RESUMEN
Tumor cell invasion involves targeted localization of proteins required for interactions with the extracellular matrix and for proteolysis. The localization of many proteins during these cell-extracellular matrix interactions relies on membrane trafficking mediated in part by SNAREs. The SNARE protein syntaxin4 (Stx4) is involved in the formation of invasive structures called invadopodia; however, it is unclear how Stx4 function is regulated during tumor cell invasion. Munc18c is known to regulate Stx4 activity, and here we show that Munc18c is required for Stx4-mediated invadopodium formation and cell invasion. Biochemical and microscopic analyses revealed a physical association between Munc18c and Stx4, which was enhanced during invadopodium formation, and that a reduction in Munc18c expression decreases invadopodium formation. We also found that an N-terminal Stx4-derived peptide associates with Munc18c and inhibits endogenous interactions of Stx4 with synaptosome-associated protein 23 (SNAP23) and vesicle-associated membrane protein 2 (VAMP2). Furthermore, expression of the Stx4 N-terminal peptide decreased invadopodium formation and cell invasion in vitro Of note, cells expressing the Stx4 N-terminal peptide exhibited impaired trafficking of membrane type 1 matrix metalloproteinase (MT1-MMP) and EGF receptor (EGFR) to the cell surface during invadopodium formation. Our findings implicate Munc18c as a regulator of Stx4-mediated trafficking of MT1-MMP and EGFR, advancing our understanding of the role of SNARE function in the localization of proteins that drive tumor cell invasion.
Asunto(s)
Adenocarcinoma/metabolismo , Matriz Extracelular/metabolismo , Fibrosarcoma/metabolismo , Proteínas Munc18/metabolismo , Proteínas de Neoplasias/metabolismo , Podosomas/metabolismo , Proteínas Qa-SNARE/metabolismo , Adenocarcinoma/patología , Unión Competitiva , Línea Celular Tumoral , Receptores ErbB/metabolismo , Matriz Extracelular/patología , Fibrosarcoma/patología , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Metaloproteinasa 14 de la Matriz/metabolismo , Proteínas Munc18/antagonistas & inhibidores , Proteínas Munc18/química , Proteínas Munc18/genética , Invasividad Neoplásica , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/química , Proteínas de Neoplasias/genética , Fragmentos de Péptidos/química , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Podosomas/patología , Dominios y Motivos de Interacción de Proteínas , Multimerización de Proteína , Transporte de Proteínas , Proteínas Qa-SNARE/química , Proteínas Qa-SNARE/genética , Proteínas Qb-SNARE/antagonistas & inhibidores , Proteínas Qb-SNARE/química , Proteínas Qb-SNARE/metabolismo , Proteínas Qc-SNARE/antagonistas & inhibidores , Proteínas Qc-SNARE/química , Proteínas Qc-SNARE/metabolismo , Interferencia de ARN , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Proteína 2 de Membrana Asociada a Vesículas/antagonistas & inhibidores , Proteína 2 de Membrana Asociada a Vesículas/química , Proteína 2 de Membrana Asociada a Vesículas/metabolismoRESUMEN
BACKGROUND: In asthma and chronic obstructive pulmonary disease (COPD), airway mucus hypersecretion contributes to impaired mucociliary clearance, mucostasis and, potentially, the development of mucus plugging of the airways. SUMMARY: Excess mucus production can be targeted via therapies that focus on inhibition mucin synthesis, via reducing expression of mucin (MUC) genes, and/or inhibition of mucin secretion into the airways. KEY MESSAGES: This review discusses a number of therapeutic approaches to reduce airway mucus in asthma and COPD, including the use of synthetic and natural products. In particular, it highlights areas where clinical trials of inhibitors of particular target molecules are lacking. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors are an example of a targeted therapy that has been researched to reduce mucus synthesis, as have inhibitors of EGFR's downstream signalling pathways, for example, mitogen-activated protein kinase-13 and hypoxia inducible factor-1. However, their efficacy and safety profiles are currently not up to the mark. There is clinical potential in Bio-11006, which reduces mucus secretion via the inhibition of myristoylated alanine-rich C-kinase substrate and is currently in Phase IIb trial.