RESUMO
BRAF is a constituent of the mitogen-activated protein kinase (MAPK) signaling pathway, which serves to activate downstream MEK, and is one of the most commonly mutated oncogenes in human tumors. Indeed, BRAF V600 mutations are present in approximately 40% of metastatic melanoma tumors. Encorafenib (LGX-818, Braftovi) and binimetinib (MEK-162, Mektovi) are small-molecule inhibitors of BRAF and MEK, respectively. BRAF and MEK inhibitors have been shown to improve overall and progression-free survival among patients with metastatic melanoma. Of these inhibitors, encorafenib and binimetinib are the newest combination, which received approval by the Food and Drug Administration (FDA) for the treatment of BRAF V600E/K-mutated melanoma in June 2018. This review will focus on the preclinical pharmacology, pharmacokinetics and clinical utility of encorafenib and binimetinib in BRAF V600-mutated melanoma.
Assuntos
Benzimidazóis/uso terapêutico , Carbamatos/uso terapêutico , Melanoma/tratamento farmacológico , Proteínas Proto-Oncogênicas B-raf/genética , Sulfonamidas/uso terapêutico , Humanos , Melanoma/genética , Mutação , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidoresRESUMO
Glycoprotein nmb (GPNMB) promotes breast tumor growth and metastasis and its expression in tumor epithelium correlates with poor prognosis in breast cancer patients. Despite its biological and clinical significance, little is known regarding the molecular mechanisms engaged by GPNMB. Herein, we show that GPNMB engages distinct functional domains and mechanisms to promote primary tumor growth and metastasis. We demonstrate that neuropilin-1 (NRP-1) expression is increased in breast cancer cells that overexpress GPNMB. Interestingly, the GPNMB-driven increase in NRP-1 expression potentiated vascular endothelial growth factor signaling in breast cancer cells and was required for the growth, but not metastasis, of these cells in vivo. Interrogation of RNAseq data sets revealed a positive correlation between GPNMB and NRP-1 levels in human breast tumors. Furthermore, we ascribe pro-growth and pro-metastatic functions of GPNMB to its ability to bind α5ß1 integrin and increase downstream signaling in breast cancer cells. We show that GPNMB enhances breast cancer cell adhesion to fibronectin, increases α5ß1 expression and associates with this receptor through its RGD motif. GPNMB recruitment into integrin complexes activates Src and Fak signaling pathways in an RGD-dependent manner. Importantly, both the RGD motif and cytoplasmic tail of GPNMB are required to promote primary mammary tumor growth; however, only mutation of the RGD motif impaired the formation of lung metastases. Together, these findings identify novel and distinct molecular mediators of GPNMB-induced breast cancer growth and metastasis.
Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Proliferação de Células/genética , Integrina alfa5beta1/genética , Glicoproteínas de Membrana/genética , Metástase Neoplásica/genética , Neuropilina-1/genética , Animais , Adesão Celular/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Feminino , Fibronectinas/genética , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Camundongos , Metástase Neoplásica/patologia , Transdução de Sinais/genética , Fator A de Crescimento do Endotélio Vascular/genéticaRESUMO
The loss of expression of the transcription factor GATA3 in breast tumors has been linked to aggressive tumor development and poor patient survival. In the present work, we address potential roles for GATA3 in breast tumor lung metastasis and progression. Using an aggressive breast cancer cell line, which metastasizes specifically to the lung, we show that GATA3 expression results in reduced tumor outgrowth in the mammary fat pad and lower lung metastatic burden in nude mice. Specifically, GATA3 expression inhibits breast cancer cell expansion inside the lung parenchyma. This phenotype correlates with the ability of GATA3 to negatively regulate the expression of several genes that promote breast cancer lung metastasis (ID1/-3, KRTHB1, LY6E and RARRES3). Conversely, the expression of genes encoding known inhibitors of lung metastasis (DLC1 (deleted in liver cancer 1) and PAEP (progestagen-associated endometrial protein)) is upregulated by GATA3. These data correlate with microarray data from human breast cancer patients, showing a strong correlation between high GATA3 expression and absence of metastases specifically to the lungs. We conclude that GATA3 inhibits primary breast tumor outgrowth and reduces lung metastatic burden by regulating key genes involved in metastatic breast tumor progression.