardless of BRAF status, and should be based on an individualized decision in each case at a multidisciplinary level.

Dataset Information

The Current State of Molecular Testing in the BRAF-Mutated Melanoma Landscape.

Publications

The Current State of Molecular Testing in the BRAF-Mutated Melanoma Landscape.

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