Penn Pancreatic Cancer Research Center

FOXP3 CD8 immune cells in mouse spleen - Captured by Andrew Rech (Vonderheide Lab)

Basic/Translational Research

Basic/Translational Researchers

Gregory L. Beatty, MD, PhD

Dr. Beatty's laboratory incorporates both basic science research and clinical investigation to examine the role of innate immunity, in particular monocyte/macrophages, in regulating tumor biology and T cell immune privilege in pancreatic ductal adenocarcinoma (PDAC). Monocytes/macrophages are continually recruited to PDAC lesions and most often support tumor growth, invasion and metastasis, whereas effector T cells are rarely observed to infiltrate tumors. The exclusion of T cells from PDAC remains a critical barrier to the successful translation of novel immunotherapies for this disease. The Beatty laboratory is employing genetic mouse models of PDAC in combination with early phase clinical trials (including adoptive cellular therapy and novel immunomodulatory drugs) to understand mechanisms that 1) determine pro- versus anti-tumor activity of myeloid cells recruited to primary and metastatic lesions and 2) regulate T cell exclusion from tumor tissue. The overall goal is to develop novel immune-based strategies that harness the anti-tumor potential of both myeloid and T cells to treat patients with PDAC.

Donita C. Brady, Ph.D.

The research interests of the Brady laboratory lie at the intersection of cancer biology, signal transduction,and transition metal homeostasis. Our lab seeks to define kinase signal transduction pathways downstreamof oncogenes that are allosterically modulated by transitional metals. Findings from these studies have thepotential to be leveraged as a means to perturb metal availability to essential kinase signaling cascades intumors. Namely, despite diverse risk factors, comprehensive whole exome sequencing has revealed that~95% of PDAC patients can be genetically characterized by a signature genetic event in which the smallGTPase KRAS is mutated to remain in an active oncogenic state. However, no effective anti-RAS therapieshave transitioned into the clinic for PDAC despite the ubiquity of KRAS mutations. Thus, the identificationof novel molecularly targetable vulnerabilities driven by oncogenic KRAS that contribute to PDAC is criticalfor combatting this disease. Many groups have demonstrated the mechanisms through which oncogenicKRAS-mediated metabolic reprogramming sustains unrestricted tumor growth, survival, and therapeuticresistance. One potent mechanism engaged by oncogenic KRAS is the constitutive induction of autophagy,which salvages building blocks for macromolecular biosynthesis and bioenergetics that are scarce due tothe nutrient- and oxygen-poor tumor microenvironment of PDAC.

Molecularly the ability of cells to initiate autophagy is governed by kinase signaling networks that senseamino acid deprivation and low cellular ATP levels. Work by our group and others is beginning to uncovernovel functions for copper (Cu) as a non-structural intracellular mediator of signaling in the context of normalphysiology as well as the pathophysiology of diseases such as cancer. Preliminary studies from our labfound that the autophagy regulatory kinases, ULK1 and ULK2, bind to Cu and that Cu chelators can inhibitULK1 and ULK2 kinase activity. Moreover, decreasing Cu influx reduces basal and nutrient deprivedautophagy induction and decreases ULK1 and ULK2 activity. Thus, the goal of our research this is to buildon these promising preliminary data to: a) elucidate the contribution of Cu to autophagy induction throughdirect regulation of the ULK1 and ULK2 kinases and b) determine whether this unique signaling paradigmcan be exploited therapeutically via Cu reducing drugs to treat KRAS-driven PDAC.

Erica L. Carpenter, MBA, PhD

The Circulating Tumor Material (CTM) Laboratory, led by Director Dr. Erica Carpenter, focuses on the identification, capture, and analysis of Circulating Tumor Cells (CTCs), Disseminated Tumor Cells (DTCs), cell-free DNA (cfDNA), and exosomes from cancer patients, including those with pancreatic cancer. Blood, bone marrow, pleural effusions, and other non-invasively captured patient samples are used to detect biomarkers which allow: 1) early detection of disease as well as post-therapy monitoring of minimal residual disease, 2) an efficient means of determining clinical and biological response to therapy and, thus, clinical decision making, and, 3) cancer genetic phenotyping to drive personalized medicine that obviates the need for serial biopsies in a population of patients for which these procedures are difficult, risky, and insufficient.

The focus of the CTM Laboratory is driven by the needs of clinicians and translational investigators, and realized through collaborative work with investigators in the Penn School of Medicine, the Penn School of Engineering, and the Center for Personalized Diagnostics. Moreover, when it is determined that outsourcing of technology development is preferable, collaborative efforts with industry partners are actively sought, and these efforts have already been initiated in focused areas. In the case of pancreatic cancer, Dr. Carpenter’s lab focuses on studying early stages of human pancreatic cancer and cancer progression in collaboration with academic and industry partners.

Ellen Puré, PhD

Cancer is a manifestation of loss of tumor suppressor mechanisms and gain of oncogenic mechanisms both intrinsic to the cells that undergo malignant transformation as well as extrinsic mechanisms mediated by local or systemic non-transformed cells that define the tumor microenvironment and ecosystem. Extrinsic factors associated with chronic inflammation and fibrosis can drive tumorigenesis with obesity, ageing, smoking, and chronic pancreatitis associated with increased risk of developing pancreatic cancer. Furthermore, malignant cells can drive the co-evolution of inflammatory, fibrotic and vascular responses in tumors as well as matrix remodeling that in turn regulate malignant cell behavior. Pancreatic cancer is associated with a particularly robust desmoplastic response and thus characterized by the prevalence of stromal cells and remarkable accumulation of matrix-associated proteins, proteoglycans and glycoaminoglycans that account for a significant portion of tumor mass in pancreatic ductal adenocarcinomas (PDAs). Impact of stromal cells and matrix are complex and change dynamically during tumor progression. Their net pro-tumorigenic effect derives from the biochemical and biomechanical signals they induce in malignant cells, their pro-inflammatory behavior, their function in suppressing anti-tumor immunity, and their ability to confer resistance to therapy through multiple mechanisms. Importantly, the microenvironment of, and the systemic response to, primary tumors play essential roles in the colonization and growth of metastatic tumors in distal organs, the most common cause of pancreatic cancer associated mortality.

Dr. Puré and her colleagues are defining the cellular and molecular basis of the anti-tumorigenic properties of the normal healthy pancreas and the pro-tumorigenic alterations associated with ageing and obesity and the initiation and progression of pancreatic cancer. They have defined phenotypic and functional heterogeneity amongst pancreatic stromal cells that explain the potential for stroma to have opposing effects on tumor progression, and identified stromal cells required for the desmoplastic response and vascularization of PDA. They are investigating stroma-dependent pro-inflammatory mechanisms and the mechanisms by which stroma exerts its suppressive effects on anti-tumor immunity. Based on their findings, they are developing stroma-targeted approaches to complement malignant cell-targeted modalities for the treatment of PDA.

 

M. Celeste Simon, PhD

Dr. Simon’s laboratory studies responses to changes in oxygen (O2) availability, and their impact on development, physiology, and disease, with a particular emphasis on certain forms of cancer. It has long been appreciated that pancreatic cancer, a highly desmoplastic malignancy, exhibits unusually dysfunctional blood vessels, and a significant number of reactive fibroblasts, lymphocytes, and inflammatory cells (e.g. macrophages). As such, these tumors are frequently severely O2 limited (“hypoxic”), a condition that usually correlates with more aggressive cases. The Simon laboratory is employing its genetic tools to disrupt O2 sensing pathways, including those regulated by hypoxia inducible factors (HIFs), to define the impact of O2/nutrient deprivation on pancreatic cancer metabolism, inflammation, and metastasis. Moreover, pancreatitis predisposes individuals to developing pancreatic ductal adenocarcinoma (PDAC), possibly because pancreatitis also results in vascular injury and hypoxia. Dr. Simon and her team are currently discerning whether hypoxia provides a mechanistic link between acute and/or chronic pancreatitis and the likelihood of pancreatic cancer initiation. The overall goal is to develop novel therapeutics to combat both pancreatitis and PDAC, based on inhibition of a variety of O2 sensitive processes.

 

Ben Z. Stanger, MD, PhD

The Stanger laboratory relies on a mouse model of pancreatic cancer in which the animals predictably develop tumors that closely resemble human pancreatic tumors. The model – originally created at Penn and the most widely used model of pancreatic cancer progression – incorporates mutations in the Kras and p53 oncogenes, two of the “signature” mutations of pancreatic cancer. Through genetic engineering, the Stanger laboratory has introduced a gene encoding Yellow Fluorescent Protein (YFP) into the genome of the cancer prone mice, a so-called “lineage tracer” which makes the pancreatic cells turn green as the tumor is developing. Microscopes and other instruments that are capable of detecting these fluorescent cells permits them to be tracked as they acquire more malignant features and spread to distant organs (“metastasis”). Using this platform, the laboratory has made several important discoveries regarding pancreatic cancer progression and metastasis. First, pancreatic epithelial cells undergo a shift to a more motile and invasive cell type through a process known as epithelial-to-mesenchymal transition (EMT), observable with the help of the lineage tracer. Second, pancreatic cells leave the pancreas and enter the circulation at a very early time-point in tumor progression, at the PanIN stage, before cancer is detectable to a pathologist. This observation is consistent with the clinical observation that most pancreatic cancer patients already have distant metastases at the time of detection. Third, the myofibroblast stroma – a non-cancerous cellular component of a tumor – slows rather than accelerates tumor growth, as its elimination led to faster growing tumors. Again, this finding is consistent with the results of clinical trials using hedgehog inhibitors, which deplete the myofibroblast stroma but unfortunately led to a worse clinical outcome.

The lab’s ongoing studies concern molecular mechanisms of invasion and metastasis. In one project, we are identifying the mechanisms of EMT in this model, providing the first molecular insights into this cellular shift in the context of a naturally progressing tumor. Another project is concerned with the cellular and molecular determinants of metastasis. We have found that the tumors which arise in the mouse model vary with respect to their ability to spread, and we hope to identify the genes that enable spread so that they may be targeted. Another collaborative project seeks to identify material circulating in the blood (cells, DNA or small vesicles) that could be used as a diagnostic test for incipient pancreatic cancer. This project employs mouse samples but insights will be rapidly translated to human specimens. Finally, we are engaged in a number of preclinical trials in collaboration with academic and industry partners to test promising compounds for the treatment of pancreatic cancer that have clinical potential.

Robert H. Vonderheide, MD, DPhil

Pancreatic cancer is well known for its very poor prognosis, a situation that this Center is dedicated to changing. The disease is highly refractory to standard therapy, especially for patients who present with metastatic disease. Unfortunately, the “statistics” are getting worse. Pancreatic cancer is one of only two cancers among 21 histotypes for which the death rate in the United States rose from 1990 to 2008 (the other is liver/intrahepatic bile duct cancer). Pancreatic cancer is likely to become the second leading cause of cancer-related death in the United States by 2020 (behind lung cancer, which is declining). Although new combination chemotherapies are able to stabilize many patients who present with metastatic pancreatic cancer (representing a major clinical advance), response rates remain <35%, and patients with long-term complete remissions after treatment with these therapies are rare.

In the context of this unmet clinical need, genetically engineered murine models of pancreatic neoplasia have become an increasingly important tool for us to use to garner biological insights that might lead to novel therapeutic strategies. Based largely on the selective expression of oncogenic Kras in the pancreas of immune-competent hosts, these models reproduce key biological aspects of the human disease, including its highly desmoplastic and inflammatory tumor microenvironment. These models offer the opportunity to uncover novel “non-tumor cell-autonomous” therapeutic targets in the tumor stroma, which can be tested for efficacy in tumor-bearing mice prior to translation to the clinic. Because pathology in these models advances from pre-invasive disease to invasive disease, agents that prevent or reverse the earliest neoplastic events can also be explored.

The Vonderheide Laboratory is particularly focused on finding new immune therapies for pancreatic cancer. In this form of cancer, a massive infiltration of immunosuppressive leukocytes into the tumor stroma is an early and consistent event in oncogenesis. In our mouse models, intratumoral effector T cells are rare, as they are in the majority of patients with pancreatic cancer. This pathophysiology is in contrast to many other solid tumors for which infiltration of effector T cells is often prominent, associated with improved clinical outcomes, and mechanistically contributes to tumor immunoediting that ultimately can mediate immune escape. In pancreatic cancer, increasing evidence suggests that an inflammatory program establishes immune privilege in the tumor microenvironment. Indeed, pancreatic tumor cells might remain intrinsically sensitive to T cell killing because they have never been exposed to Darwinian-like T-cell-selective pressure in vivo. In support of this hypothesis, recent studies demonstrate that derailing immune suppressive pathways in the pancreatic cancer microenvironment, such as tumor-derived GM-CSF, facilitates T-cell-mediated tumor rejection. In addition, various combinations of immune therapy and standard therapy can cooperate to kill pancreatic cancer cells, including blockade of checkpoint molecules such as CTLA-4 and PD-1, activation via CD40, and standard therapies such as radiation and chemotherapy. Moreover, because mutant Kras appears capable of orchestrating a tumor-promoting microenvironment beyond well-described tumor-cell-autonomous Kras mechanisms, pharmacological inhibition of oncogenic Kras and pathways downstream, therefore, might realistically be expected to derail these tumor-promoting non-cell-autonomous mechanisms, providing even more incentive (if more were needed) for renewed efforts to develop drugs for Kras.

Kathryn E. Wellen, Ph.D.

Dr. Wellen’s laboratory studies mechanisms of metabolic signaling in cancer.   Metabolism is extensively reprogrammed in cancer cells to support growth and proliferation and to allow cells to adapt to and survive in harsh microenvironments.    Metabolites also serve in important signaling functions in cells, in part through roles as substrates of chromatin modifying enzymes.  The Wellen lab is investigating how nutrient availability and oncogenic metabolic reprogramming impact the cancer epigenome during tumor development and progression.  Acetyl-CoA plays key roles both in metabolic processes such as lipid biosynthesis and in epigenetic regulation, as the acetyl donor for histone acetylation.  We have previously shown that the activity of ATP-citrate lyase (ACLY), an enzyme that produces acetyl-CoA in the cytosol and nucleus, regulates global histone acetylation levels and impacts gene expression in mammalian cells.  In a mouse model of pancreatic cancer, we have found that expression of mutant KRAS promotes elevated histone acetylation levels in pancreatic acinar cells prior to the appearance of tumors, in a manner dependent on ACLY.  We are now using genetic models to investigate the roles and regulation of acetyl-CoA metabolism in pancreatic tumorigenesis, with the goal of identifying new strategies that target metabolism for cancer prevention or treatment. 

A) Metabolites such as acetyl-CoA and S-adenosylmethionine (SAM) are substrates of chromatin modifying enzymes.  B) In cancer cells, metabolic reprogramming can alter the availability of these metabolites and contribute to cancer cell epigenetic alterations.  (Figure from: Carrer and Wellen, Curr Opin Biotech, 2015)

 

Kenneth S. Zaret, PhD

Dr. Zaret’s lab has developed a novel way to study early stages of human pancreatic cancer and cancer progression.  The lab converted late stage human pancreatic cancer cells into a type of stem cell, and then developed methods to make the stems form early, middle, and late stage human pancreatic cancer.  This allows the different stages to be studied in live cells and provides unprecedented opportunities to discover early-stage biomarkers and new drivers of this deadly form of cancer. Dr. Zaret’s lab used the system to discover a new pathway correlated with intermediate pancreatic cancer progression and they are collaborating with Dr. Ben Stanger’s lab to determine the function of the pathway, as a potential point of clinical intervention.  Furthermore, the Zaret lab is collaborating with clinicians to study blood from pancreatic cancer patients, to discover new biomarkers of early disease that have been discovered with their unique stem cell model system.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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