Biology subjects

Schaeffer, D. F.

Publications and source records attributed to Schaeffer, D. F..

7 recordsLinked to original sources

bioRxiv2026

Endogenous insulin mediates dynamic coordination between pancreatic cancer and systemic metabolism

Pancreatic ductal adenocarcinoma (PDAC) is commonly associated with obesity, diabetes, and cachexia. The pancreatic anabolic hormone, insulin, is implicated in each of these metabolic diseases, but how insulin levels affect tumor growth and relevant host physiological factors, was unclear. To address this, we transplanted orthotopic PDAC patient-derived organoids into mice consuming a hyperinsulinemia-inducing high-fat diet (HFD). We found that insulin concentrations were higher in tumors compared to circulation. Genetically reducing insulin levels reduced PDAC growth, particularly in HFD-fed mature male mice. In turn, we found the presence of pancreatic tumors increased glucose clearance and limited the expected dietary-induced gains in insulin, weight and fat mass. Interestingly, tumor growth in normal-chow-fed mice, but not HFD-fed mice, was associated with declining circulating insulin levels, as well as declines in fat and muscle mass. Together, these data provide new insights into the complex, insulin-centred interplay between PDAC and the hosts systemic metabolism that underlie cancer-associated metabolic dysfunction.

cancer biology↗

bioRxiv2024

Neutrophil Extracellular Trap gene expression signatures identify prognostic and targetable signaling axes for inhibiting metastasis of pancreatic tumours

Tumour associated neutrophils (TANs) can promote metastasis through the interaction of Neutrophil Extracellular Traps (NETs) with tumour cells. Here, we examined the contribution of NETs in the progression of Pancreatic Ductal Adenocarcinoma (PDAC), which is characterized by high metastatic propensity. We carried out consensus clustering and pathway enrichment analysis of NET-related genes in an integrated cohort of 369 resectable and metastatic PDAC patient tumour samples, and compiled two gene expression signatures comprising of either, integrin-actin cytoskeleton, and Epithelial to Mesenchymal Transition (EMT) signaling, or cell death signaling, which identified patients with very poor to better overall survival, respectively. Tumour Infiltrating neutrophils and NETs associate with ITGB1, CCDC25 and ILK, within clinical and experimental PDAC tumours. Functionally, exposure of PDAC cells to NETs identified a cytoskeletal dynamic-associated CCDC25/ITGB1/ILK signaling complex which stimulates EMT and migration/ invasion. Furthermore, NETosis-driven experimental metastasis of PDAC cells is significantly inhibited by ILK knock down. Our data identify novel NET-related gene expression signatures for PDAC patient stratification, and reveal targetable signaling axes to prevent and treat disease progression and metastasis.

cancer biology↗

bioRxiv2022

Insulin receptors in pancreatic acinar cells contribute to KrasG12D-driven cancer initiation in the context of diet-induced obesity

The rising pancreatic cancer incidence due to obesity and type 2 diabetes is closely tied to hyperinsulinemia, an independent cancer risk factor. Previous studies demonstrated reducing insulin production suppressed pancreatic intraepithelial neoplasia (PanIN) pre-cancerous lesions in Kras-mutant mice. However, the pathophysiological and molecular mechanisms remained unknown and in particular it was unclear whether hyperinsulinemia affected PanIN precursor cells directly or indirectly. Here, we demonstrate that insulin receptors (Insr) in KrasG12D-expressing pancreatic acinar cells are dispensable for glucose homeostasis, but necessary for hyperinsulinemia-driven PanIN formation in the context of diet-induced hyperinsulinemia and obesity. Mechanistically, this was attributed to amplified digestive enzyme protein translation, triggering of local inflammation and PanIN metaplasia in vivo. In vitro, insulin dose-dependently increased acinar-to-ductal metaplasia formation in a trypsin- and Insr-dependent manner. Collectively, our data shed light on the mechanisms connecting obesity-driven hyperinsulinemia and pancreatic cancer development.

cancer biology↗

bioRxiv2021

Effects of hyperinsulinemia on pancreatic cancer development and the immune microenvironment revealed through single-cell transcriptomics

Hyperinsulinemia is independently associated with increased risk and mortality of pancreatic cancer. We recently reported that a [~]50% reduction in pancreatic intraepithelial neoplasia (PanIN) pre-cancerous lesions in mice could be achieved with reduced insulin production. However, only female mice remained normoglycemic and only the gene dosage of rodent-specific Ins1 alleles was tested in our previous model. Moreover, we did not delve into the molecular and cellular mechanisms associated with modulating hyperinsulinemia. Here, we studied PanIN lesion development in both male and female Ptf1aCreER;KrasLSL-G12D mice lacking the rodent specific Ins1 gene, and possessing one or two alleles of the wild-type Ins2 gene to modulate insulin production. High-fat diet induced hyperinsulinemia was transiently and modestly reduced, without affecting glucose tolerance, in male and female mice with only one allele of Ins2. Genetic reduction of insulin production resulted in mice with a tendency for less PanIN and acinar-to-ductal metaplasia (ADM) lesions. Using single-cell transcriptomics, we found hyperinsulinemia affected multiple cell types in the pancreas, with the most statistically significant effects on local immune cell populations, which were highly represented in our analysis. Specifically, hyperinsulinemia modulated pathways associated with protein translation, MAPK-ERK signaling, and PI3K-AKT signaling, which were changed in epithelial cells and subsets of immune cells. These data suggest a role for the immune microenvironment in hyperinsulinemia-driven PanIN development. Together with our previous work, we propose that mild suppression of insulin levels may be useful in preventing pancreatic cancer by acting on multiple cell types.

cancer biology↗

bioRxiv2020

Recombinant T cell receptors specific for HLA-A*02:01-restricted neoepitopes containing KRAS codon 12 hotspot mutations

KRAS codon 12 mutations are among the most common hotspot mutations in human cancer. Using a functional screening platform we set out to identify {beta} T-cell receptors (TCRs) as potential targeting reagents for KRASG12D and/or KRASG12V neoepitopes presented by the prevalent HLA-A*02:01 allele. Here we describe isolation and characterization of three distinct CD8+ T cell clones from a pre-treated 76 year old patient with pancreatic ductal adenocarcinoma (PDAC). One clone was KRASG12V reactive and two clones were KRASG12D reactive. Tetramer staining showed high specificity of each T cell clone for its cognate HLA-A*02:01 restricted KRASG12V or KRASG12D neoepitope (>98% tetramer positive) without appreciable cross-reactivity to wild-type KRAS (<2% tetramer positive). We amplified and sequenced the full-length TCR alpha and beta chains from each of the three T cell clones and determined that these three TCRs comprised distinct combinations of two different TCR alpha chains and two distinct TCR beta chains. We resynthesized these TCR alpha and beta chain nucleotide sequences and reconstituted the original pairs in healthy donor CD8+ T cells by lentiviral transduction, substituting the human {beta} TCR constant gene segments with murine {beta} TCR constant gene segments to prevent mispairing with endogenous TCR subunits. Tetramer analysis and IFN-{gamma} ELISpot analysis confirmed the specificity of each reconstituted TCR for its cognate HLA-A*02:01 restricted KRAS neoepitope. To test cytolytic activity TCR-transduced healthy donor CD8+ T cells were co-cultured with KRASG12V, KRASG12D or KRASwt peptide-pulsed K562-HLA-A*02:01 antigen presenting cells at an effector to target cell ratio of 4:1. Under these conditions we observed neoepitope-specific killing of 16.5% to 19.0% of target cell populations. To assess in vivo activity we developed a KRASG12V/A*02:01 patient-derived xenograft (PDX) mouse model. Over a 56-day period, PDX bearing mice infused with human TCR-transduced T cells had significantly reduced tumor growth and longer survival compared to mice infused with non-transduced control T cells. In conjunction with other therapeutic approaches, immune effector cell therapies expressing these TCRs may improve outcomes for HLA-A*02:01 patients with KRASG12V and/or KRASG12D positive tumors.

immunology↗

bioRxiv2019

PRDM3 attenuates pancreatitis and pancreatic tumorigenesis by regulating inflammatory response

Pancreatic ductal adenocarcinoma (PDAC) is associated with metaplastic changes in the pancreas but the transcriptional program underlying these changes is incompletely understood. The zinc finger transcription factor, PRDM3, is lowly expressed in normal pancreatic acini and its expression increases during tumorigenesis. Although PRDM3 promotes proliferation and migration of PDAC cell lines, the role of PRDM3 during tumor initiation from pancreatic acinar cells in vivo is unclear. In this study, we showed that high levels of PRDM3 expression in human pancreas was associated with pancreatitis, and well-differentiated but not poorly differentiated carcinoma. We examined PRDM3 function in pancreatic acinar cells during tumor formation and pancreatitis by inactivating Prdm3 using a conditional allele (Ptf1aCreER;Prdm3flox/floxmice) in the context of oncogenic Kras expression and supraphysiological cerulein injections, respectively. In Prdm3-deficient mice, KrasG12D-driven preneoplastic lesions were more abundant and progressed to high-grade precancerous lesions more rapidly. This is consistent with our observations that low levels of PRDM3 in human PDAC was correlated significantly with poorer survival in patient. Moreover, loss of Prdm3 in acinar cells elevated exocrine injury, enhanced immune cell activation and infiltration, and greatly increased acinar-to-ductal cell reprogramming upon cerulein-induced pancreatitis. Whole transcriptome analyses of Prdm3 knockout acini revealed that pathways involved in inflammatory response and Hif-1 signaling were significantly upregulated in Prdm3-depleted acinar cells. Taken together, our results suggest that Prdm3 favors the maintenance of acinar cell homeostasis through modulation of their response to inflammation and oncogenic Kras activation, and thus plays a previously unexpected suppressive role during PDAC initiation.

cancer biology↗

bioRxiv2019

Endogenous insulin contributes to pancreatic cancer development

Obesity and early-stage type 2 diabetes (T2D) increase the risk for many cancers, including pancreatic ductal adenocarcinoma (PDAC). The mechanisms linking obesity and T2D to cancer have not been established, preventing targeted interventions. Arguments have been made that hyperinsulinemia, hyperglycemia, or inflammation could drive cancer initiation and/or progression1. Hyperinsulinemia is a cardinal feature of obesity and T2D, and is independently associated with PDAC incidence and mortality2-4, even in non-obese people5. Despite ample human epidemiological evidence linking hyperinsulinemia to PDAC, there is no direct in vivo evidence of a causal role for endogenous insulin in cancer in any system. Using mice with reduced insulin gene dosage6, 7, we show here that a modest reduction in endogenous insulin production leads to a ~50% reduction in pancreatic intraepithelial neoplasia (PanIN) pre-cancerous lesions in high fat diet-fed mice expressing the KrasG12D oncogene8. The significant reduction in PanIN lesions occurred in the absence of changes in fasting glucose. Reduced insulin also led to a ~50% reduction in pancreatic fibrosis, suggesting that endogenous insulin drives PanIN development, in part, via its pro-fibrotic effects on the stroma surrounding acinar cells and PanIN. Collectively, our data indicate that endogenous insulin hypersecretion contributes causally to pancreatic cancer development. This suggests a modest reduction in fasting insulin via lifestyle interventions or therapeutics may be useful in cancer prevention.

cancer biology↗