Simpson - Cancer secretome, extracellular communication, exosome and extracellular vesicle biology

Cell-cell communication is a fundamental physiological process that relies on the sending and receiving of signals. This process may involve direct contact between adjoining cells, or the release of secreted molecules. Recently, extracellular vesicles (EVs) emanating from cells have been recognized to play a key role in cell-cell communication at both paracrine and systemic levels. EVs comprise shed microvesicles (sMVs), apoptotic bodies and exosomes which differ based on their mechanism of biogenesis and size; of these, exosomes have been most widely studied. Exosomes are ~40–100 nm EVs released from a multitude of cell types that perform pleiotropic extracellular functions within the extracellular microenvironment. These functions include intrinsic and extrinsic signaling, immunological modulation, and horizontal transfer of proteins, lipids and genetic material (miRNA/mRNA/DNA) to recipient cells. The focus of our research is to utilize an integrated proteomic/genomic strategy directed towards understanding the role of the extracellular environment (specifically, EVs) in cancer progression. We utilize various in vitro and in vivo cancer/EMT models, and techniques including lipophilic-cell/EV-labelling, cell sorting, state-of-the-art fluorescence microscopy, western immunoblotting, mass spectrometry-based protein profiling for discovery and targeted strategies, and miR/mRNA/lncRNA profiling and qRT-PCR validation. We are a well-established group comprising several PhD and post-doctoral fellows.

Research projects include understanding exosome biogenesis (sorting, trafficking); understanding distinct populations of extracellular vesicles (exosome, shed microvesicles) (cancer cells, biofluids); identifying mechanisms of recipient cell update/internalization; investigating functional contribution of extracellular vesicles in EMT and cancer progression (in vitro and in vivo); characterise secretome (soluble-secreted proteins) from metastatic human cancers to establish and identify molecular differences that contribute to cancer progression; identify molecular differences in cell surface proteins (including protein complexes) between extracellular vesicle subtypes; isolate, biochemically characterize, and functionally investigate EV protein complexes.

Research areas

Understanding extracellular vesicles (EVs) in the context of cancer biology

Cell-cell communication is an integral physiological process that relies on the sending and receiving of signals. This project will focus on an integrated system biology approach directed towards isolation, characterisation and functional understanding of secreted molecules (secretome/EVs) in the context of cancer biology. We use various cell models to investigate the contribution of the extracellular environment during cancer initiation, development, epithelial-mesenchymal transition, and metastasis.

Further, these studies will investigate EV internalisation and uptake, in addition to targeted functional analyses of EVs. Conventional biological assays for cell proliferation, motility, migration, invasiveness, spheroid, fibroblast/endothelial cell activation, are already established in our lab. Using global profiling approaches, including proteomic (mass-spectrometry based profiling) and genomic (miR/mRNA profiling) analyses, we intend to catalogue and identify the contribution of EVs during cancer progression, especially induced expression of signalling pathway receptors/ modulators.

This project will investigate the following questions:

  1. How many different EV subtypes are there? Different EV types may have a definitive localisation/function in specific recipient cells due to their surface markers or specific cargo contained within
  2. What are the different methods to purify the secretome and distinct EV subtypes?
  3. What are the distinct functions of the secretome and EVs during cancer initiation, development, epithelial-mesenchymal transition, and metastasis?
  4. What cargo/surface components (protein/nucleic acids) are contained within EVs?
  5. Can distinct cargo components in EVs be perturbed using molecular biology?

Contribution of exosomal protein complexes to cell-cell communication

Exosomes, small membrane vesicles of endocytic origin, are secreted by most cell types. Although functioning as powerful intercellular communicators, the identity of exosomal protein complexes (EPCs) and their specific components, together with the molecular mechanisms underlying their functions in recipient cells, remain unknown. This project focuses on the hypothesis that multiprotein complexes contained in cancer cell-derived exosomes play a crucial role in cell-cell communication and that perturbation of EPCs may affect the functionality of stromal target cells.

This project will identify exosome protein complexes, their specific protein components and insights into their structural organization (i.e., core subunit interactions) and functionality in the context of cancer biology. Such complexes contained in cancer cell-derived exosomes play a crucial role in cell-cell communication and that perturbation of EPCs may affect target cell functionality and impact on exosome-targeted drug design.

This project will investigate the following questions:

  1. What are the different methods to isolate and biochemically characterize EPCs from human cancer cell models?
  2. Which proteins are contained within EPCs that contribute to their function? Can selected EPCs be perturbed by shRNA and/or overexpression of EPC protein subunits?
  3. What are the distinct functions of EPCs during cancer initiation, development, and metastasis?

Contribution of extracellular vesicles (EV) in epithelial-mesenchymal transition

The metastatic cascade describes the process by which tumour cells escape their primary site and colonize secondary locations. Tumour angiogenesis facilitates passage, and cells at the leading edge of the primary tumour are thought to undergo epithelial-mesenchymal transition (EMT) to acquire increased motility and invasiveness. Whether oncogenic cells that have undergone EMT directly promotes endothelial cell recruitment remains largely unknown, and the role of extracellular vesicles (EVs) (30-1,000nm diameter) in this process has not yet been definitively explored.

Conventional biological assays for cell proliferation, motility, migration, and invasion are already established in our lab. Using global profiling approaches, including proteomic (mass-spectrometry based profiling) and genomic (miR/mRNA profiling) analyses, we intend to catalogue and identify the contribution of EVs during EMT, especially induced expression of signalling pathway receptors/ modulators in recipient cells to modify their function.

Preliminary results demonstrate that oncogenic cells undergoing EMT can communicate with endothelial cells via exosomes, and establish angiogenic promoters that may function during the initial stages of metastasis.

This project will investigate the following questions:

  1. What are the different methods to purify the secretome and distinct EV subtypes?
  2. Can distinct cargo components in EVs be perturbed using molecular biology?
  3. Investigate the contribution of secreted (soluble and vesicle components) to modifying recipient cell function.
  4. How do vesicles selectively package and transfer soluble cargo such as cellular mediators directly into endothelial and epithelial cells?

Meet the team

Group members

Group LeaderGreening group

Professor Richard Simpson

Research Fellows

Dr David Greening
Dr Alin Rai
Dr Rong (Kelvin) Xu

PhD students

Maoshan Chen (co-supervised with Dr David Greening)
Adnan Shafiq (co-supervised with Dr David Greening)
Wittaya Suwakulsiri (co-supervised with Dr David Greening)

Visiting student

Emel Rothzerg