Our
Projects
Pancreatic cancer and the pro-metastatic liver niche
Pancreatic cancer outcomes remain dismal, even for the ~15-20% of patients that present with early-stage, surgically-resectable disease. Most patients that undergo months of neoadjuvant chemotherapy followed by radical pancreaticoduodenectomy will recur with metastases within a few years. These clinical challenges illustrate the fact that pancreatic tumor cells spread to distant organs early in disease, and to mitigate metastasis progression, there is a profound need for therapies that target disseminated tumor cells (DTCs). Although standard-of-care chemotherapy aids in tumor control and can be highly effective in some patients, our previous studies demonstrated that systemic chemotherapy accelerates liver metastasis outgrowth and reduces overall survival in a mouse model of pancreatic cancer liver metastasis. We have several ongoing studies aimed to define and target the pro-metastatic liver signals generated by chemotherapy that supports the survival and outgrowth of liver-resident disseminated tumor cells. Our major goal is to identify novel therapeutic approaches for reducing risk of disease recurrence.
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1. Liver endothelial and fibroblast secretion of the tissue inhibitor of matrix mellatoproteinases-1, Timp1.
Our previous studies demonstrated that oxaliplatin treatment, a chemotherapy included in the standard-of-care therapy FOLFIRINOX, accelerates liver metastasis outgrowth and reduces overall survival in a mouse model of pancreatic cancer liver metastasis. Proteomic analysis revealed that oxaliplatin triggers increased expression of Timp1 in liver interstitial fluid. Pharmacologic blockade of Timp1 significantly reduces liver metastasis progression in mice, virtually reversing the accelerated metastasis phenotype caused by oxaliplatin treatment. Further, surgically-resected pancreatic cancer patients that recur early with metastases have higher serum TIMP1 protein levels than patients that recur late or don’t recur, suggesting that high TIMP1 may functionally contribute to metastasis in patients. Timp1 is an extracellular protein that can both modulate the extracellular matrix (ECM) by inhibiting matrix metalloproteinase (MMP) function or act as a cytokine that binds and activates transmembrane receptors such as CD63. The overall objective of this project is to define the mechanisms by which oxaliplatin triggers Timp1 secretion from liver cell populations, and determine how Timp1 acts to accelerate metastasis.
This project is led by Omar Cortez-Toledo and Kai Liptow. We are grateful for funding support from American Gastroenterological Association (AGA), Vince Lombardi Cancer Foundation (VLCF), Sky Foundation, the MCW Research Affairs Committee, and support for Omar Cortez-Toledo by the MCW Cancer Center graduate student fellowship.
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2. Hepatocyte-derived secretion of the pleiotropic growth factor, Midkine.
We further performed single-cell RNA sequencing analysis of livers from mice treated with oxaliplatin or vehicle control. This revealed that oxaliplatin triggers increased expression of Midkine (MDK) in midlobular hepatocytes. MDK is a pleiotropic growth factor that mediates signaling through interaction with cell-surface proteoglycan and non-proteoglycan receptors. Our preliminary studies demonstrate that MDK is significantly higher in the serum of early-stage pancreatic cancer patients as compared to healthy adults, and increased in patients that recur with liver metastasis following surgery. Exogenous MDK increases the migratory behavior of pancreatic cancer cells suggesting that MDK may drive metastatic behavior. Further, bioinformatic analysis of publicly-available single-cell RNA-sequencing datasets revealed MDK expression is not restricted to liver, but also expressed in cancer cells. MDK is significantly enriched in cancer cells of the more aggressive basal subtype, and enriched in cancer cells from liver metastasis. Taken together, these findings suggest that high MDK may contribute to metastasis possibly through both paracrine (metastatic niche) and autocrine (cell-autonomous) signaling. The overall objective of this project is to determine the functional impact of microenvironmental- and cancer cell-derived MDK in pancreatic cancer liver metastasis and therapy response.
This project is led by Dr. Priyanga Jayakrishnan with the support of Parnian Vakili. We are grateful for funding support from We Care Fund for Medical Innovation and Research, and support for Parnian Vakili by the MCW Cancer Center – UW Milwaukee Undergraduate Research Grant.
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3. Chemotherapy-driven depletion of Kupffer cells.
Our recent studies reveal that FOLFIRINOX, a chemotherapy regimen used to treat pancreatic cancer, can also accelerate liver metastasis in mouse models. To investigate the impact of FOLFIRINOX on the metastatic liver microenvironment, we established a mouse model of pancreatic cancer liver metastasis in which the tumor cells label adjacent niche cells with a red fluorescent protein, enabling isolation of cells in the adjacent metastatic niche. Single cell RNA sequencing analysis revealed a profound shift in macrophage composition at the metastatic site following FOLFIRINOX treatment, including depletion of Kupffer cells, liver tissue-resident macrophages, and expansion of alternatively activated (M2-like) macrophages. Furthermore, remaining Kupffer cells had reduced expression of formyl protein receptor 1 (Fpr1) following FOLFIRINOX, a GPCR that responds to damage-associated molecular patterns and promotes anti-tumor immunity. Our ongoing studies are aimed to determine if Kupffer cell therapy can be leveraged to prevent metastatic recurrence to the liver following chemotherapy. Further, we are investigating the role of Fpr1 in Kupffer cell-mediated anti-tumor immunity. The overall objective of this project is to attenuate the shift towards immunosuppressive macrophage populations triggered by chemotherapy.
This project is led by Isabella Facchine.
Mammary epithelial plasticity and breast cancer progression
Cancer progression is fueled by acquired cell plasticity. For example, dysplastic cells may dedifferentiate into more primitive cell states and/or transdifferentiate into other cell types to generate malignant disease. Further, progression to metastasis and acquired therapy-resistance is often coupled with cell state transition toward more aggressive phenotypes. Despite a growing body of evidence linking cell plasticity to cancer mortality, there is a deficiency in therapies that can modulate cell plasticity and generate less aggressive disease. This is due, in part, to inadequate knowledge of the molecular regulators of plasticity. Thus, our lab is working to define regulators of cell plasticity and cell fate-switching processes in injured mammary epithelial cells, in pre-invasive ductal carcinoma in situ, and in triple-negative breast cancer (TNBC). Our overall goal is to develop therapeutic strategies for intercepting drivers of aggressive disease, ultimately improving patient outcomes
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1. Chemotherapy-associated epithelial instability contribution to second primary breast cancer.
​Second primary breast cancer (SPBC) is becoming a major challenge for achieving long-term disease-free survival in breast cancer patients. SPBCs are independent tumors that arise in the breast of patients that have been diagnosed with a first primary breast cancer. While multiple tumors may occur synchronously in a patient, SPBCs are often diagnosed years after treatment and are associated with worse overall survival. The biological mechanisms driving SPBC remain poorly understood. Recently, cisplatin, a cytotoxic agent used to treat breast cancer, was shown to trigger basal-to-luminal transdifferentiation in the mammary gland and our studies demonstrate that luminal cells generated from transdifferentiation, e.g. “fate-switched luminal cells”, are epigenetically and transcriptomically distinct from homeostatic luminal cells. This project aims to test the hypothesis that therapy-induced basal-to-luminal cell fate switching generates a pool of unstable cells that are more susceptible to initiating SPBCs.
This project is led by Dr. Priyanga Jayakrishnan with support from Isabella Facchine. We are grateful for funding support from the MCW Cancer Center American Cancer Society Institutional Research Grant, and from Advancing a Healthier Wisconsin Postdoctoral Seed Grant (granted to Priyanga Jayakrishnan).
2. The role of the AP-1 transcription factor complex in luminal-to-basal fate switching.
Matched patient biopsies of TNBCs highlight non-genetic drivers of metastasis and therapy resistance, including a selection for basal-like and loss of luminal-like cancer cell states. These findings suggest that luminal differentiation therapies may represent an untapped approach for enhancing chemotherapy response or preventing disease progression. To define programs that may trigger loss of the basal state and gain of luminal, we performed transcriptomic and epigenetic analyses of cell states during mammary epithelial basal-to-luminal transition (BLT). Expression of AP-1 transcription factor complex members were dysregulated during transition, and AP-1 binding motifs were enriched in BLT-associated open chromatin regions, suggesting programs regulated by AP-1 may contribute to BLT. Pharmacologic inhibition of AP-1 locks mammary luminal cells in a luminal state. Further, AP-1 inhibition induces expression of the luminal gene GATA3 in human TNBC organoids and accelerates BLT. High expression of the key AP-1 subunit Jun has been linked to worse prognosis in patients with TNBC but not in patients with other breast cancer subtypes, suggesting AP-1 may activate programs that are unique to the aggressive nature of TNBC. Our overall objective for this project is to define molecular processes that induce luminal programs and determine the contribution AP-1 signaling in cell plasticity that contributes to TNBC initiation, metastasis, and therapy resistance.
This project is cooperatively led by Dr. Nikki Lytle and Dr. Priyanga Jayakrishnan, with support of Troy Biermann and Alex Eng. We are grateful for funding support from Advancing a Healthier Wisconsin Postdoctoral Seed Grant (granted to Priyanga Jayakrishnan).
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3. The impact of obesity and menopause on mammary epithelial cell states and breast tumorigenesis.
Cell states influence transformation susceptibility and tumor subtype, which can be attributed, in part, to differences in epigenetic and transcriptional regulators of cell identity. Obesity and menopause are known risk factors for breast cancer, yet the impact of these conditions on mammary epithelial cell states remains understudied. We leveraged diet-induced models of obesity and a surgical-induced model of menopause to determine molecular and phenotypic changes that occur in mammary epithelium over time. Our studies reveal that obesity and menopause synergize to lead to expansion of the luminal progenitor (LP) population, which is thought to be the cell of origin for aggressive basal-like breast cancer. While LP cells normally only give rise to luminal cells in homeostatic conditions, LP from post-menopausal, obese mice are uniquely able to transdifferentiate to basal cells, suggesting that these cancer risk factors may contribute to tumorigenesis by enabling LP plasticity. Indeed, we show that obesity or menopause increases tumor susceptibility in situ and in transplant models in which LP cells serve as the cell of origin. To understand the molecular mechanisms by which obesity and menopause alter LP cell states, we performed single-nucleus ATAC sequencing. These data revealed substantial epigenetic reprogramming in LP cells isolated from both obese and post-menopausal mice, and enrichment of transcription factor binding sites in uniquely open DNA regions that are linked to breast tumorigenesis.
This project is cooperatively led by Dr. Nikki Lytle, Kai Liptow, and Dr. Priyanga Jayakrishnan, with support of Anooj Arkatkar (Michaela Patterson lab, MCW).
Newly developing projects
We are excited to continue developing the following new projects! ​
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1. Acquired dependencies in chemotherapy-resistant pancreatic cancer cells.
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2. Cancer cell secretome and recruitment of unique tumor microenvironments determine by oncogenic driver mutations.
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3. Development of novel tools for Cre-based cell-cell contact tracing.