Identification of novel melanoma biomarkers using exosomes

Overview

Tumour cells excrete exosomes, membrane vesicles (30-150 nm diameter) that encapsulate and transport proteins, metabolites and genetic material. They mediate intercellular communication within the tumor microenvironment, metastasis formation via circulation, and development of drug resistance. Circulating tumor-derived exosomes can be isolated from blood patients as a non-invasive liquid biopsy.

The chemical composition and overall properties of the exosomal membranes are expected to be similar to those of parent cell membranes and to modulate blood circulation time, and uptake and targeting of other cells. Nevertheless, the lipid composition and biophysical properties of exosomes released by metastatic melanoma is poorly characterised and have not been explored as biomarkers. Based on our preliminary lipidome studies of melanoma cells, we hypothesise that the lipid composition of exosomes released by melanoma cells is distinct from those released from healthy melanocyte cells, and can be used as complementary biomarkers to follow disease progression.

Aims

The overall goal of this project is to identify biomarkers for disease stage and acquired drug-resistance by characterizing the lipid membrane composition and properties of exosomes excreted by melanoma cells. This will be achieved by: 1) isolation of exosomes from non-cancerous melanocytes, from melanoma cells at distinct disease stages (including non-metastatic and metastatic cells) and from melanoma cells with acquired drug-resistance; 2) characterisation of exosomes lipid diversity (i.e. lipid classes and fatty acid chains) using mass spectrometry; 3) characterisation of biophysical properties of exosomes using fluorescence spectroscopy and microscopy.

Approaches, skills and techniques

Students will develop ability to:

• grow mammalian cells in tissue culture room;
• isolate and characterise exosomes from cultured cells;
• prepare membrane extracts;
• use fluorescence spectroscopy to characterise cell membrane properties;
• use fluorescence microscopy to monitor cell membrane properties;
• use mass spectrometry to identify lipids;

The student will be working in a multidisciplinary research team that works at interface of biology/chemistry/biophysics focused on developing and characterising the mode of action of peptide therapeutics to target cancer membranes and intracellular proteins involved in cancer progression.

Outcomes

This project will be a proof-of-concept study. The student conducting this work will be participating in a larger project focused on using cancer cell membranes as therapeutic targets and biomarkers. Exosomes have been explored as biomarkers and as tool to examine tumor progression, but researchers have been focused on their RNA, DNA and proteins. Not much is known about their lipid membrane composition and their involvement on metastasis formation. We propose that exosomes secreted by tumour cells can be identified via their membrane composition, and when analysed in combination with already recognised markers they can provide information on the disease stage.

Required skills and experience

The student should have quantitative skills and a keen interest in cell biology, biochemistry and biophysics.

Keywords

• cell membrane
• membrane biophysics
• cancer biomarkers
• cancer targets
• exosomes
• lipidomics

Contact

For more information, contact Dr Sonia Henriques.