Research

Our  research is aimed at understanding metastasis, the process through which cancer spreads beyond the primary tumor to distant organs.One of our first major discoveries was that primary tumors secrete factors, including cytokines, chemokines and small extracellular vesicles (sEVs, also, known as exosomes) that circulate to distant sites of future metastasis, establishing a specific microenvironment known as the pre-metastatic niche (PMN). We were also the first to show that extracellular vesicles and particles (EVPs) impact all aspects of the PMN, promoting vascular leakiness, immunosuppression and the recruitment of pro-metastatic and pro-angiogenic bone marrow progenitor cells, thus creating a  favorable microenvironment for the survival of tumor cells prior to their arrival. We have defined the content or ‘cargo’ of  tumor EVPs, which are comprised of proteins, lipids, RNA and DNA, and studied their contribution to metastatic disease progression and re-programming the stromal and immune components of the PMN. We showed that specific tumor EVP cargo, such as integrins, helps direct the homing of tumors to future metastatic niches a discovery which furthers our understanding of metastatic tropism and identifies potential therapeutic targets to hinder metastasis. In addition, we are actively studying how tumor cells selectively package their distinct cargo. We have also adapted a new technology, asymmetric-flow field-flow fractionation, to isolate EV subpopulations and discovered a novel, very abundant particle, which we named the exomere. We employ sophisticated proteomic and bioinformatic approaches to identify EVPs cargo that can serve as biomarkers for early cancer detection, or to predict cancer progression, metastasis and response to therapy. We also have an active interest in EV-based theranostics.

Systemic effects of cancer

Our current work is focusing on the systemic effects of cancer mediated by tumor EVPs. Tumor EVPs not only prepare the pre-metastatic niche, but can also travel to and be taken up by organs where the tumor does not metastasize.

We recently showed that tumor EVPs isolated from  cancers that do not metastasize to liver, can be taken up by liver and markedly alter liver metabolism, thus compromising the liver’s ability to metabolize chemotherapeutic drugs.

Primary and metastatic cancer-induced EVPs also promote other cancer-associated, often deadly systemic complications such as thrombosis and cachexia. Further understanding of the reciprocal interactions between cancer and its host at the systemic level will help define new therapeutic interventions to prevent these cancer-induced complications.

EVP Cargo and Mechanisms of EVP biogenesis

How cells selectively package protein, lipids and nucleic acids into vesicles is not well understood. Although EVP cargo can sometimes simply reflect the overall state of the cells, often times certain proteins, RNA or even DNA are selectively enriched in EVPs, while different cell types secrete EVPs carrying vastly different DNA amounts. These characteristics in turn impact EVP characteristics and function.

EVP Protein Cargo: For example, we previously showed that ß4 integrin (ITGB4) is highly enriched in EVPs derived from tumor cells that metastasize to lung, and crucially, ITGB4 directs these EVPs to lung tissues ultimately dictating organotropic pulmonary metastasis. Alternatively, other integrin adhesion receptors are enriched in EVPs shed by tumor cells that metastasize to liver, brain, or bone, such as ITGB5, ITGB1, and ITGB3, respectively. Understanding the mechanisms driving selective protein packaging may help to optimize use of EVP integrins and other EVP molecules for biomarker studies and uncover ways to potentially impair EVP-dependent metastatic and systemic phenotypes.

EVP DNA Cargo:  Our lab showed that EVPs contain double stranded DNA (EV-DNA) representing the entire genome and reflecting the mutational status of parental cells. By combining advanced microscopy methods (super-resolution and atomic force microscopy) and histone-specific mass spectrometry we recently revealed that the majority of EV-DNA is chromatinized and localized on the surface of the vesicle. Functionally, EV-DNA impedes cancer progression by stimulating the immune response. Dissecting the pathways involved in EV-DNA packaging in cancer and normal physiology is key to understanding its function and theranostic potential, as well as exploring its biomarker value.

EVPs as Biomarkers of cancer and systemic diseases

The unique cargo of EVP shed by tumors themselves, as well as other host organs in response to growing tumors or systemic diseases (autoimmunity, autism, infection),  represents a rich and reliable source of biomarkers. EVPs can be isolated from patient biofluids, such as plasma, and assessed for content specific for various disease states and stages. With the help of advanced “omics” technologies, bioinformatics and AI, these liquid biopsies could not only be applied to determine if cancer is present and predict status of disease but also the likelihood of metastatic progression or to monitor the patients response to therapy.

Novel technologies for EVP Characterization

To study EVPs, we combine a multitude of complementary, cutting-edge technologies. We use a variety of techniques such as ultracentrifugation, density gradient centrifugation, size exclusion chromatography, and affinity capturing for routine isolation of EVPs, followed by comprehensive EVP characterization by electron microscopy, atomic force microscopy, nanoparticle tracking analysis and flow cytometry. We are interested in optimizing and applying state-of-the-art methods such as asymmetric flow field flow fractionation (AF4) technology, to dissect the heterogeneity of EVP populations. Using this approach we identified a novel particle, which we named "exomere". We employ mass spectrometry to characterize the protein, metabolite and lipid cargo of EVPs from murine models of cancer as well as biofluids of cancer patients, and sequencing techniques for nucleic acid analysis. In collaboration with Dr. Jacob Geri ( https://gerilab.weill.cornell.edu/research), we are applying advanced 4DtimsTOF mass spectrometry to characterize protein cargo,  and  protein-protein interactions within EVPs. Most recently, we have been employing dSTORM technology-based ONI imaging to perform comprehensive and quantitative analyses at single EVP resolution.