Unravelling new insights into extracellular vesicle-associated proteome of cancer-associated adipocytes in ovarian cancer
Background
Ovarian cancer (OC) is the deadliest gynecological disease worldwide and often occurs with metastases, chemoresistance and immune evasion. Its late diagnosis at advanced stage is often associated with the accumulation of malignant ascites representing a unique tumor microenvironment and leading to a poor prognosis. The omentum constitutes the primary site of metastases and mainly consists of adipocytes (ADP), which undergo a reprogramming into cancer-associated ADPs (CAA). Additionally, extracellular vesicles (EVs) derived from ADPs have been shown to have pro-tumorigenic characteristics in OC but little is known about CAA-derived EVs.
Methods
We have studied ascites-driven reprogramming and its impact on EV release in two in vitro adipogenesis models (3T3-L1 and 3T3-F442A).
Results
Transcriptomic analysis (RNAseq) revealed broad effects of ascites reprogramming showing significant changes in genes involved in signaling pathways like proliferation or migration and metabolic pathways, all pointing to tumor-promoting capacities. Additionally, CAAs showed a higher expression of genes involved in lipolysis and adipocytokine signaling supporting previous findings. In parallel, EVs from ADPs and CAA-like cells were isolated by different methods using differential ultracentrifugation (dUC), tangential flow filtration (TFF) or size exclusion chromatography (SEC). Subsequent particle number and median size measurements by nanoparticle tracking analysis fluctuated among different methods but generally showed a higher particle release of CAA-like cells. Additionally, exploratory label-free proteomic analysis of EVs revealed a clustering of dUC and SEC preparations strongly separated to TFF samples, especially regarding ADP-specific proteins or certain cytokines. Furthermore, a deeper analysis of ADP- and CAA-like-derived EVs from both in vitro cell lines was performed, revealing a significantly enriched mitochondrial compartment in CAA-like-derived EVs as well as an increase of certain lipoproteins.
Conclusion
These observations support the hypothesis suggesting CAA-like cells as energy suppliers for surrounding cells, especially OC cells.
Future experiments aim to explore the effect of CAA-derived EVs on OC cells, especially regarding invasion capacities and the metabolic rewiring of OC cells with special focus on mitochondrial alterations.
Keywords
Adipocytes, EV isolation method, ovarian cancer, proteomics
Funding/Acknowledgments
This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation – 416910386 GRK 2573/1).
Authors
Johanna Pörschke1, Susanne Hermann1, Christian Preußer1, Florian Finkernagel2, 3, Viviane Ponath1, Witold Szymanski4, Johannes Graumann4, Silke Reinartz2, Rolf Müller2, Elke Pogge von Strandmann1, María Gómez-Serrano1 (Corresponding Author:
maria.gomezserrano[at]imt.uni-marburg[dot]de)