Introduction: Recently, the role of extracellular vesicles in cancer progression, specifically, in metastasis and in the capacity of several tumours to invade and colonize specific organs has been established. The aim of this project was to characterize the exosomal and tumor protein profile from patients at different stages of ovarian cancer (OvCa).
Methods: Plasma samples and biopsies from patients with ovarian cancer were obtained from Ochsner Medical Center (New Orleans, USA). Exosomes were characterized by the presence of enriched TSG101 using Western Blot, size distribution (Nanosight™), and morphology by electron microscopy. The exosomal protein profile and protein tumor profile was determined using a Liquid Chromatography (LC)/ Mass Spectrometry (MS) LC-MS/MS on a 5600 Triple TOF mass spectrometer (AB Sciex, Framingham, U.S.A.). The effects of exosomes on Epithelial to Mesenchymal Transition (EMT) were validated by the ratio of E-cadherin (epithelial marker) to N-cadherin (mesenchymal marker) by Western Blot and the expression of 84 key genes involved in the EMT (RT² Profiler™ PCR Array, QIAGEN).
Results: Exosomes were identified as spherical vesicles with a typical cup-shape, diameters ranging from 50 to 100 nm, with the expression of TSG101. We identified stage disease specific proteins in exosomes. Exosomes isolated from stage III OvCA induce EMT (increased N-cadherin/E-cadherin ratio) compared to the control. Exosomes regulated the expression of a set of transcription factors associated with EMT such as SNAIL1/SNAIL2, bHLH (E47, E2-2, and TWIST1/TWIST2), and ZEB1/ZEB2 on target cells.
Conclusion: Exosomes derived from patients with disease are able to communicate messages to induce EMT in target cells.