Extracellular vesicles (EV) are polydisperse nanometer-sized membraneous structures containing
proteins, nucleic acids and metabolites. Their secretion is tightly regulated through Rab
GTPase/effector complexes, including Rab27b-melanophilin (Mlph) and viral Gag-like proteins,
including arrestin domain containing protein-1 (Arrdc1). We will use state-of-the-art density and size
based AF4 fractionation technology to isolate monodisperse EV populations. Molecular signatures
of each monodisperse population will be achieved through –omics approaches. Preliminary
evidence suggests the existence of small and larger EV, of which the larger EV are uniquely positive
for Rab27b-Mlph and Arrdc1; in contrast small EV do not contain Rab27b-Mlph. Genetic
interference with Mlph expression in hormone-sensitive breast cancer cells induces DNA double
strand breaks and cell death. Recent reports indicate the importance of regulated EV release to
control cytosolic double stranded dsDNA levels to avoid type I interferon induced cell death. Using
loss of function point mutations and genetic interference we will investigate whether
Arrdc1/Rab27b/Mlph are differentially crucial to dispose cytosolic dsDNA through secretion of EV.
We will scrutinize the functional consequences of this cellular disposal mechanism using impedance
and image based real time monitoring of hormone sensitive breast cancer cell lines and through
orthotopic mouse models to investigate breast cancer metastasis.