Research overview
With over 200 cell types that make up the human body, each with a distinct role, there are a lot of possibilities for aberrant cellular function to lead or contribute to disease. One type of cell, the fibroblast, is a major component of the connective tissue that provides structure and support to every organ and aids in its repair in the event of injury. This support occurs via the fibroblasts' ability to transition into an activated state (often referred to as myofibroblasts), where they can secrete a variety of signaling molecules (like growth factors, cytokines, or chemokines) and the non-cellular components of the extracellular matrix (ECM). All of these activities are capable of modulating communication between cells and is essential for development, wound healing, and immune responses. However, when these processes become dysregulated, excessive secretion of the ECM occurs, contributing to fibrotic diseases (e.g. chronic obstructive pulmonary disease, liver fibrosis, pancreatitis, pancreatic cancer, etc.).
Other than transforming growth factor β (TGF-β), which is a major activator of fibroblasts, the ECM also has the ability to alter a fibroblast’s activation state. In fact, when activated fibroblasts are cultured to create their own cell-derived ECMs (CDMs) in vitro, these CDMs can activate naive (i.e. not activated) fibroblasts. CDMs produced from patient-isolated fibroblasts can also maintain the pathological function of the fibroblasts’ activation status at the time of isolation. This is despite lacking all in vivo environmental cues! These data suggest that fibroblasts have a “memory” that is acquired during fibroblast activation and retained thereafter. As the DNA sequence of these cells are not changed during this isolation process, nor also in cancer, it's likely that this "memory" is regulated by epigenetics. Indeed, others have shown that there are large scale chromatin changes during fibroblast activation and small molecule inhibitors affecting epigenetic modifications can alter fibroblast activation and fibrosis. How the ECM activates fibroblasts and contributes to this epigenetic regulation and function, however, is unknown.
Other than transforming growth factor β (TGF-β), which is a major activator of fibroblasts, the ECM also has the ability to alter a fibroblast’s activation state. In fact, when activated fibroblasts are cultured to create their own cell-derived ECMs (CDMs) in vitro, these CDMs can activate naive (i.e. not activated) fibroblasts. CDMs produced from patient-isolated fibroblasts can also maintain the pathological function of the fibroblasts’ activation status at the time of isolation. This is despite lacking all in vivo environmental cues! These data suggest that fibroblasts have a “memory” that is acquired during fibroblast activation and retained thereafter. As the DNA sequence of these cells are not changed during this isolation process, nor also in cancer, it's likely that this "memory" is regulated by epigenetics. Indeed, others have shown that there are large scale chromatin changes during fibroblast activation and small molecule inhibitors affecting epigenetic modifications can alter fibroblast activation and fibrosis. How the ECM activates fibroblasts and contributes to this epigenetic regulation and function, however, is unknown.
What we do
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Our research can be described in the following three major themes; where projects in one theme will learn from and build on our knowledge from the others. Click below to learn more about each theme and the types of questions we aim to answer!
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Working model of how the themes of our research fit together.
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Theme 1: chromatin/transcriptional regulation of fibroblastic cells
Pancreatic cancer is a devastating disease where only ~13% of patients will survive to five years after diagnosis. It is an excellent model for studying fibroblasts as the aggressiveness of this disease is largely mediated by the expansive tumor microenvironment (TME) that includes cancer-associated fibroblasts (CAFs) and the dense ECM they produce.
A recurring theme in pancreatic cancer CAF biology has been the aberrant expression of proteins that regulate fibroblast activation and function. For some, this expression can even be dependent on a pro-tumorigenic ECM. However, how the ECM leads to different gene expression is unknown.
Projects in this theme will work to investigate the interplay between ECM signaling, chromatin remodeling, and transcriptional gene activation. In particular, we aim to answer the questions:
A recurring theme in pancreatic cancer CAF biology has been the aberrant expression of proteins that regulate fibroblast activation and function. For some, this expression can even be dependent on a pro-tumorigenic ECM. However, how the ECM leads to different gene expression is unknown.
Projects in this theme will work to investigate the interplay between ECM signaling, chromatin remodeling, and transcriptional gene activation. In particular, we aim to answer the questions:
- How do fibroblasts maintain a chronic activation status in fibrotic diseases (i.e. fibrosis and cancer) despite lacking in vivo cues?
- How does the chromatin of fibroblastic cells change over the course of fibrotic disease development?
- How are the above questions affected by different ECM components?
We will start our research using pancreatic cancer as a model but will expand to other fibrotic diseases in the future!
Theme 2: Viral manipulation of the extracellular matrix
Our team are pioneers in establishing research into the “viral microenvironment”. Most questions in virology – the study of viruses – work to understand either 1) the intricate details of how viruses enter, reproduce, and exit the cell or 2) how the immune system responds to viral infection. While important, the virus, infected cells, and our immune cells, interact and communicate with many other types of cells and molecules that make up our organs. That means there is so much more to explore!
Projects in this theme work to answer the questions:
Projects in this theme work to answer the questions:
- How do virally infected cells alter the local environment they are in?
- How do changes in the microenvironment resolve or persist after a viral infection is cleared?
- Are changes in the viral microenvironment the same as other initiators of fibrotic diseases?
Initial viruses we are interested in studying are Coxsackieviruses and viruses known to infect the pancreas or fibroblasts.
Theme 3: Non-oncogenic viruses and cancer
It's estimated that approximately 15-20% of all cancers are caused by viruses. Typically, these oncogenic viruses (oncoviruses) contribute to cancer by inhibiting tumor suppressor genes, taking advantage of a weakened immune system, or expressing pro-tumor oncogenes themselves. However this only considers the malignant tumor cells and not the surrounding microenvironment. This is a major gap in our understanding of how viruses contribute to cancer because although viruses have specific cells they infect (i.e. tropism), cells exists within the context of where it lives and what came before it. For example, despite not being an oncogenic virus, people living with HIV have increased incidences of non-AIDS defining cancers over the general population.
Additionally, one avenue of cancer treatment research has focused on using viruses to target and kill cancer cells. These oncolytic viruses have been showing amazing promise, but how these viruses affect more than the cancer cells are incompletely understood.
Projects in this theme work to answer the questions:
Additionally, one avenue of cancer treatment research has focused on using viruses to target and kill cancer cells. These oncolytic viruses have been showing amazing promise, but how these viruses affect more than the cancer cells are incompletely understood.
Projects in this theme work to answer the questions:
- How do non-oncogenic viral infections affect cancer formation and metastasis?
- How do anti-viral treatments alter the microenvironment?
- What is the impact of oncolytic viruses on the surrounding microenvironment?
How we do it
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In vitro cell culturing and ECM generation
Schematic of CDM production.
Illustration by Jaye Gardiner
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Live and fixed cell microscopy
Immunofluorescent image of fibronectin in a CDM, analyzed for fiber alignment (more colors = less aligned)
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Molecular biology and sequencing
Chromatin and modifications illustration taken from bpsbioscience.com
NGS workflow image taken from microbenotes.com
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The bread and butter of what we do revolves around cellular and molecular biology techniques (including cell culture, CRISPR gene editing, cloning, etc.), next generation sequencing approaches, and live and fixed cell microscopy because seeing is believing! To round out a project, we validate the relevance of our in vitro work in animal disease models.
Why we do it
Fibrosis, the excessive accumulation of extracellular matrix (ECM) fibers, can affect nearly every organ of the body. Although recent research is starting to understand the conditions that allow for the resolution of fibrosis, most fibrotic conditions remain unresolved and leads to organ failure or a predisposition to cancer.
In highly fibrotic cancers, like pancreatic ductal adenocarcinoma (one type of pancreatic cancer), the fibrosis is so intense that it collapses blood vessels and interferes with drug delivery. And at such a low survival rate, we desperately need to better understand the basic biology so we can find better therapeutic targets.
In highly fibrotic cancers, like pancreatic ductal adenocarcinoma (one type of pancreatic cancer), the fibrosis is so intense that it collapses blood vessels and interferes with drug delivery. And at such a low survival rate, we desperately need to better understand the basic biology so we can find better therapeutic targets.
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We do this research both to fuel our natural curiosity of how diseases work and to honor the people in our lives affected by these diseases.
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We've been fortunate to receive generous funding and support from:
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