Unravelling c-Met signalling from autophagic endomembranes

Our body is composed of billions of cells. These cells are constantly exchanging information in the form of signals, which is crucial for them to act in a coordinated fashion. These signals can induce cell multiplication, movement, and cell death. This communication is often initiated by the interaction of two proteins: a ligand and a receptor. Ligands bind to the receptors, which are normally present at the surface of cells, to transmit signals from outside the cell. The receptors then activate additional proteins, called signal transducers, to transmit the signals to the inside of the cell, where they are interpreted and alter the cell's behaviour. Cells must tightly control the activity of these receptors because deregulated receptor activity can lead to diseases, such as chronic inflammation or cancer. Thus, there is a need to better understand how receptors operate so that they can be corrected when they go wrong.

A cell is like a town, and each building block in a cell has a role. Autophagy is one of these blocks; it is like a household waste recycling centre: cell waste are sent to autophagic sites to be destroyed and recycled. Surprisingly we recently find out that in cancer cells, these recycling centre were hijacked for some "illegal activities": we have found that receptors responsible for cancer go there not to be degraded but on the contrary to be even more active. This new scientific concept changes our understanding of how receptors operate. It opens new challenges to understand how receptors transmit information to signal transducers inside the cell, and why receptor activity on autophagic sites, as opposed to activity at the cell surface, is required to modulate cell behaviour.

We propose investigating this concept using one receptor model, c-Met. This receptor plays a major role in controlling cell growth, cell survival and cell movement, thus contributing to proper organ function and renewal. It is also deregulated in diseases such as chronic inflammation and cancer and therefore need to be targeted in these conditions. We aim to fully understand the mechanisms necessary for c-Met to transmit signals from autophagic sites. To achieve our objectives we will use state of the art cell biology, imaging and biochemistry techniques. In particular, we will use a novel technique that allows the capturing of all the partners of c-Met that are present on autophagic sites.

Our work will lead to the discovery of novel molecular mechanisms controlling receptor activity. Our results should benefit researchers working on receptors, signal transducers, cell growth, cell survival and cell movement, both within the UK and internationally. Since autophagic c-Met activity accounts for the aggressiveness of certain tumours, our research could also benefit researchers working on cancer. Furthermore, given that c-Met is necessary for proper organ function and renewal, our results may have an impact in the fields of regenerative medicine and ageing. Thus the beneficiaries of this research include pharmaceutical companies, the public health domain (NHS) and patients.

The receptor tyrosine kinase c-Met, implicated in cancer and chronic inflammation, signals on endosomes, enhancing cell migration, growth and malignant transformation.

We have discovered that c-Met traffics and signals from autophagic related endomembranes, ARE, leading to enhanced cell viability in anchorage independent conditions.

We hypothesize that autophagy, considered conduit for degradation only, also has a signalling role, which may be targeted in diseases such as cancer. Moreover, this signalling occurs on novel non-canonical autophagy endomembranes, poorly characterized.

We aim to understand the signalling of c-Met on non-canonical autophagy endomembranes.

Using state-of-the-art cell biology and microscopy, we will characterise the ARE and the role of non-canonical autophagy on c-Met trafficking and signalling. Using a recently described approach of proximal proteomic mapping in live cells by engineered ascorbic peroxidase, APEX, we will determine the molecular partners of c-Met trafficking and signalling on ARE. We will assess the physiological and pathological relevance of c-Met signalling on ARE.

This project will be performed using panels of normal and cancer cell lines modified by CRISPR technology, with impaired canonical or impaired non-canonical autophagy.

Shedding light and further the understanding of a totally novel function of autophagy (signalling) will have major impacts in cell biology. Moreover, a new physiological role of a recently discovered non-canonical autophagy pathway will be uncovered. This project could lead to the development of strategies to reduce or enhance c-Met signalling and more generally of other receptors. The relevance of our results will be applied to cancer in the view of finding new targets. Our results will have larger implications as autophagy and RTK signalling both play major roles in numerous physiological and pathological processes.

We aim to understand the mechanisms of c-Met compartmental signalling and how it impacts on cell cell survival and cell migration. c-Met and its ligand, HGF, are essential genes, as c-Met/HGF knock out mice die in utero. c-Met is often overexpressed or mutated in cancer, where it is associated with a poor prognosis, and associated with tissue regeneration (e.g. wound healing in the liver and lung repair in COPD, Chronic obstructive pulmonary disease).

Our research demonstrating c-Met signalling from autophagy endomembranes could lead to evidence for a role of c-Met in ageing, due to the research currently linking autophagy with ageing.

Research into c-Met/HGF biology addresses issues of fundamental importance to cell and developmental biology and impacts clinically significant issues such as tumour growth and metastasis. Many efforts are directed towards the development of inhibitors of c-Met/HGF. Several inhibitors are currently undergoing testing in clinical trials, but like many other RTK inhibitors, may give disappointing results. Alternatives are urgently required. We have evidence that endocytosis inhibition leads to a reduction of c-Met dependent tumour growth and metastasis and can overcome resistance to c-Met specific inhibition (Joffre, Nat. Cell. Biol 2011).

Using a systems biology approach, through proximal proteomics (APEX), we hope to unravel global c-Met partners on autophagy endomembranes and the importance of c-Met localisation in regulating this signalling. Pharmaceutical companies may benefit from our research, as it may lead to novel ways to target the c-Met pathway in human disease.

This project will also provide a new zebrafish embryo model for observing c-Met's role in cell migration and the ability to test pharmaceutical agents on a large scale and without the need for mice, thus fulfilling the requirement for the 3Rs. The publication of this study and awareness of it within the scientific community will help to increase animal welfare standards, reduce the costs to research and provide value to the pharmaceutical industry.

Diseases, including cancer and chronic inflammatory diseases such as COPD, are a huge cost for the NHS, and therefore novel treatments, such as drugs targeting c-Met, may be of huge benefit. Over 10 years, this study has the potential to enhance the global economy and economic competitiveness of the UK, by leading to new therapies, and to enhance the quality of life of people suffering from ageing related diseases, inflammatory diseases, and cancer.

Our research will also benefit the scientific research community by increasing the general scientific knowledge of the novel mode of receptor signalling that is compartmental signalling and moreover signalling on autophagy endomembranes. Through using one important receptor as a model, our research will not only provide mechanisms for this receptor but could provide proof of principle for others.

The researchers will gain a wide range of practical laboratory skills, both in vitro and in vivo, and professional skills, such as presentation of data to the scientific and wider community, management and collaboration, which will immediately benefit them in their careers.

Beneficiaries also include the wider public, as I regularly present my work at fundraisers for cancer research charities. I also actively participate in an outreach programme to local communities and schools, raising awareness of the work performed at Barts Cancer Institute. It also helps to inspire young people to become scientists, potentially having wide spread benefits to individuals and the UK economy within the next 10-15 years.