Pancreatic Adenocarcinoma Cells Research Articles

The polymeric fluoropyrimidine CF10 overcomes limitations of 5-FU in pancreatic ductal adenocarcinoma cells through increased replication stress

ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease soon to become the second leading cause of cancer deaths in the US. Beside surgery, current therapies have narrow clinical benefits with systemic toxicities. FOLFIRINOX is the current standard of care, one component of which is 5- Fluorouracil (5-FU), which causes serious gastrointestinal and hematopoietic toxicities and is vulnerable to resistance mechanisms. Recently, we have developed polymeric fluoropyrimidines (F10, CF10) which unlike 5-FU, are, in principle, completely converted to the thymidylate synthase inhibitory metabolite FdUMP, without generating appreciable levels of ribonucleotides that cause systemic toxicities while displaying much stronger anti-cancer activity. Here, we confirm the potency of CF10 and investigate enhancement of its efficacy through combination with inhibitors in vitro targeting replication stress, a hallmark of PDAC cells. CF10 is 308-times more potent as a single agent than 5-FU and was effective in the nM range in primary patient derived models. Further, we find that activity of CF10, but not 5-FU, is enhanced through combination with inhibitors of ATR and Wee1 that regulate the S and G2 DNA damage checkpoints and can be reversed by addition of dNTPs indicative of CF10 acting, at least in part, through inducing replication stress. Our results indicate CF10 has the potential to supersede the established benefit of 5-FU in PDAC treatment and indicate novel combination approaches that should be validated in vivo and may be beneficial in established regimens that include 5-FU.

The Far Side of Resistance to RAS Inhibitors.

In this issue, four articles highlight the critical role of nongenetic mechanisms and cell plasticity in mediating resistance to different classes of RAS inhibitors in pancreatic ductal adenocarcinoma and non-small cell lung cancer. See related article by Benitz et al., p. 2162 See related article by Dilly et al., p. 2135 See related article by Araujo et al., p. 2183 See related article by Singhal et al., p. 2122.

The Role of Heat Shock Factor 1 in Preserving Proteomic Integrity During Copper-Induced Cellular Toxicity.

Copper is crucial for many physiological processes across mammalian cells, including energy metabolism, neurotransmitter synthesis, and antioxidant defense mechanisms. However, excessive copper levels can lead to cellular toxicity and "cuproptosis", a form of programmed cell death characterized by the accumulation of copper within mitochondria. Tumor cells are less sensitive to this toxicity than normal cells, the mechanism for which remains unclear. We address this important issue by exploring the role of heat shock factor 1 (HSF1), a transcription factor that is highly expressed across several types of cancer and has a crucial role in tumor survival, in protecting against copper-mediated cytotoxicity. Using pancreatic ductal adenocarcinoma cells, we show that excessive copper triggers a proteotoxic stress response (PSR), activating HSF1 and that overexpressing HSF1 diminishes intracellular copper accumulation and prevents excessive copper-induced cell death and amyloid fibrils formation, highlighting HSF1's role in preserving proteasomal integrity. Copper treatment decreases the lipoylation of dihydrolipoamide S-acetyltransferase (DLAT), an enzyme necessary for cuproptosis, induces DLAT oligomerization, and induces insoluble DLAT formation, which is suppressed by overexpressing HSF1, in addition to enhancing the interaction between HSF1 and DLAT. Our findings uncover how HSF1 protects against copper-induced damage in cancer cells and thus represents a novel therapeutic target for enhancing copper-mediated cancer cell death.

TGF-β-Induced PAUF Plays a Pivotal Role in the Migration and Invasion of Human Pancreatic Ductal Adenocarcinoma Cell Line Panc-1.

Pancreatic adenocarcinoma upregulated factor (PAUF) was initially identified as a secreted protein that is substantially expressed in pancreatic ductal adenocarcinoma (PDAC). PAUF also affects invasiveness, motility, and the proliferation of cells in several types of cancer. Recently, PAUF was reported to play a pivotal role in the TLR4-mediated migration and invasion of PDAC cells. However, the mechanism inducing PAUF expression and its functional role in TGF-β-stimulated PDAC cells have not yet been studied. Thus, we first assessed whether TGF-β regulates PAUF expression in several PDAC cell lines and found a significant increase in PAUF expression in Smad signaling-positive Panc-1 cells treated with TGF-β. We also found that the PAUF promoter region contains a Smad-binding element. TGF-β-treated Panc-1 cells showed an increase in PAUF promoter activity, but this effect was not observed in TGF-β-stimulated Smad4-null BxPC-3 cells. Restoring Smad4 expression increased the PAUF promoter activity and expression in Smad4-overexpressing BxPC-3 cells treated with TGF-β. We further found that PAUF aggravated the TGF-β-induced epithelial-mesenchymal transition (EMT) in Panc-1 and BxPC-3 cells via the activation of MEK-ERK signaling. These results indicate that TGF-β/Smad signaling-mediated upregulation of PAUF plays a crucial role in EMT progression by activating the TGF-β-mediated MEK-ERK signaling pathway.

Application of LEF-1 immunohistochemical staining in the diagnosis of solid pseudopapillary neoplasm of the pancreas

IntroductionSolid pseudopapillary neoplasm (SPN) is a tumor of young females with gain-of-function mutation in catenin beta 1 gene involved in Wnt signal transduction pathway. Beta-catenin immunohistochemistry (IHC) is used to diagnose SPN. Lymphoid enhancer-binding factor 1 (LEF-1) has been recognized in the transactivation of Wnt pathway. We aim to study LEF-1 IHC in SPN and other pancreatic tumors and compare it with beta-catenin IHC. MethodsWe retrieved cases of SPN, pancreatic neuroendocrine tumor (PanNET), serous cystadenoma (SCA), ductal adenocarcinoma (PDAC) and acinar cell carcinoma (ACC) from 2011 to 2023. Formalin-fixed, paraffin-embedded blocks with adequate tumor were cut and stained with beta-catenin (B-Catenin-1 clone) and LEF-1 (EP310 clone) IHC. Cases were reviewed by two pathologists independently. Nuclear staining with LEF-1 and beta-catenin was considered as positive. ResultsOur cohort consisted of 111 cases [SPN = 59 (42 resections, 11 FNA, 6 biopsies), PDAC = 24, PanNET = 22, SCA = 5, ACC = 1]. For SPN cases male to female ratio was1:8. Age ranged from 9 to 81 years (average: 32 years). Pancreatic tail was the most common location (47 %) followed by head (28 %), body (19 %) and neck (6 %). Tumor size ranged from 1.0 to 12.2 cm (average: 5 cm). Among the SPN cases 57/59 demonstrated strong nuclear LEF-1 staining. 2/49 cases were negative for LEF-1 (both pathologist in agreement). All SPN tumors demonstrated nuclear staining with beta-catenin. Among the non-SPN tumors, beta-catenin showed nuclear staining in 2/52 cases (2 PDAC). The remaining 50 cases were negative for nuclear beta-catenin and demonstrated variable staining pattern with interpretation variability between the two pathologists. The sensitivity and specificity for LEF-1 were 97 % and 100 %, respectively, while for beta-catenin, they were 100 % and 96 % respectively. ConclusionCrisp nuclear staining of LEF-1 without background staining makes diagnostic interpretation relatively easy and accurate compared to beta-catenin IHC. This is further helpful for small biopsy samples to help differentiate SPN from mimickers such as PanNET. None of the non-SPN cases displayed nuclear LEF-1 rendering it a valuable adjunct to beta-catenin in the diagnostic evaluation of SPN.

MUC17 is a potential new prognostic biomarker and promotes pancreatic cancer progression in obstructive jaundice.

Our working group has previously shown that bile acids (BAs) accelerate carcinogenic processes in pancreatic cancer (PC) in which mucin 4 (MUC4) expression has a central role. However, the role of other mucins in PC are less clear, especially in bile-induced cancer progression. The study aim was to investigate expression of MUC17 in BAs- or human serum-treated pancreatic ductal adenocarcinoma (PDAC) cell lines and use different assays with RNA silencing/overexpression to study the role of MUC17 in cancer progression. Protein expression of MUC17 was evaluated in 55 human pancreatic samples by immunohistochemistry, and Kaplan-Meier survival analysis was used to compare survival curves. Expression of MUC17 increased in PDAC patients, especially in obstructive jaundice (OJ) and the elevated MUC17 expression associated with poorer overall survival (10.66±1.99 vs. 15.05±2.03 months; Log rank: 0.0497). Treatment of Capan-1 and AsPC-1 cells with BAs or with human serum obtained from PDAC + OJ patients enhanced the expression of MUC17, as well as the proliferative potential of the cells, whereas knockdown of MUC17 alone or in combination with MUC4 decreased BAs-induced carcinogenic processes. Our results demonstrated that MUC17 has a central role in bile-induced PC progression, and in addition to MUC4, this isoform also can be used as a novel prognostic biomarker.

KLF15 suppresses stemness of pancreatic cancer by decreasing USP21-mediated Nanog stability

The existence of cancer stem cells (CSCs) in pancreatic ductal adenocarcinoma (PDAC) is considered to be the key factor for metastasis and chemoresistance. Thus, novel therapeutic strategies for eradicating CSCs are urgently needed. Here we aimed to explore the role of KLF15 in stemness and the feasibility of using KLF15 to inhibit CSCs and improve chemotherapy sensitivity in PDAC. In this study, we report that KLF15 is negatively associated with poor survival and advanced pathological staging of PDAC. Moreover, tumorous KLF15 suppresses the stemness of PDAC by promoting the degradation of Nanog, and KLF15 directly interacts with Nanog, inhibiting interaction between Nanog with USP21. We also demonstrate that the KLF15/Nanog complex inhibit the stemness in vivo and in PDX cells. Tazemetostat suppresses stemness and sensitizes PDAC cells to gemcitabine by promoting KLF15 expression in PDAC. In summary, the findings of our study confirm the value of KLF15 level in diagnosis and prognosis of PDAC, it is the first time to explore the inhibition role of KLF15 in stemness of PDAC and the regulation mechanism of Nanog, contributing to provide a new therapeutic strategy that using Tazemetostat sensitizes PDAC cells to gemcitabine by promoting KLF15 expression for PDAC.Graphical

Combined PET Radiotracer Approach Reveals Insights into Stromal Cell-Induced Metabolic Changes in Pancreatic Cancer In Vitro and In Vivo.

Background/Objective Pancreatic stellate cells (PSCs) in pancreatic adenocarcinoma (PDAC) are producing extracellular matrix, which promotes the formation of a dense fibrotic microenvironment. This makes PDAC a highly heterogeneous tumor-stroma-driven entity, associated with reduced perfusion, limited oxygen supply, high interstitial fluid pressure, and limited bioavailability of therapeutic agents. Methods In this study, spheroid and tumor xenograft models of human PSCs and PanC-1 cells were characterized radiopharmacologically using a combined positron emission tomography (PET) radiotracer approach. [18F]FDG, [18F]FMISO, and [18F]FAPI-74 were employed to monitor metabolic activity, hypoxic metabolic state, and functional expression of fibroblast activation protein alpha (FAPα), a marker of activated PSCs. Results In vitro, PanC-1 and multi-cellular tumor spheroids demonstrated comparable glucose uptake and hypoxia, whereas FAPα expression was significantly higher in PSC spheroids. In vivo, glucose uptake as well as the transition to hypoxia were comparable in PanC-1 and multi-cellular xenograft models. In mice injected with PSCs, FAPα expression decreased over a period of four weeks post-injection, which was attributed to the successive death of PSCs. In contrast, FAPα expression increased in both PanC-1 and multi-cellular xenograft models over time due to invasion of mouse fibroblasts. Conclusion The presented models are suitable for subsequently characterizing stromal cell-induced metabolic changes in tumors using noninvasive molecular imaging techniques.

Spatial Organization of Chromatin of the KLF5 Gene Promoter Region in Pancreatic Ductal Adenocarcinoma Cells

Spatial Organization of Chromatin of the KLF5 Gene Promoter Region in Pancreatic Ductal Adenocarcinoma Cells

Unveiling the 4-aminoquinoline derivatives as potent agents against pancreatic ductal adenocarcinoma (PDAC) cell lines

Common antimalarials such as artemisinins, chloroquine and their derivatives also possess potent anti-inflamantory, antiviral and anticancer properties. In the search for new therapeutics to combat difficult-to-treat pancreatic carcinomas, we unveiled that 4-aminoquinoline derivatives, with significant antiplasmodial properties and a great safety profile in vivo, have remarkable anticancer activity against pancreatic ductal adenocarcinoma (PDAC) and considerable efficacy in the xenograft model in vivo. The aim of the present study was to further investigate anticancer properties of these compounds in a drug-repurposing manner. The compounds showed profound cytotoxic effects at nanomolar to low micromolar concentration in 2D cultured cells (in vitro) and in the zebrafish PDAC xenograft model (in vivo). A deeper insight into their mechanisms of cytotoxic action showed these compounds induce apoptosis while increasing reactive oxygen species levels along with autophagy inhibition. Additional investigation of the autophagy modulation proved that tested quinoline derivatives cause P62 and LC3-II accumulation in PDAC cells alongside lysosomal alkalinization. Further, in vivo toxicity studies in the zebrafish model showed low toxicity without developmental side effects of the investigated 4-aminoquinolines, while the applied compounds effectively inhibited tumor growth and prevented the metastasis of xenografted pancreatic cells. Taken together, these results highlight the 4-aminoquinolines as privileged structures that ought to be investigated further for potential application in pancreatic carcinoma treatment.

Keratin 17 and A2ML1 are negative prognostic biomarkers in non-small cell lung cancer

Although the overall prognosis for patients with non-small cell lung cancer (NSCLC) has improved over the past several decades, there are still survival differences that are not accurately defined by clinicopathological factors. Thus, there is an unmet clinical need to develop novel approaches to enhance prognostic accuracy for these patients. Keratin 17 (K17) is a negative prognostic biomarker in a wide range of cancer types, including pancreatic ductal adenocarcinoma, head and neck squamous cell carcinoma, and pulmonary adenocarcinoma (LUAD), but has yet to be investigated as a prognostic biomarker in primary lung squamous cell carcinoma (LSCC). Based on TCGA RNA-seq data, alpha-2-macroglobulin like 1 (A2ML1), a protease inhibitor, is highly correlated with K17 in other solid tumors, including pancreatic ductal adenocarcinoma and is also a prognostic biomarker for LSCC, although the prognostic accuracy of A2ML1 for LUAD has not been tested. Thus, we hypothesized that A2ML1 expression correlates with K17 expression and that K17/A2ML1 co-testing could provide complementary prognostic data for NSCLC. The aims of this study were to explore K17 and A2ML1 as dual prognostic biomarkers, using publicly available gene expression databases [The Cancer Genome Atlas (TCGA)] LSCC (n=266), LUAD (n=271)] and multiplexed immunohistochemistry (mIHC) on representative sections of LSCC (n=104) and LUAD (n=107) from two major academic medical centers. Our results suggest that using either mRNA or mIHC-based methods, combined K17 and A2ML1 testing provides information, independent of other clinicopathologic variables, that could impact treatment decisions for patients with NSCLC.

Influences of Ipomoea batatas Anti-Cancer Peptide on Tomato Defense Genes.

This study investigates the impact of IbACP (Ipomoea batatas anti-cancer peptide) on defense-related gene expression in tomato leaves, focusing on its role in plant defense mechanisms. Previously, IbACP was isolated from sweet potato leaves, and it was identified as a peptide capable of inducing an alkalinization response in tomato suspension culture media. Additionally, IbACP was found to regulate the proliferation of human pancreatic adenocarcinoma cells. Elucidate IbACP's molecular influence on defense-related gene expression in tomato leaves using next-generation sequencing analysis. To assess the impact of IbACP on defense-related gene expression, transcriptome data were analyzed, encompassing various functional categories such as photosynthesis, metabolic processes, and plant defense. Semi-quantitative reverse-transcription polymerase chain reaction analysis was employed to verify transcription levels of defense-related genes in tomato leaves treated with IbACP for durations ranging from 0 h (control) to 24 h. IbACP induced jasmonic acid-related genes (LoxD and AOS) at 2 h, with a significant up-regulation of salicylic acid-dependent gene NPR1 at 24 h. This suggested a temporal antagonistic effect between jasmonic acid and salicylic acid during the early hours of IbACP treatment. Downstream ethylene-responsive regulator genes (ACO1, ETR4, and ERF1) were consistently down-regulated by IbACP at all times. Additionally, IbACP significantly up-regulated the gene expressions of suberization-associated anionic peroxidases (TMP1 and TAP2) at all time points, indicating enhanced suberization of the plant cell wall to prevent pathogen invasion. IbACP enhances the synthesis of defense hormones and up-regulates downstream defense genes, improving the plant's resistance to biotic stresses.

Dynamic glycolytic reprogramming effects on dendritic cells in pancreatic ductal adenocarcinoma

BackgroundPancreatic ductal adenocarcinoma tumors exhibit resistance to chemotherapy, targeted therapies, and even immunotherapy. Dendritic cells use glucose to support their effector functions and play a key role in anti-tumor immunity by promoting cytotoxic CD8+ T cell activity. However, the effects of glucose and lactate levels on dendritic cells in pancreatic ductal adenocarcinoma are unclear. In this study, we aimed to clarify how glucose and lactate can impact the dendritic cell antigen-presenting function and elucidate the relevant mechanisms.MethodsGlycolytic activity and immune cell infiltration in pancreatic ductal adenocarcinoma were evaluated using patient-derived organoids and resected specimens. Cell lines with increased or decreased glycolysis were established from KPC mice. Flow cytometry and single-cell RNA sequencing were used to evaluate the impacts on the tumor microenvironment. The effects of glucose and lactate on the bone marrow-derived dendritic cell antigen-presenting function were detected by flow cytometry.ResultsThe pancreatic ductal adenocarcinoma tumor microenvironment exhibited low glucose and high lactate concentrations from varying levels of glycolytic activity in cancer cells. In mouse transplantation models, tumors with increased glycolysis showed enhanced myeloid-derived suppressor cell infiltration and reduced dendritic cell and CD8+ T cell infiltration, whereas tumors with decreased glycolysis displayed the opposite trends. In three-dimensional co-culture, increased glycolysis in cancer cells suppressed the antigen-presenting function of bone marrow-derived dendritic cells. In addition, low-glucose and high-lactate media inhibited the antigen-presenting and mitochondrial functions of bone marrow-derived dendritic cells.ConclusionsOur study demonstrates the impact of dynamic glycolytic reprogramming on the composition of immune cells in the tumor microenvironment of pancreatic ductal adenocarcinoma, especially on the antigen-presenting function of dendritic cells.

Pancreatic cancer cells overexpressing interleukin 6 induce T-cell-mediated tumor clearance and durable anti-tumor immune response.

Tumor immune resistance is recognized as a contributor to low survivorship in pancreatic ductal adenocarcinoma (PDAC). We developed a novel murine model of spontaneous PDAC clearance, generated by overexpressing interleukin-6 (IL-6) in orthotopically implanted PDAC cancer cells (OT-PDACIL6). Circulating IL-6 was 100-fold higher in OT-PDACIL6 than in OT-PDACparental mice. OT-PDACIL6 tumors were present at 5 days post-implantation, and undetectable by 10 days post implantation. Flow cytometry revealed increased T cells and NK cells, and decreased T regulatory cells in OT-PDACIL6 as compared to OT-PDACparental tumors. Increased lymphoid aggregates were apparent by histological assessment and may account for elevated T cell content. Antibody-based depletion of CD4+ and CD8+ T cells prevented tumor clearance and significantly reduced survival of OT-PDACIL6 mice. The anti-tumor immune response to OT-PDACIL6 rendered mice immune to re-challenge with OT-PDACparental tumors. In high concentrations, IL-6 acts in opposition to previously described pro-tumorigenic effects by enhancing the T cell-mediated anti-tumor response to PDAC.

Expression, potential biological behaviour and clinical significance of MCM3 in pancreatic adenocarcinoma: a comprehensive study integrating high throughput sequencing, CRISPR screening and in-house immunohistochemistry

Background Minichromosome maintenance complex component 3 (MCM3) plays a key role in various tumours. However, it remains largely unknown what the specific role and clinical significance of MCM3 in pancreatic adenocarcinoma (PAAD) are. Materials and Methods We integrated high-throughput data from PAAD worldwide to analyse the expression level of MCM3 mRNA. We used immunohistochemistry to analyse MCM3 protein expression levels in 145 cases in the PAAD group and 29 cases in the non-PAAD group. We also mainly analysed the necessity of MCM3 for PAAD growth based on CRISPR screen data. In addition, we used enrichment analysis and protein–protein interaction networks to explore the molecular mechanism of MCM3 in PAAD. We also analysed the correlation between MCM3 expression, components of the immune microenvironment in PAAD tissue and clinical prognosis. Results In PAAD, we observed for the first time that MCM3 was significantly highly expressed at both the mRNA (SMD = 0.67, 95% CI: 0.38 ∼ 0.96) and the protein level (p < 0.05). The mRNA (AUC = 0.78, 95% CI: 0.74 ∼ 0.81; sensitivity = 0.66, 95% CI: 0.55 ∼ 0.76; specificity = 0.76, 95% CI: 0.67 ∼ 0.84) and protein (AUC = 0.929) expression levels of MCM3 had a good ability to distinguish between PAAD and non-PAAD tissue. There was heterogeneity reflected by the differential expression of MCM3 protein in PAAD cells. MCM3 played an essential role in PAAD growth, through abnormal DNA replication, p53 signalling and cell cycle checkpoints. PAAD with high MCM3 expression was sensitive to c-75, brivanib, flavopiridol and VNLG/124 drugs, with stable molecular docking models. Conclusion MCM3 is likely to be a critical element in promoting the initiation and growth of PAAD. Flavopiridol may exert its anti-PAAD effect through the interaction between MCM3, classic CDK1 targets in the cell cycle checkpoint and p53 pathway as well as related molecules in other pathways.

C-FOS inhibition promotes pancreatic cancer cell ferroptosis by transcriptionally regulating the expression of SLC7A11.

Cellular proto-oncogene C-Fos forms the AP-1 transcription factor by dimerizing with proto-oncogene c-Jun; this factor upregulates the transcription of genes associated with different malignancies. However, its functions in pancreatic adenocarcinoma (PAAD) remain poorly understood. In this study, the c-Fos was increased in PAAD cells and tissues through bioinformatic analysis, RT-PCR, and WB. In two PAAD cell lines, PANC-1 and BxPC-3, we performed c-Fos knockdown studies using short hairpin RNA (shRNA). Functional analysis indicated that c-Fos depletion in PAAD cells inhibits cell proliferation and promotes ferroptosis. Chromatin Immunoprecipitation (ChIP) and Dual-luciferase experiments showed that c-Fos coupled to the promoter region of SLC7A11 stimulated its transcription, providing mechanistic insight into the process. Moreover, SLC7A11 blocked the decline of proliferation and ferroptosis by c-Fos knockdown in PAAD cells. Furthermore, a xenograft nude mouse model was established to study the impact of c-Fos on tumorigenesis in vivo. Depletion of c-Fos could suppress PC tumor growth and the expressions of SLC7A11, ki-67, and 4HNE, but overexpression of SLC7A11 reversed this process. In summary, our investigation has shown that c-Fos acts as a transcriptional regulator of SLC7A11, which may enhance tumour growth in pancreatic cancer by inhibiting ferroptosis. These results indicate that c-Fos might be a promising target for treating ferroptosis in PAAD.

Abstract PR-19: Cell polarity proteins as novel regulators of macropinocytosis

Abstract Macropinocytosis has emerged as a nutrient-scavenging pathway that cancer cells exploit to survive the nutrient-deprived conditions of the tumor microenvironment. Cancer cells are especially reliant on glutamine for their survival, and in pancreatic ductal adenocarcinoma (PDAC) cells, glutamine deficiency can enhance the stimulation of macropinocytosis, allowing the cells to escape metabolic stress through the production of extracellular-protein-derived amino acids. Here, we identify the atypical protein kinase C (aPKC) enzymes, PKCz and PKCi, as novel regulators of macropinocytosis. In normal epithelial cells, aPKCs are known to regulate cell polarity in association with the scaffold proteins Par3 and Par6, controlling the function of several targets, including the microtubule-associated Par1 kinases. In PDAC cells, we identify that each of these cell polarity proteins are required for glutamine stress-induced macropinocytosis. Mechanistically, we find that the aPKCs are regulated by EGFR signaling or by the transcription factor CREM to promote the relocation of Par3 to microtubules, facilitating macropinocytosis in a dynein-dependent manner. Importantly, we determine that cell fitness impairment caused by aPKC depletion in glutamine stress is rescued by the restoration of macropinocytosis and that aPKCs support PDAC growth in vivo. These results identify a previously unappreciated role for the cell polarity protein network in the regulation of macropinocytosis and provide a better understanding of the mechanistic underpinnings that control macropinocytic uptake in the context of metabolic stress. Citation Format: Guillem Lambies Barjau, Szu-Wei Lee, Karen Duong-Polk Duong-Polk, David Dawson, Cheska Marie Galapate, Swetha Maganti, Cosimo Commisso. Cell polarity proteins as novel regulators of macropinocytosis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr PR-19.

Abstract IA-06: Elucidation of metabolic resistance mechanisms to RAS inhibition

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized by KRAS- and autophagy-dependent growth. We previously determined that concurrent inhibition of autophagy, using the lysosomal inhibitor chloroquine (CQ), and of ERK, using a small molecule ERK inhibitor (ERKi), synergistically suppressed the growth of pancreatic ductal adenocarcinoma (PDAC) cell lines and patient xenograft-derived (PDX) organoids in vitro and PDX tumors in vivo. Our findings provided the rationale for our initiation of Phase I and Phase I/II clinical trials evaluating the combination of MEKi (binimetinib; NCT04132505) or ERKi (LY3214996; NCT04386057) with hydroxychloroquine (HCQ) in PDAC. We have extended these findings and determined that the combined inhibition of KRASG12C or KRASG12D and autophagy was effective in KRAS-mutant cancers. Our ongoing studies are centered on developing additional combinations for targeting metabolic resistance mechanisms to KRAS or ERK MAPK targeted therapies. First, we performed a CRISPR/Cas-9 mediated genetic loss-of-function screen in the presence of CQ to determine additional sensitizers to autophagy inhibition. Top sensitizers included multiple facilitators of the DNA damage response, mTOR pathway components, and genes involved in the upstream regulation of the autophagy pathway. Additionally, we identified PIKfyve, a lipid kinase critical for the recycling dynamics of lysosomes, as an essential autophagy-related gene in PDAC cells. PIKfyve inhibition with apilimod resulted in a potent reduction of autophagic flux and growth. Importantly, PIKfyve inhibition blocked the compensatory increases in autophagic flux associated both with MEK inhibition and with direct RAS inhibition. Accordingly, combined inhibition of PIKfyve and either the RAS ERK-MAPK pathway or RAS itself showed robust growth suppression across a panel of KRAS-mutant PDAC models. Growth suppression was due, in part, to potentiated cell cycle arrest and induction of apoptosis following loss of IAP proteins. We conclude that concurrent inhibition of RAS and PIKfyve is a synergistic, cytotoxic combination that may represent a novel therapeutic strategy for PDAC. In a parallel line of investigation, we determined that autophagic signaling is temporally regulated following RAS pathway inhibition, peaking at 48-72 hours, and returning to basal levels by 7 days. Interestingly, we found that as autophagic upregulation subsides, another nutrient scavenging pathway, macropinocytosis, increases. We hypothesize that further dissection of the dynamic regulation of autophagy and macropinocytosis will improve current anti-nutrient scavenging treatment strategies. We conclude that concurrent suppression of multiple metabolic processes, to block compensatory rebound activities, will be needed for effective PDAC treatment. Citation Format: Jonathan M. DeLiberty, Ryan Robb, Mallory K. Roach, Sarah E. Ackermann, Runying Yang, Noah L. Pieper, Khalilah E. Taylor, Scott Bang, Elisa Baldelli, Emanuel F. Petricoin III, John P. Morris IV, Clint A. Stalnecker, Kirsten L. Bryant. Elucidation of metabolic resistance mechanisms to RAS inhibition [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr IA-06.

Abstract B036: Hypoxic cancer cells condition immunosuppressive macrophages via secreted non-protein mediators in pancreatic ductal adenocarcinoma

Abstract INTRODUCTION: Hypoxia is a defining feature of pancreatic ductal adenocarcinoma (PDAC) that contributes to the immunosuppressive microenvironment defined by increased tumor-associated macrophages (TAMs). However, there is an unmet need to define mechanisms by which hypoxia drives the immunosuppressive macrophage phenotype. We hypothesize that hypoxic cancer cells secrete non-protein metabolites to induce immunosuppressive phenotypes in macrophages. METHODS: We generated conditioned media (CM) by culturing the pancreatic adenocarcinoma cell line KPC under normoxia (21% O2) or hypoxia (0.5% O2) conditions for 48 hours. We treated bone marrow-derived macrophages (BMDMs) or the macrophage line RAW264.7 with CM. We assessed immunosuppressive gene expression using RNAseq and qRT-PCR. Proteins in CM were depleted using Sera-Mag Magnetic Carboxylate Modified Beads or denatured by boiling at 100°C for 15 minutes. We identified changes in metabolites between hypoxic and normoxic CM using HPLC. RESULTS: Compared to BMDMs treated with normoxic CM, we observed that BMDMs treated with hypoxic CM induced multiple immunosuppressive proteins (Arg1), cytokines (Ccl22, Cxcl3) and interleukins (Il1b, Il1a, Il6). Similarly, GSEA analysis demonstrated that hypoxic CM induced TNFa signaling via NfkB and IL6-JAK-STAT3 signaling. Consistent with RNA-seq analysis, qRT-PCR measured Arg1 expression 53 times higher in hypoxic CM-treated BMDMs compared to nomoxic CM (p=0.0286). Compared to normoxic CM, hypoxic CM stimulated macrophage migration, a marker for macrophage infiltration, as measured by transwell assays (p&amp;lt;0.0001). An increase in Arg1 expression in RAW264.7 cells was still observed when treated with protein depleted or boiled hypoxic CM, excluding proteins as soluble factor(s) mediating immunosuppression. To identify non-protein mediators of immune suppression, mass spectrometry quantified lipids and metabolites enriched in HCM. Metabolomic analysis identified 40 metabolites increased in hypoxic CM including the monounsaturated or polyunsaturated fatty acids linoelaidic acid, DGLA, and arachidonic acid. Similarly, lipidomic analysis revealed that multiple PC (phosphatidylcholine) and LPC (lysophosphatidylcholine) lipid species were enriched in HCM. CONCLUSION: We observe that hypoxic tumor cells induce immunosuppressive changes in macrophages likely via secreted non-protein metabolites. The hypoxic metabolome of PDAC tumor cells may be a key driver of the accumulation of immunosuppressive tumor associated macrophages. We are currently characterizing the role of individual lipids or metabolites in macrophage polarization. Citation Format: Matthew T Cribb, Sahar Fattani, Ayeisha Colon-Ortiz, Dadi Jiang, Michael Spiotto, Albert Koong. Hypoxic cancer cells condition immunosuppressive macrophages via secreted non-protein mediators in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B036.

Upregulation of HSD11B1 promotes cortisol production and inhibits NK cell activation in pancreatic adenocarcinoma

Cortisol is a glucocorticoid hormone that has immunosuppressive function. Elevated basal cortisol levels are present in patients with some kinds of cancers, but its role in the microenvironment of pancreatic adenocarcinoma (PAAD) remains unclear. This study analyzed the expression of genes involved in cortisol generation by using high-throughput sequencing data from TCGA portal and found HSD11B1 was significantly upregulated in patients with PAAD. The correlations between HSD11B1 level and the expression of 23 immunosuppressive receptors were analyzed by Spearman’s correlation analysis. The function of HSD11B1 was examined in primary NK cells and PAAD cell lines. The levels of cortisol in medium and cell lysates were detected by ELISA. In vitro killing assay was used to evaluate the cytotoxicity of NK cells. Cell surface levels of CD96, Tim-3, PD-1, TIGIT, CTLA-4, NKp46, NKp30, NKD2G and LFA-1A, and intracellular levels of CD107a and IFN-γ were examined by flow cytometry. We observed that patients with higher HSD11B1 level had shorter survival time. HSD11B1 is positively correlated with the mRNA levels of 11 immunosuppressive receptors in PAAD. Higher HSD11B1 level relates to reduced abundance of activated NK cells in the tumors. HSD11B1 overexpressed NK cells exhibit exhausted phenotype with increased cortisol production, reduced viability, and reduced cytotoxicity against cancer cells. Overexpression of HSD11B1 did not change the viability of tumor cells but upregulated cortisol production. Targeting HSD11B1 by a specific inhibitor improved the NK cells responsiveness. In conclusion, HSD11B1 is upregulated in patients with PAAD, and higher HSD11B1 level is related to poor prognosis. Upregulation of HSD11B1 in NK and tumor cells increased the production and secretion of cortisol and induces NK cell exhaustion.