Pancreatic Tumor Cells Research Articles

Kinome state is predictive of cell viability in pancreatic cancer tumor and cancer-associated fibroblast cell lines.

Numerous aspects of cellular signaling are regulated by the kinome-the network of over 500 protein kinases that guides and modulates information transfer throughout the cell. The key role played by both individual kinases and assemblies of kinases organized into functional subnetworks leads to kinome dysregulation driving many diseases, particularly cancer. In the case of pancreatic ductal adenocarcinoma (PDAC), a variety of kinases and associated signaling pathways have been identified for their key role in the establishment of disease as well as its progression. However, the identification of additional relevant therapeutic targets has been slow and is further confounded by interactions between the tumor and the surrounding tumor microenvironment. In this work, we attempt to link the state of the human kinome, or kinotype, with cell viability in treated, patient-derived PDAC tumor and cancer-associated fibroblast cell lines. We applied classification models to independent kinome perturbation and kinase inhibitor cell screen data, and found that the inferred kinotype of a cell has a significant and predictive relationship with cell viability. We further find that models are able to identify a set of kinases whose behavior in response to perturbation drive the majority of viability responses in these cell lines, including the understudied kinases CSNK2A1/3, CAMKK2, and PIP4K2C. We next utilized these models to predict the response of new, clinical kinase inhibitors that were not present in the initial dataset for model devlopment and conducted a validation screen that confirmed the accuracy of the models. These results suggest that characterizing the perturbed state of the human protein kinome provides significant opportunity for better understanding of signaling behavior and downstream cell phenotypes, as well as providing insight into the broader design of potential therapeutic strategies for PDAC.

Epidermal Growth Factor Receptor (EGFR) Inhibitors Screened from Autodisplayed Fv-Antibody Library.

Inhibitors of the epithermal growth factor receptor (EGFR) were screened from an autodisplayed Fv-antibody library using an anti-EGF antibody. The Fv-antibody library was expressed on the outer membrane of Escherichia coli, which corresponds to the heavy chain VH region of immunoglobulin G. The library was constructed by randomizing the CDR3 region of expressed VH regions (11 amino acid residues) by site-directed mutagenesis. Using an anti-EGF antibody as a screening probe, amino acid sequences (CDR3 region) with antibody binding affinity were screened from the Fv-antibody library. These amino acid sequences were considered to have similar chemical properties to EGF, which can bind to EGFR. Two autodisplayed clones with Fv-antibodies against EGFR were screened from the Fv-antibody library, and the screened Fv-antibodies were expressed as soluble proteins. The binding affinity (KD) was estimated using an SPR biosensor, and the inhibitory activity of expressed Fv-antibodies was observed for PANC-1 pancreatic tumor cells and T98G glioblastoma cells using Western blot analysis of proteins in the EGFR-mediated signaling pathway. The viability of PANC-1 and T98G cells was observed to decrease via the inhibitory activity of expressed Fv-antibodies. Finally, interactions between Fv-antibodies and EGFR were analyzed by using molecular docking simulations.

The Wdr5-H3K4me3 Epigenetic Axis Regulates Pancreatic Tumor Immunogenicity and Immune Suppression.

The WDR5/MLL1-H3K4me3 epigenetic axis is often activated in both tumor cells and tumor-infiltrating immune cells to drive various cellular responses in the tumor microenvironment and has been extensively studied in hematopoietic cancer, but its respective functions in tumor cells and immune cells in the context of tumor growth regulation of solid tumor is still incompletely understood. We report here that WDR5 exhibits a higher expression level in human pancreatic tumor tissues compared with adjacent normal pancreas. Moreover, WDR5 expression is negatively correlated with patients' response to chemotherapy or immunotherapy in human colon cancer and melanoma. However, WDR5 expression is positively correlated with the HLA level in human cancer cells, and H3K4me3 enrichment is observed at the promoter region of the HLA-A, HLA-B, and HLA-C genes in pancreatic cancer cells. Using mouse tumor cell lines and in vivo tumor models, we determined that WDR5 deficiency or inhibition significantly represses MHC I expression in vitro and in vivo in pancreatic tumor cells. Mechanistically, we determine that WDR5 deficiency inhibits H3K4me3 deposition at the MHC I (H2K) promoter region to repress MHC I (H2K) transcription. On the other hand, WDR5 depletion leads to the effective downregulation of immune checkpoints and immunosuppressive cytokines, including TGFβ and IL6, in the pancreatic tumor microenvironments. Our data determine that WDR5 not only regulates tumor cell immunogenicity to suppress tumor growth but also activates immune suppressive pathways to promote tumor immune evasion. Selective activation of the WDR5-MHC I pathway and/or selective inhibition of the WDR5-immune checkpoint and WDR5-cytokine pathways should be considered in WDR5-based epigenetic cancer immunotherapy.

Adhesion of pancreatic tumor cell clusters by desmosomal molecules enhances early liver metastases formation

Desmosomes are intercellular adhesion complexes providing mechanical coupling and tissue integrity. Previously, a correlation of desmosomal molecule expression with invasion and metastasis formation in several tumor entities was described together with a relevance for circulating tumor cell cluster formation. Here, we investigated the contribution of the desmosomal core adhesion molecule desmoglein-2 (DSG2) to the initial steps of liver metastasis formation by pancreatic cancer cells using a novel ex vivo liver perfusion mouse model. We applied the pancreatic ductal adenocarcinoma cell line AsPC-1 with and without a knockout (KO) of DSG2 and generated mouse lines with a hepatocyte-specific KO of the known interacting partners of DSG2 (DSG2 and desmocollin-2). Liver perfusion with DSG2 KO AsPC-1 cells led to smaller circulating cell clusters and a reduced number of cells adhering to murine livers compared to control cells. While this was independent of the expression levels of desmosomal adhesion molecules in hepatocytes, we show that increased cluster size of cancer cells, which correlates with stronger cell–cell adhesion and expression of desmosomal molecules, is a major factor contributing to the early phase of metastatic spreading. In conclusion, impaired desmosomal adhesion results in reduced circulating cell cluster size, which is relevant for seeding and attachment of metastatic cells to the liver.

The YY1-CPT1C signaling axis modulates the proliferation and metabolism of pancreatic tumor cells under hypoxia

Carnitine palmitoyltransferase 1C (CPT1C) is an enzyme that regulates tumor cell proliferation and metabolism by modulating mitochondrial function and lipid metabolism. Hypoxia, commonly observed in solid tumors, promotes the proliferation and progression of pancreatic cancer by regulating the metabolic reprogramming of tumor cells. So far, the metabolic regulation of hypoxic tumor cells by CPT1C and the upstream mechanisms of CPT1C remain poorly understood. Yin Yang 1 (YY1) is a crucial oncogene for pancreatic tumorigenesis and acts as a transcription factor that is involved in multiple metabolic processes. This study aimed to elucidate the relationship between YY1 and CPT1C under hypoxic conditions and explore their roles in hypoxia-induced proliferation and metabolic alterations of tumor cells. The results showed enhancements in the proliferation and metabolism of PANC-1 cells under hypoxia, as evidenced by increased cell growth, cellular ATP levels, up-regulation of mitochondrial membrane potential, and decreased lipid content. Interestingly, knockdown of YY1 or CPT1C inhibited hypoxia-induced rapid cell proliferation and vigorous cell metabolism. Importantly, for the first time, we reported that YY1 directly activated the transcription of CPT1C and clarified that CPT1C was a novel target gene of YY1. Moreover, the YY1 and CPT1C were found to synergistically regulate the proliferation and metabolism of hypoxic cells through transfection with YY1 siRNA to CRISPR/Cas9-CPT1C knockout PANC-1 cells. Taken together, these results indicated that the YY1-CPT1C axis could be a new target for the intervention of pancreatic cancer proliferation and metabolism.

Down-Regulation of AKT Proteins Slows the Growth of Mutant-KRAS Pancreatic Tumors.

Serine/threonine kinase AKT isoforms play a well-established role in cell metabolism and growth. Most pancreatic adenocarcinomas (PDACs) harbor activation mutations of KRAS, which activates the PI3K/AKT signaling pathway. However, AKT inhibitors are not effective in the treatment of pancreatic cancer. To better understand the role of AKT signaling in mutant-KRAS pancreatic tumors, this study utilized proteolysis-targeting chimeras (PROTACs) and CRISPR-Cas9-genome editing to investigate AKT proteins. The PROTAC down-regulation of AKT proteins markedly slowed the growth of three pancreatic tumor cell lines harboring mutant KRAS. In contrast, the inhibition of AKT kinase activity alone had very little effect on the growth of these cell lines. The concurrent genetic deletion of all AKT isoforms (AKT1, AKT2, and AKT3) in the KPC (KrasG12D; Trp53R172H; Pdx1-Cre) pancreatic cancer cell line also dramatically slowed its growth in vitro and when orthotopically implanted in syngeneic mice. Surprisingly, insulin-like growth factor-1 (IGF-1), but not epidermal growth factor (EGF), restored KPC cell growth in serum-deprived conditions, and the IGF-1 growth stimulation effect was AKT-dependent. The RNA-seq analysis of AKT1/2/3-deficient KPC cells suggested that reduced cholesterol synthesis may be responsible for the decreased response to IGF-1 stimulation. These results indicate that the presence of all three AKT isoforms supports pancreatic tumor cell growth, and the pharmacological degradation of AKT proteins may be more effective than AKT catalytic inhibitors for treating pancreatic cancer.

Kaempferide triggers apoptosis and paraptosis in pancreatic tumor cells by modulating the ROS production, SHP-1 expression, and the STAT3 pathway.

Pancreatic cancer is one of the deadliest diseases with a poor prognosis and a five-survival rate. The STAT3 pathway is hyperactivated which contributes to the sustained proliferative signals in pancreatic cancer cells. We have isolated kaempferide (KF), an O-methylated flavonol, from the green propolis of Mimosa tenuiflora and examined its effect on two forms of cell death namely, apoptosis and paraptosis. KF significantly increased the cleavage of caspase-3 and PARP. It also downmodulated the expression of Alix (an intracellular inhibitor of paraptosis) and increased the expression of CHOP and ATF4 (transcription factors that promote paraptosis) indicating that KF promotes apoptosis as well as paraptosis. KF also increased intracellular reactive oxygen species (ROS) suggesting the perturbance of the redox state. N-acetylcysteine reverted the apoptosis- and paraptosis-inducing effects of KF. Some ROS inducers are known to suppress the STAT3 pathway and investigation revealed that KF downmodulates STAT3 and its upstream kinases (JAK1, JAK2, and Src). Additionally, KF also elevated the expression of SHP-1, a tyrosine phosphatase which is involved in the negative modulation of the STAT3 pathway. Knockdown of SHP-1 prevented KF-driven STAT3 inhibition. Altogether, KF has been identified as a promoter of apoptosis and paraptosis in pancreatic cancer cells through the elevation of ROS generation and SHP-1 expression.

642: Characterization of radiation response of pancreatic tumor cells in correlation with MYC expression

642: Characterization of radiation response of pancreatic tumor cells in correlation with MYC expression

E2F transcription factors promote tumorigenicity in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers with limited treatment options, illustrating an urgent need to identify new drugable targets in PDACs. Using the similarities between tumor development and normal embryonic development, which is accompanied by rapid cell expansion, we aimed to identify and characterize embryonic signaling pathways that were reinitiated during tumor formation and expansion. Here, we report that the transcription factors E2F1 and E2F8 are potential key regulators in PDAC. E2F1 and E2F8 RNA expression is mainly localized in proliferating cells in the developing pancreas and in malignant ductal cells in PDAC. Silencing of E2F1 and E2F8 in PANC-1 pancreatic tumor cells inhibited cell proliferation and impaired cell spreading and migration. Moreover, loss of E2F1 also affected cell viability and apoptosis with E2F expression in PDAC tissues correlating with expression of apoptosis and mitosis pathway genes, suggesting that E2F factors promote cell cycle regulation and tumorigenesis in PDAC cells. Our findings illustrate that E2F1 and E2F8 transcription factors are expressed in pancreatic progenitor and PDAC cells, where they contribute to tumor cell expansion by regulation of cell proliferation, viability, and cell migration making these genes attractive therapeutic targets and potential prognostic markers for pancreatic cancer.

Expression of versican isoforms V0/V1 by pancreatic cancer associated fibroblasts increases fibroblast proliferation

BackgroundVersican is a large extracellular matrix (ECM) proteoglycan with four isoforms V0-3. Elevated V0/V1 levels in breast cancer and glioma regulate cell migration and proliferation, but the role of versican in pancreatic ductal adenocarcinoma (PDAC) remains unclear. MethodsIn this study, we evaluated the expression levels of versican isoforms, as well as their cellular source and interacting partners, in vivo, in human and mouse primary and metastatic PDAC tumours and in vitro, in pancreatic tumour cells and fibroblasts using immunostaining, confocal microscopy and qPCR techniques. We also investigated the effect of versican expression on fibroblast proliferation and migration using genetic and pharmacological approaches. ResultsWe found that versican V0/V1 is highly expressed by cancer-associated fibroblasts (CAFs) in mouse and human primary and metastatic PDAC tumours. Our data also show that exposing fibroblasts to tumour-conditioned media upregulates V0 and V1 expressions, while Verbascoside (a CD44 inhibitor) downregulates V0/V1 expression. Importantly, V0/V1 knockdown significantly inhibits fibroblast proliferation. Mechanistically, we found that inhibiting hyaluronan synthesis does not affect versican co-localisation with CD44 in fibroblasts. ConclusionCAFs express high levels of versican V0/V1 in primary and liver metastatic PDAC tumours and versican V0/V1 supports fibroblast proliferation.

Interrogating Matrix Stiffness and Metabolomics in Pancreatic Ductal Carcinoma Using an Openable Microfluidic Tumor-on-a-Chip.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense fibrotic stroma that contributes to aggressive tumor biology and therapeutic resistance. Current in vitro PDAC models lack sufficient optical and physical access for fibrous network visualization, in situ mechanical stiffness measurement, and metabolomic profiling. Here, we describe an openable multilayer microfluidic PDAC-on-a-chip platform that consists of pancreatic tumor cells (PTCs) and pancreatic stellate cells (PSCs) embedded in a 3D collagen matrix that mimics the stroma. Our system allows fibrous network visualization via reflected light confocal (RLC) microscopy, in situ mechanical stiffness testing using atomic force microscopy (AFM), and compartmentalized hydrogel extraction for PSC metabolomic profiling via mass spectrometry (MS) analysis. In comparing cocultures of gel-embedded PSCs and PTCs with PSC-only monocultures, RLC microscopy identified a significant decrease in pore size and corresponding increase in fiber density. In situ AFM indicated significant increases in stiffness, and hallmark characteristics of PSC activation were observed using fluorescence microscopy. PSCs in coculture also demonstrated localized fiber alignment and densification as well as increased collagen production. Finally, an untargeted MS study putatively identified metabolic contributions consistent with in vivo PDAC studies. Taken together, this platform can potentially advance our understanding of tumor-stromal interactions toward the discovery of novel therapies.

Abstract CT134: Safety and immunologic impact of neoadjuvant/adjuvant GM-CSF-secreting allogenic pancreatic tumor cell vaccine (GVAX) combined with cyclophosphamide, pembrolizumab, and macrophage-targeting CSF1R inhibitor IMC-CS4 in pancreatic adenocarcinoma

Abstract Background: Strategies are needed to improve effectiveness of immunotherapy in pancreatic ductal adenocarcinoma (PDA). Our recently published study (NCT02648282) showed that increased M1/M2 ratio and decreased PDL1+ M2-like tumor associated macrophages (TAM) in locally advanced PDA is associated with longer overall survival (OS) following combination of stereotactic body radiotherapy, GVAX and anti-PD1 antibody pembrolizumab (Pem). We hypothesized targeting M2-like macrophages, regulated by the colony stimulating factor-1 (CSF1) pathway, would improve outcomes. In this pilot study we investigated the safety and intratumoral immune response of neoadjuvant/adjuvant triplet immunotherapy: GVAX/cyclophosphamide (CY), Pem, and CSF1 receptor blockade (IMC-CS4) in patients with resectable or borderline resectable PDA. Methods: After completing chemotherapy and radiation patients received two 3-week cycles of neoadjuvant triplet immunotherapy. Following surgery, patients received 4 additional cycles followed by booster Pem every 3 weeks and GVAX/CY every 6 months, for one year. Co-primary endpoints were safety, assessed by NCI Common Terminology Criteria for Adverse Events (AEs), and immune response (increased CD8+ T-cell density in surgical specimen as compared to pre-treatment core). Secondary endpoints included disease free survival (DFS), OS, surgical resectability, and pathologic response (PR). Results: Nine patients were enrolled. Two immune related grade 3/4 AEs (diarrhea and rash) were reported. Median DFS was 12.6 months (95% CI: 7.3, NR) and median OS was 20.4 months (95% CI: 17.5, NR). All patients underwent surgery with major PR rate of 78% (defined as <10% residual viable tumor), including one complete PR. Comparing paired biopsies, the study met its primary immunologic endpoint showing 6/8 patients (75%) had a >80% increase of CD8+ T cells; the increase was at least 1.8 times the baseline median absolute deviation following triple therapy (p=0.012). There was a significant increase of Granzyme B+ CD8+ T cells among all patients (p=0.045). No significant change in myeloid cell density, including TAM, was observed, suggesting IMC-CS4 did not deplete macrophages, but potentially reprogrammed them. The 4 patients with greatest drop in CD66b+ granulocyte levels had major PR (grade 0 or 1). Conclusion: The triplet was safe and significantly increased activated CD8+ T cells suggesting the combination can induce an effector T cell response. Decreased granulocyte levels correlated with PR. Citation Format: Arielle Urman, Yingjun Ding, Hao Wang, Richard A. Burkhart, Jin He, Elizabeth M. Jaffee, Amol K. Narang, Dung Le, Daniel A. Laheru, Lei Zheng, Ana De Jesus-Acosta. Safety and immunologic impact of neoadjuvant/adjuvant GM-CSF-secreting allogenic pancreatic tumor cell vaccine (GVAX) combined with cyclophosphamide, pembrolizumab, and macrophage-targeting CSF1R inhibitor IMC-CS4 in pancreatic adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT134.

Tumor cell-intrinsic epigenetic dysregulation shapes cancer-associated fibroblasts heterogeneity to metabolically support pancreatic cancer

The tumor microenvironment (TME) in pancreatic ductal adenocarcinoma (PDAC) involves a significant accumulation of cancer-associated fibroblasts (CAFs) as part of the host response to tumor cells. The origins and functions of transcriptionally diverse CAF populations in PDAC remain poorly understood. Tumor cell-intrinsic genetic mutations and epigenetic dysregulation may reshape the TME; however, their impacts on CAF heterogeneity remain elusive. SETD2, a histone H3K36 trimethyl-transferase, functions as a tumor suppressor. Through single-cell RNA sequencing, we identify a lipid-laden CAF subpopulation marked by ABCA8a in Setd2-deficient pancreatic tumors. Our findings reveal that tumor-intrinsic SETD2 loss unleashes BMP2 signaling via ectopic gain of H3K27Ac, leading to CAFs differentiation toward lipid-rich phenotype. Lipid-laden CAFs then enhance tumor progression by providing lipids for mitochondrial oxidative phosphorylation via ABCA8a transporter. Together, our study links CAF heterogeneity to epigenetic dysregulation in tumor cells, highlighting a previously unappreciated metabolic interaction between CAFs and pancreatic tumor cells.

Abstract 4463: Metabolic reprogramming through Notch1 signaling promotes a survival advantage in pancreatic neuroendocrine tumor cells

Abstract Background: Cancer cells utilize both oxidative phosphorylation (OXPHOS) and glycolysis to generate energy. Switching between OXPHOS and glycolysis can promote tumor progression. The mechanisms governing oncogenic metabolic reprogramming are largely unknown, but recent data has suggested that Notch1 dysregulation in cancer cells can contribute to altered metabolic phenotypes. We hypothesized that Notch1 signaling supports metabolic reprogramming in pancreatic neuroendocrine tumor (pNET) cells. Methods: We established a Notch1-knockout pNET cell line (BON-N1-KO) by deleting Notch1 at exon 3 in a pNET cell line (BON) using CRISPR/Cas9. Proliferation over time was measured using a trypan blue exclusion test. Seahorse Glycolytic Rate Assay and Mitochondria Stress Test were used to measure the glycolytic and mitochondrial activities of cells. A glycolysis deprivation assay was employed to determine cell viability at varying glucose concentrations. Single end RNAseq was performed using the Illumina NGS platform, to a read depth of 50M. Results: Over time, pNET cells lacking Notch1 (BON-N1-KO) proliferated slower than wildtype (WT) cells (p=0.034). Compared to WT BON, the BON-N1-KO cells had reduced basal oxygen consumption rate (28.2 ± 1.3 vs. 40.7 ± 1.4; p=0.02, ATP production (21.9 ± 1.0 vs. 29.6 ± 0.98; p=0.04), and maximal respiration (39.4 ± 1.7 vs. 63.7 ± 2.1; p=0.004). BON-N1-KO cells also had a reduction in basal glycolysis, as measured by proton efflux rate, compared to WT (48.7 ± 2.6 vs. 57.7 ± 6.2; p=0.2). To further test metabolic reprogramming, WT and BON-N1-KO cells were starved of glucose (0mM), compared to normal glucose (17.5mM) and viability was measured over time. By day 5, the BON-N1-KO group had a viability of 0%, whereas 12.8% of WT cells were alive (p=0.038). To determine if Notch1 loss was associated with altered expression of established metabolic genes, we performed RNAseq. Differential gene expression analysis found that OXPHOS-related genes (UQCC2, COX15, COX20) and glycolysis-related genes (Slc1a1, Slc2a4, Hk1, Hk2) were significantly down-regulated in BON-N1-KO cells. Conclusions: Our study shows that Notch1 signaling facilitates metabolic reprogramming as a survival advantage in pNET cells. Targeting Notch1 signaling to mediate cellular metabolism may be a novel therapeutic strategy in pNETs. Citation Format: Rachael Guenter, Weisheng Chen, Brendon Herring, Yuvasri Golivi, Melissa Sammy, Jason Whitt, Renata Jaskula-Sztul, Herbert Chen, J. Bart Rose. Metabolic reprogramming through Notch1 signaling promotes a survival advantage in pancreatic neuroendocrine tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4463.

Abstract 2367: STING agonist ADU-S100 improves the antitumor response of CLDN18.2/CD3 BiTEs by enhancing stem-like tumor-reactive CD8+ T cells in pancreatic adenocarcinoma

Abstract Background: Immunotherapy with CLDN18.2/CD3 BiTEs (bispecific T-cell engagers) has shown clinical activity in pancreatic adenocarcinoma. However, only few patients benefit from the treatment, and most responders develop acquired resistance. STING agonists may promote the development of stem-like central memory CD8+ T cells and enhance antitumor responses. This study aimed to investigate the synergistic effect and related mechanism of STING agonist plus CLDN18.2/CD3 BiTEs regimen. Methods: Single-cell RNA sequencing and flow cytometry were used to examine the tumor immune landscape in humanized PDX mouse models. By qPCR, western blot and flow cytometry, an orthotopic transplantation mouse model of pancreatic cancer and an in vitro tumor-PBMC coculture system were established to reveal the potential molecular mechanism of STING agonist ADU-S100 in optimizing the effects of CLDN18.2/CD3 BiTEs (IBI389). Results: In PDAC organoids, IBI389 induced potent, specific cytotoxicity, the CLDN18.2 BiTEs significantly engaged human CD3+ T cells with tumor cells in an organoid-PBMC coculture system in vitro, resulting in the formation of the immunological synapse (IS). IBI389 monotherapy significantly suppressed tumor growth and improved survival in vivo in hCD3e C57BL/6 and humanized hCD34+ PDX mouse models. Further, single-cell RNA sequencing and flow cytometry analysis revealed that the intertumoral TCF1+PD-1+ stem-like T cells and STING signaling activity of T cells were enriched in the early stage of tumor development and sharply decreased in the late stage during CLDN18.2 BiTEs administration. Furthermore, we discovered that the STING agonist ADU-S100 could significantly induce the enrichment of TCF1+PD-1+ stem-like CD8+ T cells in vitro and in vivo, increasing IBI389’s therapeutic effects. Furthermore, humanized PDX mice that were given the combination of IBI389 and ADU-S100 and survived after complete tumor rejection were rechallenged with PDX tumors. Humanized PDX tumors and hCD3e KPC orthotopic tumors from mice treated with the combination contained increased numbers of TCF1+PD-1+ stem-like CD8+ T cells, CD4+CD127+ memory T cells, CD8+CD127+ memory T cells, and fewer numbers of CD4+PD-1+Tim-3+ exhausted T cells, CD8+PD-1+Tim-3+ exhausted T cells and CD4+CD25+ Treg cells. Conclusions: Pancreatic tumors appear to evade immune response by inducing immune-suppressive tumor microenvironment development. In mice, the combination of STING agonist ADU-S100 and CLDN18.2 BiTEs increased the proportion of memory and stem-like CD4+ and CD8+ T cells while decreasing the proportion of regulatory and exhausted T cells in pancreatic tumors, eradicating all detectable tumors. This data may be utilized to formulate immune-based combination therapies for PDAC. Citation Format: Tianxing Zhou, Jingrui Yan, Bin Wang, Yongjie Xie, Chao Yang, Jun Yu, Jihui Hao. STING agonist ADU-S100 improves the antitumor response of CLDN18.2/CD3 BiTEs by enhancing stem-like tumor-reactive CD8+ T cells in pancreatic adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2367.

Abstract 2979: Pancreatic cancer cells upregulate LPAR4 in response to isolation stress to create a fibronectin-rich extracellular matrix niche and promote tumor initiation

Abstract Tumor initiation is an inefficient process in which tumor cells must develop cell-autonomous mechanisms to survive harsh microenvironments, establish colonies, and thereby overcome “isolation stress.” We report that pancreatic cancer cells transiently upregulate lysophosphatidic acid receptor 4 (LPAR4), a G-protein coupled receptor, in response to microenvironmental stress or chemotherapy, which promotes stress tolerance, drug resistance, and tumor initiation. Even without exogenous LPA, LPAR4 drives the expression of a subset of extracellular matrix (ECM) genes via an AKT/CREB axis, including fibronectin and versican, which are established drivers of cancer stemness. The upregulation of fibronectin is indispensable for LPAR4-induced tumor initiation in vivo and anchorage-independent growth in vitro. Furthermore, the ligation of this fibronectin-containing ECM created by LPAR4-positive cells via integrins α5β1 or αvβ3 can transfer cancer stemness and stress tolerance to LPAR4-negative cells by activating Yes-associated protein 1 (YAP). Our findings reveal that in response to isolation stress, pancreatic tumor cells that upregulate LPAR4 can autonomously generate a fibronectin-enriched ECM niche and thereby initiate tumor formation. Citation Format: Chengsheng Wu, Taha Rakhshandehroo, Hiromi I. Wettersten, Alejandro Campos, Tami Von Schalscha, Shashi Jain, Ziqi Yu, Jiali Tan, Evangeline Mose, Betzaira G. Childers, Andrew M. Lowy, Sara M. Weis, David A. Cheresh. Pancreatic cancer cells upregulate LPAR4 in response to isolation stress to create a fibronectin-rich extracellular matrix niche and promote tumor initiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2979.

Abstract 6497: Molecular characterization and drug sensitivity of a gastric FGFR2-TACC2 and a pancreatic KRAS p.G12C primary culture

Abstract Introduction and Objectives: Gastric and pancreatic cancers lack effective therapies, leading to low survival rates particularly in the metastatic setting. Fibroblast growth factor receptor 2 (FGFR2) amplification and fusions with TACC2 appear in 5.5% and 2.1% of gastric tumors, respectively. In pancreatic cancers, the KRAS p.G12C mutation is limited to 1-2% of cases. FDA has recently approved drugs targeting both alterations, pemigatinib and infigratinib for cholangiocarcinoma with FGFR2 fusions; sotorasib and adagrasib for KRAS p.G12C mutant lung cancers. Here, we report the initiation of primary cultures that can be used as preclinical models for testing antitumor agents in gastric and pancreatic tumor cells. Materials and Methods: Pleural effusions were collected from a gastric and a pancreatic cancer patient, both metastatic. Cells were isolated by centrifugation, cultured for 2-3 months in complete medium and genotyped using next generation sequencing (NGS) and RNA nCounter hybridization. Primary cultures were treated with specific drugs depending on their molecular alterations and clinical guidelines. Cell viability was determined by MTT. Results: Tumor cells from the pleural effusion of the gastric cancer patient were grown in suspension. NGS and nCounter revealed a FGFR2-TACC2 fusion, a FGFR2 amplification (160 copies) and a TP53 p.G245S mutation (100% variant allele fraction, VAF). The fusion and the amplification were confirmed by FISH. Cells were sensitive to erdafitinib, with IC50=40 nM in MTT assays. Irinotecan, 5-fluorouracil and cisplatin were also tested; IC50 were below the described plasma Cmax in the first two cases. The patient was treated with first-line fluoropyrimidine and oxaliplatin with partial response and a 5-month progression-free survival. Due to rapid deterioration, 2nd line treatment was not administered. The tumor cells from the pancreatic cancer patient were adherent, NGS revealed a KRAS amplification (9 copies) accompanied by a KRAS p.G12C mutation (81% VAF) and a TP53 p.R175H mutation (99% VAF). MTT assays were performed to determine the cells’ response to oxaliplatin, 5-fluorouracil, irinotecan, gemcitabine, nab-paclitaxel, adagrasib and sotorasib. IC50s below plasma Cmax were found in the last three cases. Remarkably, the IC50 for sotorasib was 100 nM and for adagrasib was 300 nM. The patient was treated with first-line gemcitabine and nab-paclitaxel with partial response but discontinued after three months due to hematological toxicity. Conclusions: Primary cultures can be initiated from malignant pleural effusions and used for genetic characterization and drug sensitivity profiling. Primaries with specific alterations can be employed as preclinical models to test targeted therapies. Citation Format: Silvia Garcia-Roman, Ekaterina Meshoulam Nikolaeva, Juan José García Mosquera, Mónica Garzón Ibáñez, Ruth Roman, Sonia Rodríguez, Cristina Rodríguez, Clara Mayo de las Casas, Rafael Rosell, Miguel A. Molina-Vila, Cristina Aguado Esteban. Molecular characterization and drug sensitivity of a gastric FGFR2-TACC2 and a pancreatic KRAS p.G12C primary culture [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6497.

Abstract 4161: Identification of pancreatic adenocarcinoma using urokinase plasminogen activator probe detected using optoacoustic imaging

Abstract Purpose: Diagnosing and treating pancreatic cancer remains a challenge. The hypovascularized nature of pancreatic cancer renders modern chemotherapeutics and cancer detection contrast agents ineffective. A promising approach to the challenges is the adoption of a novel imaging technique known as Multispectral Tomography (MSOT). We hypothesize that a urokinase plasminogen activator (UPA) probe will enhance the detection of orthotopic pancreatic cancer xenografts. Methods: Pancreatic tumor cell lines (Panc1, MiaPaca-2, S2VP10, and S2C9) were assessed for UPA-receptor expression using western blot analysis. UPA peptide was synthesized and to the HiLyte-750 NIR dye. Flow cytometry and immunofluorescence were utilized to examine the specificity and activity of this UPA-750. The UPA-750 binding efficiency was assessed through a competitive inhibition assay with a UPAR-blocking antibody using fluorescence microscopy. Then SCID mice (5 mice/group) received orthotopic implantation of S2C9 (1.5 x 105) or MiaPaCa2 (2.0 × 106) pancreatic tumor cells. UPA-750 or 750 dye alone was IV injected into mice after the tumors reached 3mm. Biodistribution and accumulation of UPA-750 were observed through MSOT images taken at 2-hour intervals over 8 hours and at 24 hours. UPA-750 in the tumor, liver, and kidney was confirmed through ex vivo fluorescent imaging. Results: UPAR expression was observed in every pancreatic cancer cell line, with the greatest relative abundance in S2P9 cells (3.0X), followed by S2VP10 (2.5X), Panc1 (1.77X), and MiaPaca-2 (1.3X). Application of the UPAR blocking antibody on S2CP9, S2VP10, MiaPaCa2, and SKOV3p1 (positive control) cell lines resulted in the inhibition of cellular binding of the UPA-750, as evidenced by fluorescence microscopy. UPA-probe was successfully observed in pancreas tumor slices with peak intensity at 4-hrs of imaging by MSOT. Ex vivo NIR fluorescence imaging confirmed UPA-750 signal in pancreatic tumors but not in liver or kidney. Conclusion: UPA-probe exhibits potential as a marker for pancreatic cancer. Citation Format: Vung Kim, Phillip Chuong, Ryan Bynum, William Grizzle, Lacey R. McNally. Identification of pancreatic adenocarcinoma using urokinase plasminogen activator probe detected using optoacoustic imaging [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4161.

Abstract 6631: Aging influences the pancreatic ductal adenocarcinoma tumor immune microenvironment to promote features of immunosuppression

Abstract Advancing age is the strongest independent risk factor for the development of pancreatic ductal adenocarcinoma (PDAC) and a negative prognostic factor. PDACs are typically immunologically “cold” tumors and do not often respond to currently approved immunotherapy treatment approaches. How aging may alter non-malignant cells, such as fibroblasts and immune cell populations, in the PDAC tumor microenvironment (TME) to decrease anti-tumor immune responses is not understood. We identified that aged microenvironments significantly alter the growth and progression of PDAC tumors. Orthotopic KPC and Panc02 mouse PDAC cell line injections into the pancreata of aged (>64-week-old) compared to young (6-8-week-old) C57BL/6 mice result in more rapid tumor growth and increased frequency of liver metastases in vivo. Tumors from aged mice have high expression of the TGFβ family member GDF-15 and hyperactivation of AKT signaling driven by the release of secreted factors from aged pancreatic fibroblasts. We found that in aged microenvironments there is a marked reduction in the number of CD8+ T cells and an increase in FoxP3+ regulatory T cells in primary orthotopic pancreatic tumors using the KPC and Panc02 models. In addition, we performed portal vein injections to establish liver metastases to study the differences in immune cell infiltration in metastases from young vs. aged microenvironments. Aged mice form more and larger liver metastases compared to young mice, and metastatic lesions in aged mice have decreased CD8+ T cell infiltration when compared to young mice. Since tumors in aged microenvironments have increased AKT activation compared to young microenvironments, we next tested if AKT signaling was sufficient to alter immune cell infiltration in PDAC tumors. In young mice, treatment with recombinant GDF-15, which activates AKT signaling, reduced CD8+ T cell infiltration into tumors. Conversely, in KPC tumors grown in aged mice treated with the AKT inhibitor MK-2206, there was a trend toward increased CD8+ T cell infiltration and a significant reduction in immunosuppressive FoxP3+ Tregs. Together, these data highlight age-dependent differences in the immune infiltration in PDAC tumors. They suggest that activation of AKT signaling can drive features of immunosuppression in PDAC, providing the rationale for targeting AKT signaling to improve antitumor immune responses in PDAC. Citation Format: Emma Kartalia, James M. Leatherman, Jae W. Lee, Elizabeth M. Jaffee, Ashani T. Weeraratna, Daniel J. Zabransky. Aging influences the pancreatic ductal adenocarcinoma tumor immune microenvironment to promote features of immunosuppression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6631.

Abstract 5957: Development of a selective, oral ATP-competitive CDK9 inhibitor, BLX-3030, for treatment of pancreatic cancer

Abstract Introduction Transcription regulators, such as cyclin-dependent kinase 9 (CDK9), have been implicated in the super-enhancer driven transcriptional control of oncogenes in multiple cancers including pancreatic cancer. CDK9 has been shown to be employed by cancer cells for the constant production of short-lived oncoproteins such as c-Myc to maintain their survival. Due to its critical role in regulating transcription in cancer cells, CDK9 has emerged as a potential therapeutic target. Here, we report the antitumor activity of a selective, oral ATP-competitive CDK9 inhibitor, BLX-3030, in preclinical models for pancreatic cancer. Experimental Procedures Fragment-based MolecuLern driven AI workflow methods were used to design a series of ATP-competitive CDK9 specific kinase inhibitors. BLX-3030 was selected as one of the most potent leads with an IC50 of 1.1 nM in a cell-free CDK9 kinase assay. A Sulforhodamine B (SRB) assay was used to evaluate the cell growth inhibitory activity of BLX-3030 in a panel of 10 pancreatic ductal adenocarcinoma (PDAC) and 2 pancreatic neuroendocrine tumor (pNET) cell lines. Western blotting was used to determine the effects of BLX-3030 treatment on c-Myc expression in cancer cells. The combination effects between BLX-3030 and standard of care regimen, gemcitabine (GEM) and nab-paclitaxel (NP), was assessed using the SRB assay. Finally, the in vivo antitumor activity of BLX-3030 alone or in combination with GEM and NP was evaluated in a mouse cell line xenograft model for pancreatic cancer. Results BLX-3030 exhibited potent cell growth inhibitory activity in the panel of pancreatic cancer cell lines with IC50 values ranging from 133.5 nM to 508.1 nM. The potency of BLX-3030 in the cell lines appears to correlate with the expression level of c-Myc in the cell lines. BLX-3030 showed similar activities in PDAC and pNET cell lines with mean IC50 values of 244.5 nM and 194.6 nM, respectively. However, treatment with BLX-3030 for 48 hours did not seem to significantly reduce c-Myc expression in PSN-1 PDAC cells. When combined with GEM and NP, BLX-3030 demonstrated mostly additive effects in PSN-1 cells. Preliminary data from the in vivo study show that BLX-3030 improves the antitumor activity of GEM and NP. Conclusion In summary, BLX-3030 potently inhibited the growth of both PDAC and pNET cells in vitro. The growth inhibitory activity of BLX-3030 in PDAC cell lines correlates with their c-Myc expression levels. BLX-3030 showed an additive effect when combined with standard of care drugs (GEM and NP) in PDAC cell lines. Overall, the novel CDK9 inhibitor, BLX-3030, demonstrated potent activity in pancreatic cancer cell line models and presents a promising preclinical lead for pancreatic cancer. (This work was supported in part by Biolexis Therapeutics and the Seena Magowitz Foundation). Citation Format: Yesenia Barrera-Millan, Zhaoliang Li, Hariprasad Vankayalapati, David J. Bearss, Daniel D. Von Hoff, Haiyong Han. Development of a selective, oral ATP-competitive CDK9 inhibitor, BLX-3030, for treatment of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5957.