Melanoma is a highly invasive and metastatic cancer, with high rates of mortality and chemoresistance. The MAPK pathway is constitutively activated, and there are already available powerful target-specific chemotherapeutics, such as BRAF inhibitors (Vemurafenib and Dabrafenib). However, resistance to BRAF inhibitors is observed after about 7 months of treatment, primarily because of the high degree of phenotypic, genetic and epigenetic intra-tumor heterogeneity. Although, combination therapies benefit patients, and immunotherapy has shown highly promising results, overcoming resistance remains major challenge. In silico screening studies from our laboratory using the TCGA and Gene Expression Omnibus (GEO) databases identified the TOP1 and ATP6V0B genes as being differentially expressed between invasive melanoma when compared with nevi (non-malignant lesion). The TOP1 gene is amplified and in melanomas associated with the worst prognosis, and is involved in the replication, translation, recombination and DNA repair. The ATP6V0B gene is involved in lysosomal transport, inhibition of autophagy and also impacts on invasion and metastasis. Understanding the role and regulation of TOP1 and ATP6V0B should provide insights into the molecular mechanisms underpinning melanoma progression and ultimately resistance to therapy. In this study we will characterize the action of TOP1 and ATP6V0B genes in the progression of humans melanomas, as well, in vemurafenib-chemoresistant cells. The objective is to identify target genes and mechanisms that contribute to vemurafenib resistance. To achieve this goal, the expression of TOP1 and ATP6V0B will be explored in a broad panel of human melanomas at different stages of progression and mutation status, as well as in vemurafenib-sensitive and resistant cell lines. We will employ both monolayer culture and organotypic models that simulate invasion in reconstructed skin containing melanoma, and explore histological samples from patients coming from a partnership with the Barretos Cancer Hospital. We will dissect the molecular pathways associated with TOP1 andATP6V0B expression using gene manipulation tools, and evaluate the impact of these genes on proliferation, migration, invasion, angiogenesis, and cell death induction. Once their mode of action has been characterized, xenograft models will be used for molecular imaging (18F-FDG) PET/CT to understand the genes influence in the metastatic process. This study, like others already developed in our laboratory, can characterize genes that generate tumor subpopulations of resistant cells and aims at identifying pharmacologically tractable targets that may be used in combination to enhance therapeutic response. (AU)
News published in Agência FAPESP Newsletter about the scholarship:
WATANABE, LUIS R. M.;
DE OLIVEIRA, ERICA APARECIDA;
VAZQUEZ, VINICIUS DE LIMA;
SOUZA, PAOLA DA COSTA;
LOPES CONSOLARO, MARCIA EDILAINE;
MARIA-ENGLER, SILVYA STUCHI.
Indoleamine 2,3-dioxygenase in melanoma progression and BRAF inhibitor resistance.
Web of Science Citations: 0.