SNX16 negatively regulates the migration and tumorigenesis of MCF-7 cells.

Sorting nexins are a large family of proteins that are associated with various components of the endosome system and they play many roles in processes such as endocytosis, intracellular protein trafficking and cell signaling. The subcellular distribution patterns of many of them remain controversial and their in vivo functions have not been characterized yet. We investigated the subcellular distribution and function of SNX16 in this study. SNX16 is detected on Rab5-positive endosomes localized adjacent to focal adhesions at cell cortex. Inhibition of SNX23, polymerization of microtubule filaments as well as the PI3-kinase all disrupt the cell cortex distribution of SNX16. Ectopic expression of SNX16 reduces the migration and the tumor formation activity of MCF-7 cells. Our results indicate that, in addition to the PI3P, there is a SNX23- and microtubule-dependent cargo transport pathway required for the proper subcellular distribution of SNX16. SNX16 plays a negative regulatory role during cell migration and tumorigenesis.