Target-specific inhibition of the BRAFV600E mutant protein has been a major breakthrough in the treatment of metastatic cutaneous melanoma. However, the success of therapies is significantly overshadowed by the development of resistance. Understanding the molecular mechanisms associated with acquired resistance is an important step to increase the effectiveness of melanoma treatment. Our aim was to elucidate the molecular differences underlying the development of drug resistance using a mutant BRAF protein inhibitor (vemurafenib analogue: PLX4720) in BRAFV600E mutant melanoma cell lines. We developed four BRAF inhibitor-resistant cell lines and examined the effect of BRAF inhibitor "withdrawal" on cell division. ArrayCGH was used to define genetic, and Affymetrix HumanGene 1.0 microarray to monitor gene expression alterations between the sensitive and resistant cell lines. Protein expression was determined using Proteome Profiler Human XL Oncology Array. We found that withdrawal of the inhibitor reduces cell proliferation in the resistant cells. The invasive potential of the resistant cells increased. Using genomic and proteomic methods we described new molecular alterations associated with acquired resistance.
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Curr Oncol
December 2024
Department of Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
The incidence of melanoma, the most lethal form of skin cancer, has increased mainly due to ultraviolet exposure. The molecular characterization of melanomas has shown a high mutational burden led to the identification of some recurrent genetic alterations. gene is mutated in 40-50% of melanomas and its role in melanoma development is paramount.
View Article and Find Full Text PDFCancer Rep (Hoboken)
December 2024
Department of Hematology and Clinical Immunology, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
Background: Erdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis with diverse clinical manifestations, often associated with mutations in the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway. BRAF and KRAS mutations, which are driver mutations of oncogenes, participate in the same signaling pathway (MAPK/ERK pathway) and are usually mutually exclusive. We report a case of ECD with concurrent BRAF and KRAS mutations treated using BRAF and MEK inhibitors.
View Article and Find Full Text PDFLancet Oncol
December 2024
Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada. Electronic address:
Background: Gliomas are a major cause of cancer-related death among children, adolescents, and young adults (age 0-40 years). Primary mismatch repair deficiency (MMRD) is a pan-cancer mechanism with unique biology and therapeutic opportunities. We aimed to determine the extent and impact of primary MMRD in gliomas among children, adolescents, and young adults.
View Article and Find Full Text PDFMetastatic melanoma remains a major clinical challenge. Large-scale genomic sequencing of melanoma has identified bona fide activating mutations in RAC1, which are associated with resistance to BRAF-targeting therapies. Targeting the RAC1-GTPase pathway, including the upstream activator PREX2 and the downstream effector PI3Kβ, could be a potential strategy for overcoming therapeutic resistance, limiting melanoma recurrence, and suppressing metastatic progression.
View Article and Find Full Text PDFSignal Transduct Target Ther
December 2024
The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing, 100871, China.
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