Finding new insights into cancer metastasis: Linking cell migration to metabolic energy flux

Lead Research Organisation: University of Glasgow
Department Name: College of Medical, Veterinary &Life Sci

Abstract

The vast majority of deaths due to cancer are caused by recurrence or spread around the body, termed as metastasis. Surgery and chemotherapy can often be used to remove a primary tumour, but if cancer spreads to other parts of the body, treatment options are more limited. Cells move out of the primary tumour when nutrients are scarce and this is how they spread around the body. Pancreatic cancer is one of the worst types of cancer for metastasis and recurrence and only limited treatments are currently available. Our aim is to use pancreatic cancer cells to discover new ways to target this disease and stop it spreading.

Tumours typically grow rapidly and consume a large amount of energy to fuel this growth. Consequently, tumour cells have adapted ways to produce more energy and obtain alternative food sources to normal cells. To identify metabolic regulators that were tightly coupled with cell shape and cytoskeletal organisation, we performed a high content imaging based siRNA screen against 494 genes known to be metabolic regulators. Two mouse KPC PDAC cell lines (A and B, both KRasG12D and p53R172H) were independently screened to maximise reliability. We identified the top 10% of hits consistent between the two cell lines showing abnormal shape and impaired in migration but not growth rate, suggesting multiple pathways connecting migration and metabolism. Our screen has uncovered two main functional categories connecting migration to metabolism- mitochondrial (OXPHOS) related (Group 1) or glycolytic related (Group 2).

In this project, we will focu on those two main classes of hits and perform cell biological analysis on the candidates to determine the mechanisms by which they affect energy production/consumption and cell migration. Our experiments will focus on how cells couple energy production and nutrient uptake with migration and invasion. Our goal is to identify 1-2 key pathways connecting these processes that could be targetted in vivo in the future to develop new therapeutic angles against pancreatic ductal adenocarcinoma.

The outcomes that we expect from this project include:
Uncovering key molecular pathways regulating the coupling between mitochondrial energy production and cell migration and invasion.
Developing a coherent model for how the actin cytoskeleton scaffolds the vacuolar V-ATPase and glycolytic enzymes to regulate the pH balance when cells are glycolytic.
Understanding how integrin trafficking couples with V-ATPase trafficking to regulate tumour cell invasion and maintenence of pH homeostasis by mechanosensing.
Modeling how these genes affect invasion into a reconstituted tumour environment, simulating the process of cancer cells migrating out from the primary tumour.
Determination of which key aspects of cell migration regulate energy production and consumption so that these can be therapeutically targetted, first for pancreatic cancer, and then for other cancers that also spread through metastasis.

Technical Summary

Pancreatic cancer has less than a 5% 5-year survival rate and this figure hasn't improved in decades. Mutation of the KRas oncogene occurs in almost all pancreatic ductal adenocarcinomas (PDAC) and drives metabolic reprogramming. Our aim in this proposal is to link this metabolic programming with the enhanced migratory and metastatic state of PDAC to find new therapeutic targets. We screened 494 metabolic regulatory genes in a bespoke library of siRNA using high content confocal imaging to identify metabolic regulators of cell shape and migration. Out of 22 hits selected for shape and migration speed alterations with minimal effects on proliferation, 2 classes of hits emerged. This project aims to characterise the top hits from these 2 classes to reveal new targets linking metabolism to cell migration.
Class 1: Mitochondrial regulatory genes modulating oxidative phosphorylation driven ATP-production to fuel motility
Class 2: Glycolysis regulators which connect trafficking of integrins to nutrient receptors and glycolytic enzymes
Our aim in this 2-year project is to use cell biological and biochemical methods to identify 1-2 key pathways linking metabolic control to migration as candidates for anti-metastatic therapy. Future studies will take the top hits in vivo to test their clinical potential.

Planned Impact

Pancreatic cancer has a very poor overall 5-year survival rate (5% or less) and this has not improved in decades. It is a cancer where urgent studies are needed to develop new targets and strategies for therapy. Pancreatic cancer is highly metastatic and often spreads to distant sites in the body, such as the liver and abdominal cavity. Cancer spread, or metastasis, causes many of the problems associated with this disease. Our aim is to study how the tumour grows and gains nutrients from the environment and how this process links to cancer spread.

Tumours often grow at a high rate and the tumour cells have to seek additional energy sources to survive, as they do not receive a sufficient supply of blood from the body. Pancreatic tumours are frequently very stiff and full of fibers that restrict the flow of blood and nutrients. While this may seem beneficial as it can keep the tumour contained, it can also result in the tumours being more aggressive, as they seek to fuel their growth and are thus motivated to migrate away from the site of the primary tumour and gain access to the bloodstream to grow elsewhere in the body. Our work aims to understand how the need for more nutrients motivates the cancer cells to leave the primary tumour and migrate toward blood vessels. This work will allow us to identify new ways of stopping cancer cells from moving and provide insight for development of new therapies to prevent metastasis.

We have performed a screen for genes involved in cancer cell nutrition and survival that also affect how the cells move. Our screen used pancreatic cancer cells and high resolution microscopic imaging to pick out effects of perturbing individual genes on cell shape. Out of over 490 genes screened, we identified 22 that affect both nutrition and movement and this grant aims to charcterise these further to select the top 2-5 candidates for study as possible therapeutic targets to develop new medicines.

Cell movement requires energy and just like exercise makes people hungry, cells require "food" as fuel for movement. We will identify which genes control how pancreatic cancer cells use energy to fuel their movement so that we can target these genes and try to stop the cells from moving away from the primary tumour or kill them as they try to move away.

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