bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract B048: Targeting PPARG to block obesity-associated pancreatic cancer progression
Authors: Ferguson L. Paige
Published: January 2024

Pancreatic ductal adenocarcinoma (PDA) is the 3rd leading cause of cancer-related death in the United States and one of the few cancers for which incidence is increasing. This trend in increased incidence has been attributed in part to obesity. Obesity is associated with increased risk of pancreatic cancer and advanced disease stage in patients, concordant with rodent studies showing that obesity accelerates tumorigenesis and metastasis. Although studies have largely focused on the role of inflammation in obesity-associated pancreatic cancer, the cancer cell-autonomous mechanisms by which lipid availability in obesity impacts tumorigenesis remain quite poorly understood. Given the abundant evidence for dysregulated lipid metabolism in tumors, I hypothesized that cancer cells are primed to exploit exogenous lipids in obesity, accelerating disease progression. By mapping lipid-protein interactions in tumor and metastasis-enriched RNA-seq networks, I identified the nuclear hormone receptor PPARG as a potential mediator of obesity-associated lipid signaling in pancreatic cancer. PPARG is an attractive prospective mediator of obesity-associated PDA progression because it is a metabolic regulator activated by a broad set of lipid ligands, suggesting a dual role in lipid sensing and metabolic control. PPARG is also positioned at an interesting junction in PDA etiology; PPARG agonists are used to treat diabetes (a PDA risk factor) and have previously been studied for anti-cancer effects. However, PPARG agonists have seen little clinical success in and recent work has suggested that their use may even increase bladder cancer risk. PPARG is overexpressed in pancreatic tumors where it is associated with poor prognosis, further casting doubt on its anti-tumorigenic function. In my own studies, I found that PPARG agonists had no effect on tumor viability, while the PPARG antagonist T0070907 reduced organoid viability in vitro. Modeling the convergent effects of PPARG and obesity, I supplemented organoids with a mixture of lipids in the presence of PPARG antagonist and found that lipids boosted the viability of both tumor and metastatic organoids dependent on PPARG activity in vitro. These results suggest that PPARG can mediate the pro-tumorigenic function of exogenous lipids. As the incidence of both obesity and pancreatic cancer continue to rise, defining the role of PPARG in PDA could have significant implications for the development of new strategies to treat or prevent obesity-associated cancer.

Citation Format: L. Paige Ferguson. Targeting PPARG to block obesity-associated pancreatic cancer progression [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B048.
Abstract B063: Tertiary lymphoid organogenesis and lymphocyte activation in human organ chips
Authors: Zhai Yunhao , Prabhala Pranav , Barck Lucas , Ku Min Wen , Patil Aditya , Horvath Viktor , Gould Russell A. , Ingber Donald E. , Goyal Girija
Published: January 2024

The rates of tertiary lymphoid organ (TLO) formation in pancreatic cancer are very low but patients with TLO have dramatically better survival rates. Our goal is to understand how pancreatic cancer suppresses TLO so that we can improve patient survival and reduce recurrence. We integrated human cell lines from pancreatic and lung cancer with either high or low PDL1/L2 expression into our previously described lymphoid follicle (LF) chip (Goyal et al., Adv. Sci, 2022), where peripheral blood mononuclear cells are induced to form 3D TLO-like structures. The hot lung cancer cell line, which expressed high levels of PDL1/L2 and a “hot” phenotype in published murine studies, produced a high levels of cytokines and stimulated increased TLO formation in the LF chip. In contrast, the cold lung and pancreatic cell lines did not induce the cytokine signature or TLOs. Importantly, TLO formation correlated with increased B cell activation, anti-tumor CD8 activity and tumor cell death. We have coupled this in vitro study with analysis of the pancreatic cancer transcriptome from the Cancer Genome Atlas to identify therapeutic targets to promote TLO formation in pancreatic cancer. In ongoing studies, we are assessing the functionality of the lung cancer TLO in vitro and in vivo and identifying therapeutics that may improve TLO formation in pancreatic cancer.

Citation Format: Yunhao Zhai, Pranav Prabhala, Lucas Barck, Min Wen Ku, Aditya Patil, Viktor Horvath, Russell A. Gould, Donald E. Ingber, Girija Goyal. Tertiary lymphoid organogenesis and lymphocyte activation in human organ chips [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B063.
Abstract B081: SOAT1 as a targetable KRAS dependency in PDAC
Authors: Lan Wenjun , Sun Shoujun , Nigri Jeremy , Homer Josh , Park Young , Deschenes Astrid , Cifani Paolo , Cross Justin , Gaeth Victoria , Kim Sunny , Ting Shawn , Rubino Rachel , Moses John , Tuveson David
Published: January 2024

Metabolic rewiring is an emerging hallmark of neoplasia. In pancreatic ductal adenocarcinoma (PDAC), KRAS alters myriad metabolic programs to promote cellular transformation. Among them, the cholesterol synthesis pathway has emerged as a vulnerability of cancer cells due to the importance of cholesterol in membrane fluidity and the production of isoprenoid intermediates that enable KRAS membrane localization and activation in pancreatic cancer. We recently reported that the non-essential gene SOAT1 (Sterol-O-Acyl transferase 1), encoding an enzyme that esterifies free cholesterol into an insoluble form for storage and transport, is markedly upregulated in metastatic PDAC cells. SOAT1 promotes the hyperactivation of the mevalonate synthesis pathway due to loss of negative feedback by free cholesterol, thereby leading to increased production of isoprenoids such as farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP), which are required for RAS and RHO membrane localization and activity, respectively. Genetic ablation of Soat1 reduced RAS and RHO membrane localization and inhibited cellular proliferation and mitochondrial function in vitro, and these effects were largely rescued by exogenous FPP and GGPP. Therefore, our study nominated SOAT1 as a new candidate gene for therapeutic targeting. Based on SuFEx Click Chemistry (ASCC) technology, we have designed and synthesized a panel of drug-like candidates. The first series of Soat1 probes selectively impair the proliferation of PDAC cells that express SOAT1, reduce SOAT1 protein content in cells, and covalently bind to SOAT1. In mice, the most active SOAT1 probes were tolerated in a 28-day daily dosing study up to 120 mg/kg. Marked tumor growth inhibition was noted in mice bearing PDAC xenografts and GEMM mice treated as monotherapy with 15 mg/kg/d of the most active SOAT1 probe, and tissue analysis demonstrated tumor necrosis, decreased proliferation, and increased apoptosis. Mechanistically, SOAT1 loss or inhibition targets multiple important components of cellular transformation in PDAC including KRAS, RHO, and mitochondrial biology, and our work suggests that it is an attractive target to pursue for further drug development in this cancer.

Citation Format: Wenjun Lan, Shoujun Sun, Jeremy Nigri, Josh Homer, Young Park, Astrid Deschenes, Paolo Cifani, Justin Cross, Victoria Gaeth, Sunny Kim, Shawn Ting, Rachel Rubino, John Moses, David Tuveson. SOAT1 as a targetable KRAS dependency in PDAC [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B081.
Abstract B084: Overcoming drug resistance of ‘tri-complex’ pan-RAS inhibitors: Inhibition of mTOR signaling
Authors: Lin Qingxiang (Nick)
Published: January 2024

Background: RAS mutations occur in ~20% of all cancers that drive tumor progression, and therapy targeting most predominant RAS mutations remains unavailable. Mutant-selective RAS inhibitors (RASi), such as FDA-approved KRAS G12C inhibitors, have demonstrated initial clinical responses but drug resistance frequently emerges that minimize the drug efficacy, mechanistically mediated by RAS signaling reactivation. Methods and Results: To address this challenge, we characterized a class of novel pan-RASi that universally inhibit all RAS mutations, which forms a ‘tri-complex’ with the chaperone protein (cyclophilin A) that specifically binds to RAS, including wild-type RAS (KRAS, NRAS, HRAS). Mutant-selective RASi induced RAS signaling rebound intensively, whereas pan-RASi enabling to inhibit wild-type RAS minimized this rebound, which was surmountable in a concentration-dependent manner. Importantly, pan-RASi abrogated cell viability in patient-derived KRAS-mutant cancer organoids rather than in normal patient-derived wild-type RAS organoids, implicating drug selectivity and manageable toxicity. Interestingly, intrinsic resistance to pan-RASi was rare in RAS-mutant cancer cell screening but was observed only in a handful of pancreatic and lung cancer cell lines. Our time-resolved signaling analyses of pan-RASi treatment showed the re-activation of mTOR signaling and a contrast correlation that mTOR signaling decreased in sensitive lines but remained in resistant lines, underscoring the critical contribution of mTOR pathways to RASi resistance. Mechanistically, we further identified mTOR signaling that drives intrinsic resistance to pan-RASi, and combined pan-RASi with mTOR inhibitors (mTORi) suppressed mTOR signaling in resistant lines, thereby improving efficacy. Conclusion: Pan-RASi hold promise in treating RAS-mutant cancer clinically and a combination of pan-RASi with mTORi can improve drug efficacy.

Citation Format: Qingxiang (Nick) Lin. Overcoming drug resistance of ‘tri-complex’ pan-RAS inhibitors: Inhibition of mTOR signaling [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B084.
Abstract B092: CDK8 and CXCL2 remodel the tumor microenvironment to contribute to KRASG12D small molecule inhibition resistance in pancreatic ductal adenocarcinoma
Authors: McAndrews Kathleen M. , Mahadevan Krishnan K. , Li Bingrui , Sockwell Amari M. , Morse Sami J. , Kelly Patience J. , Kirtley Michelle L. , Conner Meagan R. , Patel Sarah I. , Khumbar Shreyasee V. , Arian Kent A. , Barekatain Yasaman , Moreno Diaz Barbara A. , Lyu Hengyu , Sugimoto Hikaru , Sthanam Lakshmi Kavitha , Sobhani Navid , Paradiso Francesca , Bernard Vincent , Guerrero Paola , Ying Haoqiang , Maitra Anirban , Heffernan Timothy P. , Kalluri Raghu
Published: January 2024

Mutations in KRAS are a dominant driver of pancreatic ductal adenocarcinoma (PDAC), with over 50% of PDAC patients presenting with KRASG12D mutations. The recent development of small molecule inhibitors targeting KRASG12D has enabled effective targeting of mutant KRAS signaling and suppression of tumor growth; however, the contribution of the tumor microenvironment to the therapeutic efficacy of KRASG12D inhibition and mechanisms of resistance to KRASG12D suppression remain to be fully elucidated. Here, we employed spatial transcriptomics and proteomics to evaluate cancer cell intrinsic and extrinsic responses to KRASG12D inhibition with MRTX1133. MRTX1133 treatment was associated with increased antigen presenting cells (APCs), T cells, and putative tumor-restraining fibroblasts within proximity to cancer cells, suggesting that antigen presentation and remodeling of the local microenvironment facilitates an effective response to KRASG12D inhibition. In the context of relapsed MRTX1133 treated tumors, single cell RNA sequencing and validation identified CDK8 as an intrinsic mediator of resistance and CXCL2 as an extrinsic mediator of resistance. Together, these studies identify APCs and CDK8 as therapeutic targets for enabling long term responses to small molecule KRASG12D inhibition with MRTX1133.

Citation Format: Kathleen M. McAndrews, Krishnan K. Mahadevan, Bingrui Li, Amari M. Sockwell, Sami J. Morse, Patience J. Kelly, Michelle L. Kirtley, Meagan R. Conner, Sarah I. Patel, Shreyasee V. Khumbar, Kent A. Arian, Yasaman Barekatain, Barbara A. Moreno Diaz, Hengyu Lyu, Hikaru Sugimoto, Lakshmi Kavitha Sthanam, Navid Sobhani, Francesca Paradiso, Vincent Bernard, Paola Guerrero, Haoqiang Ying, Anirban Maitra, Timothy P. Heffernan, Raghu Kalluri. CDK8 and CXCL2 remodel the tumor microenvironment to contribute to KRASG12D small molecule inhibition resistance in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B092.
Abstract B096: Acquired resistance to KRAS inhibition modulates the pancreatic cancer tumor microenvironment
Authors: Gulay Kevin Christian Montecillo , Patel Jay , Ng Isabella , de Mendoza Tatiana Hurtado , Tiriac Herve , Lowy Andrew
Published: January 2024

Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with dismal patient outcomes. Acquired resistance to chemotherapeutics is a major barrier to successful pancreatic cancer treatment. MRTX-1133 is a potent, selective KRAS G12D inhibitor that is in early-phase clinical trials. While initially effective, clinical experience with KRAS G12C inhibitors has shown tumors rapidly acquire therapeutic resistance. The tumor microenvironment (TME) plays a pivotal role in resistance development by activating prosurvival pathways, promoting epithelial-mesenchymal transition (EMT) and stemness, and inhibiting apoptosis. In this study, we sought to understand changes in the PDAC TME associated with acquired resistance to KRAS G12D inhibition. Methods: In order to investigate resistance to KRAS G12D inhibition in PDAC, we developed various mouse and human MRTX-1133 resistant (MRTXR) cell models (FC1199, FC1242, FC1245, and SUIT2). Intriguingly, these models also displayed resistance to several pan-RAS(ON) inhibitors. We utilized flow cytometry analysis to investigate the dynamic changes occurring in the TME following resistance to MRTX-1133, and we employed cytokine array and RNA-seq analyses to elucidate the impact of cancer cells on gene and protein expression of TME cells. Results: A comparative analysis between parental PDAC cells and MRTXR tumors revealed significant alterations within the TME. We found a significant decrease (p=0.013, p=0.045, respectively) in the number of inactivated and naïve CD8 T cells (CD8+/CD69+ and CD44-/CD62L+ cells) in MRTXR tumors. We also observed an upregulation of CXCL1, CCL20, and CXCL2 secretion in MRTXR cells compared to parental cells. Conclusions: Pancreatic cancer cells with acquired resistance to KRAS inhibitors modulate their tumor microenvironment uniquely. Ongoing studies aim to identify the critical pathways responsible for these alterations and to develop alternative treatment strategies for KRAS therapy-resistant tumors.

Citation Format: Kevin Christian Montecillo Gulay, Jay Patel, Isabella Ng, Tatiana Hurtado de Mendoza, Herve Tiriac, Andrew Lowy. Acquired resistance to KRAS inhibition modulates the pancreatic cancer tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B096.
Abstract C011: Detection of circulating tumor cells for the early detection of pancreatic cancer
Authors: Yeo Dannel , Klemm Vera , Saxena Payal , Bastian Althea , Strauss Heidi , Sandroussi Charbel , Wahlroos Sara , Grimison Peter , Rasko John E.J.
Published: January 2024

Introduction The majority of pancreatic cancer patients are diagnosed with advanced, metastatic disease. Biomarkers to detect pancreatic cancer at earlier stages could drastically improve the poor survival rates. Circulating tumor cells (CTCs) are tumor cells that disseminate or are shed into the vascular system and have been detected in patients at pre-malignant stages. However, detecting these rare cells accurately and reliably remains a challenge. The AccuCyte-CyteFinder system uses density-based enrichment of blood nucleated cells followed by detection of CTCs using fluorescence staining, whole slide scanning and automated image analysis. This study aimed to examine whether CTCs could be used to identify patients with pancreatic lesions likely to malignant. Methods 50 patients undergoing an endoscopic ultrasound procedure for a pancreatic mass were recruited at the Royal Prince Alfred Hospital, Sydney, Australia or Chris O’Brien Lifehouse, Sydney, Australia. Peripheral blood was collected prior to the procedure and processed for CTCs on the AccuCyte-CyteFinder platform using a CK+ EpCAM+ CD45- staining panel. Results 28% (14/50) were found to have an intraductal papillary mucinous neoplasm (IPMN), 10% (5/50) pancreatic ductal adenocarcinoma (PDAC), 6% (3/50) pancreatic neuroendocrine tumor (PNET), 42% (21/50) non-neoplastic pancreatic cyst, and 14% (7/50) normal (no mass found). CTCs were highest in the PDAC group with an average of 5 cells/ml, followed by the IPMN (3 cells/ml), pancreatic cyst (2.5 cells/ml), and PNET (0 cells/ml). 86% (12/14) of IPMN patients had detectable CTCs. 2 IPMN patients with CTC counts of more than 5 cells/ml resulted in a resected sample having high-grade dysplasia while 3 IPMN patients with no/low CTC counts resulted in a resected sample having low-grade dysplasia. There was no correlation with the size of the pancreatic mass and CTC number. Conclusions CTCs could be detected in patients with pre-malignant pancreatic cancer and could determine malignancy. CTCs could potentially be used to detect pancreatic cancer early however, larger patient numbers and longer follow-up are required to validate these findings.

Citation Format: Dannel Yeo, Vera Klemm, Payal Saxena, Althea Bastian, Heidi Strauss, Charbel Sandroussi, Sara Wahlroos, Peter Grimison, John E.J. Rasko. Detection of circulating tumor cells for the early detection of pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C011.
Abstract C017: The anti-fungal itraconazole improves immunotherapy efficacy in pancreatic ductal adenocarcinoma by reversing the immune-suppressive tumor microenvironment
Authors: Porazinski Sean , Man Jennifer , Chacon-Fajardo Diego , Yim Howard , El-Omar Emad , Joshua Anthony , Pajic Marina
Published: January 2024

Pancreatic cancer (PC) has 5-year survival rates of 11% and is projected to become the second leading cause of cancer-related deaths by 2030. Poor outcomes result from early metastasis and a lack of effectual therapies for advanced disease. Our previous large-scale genomics studies revealed PC is molecularly highly varied (1). This heterogeneity, lack of effective therapies and high mortality rate make PC a prime arena to advance personalised medicine strategies, where individual cancers are selected for optimal therapy depending on molecular subtype. Utilising our significant experience of molecular-guided anti-cancer therapies (2-6) and stromal biology expertise (2,6,7), we are taking drug-repurposing approaches to test agents with effects on stromal biology in combination with standard-of-care chemotherapies and immunotherapy, to improve clinical outcomes. Itraconazole is an FDA-approved anti-fungal with potential anti-cancer effects, although its efficacy in PC remains relatively unexplored. Preliminary in vivo findings indicate that itraconazole, in combination with standard-of-care chemotherapy gemcitabine/nab-paclitaxel, significantly delays disease progression in both mouse and patient-derived xenograft models of PC. Single cell RNA-seq analyses of tumors from the KPC orthotopic model of PC suggest itraconazole treatment can inhibit immunosuppressive aspects of the stroma and pro-tumorigenic, pro-metastatic signalling. Excitingly, combining itraconazole with anti-PD1/-CTLA4 immunotherapy provides significant survival advantages in the KPC orthotopic model of PC. Finally, using a model of metastatic PC, we show that itraconazole hinders metastatic colonisation in the liver. This work aims to identify subtypes of PC responsive to itraconazole allowing optimisation and translation of tailored therapies combining itraconazole and the latest clinically-utilised chemotherapies and immunotherapies. References1. Waddell, N. et al. Nature (2015). 2. Chou, A. et al. Gut (2018). 3. Li, L. et al. Br. J. Cancer (2020). 4. Belali, T. et al. BBA - GRM (2020). 5. Uzor, S. et al. Sci. Rep. (2021). 6. Porazinski, S. et al. Nature (2015). 7. Vennin, C. et al. Science Translational Medicine (2017).

Citation Format: Sean Porazinski, Jennifer Man, Diego Chacon-Fajardo, Howard Yim, Emad El-Omar, Anthony Joshua, Marina Pajic. The anti-fungal itraconazole improves immunotherapy efficacy in pancreatic ductal adenocarcinoma by reversing the immune-suppressive tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C017.
Abstract C019: The circadian master regulator BMAL1 blocks immune cell recognition of pancreatic ductal adenocarcinomas by reducing proteasome activity and MHC1 cell surface localization
Authors: Prela Orjola , Wang Lan , Shih Ching-Hua , de Menezes Juliana Cazarin , Altman Brian , Vertino Paula M. , Harris Chris R. , Carpizo Darren R.
Published: January 2024

Many tumor types, including pancreatic adenocarcinomas, have dysregulated circadian rhythms. Here we show that the master regulator of circadian control, BMAL1, is overexpressed in pancreatic ductal adenocarcinoma (PDAC) relative to normal tissue and plays a role in protecting PDAC cells from recognition by the immune system. Using CRISPR-generated knockout (KO) cell lines, we evaluated the cells ability to create liver metastasis using a splenic metastasis assay and found that loss of Bmal1 KO abrograted metastasis. We hypothesized that could be through an immune mediated mechanism and evaluated the Bmal KO cells for their expression of cell surface MHCI. Remarkably loss of Bmal1 led to a significant increase in cell surface MHCI expression. This was due to a change in localization of the MHCI molecule. Proper localization of MHC1 is known to depend upon proteasome-generated peptides, and we found that loss of Bmal1 increased proteosomal activity. We used Cut and Run to demonstrate that Bmal1 binds directly to the promoters for core components of the proteosome. Taken together these studies implicate Bmal1 in regulating anti-tumor immunity in PDAC through its regulation of protesomal activity and MHC1 surface expression. This is a novel function for a circadian rhythm gene in PDAC biology.

Citation Format: Orjola Prela, Lan Wang, Ching-Hua Shih, Juliana Cazarin de Menezes, Brian Altman, Paula M. Vertino, Chris R. Harris, Darren R. Carpizo. The circadian master regulator BMAL1 blocks immune cell recognition of pancreatic ductal adenocarcinomas by reducing proteasome activity and MHC1 cell surface localization [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C019.
Abstract C022: T cell movement through complex obstacles presented by the microenvironment of pancreatic tumor spheroids
Authors: Roy Shambojit , Chen Zhongming , Qian Guhan , Provenzano Paolo P.
Published: January 2024

Immunotherapy has emerged as a promising approach for treating pancreatic cancer, however its efficacy against solid tumors has been largely limited. In order to be effective, cell-based immunotherapies are required to be in close proximity with the target cancerous cells. However, owing to its dense desmoplastic stroma, many regions of a pancreatic tumor, have areas within the tumor volumes that exclude anti-tumor immune cells. Therefore, we need to define mechanisms used by therapeutic T cells to navigate effectively in some tumor regions and the barriers that limit their infiltration and distribution in other regions of the tumor microenvironment (TME). In this work, we have advanced our knowledge of T cell migration and infiltration through complex TMEs by analyzing T cell dynamics in 3D engineered in vitro environments that can replicate key TME features of pancreatic ductal adenocarcinoma (PDA). Using our state-of the-art imaging techniques with multiphoton excitation (MPE) and second harmonic generation (SHG), we have monitored the migration of engineered human mesothelin reactive CAR-T cells through fibrous microenvironments and their interactions with pancreatic tumor spheroids. Quantitative analysis of interactions between CAR-T cells and carcinoma cells, in terms of velocity, directionality and mean square displacement (MSD) were performed, with the aim of utilizing these phenotypes as “design criteria” for the development of more effective engineered T cell therapies. The therapeutic efficacy of engineered T cells was also evaluated in standard 2D killing assays and then new 3D assays of increased complexity, both of which revealed mesothelin specific cancer cell death. Overall, we are starting to define the physical and molecular mechanisms that result in resistance to immunotherapy against pancreatic cancer, and we anticipate that our work will be applicable to other solid tumors with similar challenges and address key unanswered question in cancer biology.

Citation Format: Shambojit Roy, Zhongming Chen, Guhan Qian, Paolo P. Provenzano. T cell movement through complex obstacles presented by the microenvironment of pancreatic tumor spheroids [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C022.
Abstract C033: The circadian rhythm gene Dec2 promotes pancreatic cancer dormancy by facilitating immune evasion
Authors: Wang Lan , Prela Orjola , Shih Ching-Hua , de Menezes Juliana Cazarin , Altman Brian , Vertino Paula , Harris Chris , Carpizo Darren
Published: January 2024

Metastatic recurrence following curative-intent pancreatic cancer surgery is a major clinical problem as nearly all die of this at both early and latent periods following surgery. Latent recurrences are due to reactivation of dormant tumor cells that disseminate before the primary tumor has been removed. The mechanisms that drive cancer dormancy are poorly understood in part because of the lack of animal models that recapitulate the biology of the resected patient. Here we introduce a novel mouse model of pancreatic cancer dormancy in which we establish distal pancreatic tumors by orthotopic injection, resect them four weeks later and then follow the mice for recurrence. We observed recurrence patterns and survival outcomes that mimic human patients undergoing surgery for pancreatic cancer where two thirds of the mice succumb to early metastatic recurrence (median survival 26 days) and one third of the mice (called dormant mice) live substantially long (median survival 554 days) without clinical evidence of disease yet harbor disseminated tumor cells in most organs of the body. Disseminated tumor cells isolated from the livers of dormant mice were quiescent, exhibited stem cell properties and upregulated the expression of Dec2, a transcriptional repressor previously best known for its importance in maintaining circadian rhythms. Dec2 enabled the dormant tumor cells to evade the immune system by reducing the amount of MHC1 on their surfaces, and thereby lowered the number of CD8+ T cells within the tumor microenvironment. Knocking out Dec2 significantly improved the overall survival of immunocompetent mice and increased CD8+ T cell tumor infiltration. The decrease in cell surface MHCI was likely due to impaired surface localization of the protein. RNA-seq analysis demonstrated a loss of antigen presentation pathway genes in Dec2 WT cells, particularly in genes encoding subunits of the proteasome. Proper localization of MHC1 is known to depend upon proteasome-generated peptides. By cut-and-run analysis, Dec2 bound directly to the promoters of a number of proteasomal genes, lowered expression of these genes, and decreased proteasomal activity. These studies describe a new mechanism for Dec2 in regulating cancer dormancy through its downregulation of proteasomal activity which in turn converts a hot to a cold TME by decreasing cell surface MHC1.

Citation Format: Lan Wang, Orjola Prela, Ching-Hua Shih, Juliana Cazarin de Menezes, Brian Altman, Paula Vertino, Chris Harris, Darren Carpizo. The circadian rhythm gene Dec2 promotes pancreatic cancer dormancy by facilitating immune evasion [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C033.
Abstract C040: Investigating oncogene-inflammation cooperativity in pancreatic cancer
Authors: Woess Katharina , Araguás Sandra Blázquez , Diéguez Andrea , Mateo Lidia , Curbelo Direna Alonso
Published: January 2024

Pancreatic ductal adenocarcinoma (PDAC) is generally diagnosed at advanced late stages when current treatments are usually ineffective. It is initiated from a poorly understood interplay between genetic mutations (mutant KRAS) and inflammatory insults that cooperatively remodel the pancreatic epithelium and its tissue environment. Through integrating innovative autochthonous mouse models, single-cell technologies, and genomics methods, we recently identified early, tumor-specific chromatin changes induced by cooperative effects between mutant KRAS and inflammation, and which establish functionally-relevant cell-cell communication networks that direct pancreatic tumorigenesis (Alonso-Curbelo et al. Nature 2021; Burdziak*, Alonso-Curbelo* et al. Science 2023). These findings provide a molecular and cellular framework to understand inflammation-driven tumorigenesis, and raise the possibility of harnessing epigenetically-dysregulated cell-cell communication traits of KRAS-mutant cells to detect or block PDAC development. Towards this end, we are currently combining single-cell multiomics, multiplexed tissue analyses, and functional approaches in pre-clinical models to identify how tissue signals shape the state and fate of early KRAS-mutant cells, define paracrine effects of these changes in reprogramming the immune microenvironment, and establish the functional significance of these interactions in disease progression. With the advent of inhibitors targeting mutant KRAS, we expect that the proposed dissection of the cell-cell crosstalk networks cooperating with mutant KRAS in driving tumor development will uncover tissue-level mechanisms that may be harnessed for the interception and rationale treatment of PDAC.

Citation Format: Katharina Woess, Sandra Blázquez Araguás, Andrea Diéguez, Lidia Mateo, Direna Alonso Curbelo. Investigating oncogene-inflammation cooperativity in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C040.
Abstract C046: Enhancing T cell infiltration and migration in the pancreatic tumor microenvironment
Authors: Zhang Hongrong , Qian Guhan , Chen Zhongming , Moriarity Branden , Stromnes Ingunn , Odde David , Provenzano Paolo
Published: January 2024

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancers, with a five-year survival rate only increasing from 6% to 12% in the last decade, indicating an urgent need for new therapeutic approaches. In recent years, immunotherapies like chimeric antigen receptor (CAR)-T cell therapy, have demonstrated promising therapeutic results in treating several hematological malignancies. However, the success has been limited in treating solid tumors, especially for PDAC. Factors contributing to this poor response include poor immunogenicity, highly heterogeneous and robust fibrotic and immunosuppressive tumor microenvironments (TMEs). Here, we used state-of-the-art imaging coupled with quantitative analysis to study dynamic T cell migration behavior in organotypic pancreatic tumor slices harvested from genetically engineered KPC mice. Our data showed that T cell speed and overall motility are both significantly lower in stroma-rich region PDA regions than observations in carcinoma cell-rich regions, where collagen fibers are loosely connected. Next, we utilized stroma-targeted approaches to deplete collagen and hyaluronan, the most abundant ECM components in the TME, to remove the biophysical barriers for effective immune therapy. Indeed, preliminary data demonstrated improved T cell infiltration and migration in the tumor slices in the STT-treated groups compared to the control groups. The observation is also confirmed with a therapeutic cell line generated with mesothelin-specific T cell receptors. Furthermore, we utilized genome engineering to generate CD8+ T cells that more effectively migrate in fibrous TMEs. Time-lapse imaging of the engineered T cells shows an increased 3D migration compared to control groups. Taken together, our data suggest that engineered T cell approaches in combination with stromal targeted therapies to diminish stromal ECM content have the potential to improve immunotherapy by allowing effector T cells to sample the tumor volume more effectively.

Citation Format: Hongrong Zhang, Guhan Qian, Zhongming Chen, Branden Moriarity, Ingunn Stromnes, David Odde, Paolo Provenzano. Enhancing T cell infiltration and migration in the pancreatic tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C046.
Abstract C058: Identifying cell-intrinsic drivers of transcriptional plasticity in pancreatic cancer
Authors: Tong Yuzhou Evelyn , Katan Walaa E. , Bott Alex , Joung Julia , Shalek Alex K. , Winter Peter S. , Raghavan Srivatsan
Published: January 2024

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with few effective therapies. Contributing to the complexity of this deadly cancer, PDAC tumors with similar genomic backgrounds can express divergent transcriptional programs with clinical importance. These transcriptional subtypes, termed “cell states”, have prognostic significance: PDAC tumors in the “classical state” generally have better outcomes and are thought to be more responsive to chemotherapy while those in the “basal state” are more aggressive. Currently, cell state is not used to direct therapy. Cell state is an integrative property shaped by both cell-intrinsic (e.g., mutations, epigenetics) and cell-extrinsic (e.g., growth factors, cytokines) factors. In our prior work, single-cell analysis of clinical PDAC samples demonstrated notable intra-tumoral cell state heterogeneity with evidence for cells that co-expressed both basal and classical markers, suggestive of cell state plasticity. In addition, longitudinal monitoring of patient-derived organoids has shown that cells can shift from classical to coexpressor/basal states as the environment changes, and this shift in cell states can drastically influence drug response. However, it remains unknown which signaling and transcriptional pathways induce basal or classical states, and whether these gene regulatory networks can be targeted therapeutically. Thus, there is a pressing need to devise scalable methods to determine essential drivers for prognostically-relevant cancer cell states. Here, we aim to define transcriptional drivers of basal and classical cell states in pancreatic cancer. We are currently optimizing a flow cytometry-fluorescence in situ hybridization (Flow-FISH) workflow to enable a multi-gene cell state readout. We plan to perform a transcription factor over-expression screen within a cohort of PDAC models using this Flow-FISH readout to identify those factors that can drive cells toward basal (n=3), classical (n=2), or coexpressor (n=3) states. As a proof of concept, we have confirmed that TP63A overexpression induces basal state expression, even in models that initially express a classical phenotype. Through these efforts, we aim to construct high-fidelity isogenic but state-variant PDAC models for use both in therapeutic screening and as a substrate for investigating mechanisms governing cancer cell state plasticity.

Citation Format: Yuzhou Evelyn Tong, Walaa E. Katan, Alex Bott, Julia Joung, Alex K. Shalek, Peter S. Winter, Srivatsan Raghavan. Identifying cell-intrinsic drivers of transcriptional plasticity in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C058.
Abstract C066: Metaplastic tuft cells transdifferentiate into metaplastic neuroendocrine cells as pancreatic cancer progresses into late stage carcinoma
Authors: Salas-Escabillas Daniel J. , Moore Jacee , Long Dan , Hoffman Megan , Rempinski Don , Steele Nina , Crawford Howard
Published: January 2024

Progression of pancreatic disease is in part driven by the transdifferentiation of acinar cells into metaplastic ducts in the pancreas. Metaplastic tuft cells (MTCs) are a specialized subset of the metaplastic epithelium that have the potential to drive tumor progression through communication with the microenvironment and modulate PDA progression. Also known as solitary chemosensory cells, tuft cells were first discovered in rodent luminal surfaces, including the nose, stomach, intestine, and bladder, more than 60 years ago. They are characterized by the “tuft” of microvilli reaching into the lumen and, only recently, have studies started to determine the role of normal tuft cells in different organs. These studies determined that tuft cells have different roles depending on the organ in which they reside. Tuft cells are found in several different organs during normal development; however, studies have shown that tuft cells are not present in a normal pancreas. MTCs are only present in the pancreas in PanINs during PDA progression in both humans and mice. Furthermore, the population of MTCs in the pancreas disappears as PDA progresses into invasive carcinoma when using canonical markers of tuft cells. We know little about the role of MTCs in the pancreas, but prior studies have suggested their role as a progenitor cell during PDA. However, these studies do not exclusively mark MTCs during their genesis in a progressive model to of PDA due to a lack of mouse model as well as the complexity of culturing them ex vivo. We have generated a unique dual recombinase mouse model to drive lineage tracing of MTCs during PDA, and our data to suggests that MTCs are not disappearing as PDA progresses but can transdifferentiate into metaplastic neuroendocrine cells.

Citation Format: Daniel J. Salas-Escabillas, Jacee Moore, Dan Long, Megan Hoffman, Don Rempinski, Nina Steele, Howard Crawford. Metaplastic tuft cells transdifferentiate into metaplastic neuroendocrine cells as pancreatic cancer progresses into late stage carcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C066.
Abstract C078: Inhibiting the autophagy-lysosomal pathway in pancreatic ductal adenocarcinoma using novel small molecules
Authors: Ruan Yangjingyi , Worroll Daniel W. , Nelson Grady , Li Yue-Ming
Published: January 2024

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers with a 5-year survival rate of 11.5% due to poor early detection and a lack of effective therapies. To meet the energetic demands, PDAC relies on autophagy to sustain growth and proliferation. Autophagy inhibitors such as hydroxychloroquine (HCQ) only showed limited autophagy inhibition in vivo and failed to provide clinical benefit to patients. However, studies have shown that the combination of HCQ and the MEK/ERK inhibitors can render better therapeutic results with stronger cytotoxicity. Our lab has designed and developed a class of small molecules (GN compounds) that target the autophagy-lysosomal pathway (ALP). Our GN compounds show autophagy inhibition and induction of extrinsic apoptosis markers by Western blot. Furthermore, GN64 affects the function of endosomes and lysosomes by immunofluorescence (IF). The combination treatment of GN79 and Binimetinib, a MEKi, inhibits the ALP and confers enhanced cytotoxicity in a panel of human PDAC cell lines. Future directions are aimed at determining the protein target and mechanism of GN compounds that leads to ALP inhibition. Completion of this project will advance the therapeutic development of novel ALP inhibitors and advance our understanding of the ALP with the possibility to imrpove the current therapeutic regimen for PDAC patients.

Citation Format: Yangjingyi Ruan, Daniel W. Worroll, Grady Nelson, Yue-Ming Li. Inhibiting the autophagy-lysosomal pathway in pancreatic ductal adenocarcinoma using novel small molecules [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C078.
Abstract C091: Harnessing proteostatic vulnerabilities in pancreatic cancer
Authors: Vogt Sandra , Bar-Sagi Dafna
Published: January 2024

Pancreatic ductal adenocarcinoma (PDAC) harbors mutations in KRAS in greater than 90% of cases and is characterized by a dense, fibrotic stroma that fosters the formation of a hypoxic, nutrient-poor tumor microenvironment, rendering tumor cells susceptible to proteotoxic stress. In order to prevent endoplasmic reticulum (ER) stress-induced cell death caused by accumulation of toxic protein aggregates, tumor cells must adapt proteostatic mechanisms including activation of the unfolded protein response (UPR) pathway and degradation of misfolded or aggregated proteins through proteasome-dependent or -independent mechanisms, such as ER-specific autophagy (ERphagy). Despite evidence suggesting that tumor cells may experience proteotoxic stress, little is known about the mechanisms pancreatic cancer cells employ to maintain proteostasis. We found that pancreatic cancer cells exhibit KRas-dependent constitutive UPR activation at the expense of ERphagy, suggesting that tumor cells preferentially employ UPR signaling to maintain proteostasis. Accordingly, mutant KRas pancreatic cancer cells have little to no aggregated proteins at baseline as a consequence of UPR activation. Furthermore, upon pharmacological enhancement of ER stress by 26S proteasome inhibition with bortezomib, ERphagy is engaged as a protective mechanism against UPR hyperactivation and apoptosis. In order to target protective ERphagy to promote apoptosis, we suppressed ERphagy activation through siRNA-mediated knockdown of ERphagy receptors under conditions of bortezomib-induced ER stress and found that depletion of CCPG1 but not other ERphagy receptors augmented the growth-suppressive effects of bortezomib due to greater UPR activation and accumulation of aggregated proteins. Overall, our findings implicate context-dependent reliance on both UPR signaling and ERphagy in pancreatic cancer cell survival and identify a targetable cell-intrinsic vulnerability that can leveraged for enhancing the cytotoxic effects of bortezomib, which alone is clinically ineffective in treating PDAC.

Citation Format: Sandra Vogt, Dafna Bar-Sagi. Harnessing proteostatic vulnerabilities in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C091.
Abstract PR14: Ex vivo models of pancreatic cancer that recapitulate the metabolic tumor microenvironment identify glycine as a chemoresistance-inducing oncometabolite
Authors: Cognet Guillaume , Sheehan Colin , Croley Grace , Hu Lyndon , Muir Alexander
Published: January 2024

Pancreatic adenocarcinoma (PDAC) tumors are poorly perfused due to intense desmoplasia and dysfunctional vasculature. This limited perfusion leads to abnormal availability of nutrients and metabolic substrates in the tumor microenvironment. To understand how microenvironmetnal nutrient availability impacts PDAC biology, we performed quantitative metabolomics of the interstitial fluid (the local perfusate) of PDAC tumors to comprehensively characterize nutrient availability in the PDAC microenvironment. We have used this information to develop Tumor Interstitial Fluid Medium (TIFM), a cell culture medium that contains nutrient levels representative of the PDAC microenvironment, enabling the study of PDAC biology under physiological nutrition. By transcriptomic analysis, we show that PDAC cells cultured in TIFM, compared to standard ex vivo models, adopt a cellular state more similar to PDAC cells in tumors, identifying TME nutrient availability as a key microenvironmental factor regulating PDAC biology in vivo. Given that PDAC cells in TIFM adopt an in vivo-like cell state, we next asked if PDAC cells in TIFM would exhibit phenotypes that PDAC cells primarily exhibit in vivo, such as resistance to chemotherapeutic treatment. We found that TIFM culture dramatically increases the resistance of PDAC cells to chemotherapeutic challenge. As TIFM is chemically defined, we systemically screened microenvironmental nutrient cues to identify those triggering therapy resistance. We found that glycine, an amino acid that accumulates to high levels in the PDAC microenvironment, was necessary and sufficient to cause PDAC therapy resistance. Glycine, at the concentrations found in the PDAC microenvironment, has been found to broadly cytoprotective by inhibiting cell death elicited by diverse cellular stresses. In mechanistic experiments, we similarly find that microenvironmental glycine does not prevent chemotherapeutic damage of PDAC cells but blocks cell death in response to this damage. Thus, we propose glycine is a novel oncometabolite that PDAC tumors accumulate, enabling them to cope with diverse stresses, including chemotherapeutic challenge. Altogether, these data show that nutrient availability in the microenvironment is an important determinant of PDAC biology, and models incorporating tumor nutrition can enable mechanistic study of microenvironmentally-programmed PDAC phenotypes.

Citation Format: Guillaume Cognet, Colin Sheehan, Grace Croley, Lyndon Hu, Alexander Muir. Ex vivo models of pancreatic cancer that recapitulate the metabolic tumor microenvironment identify glycine as a chemoresistance-inducing oncometabolite [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr PR14.