Periodic Reporting for period 4 - DiSect (The Tumour Stroma as a Driver of Clonal Selection)
Reporting period: 2022-12-01 to 2024-05-31
Cancer develops within the context of a complex microenvironment. Here, mutated cancer cells form an eco-system with other non-mutated ‘host’ cells, such as cells from the immune system, stromal fibroblasts and vascular structures. Importantly, mutated cancer cells engage ‘host’ cells to support the developing cancer. This phenomenon is particular prominent in pancreatic ductal adenocarcinoma (the most common form of pancreatic cancer), where non-cancer cells make up 85% of the tumour on average. Several pro-tumorigenic functions have been ascribed to coerced host cells, including the delivery of nutrients, avoidance of immune recognition, and survival signals to overcome therapy. However, recent data has revealed that non-mutated ‘host’ cells can also restricted tumour development, where non-selected targeting of ‘host’ cells invertedly has accelerated tumour development and metastasis. Therefore, understanding how different types of ‘host’ cells function to promote and restrict tumour development is important to future development of therapies against the complex microenvironment of the tumour.
A critical part of determining how the microenvironment may both prevent and support tumour development in the pancreas includes understanding the role of ‘host’ cells in both the normal pancreas and in early stages of tumour development. The majority of pancreatic ductal adenocarcinoma arise from small clusters of cells, which all have mutations in the main oncogenic driver KRAS. Importantly, while there are early signs of ‘host’ cell deregulation already at these early stages, its is not clear how early stages of tumour cells modify these cells to bypass restrictive functions and conscript ‘host’ cells to support tumour development. Determining these interactions may be important for early detection and improved therapy.
A critical part of determining how the microenvironment may both prevent and support tumour development in the pancreas includes understanding the role of ‘host’ cells in both the normal pancreas and in early stages of tumour development. The majority of pancreatic ductal adenocarcinoma arise from small clusters of cells, which all have mutations in the main oncogenic driver KRAS. Importantly, while there are early signs of ‘host’ cell deregulation already at these early stages, its is not clear how early stages of tumour cells modify these cells to bypass restrictive functions and conscript ‘host’ cells to support tumour development. Determining these interactions may be important for early detection and improved therapy.
This project has focussed on delineating how pancreatic tumour cells interact with non-mutated host cells and how these interactions ultimately regulate tumour development and tumour cell function. At the outset of this proposal I hypothesised that interactions between tumour cells and cells in the microenvironment may promote tumour development.
Throughout this project we have 1) developed, benchmarked and validated new models to study interactions between tumour and host cells; 2) mapped the composition of the tumour microenvironment in both primary and metastatic tumours and identification and characterisation of a novel bona-fide tumour suppressive ‘host’ cell population; and 3) Mapped novel signalling interactions between tumour cells and cells in the host microenvironment.
1) Technological advances have enabled isolation and expansion of epithelial pancreatic cells in vitro (outside the body), known as organoids. This, in turn has provided ability for isolation and expansion of human patient samples for in vitro testing of novel therapies and for development of novel models through genetical engineering. This this project we have made significant advances in both areas.:
Firstly, we have used genetic engineering to develop a series of models with specific genetic alterations which are being used to understand how individual genes in isolation and in combination are important for the establishment of a tumour favourable microenvironment. This model has allowed us to work systematically in defining key signals and receptors that control early stages of pancreatic cancer development.
Secondly, we have developed a novel, fully controllable, in vitro model of pancreatic cancer and host cells. While the microenvironment is undeniably an important player in controlling tumour development and therapeutic response in patients, current models poorly reflect this complexity. Together with collaborators at MIT and University of Manchester, we have interrogated how tumour cells interact with and depend on signals from the tissue scaffold (extracellular matrix) and used this to develop a model that now allows us to grow host cells with tumour cells to delineate how these interactions develop to, hopefully, reveal new targets for therapies (Below et al, Chastney et al, Gough et al, Humphries et al).
2) Improved understanding of the host microenvironment depends on firstly mapping out and cataloguing components, after which functional interrogation becomes essential for future therapeutic development. Using high-dimensional analysis by mass cytometry we mapped the cellular constituency in primary tumours of pancreatic cancer and subsequently compared these interactions across primary and metastatic sites (Hutton et al, Blanco-Gomez in prep). A major novel observation from these studies was the identification of a novel, tumour suppressive fibroblast ‘host’ population. These cells are present in all normal, primary and metastatic tumours analysed thus far. Functional analysis suggests that the tumour suppressive fibroblast population may be a lineage and have fixed characteristics. Future analyses will be critical to unravel how these host cells may be used to improve therapies.
3) Emerging tumours induce a local microenvironment pliable to tumour progression, which over time also enable rapid adaptation to therapies and metastasis. Defining the identify and effects of the tumour cell signals that drive this reaction and in turn revealing which ‘host’ cell populations mediate these effects are important for future intervention strategies. Using in vitro models we have studied how tumour cell heterogeneity underpins diversity of heterocellular interactions and how these interactions engage distinct but clone selective tumour cell signals (McCarthy et al under review). Moreover, some of these cellular interactions form metabolic support network opening up a novel approach of disrupting tumours dependencies (Halbrook et al). We have also described a novel signalling circuitry which is driven by tumour cells but depends on subsequent interactions between fibroblasts and immune suppressive myeloid cells, to drive tumour growth and metastasis (Lee, Hogg et al). These studies continue to be important in defining specific heterocellular interaction networks that control tumour development, metastasis and response.
Throughout this project we have 1) developed, benchmarked and validated new models to study interactions between tumour and host cells; 2) mapped the composition of the tumour microenvironment in both primary and metastatic tumours and identification and characterisation of a novel bona-fide tumour suppressive ‘host’ cell population; and 3) Mapped novel signalling interactions between tumour cells and cells in the host microenvironment.
1) Technological advances have enabled isolation and expansion of epithelial pancreatic cells in vitro (outside the body), known as organoids. This, in turn has provided ability for isolation and expansion of human patient samples for in vitro testing of novel therapies and for development of novel models through genetical engineering. This this project we have made significant advances in both areas.:
Firstly, we have used genetic engineering to develop a series of models with specific genetic alterations which are being used to understand how individual genes in isolation and in combination are important for the establishment of a tumour favourable microenvironment. This model has allowed us to work systematically in defining key signals and receptors that control early stages of pancreatic cancer development.
Secondly, we have developed a novel, fully controllable, in vitro model of pancreatic cancer and host cells. While the microenvironment is undeniably an important player in controlling tumour development and therapeutic response in patients, current models poorly reflect this complexity. Together with collaborators at MIT and University of Manchester, we have interrogated how tumour cells interact with and depend on signals from the tissue scaffold (extracellular matrix) and used this to develop a model that now allows us to grow host cells with tumour cells to delineate how these interactions develop to, hopefully, reveal new targets for therapies (Below et al, Chastney et al, Gough et al, Humphries et al).
2) Improved understanding of the host microenvironment depends on firstly mapping out and cataloguing components, after which functional interrogation becomes essential for future therapeutic development. Using high-dimensional analysis by mass cytometry we mapped the cellular constituency in primary tumours of pancreatic cancer and subsequently compared these interactions across primary and metastatic sites (Hutton et al, Blanco-Gomez in prep). A major novel observation from these studies was the identification of a novel, tumour suppressive fibroblast ‘host’ population. These cells are present in all normal, primary and metastatic tumours analysed thus far. Functional analysis suggests that the tumour suppressive fibroblast population may be a lineage and have fixed characteristics. Future analyses will be critical to unravel how these host cells may be used to improve therapies.
3) Emerging tumours induce a local microenvironment pliable to tumour progression, which over time also enable rapid adaptation to therapies and metastasis. Defining the identify and effects of the tumour cell signals that drive this reaction and in turn revealing which ‘host’ cell populations mediate these effects are important for future intervention strategies. Using in vitro models we have studied how tumour cell heterogeneity underpins diversity of heterocellular interactions and how these interactions engage distinct but clone selective tumour cell signals (McCarthy et al under review). Moreover, some of these cellular interactions form metabolic support network opening up a novel approach of disrupting tumours dependencies (Halbrook et al). We have also described a novel signalling circuitry which is driven by tumour cells but depends on subsequent interactions between fibroblasts and immune suppressive myeloid cells, to drive tumour growth and metastasis (Lee, Hogg et al). These studies continue to be important in defining specific heterocellular interaction networks that control tumour development, metastasis and response.
This project has made progress beyond state of the art in following key areas:
Firstly, we have provided a quantitative map of host cells of primary and metastatic cancers. On contrast to other approaches, we have deployed antibody based methodologies, which enables isolation and functional characterisation of cell populations of interest. This has been made freely available to support other research groups to pursue host cell characterisation within tissues and models of their interest
We also described a bona fide tumour suppressive fibroblast population. This is the first time such a population has been described and therefore our studies have opened up a new area within the field and challenged consensus. Future studies are now undergoing to determine mechanisms.
We developed and bench marked a novel 3D model of tumour cells in co-culture with host fibroblasts and immune cells. The model replicates salient features of the microenvironment including an extracellular matrix specifically derived from tumour and host cells, control of stiffness and induction of relevant host cell phenotypes. This model therefore offers new pre-clinical modelling opportunities.
Firstly, we have provided a quantitative map of host cells of primary and metastatic cancers. On contrast to other approaches, we have deployed antibody based methodologies, which enables isolation and functional characterisation of cell populations of interest. This has been made freely available to support other research groups to pursue host cell characterisation within tissues and models of their interest
We also described a bona fide tumour suppressive fibroblast population. This is the first time such a population has been described and therefore our studies have opened up a new area within the field and challenged consensus. Future studies are now undergoing to determine mechanisms.
We developed and bench marked a novel 3D model of tumour cells in co-culture with host fibroblasts and immune cells. The model replicates salient features of the microenvironment including an extracellular matrix specifically derived from tumour and host cells, control of stiffness and induction of relevant host cell phenotypes. This model therefore offers new pre-clinical modelling opportunities.