Search

Despite a surge in the merger of companies listed on the KOSDAQ market with special purpose acquisition companies (SPACs), limited domestic studies have systematically compared the listing through SPAC mergers and the general IPO. This study analyzes the impact of such companies going public after merging with SPACs as well as their performance by comparing them with the conventional IPOs. First, the firms listed through SPAC mergers are smaller and have a higher proportion of non-manufacturing industries than the conventional IPOs. Second, the operational and stock price performance of the firms listed through SPACs are not inferior to that of the conventional IPOs. Finally, a higher share allocation to institutional investors and subscription rates, for the shares recorded at the time of the SPAC listing, are related to the stock price performance observed after SPAC mergers. According to the empirical results of this study, going public by merging with SPACs provides early listing opportunities to small- and medium-sized companies; they do not experience a deterioration in their financial performance after being listed. The listing of SPACs creates a different and valuable path to enter the KOSDAQ market for such companies as compared to the conventional IPOs.

Inflammation is strongly associated with pancreatic ductal adenocarcinoma (PDAC), a highly lethal malignancy. Dysregulated RNA splicing factors have been widely reported in tumorigenesis, but their involvement in pancreatitis and PDAC is not well understood. Here, we report that the splicing factor SRSF1 is highly expressed in pancreatitis, PDAC precursor lesions, and tumors. Increased SRSF1 is sufficient to induce pancreatitis and accelerate KRASG12D-mediated PDAC. Mechanistically, SRSF1 activates MAPK signaling—partly by upregulating interleukin 1 receptor type 1 (IL1R1) through alternative-splicing-regulated mRNA stability. Additionally, SRSF1 protein is destabilized through a negative feedback mechanism in phenotypically normal epithelial cells expressing KRASG12D in mouse pancreas, and in pancreas organoids acutely expressing KRASG12D, buffering MAPK signaling and maintaining pancreas-cell homeostasis. This negative-feedback regulation of SRSF1 is overcome by hyperactive MYC, facilitating PDAC tumorigenesis. Our findings implicate SRSF1 in the etiology of pancreatitis and PDAC, and point to SRSF1-misregulated alternative splicing as a potential therapeutic target.

Engrailed-1(EN1) is a critical homeodomain transcription factor (TF) required for neuronal survival, and EN1 expression has been shown to promote aggressive forms of triple negative breast cancer. Here, we report thatEN1is aberrantly expressed in a subset of pancreatic ductal adenocarcinoma (PDA) patients with poor outcomes. EN1 predominantly repressed its target genes through direct binding to gene enhancers and promoters, implicating a role in the acquisition of mesenchymal cell properties. Gain- and loss-of-function experiments demonstrated thatEN1promoted PDA transformation and metastasisin vitroandin vivo. Our findings nominate the targeting ofEN1and downstream pathways in aggressive PDA.

Supplementary Table S1 shows patient information, Supplementary Table S2 shows cell numbers analyzed from each human PDAC sample, Supplementary Table S3 shows statistics of the clustering analysis of the human PDAC single cell RNA sequencing, Supplementary Table S5 shows statistics of the human PDAC ductal cell analysis, Supplementary Table S7 shows statistics of the human PDAC myeloid cell analysis, Supplementary Table S9 shows statistics of the human PDAC T & NK cell analysis, Supplementary Table S11 shows cell numbers analyzed for fibroblast subtypes from each human PDAC sample, Supplementary Table S12 shows statistics of the human PDAC fibroblast analysis, Supplementary Table S17 shows statistics of all viable KPC mouse cell analysis, Supplementary Table S19 shows statistics of the KPC mouse fibroblast-enriched fraction analysis, Supplementary Table S21 shows statistics of the fibroblasts from KPC mouse fibroblast-enriched population

Supplementary Table S16 shows protein activity of transcription factors in human CAFs, as analyzed by VIPER

Supp figure 4

Cancer-associated fibroblasts (CAF) are major players in the progression and drug resistance of pancreatic ductal adenocarcinoma (PDAC). CAFs constitute a diverse cell population consisting of several recently described subtypes, although the extent of CAF heterogeneity has remained undefined. Here we use single-cell RNA sequencing to thoroughly characterize the neoplastic and tumor microenvironment content of human and mouse PDAC tumors. We corroborate the presence of myofibroblastic CAFs and inflammatory CAFs and define their unique gene signatures in vivo. Moreover, we describe a new population of CAFs that express MHC class II and CD74, but do not express classic costimulatory molecules. We term this cell population “antigen-presenting CAFs” and find that they activate CD4+ T cells in an antigen-specific fashion in a model system, confirming their putative immune-modulatory capacity. Our cross-species analysis paves the way for investigating distinct functions of CAF subtypes in PDAC immunity and progression.Significance:Appreciating the full spectrum of fibroblast heterogeneity in pancreatic ductal adenocarcinoma is crucial to developing therapies that specifically target tumor-promoting CAFs. This work identifies MHC class II–expressing CAFs with a capacity to present antigens to CD4+ T cells, and potentially to modulate the immune response in pancreatic tumors.See related commentary by Belle and DeNardo, p. 1001.This article is highlighted in the In This Issue feature, p. 983

Comparison of invasive and intraductal regions of tumors derived from IGO transplants of Slow-progressor organoids

Supplementary Table S1 Survival times of IGO and OGO mice Supplementary Table S2 Characteristics of patient-derived organoids, including KRAS, TP53, SMAD4, CDKN2A mutation status and patient stage Supplementary Table S3 Summary of Survival Data, including engraftment rate, mean survival, metastatic frequency Supplementary Table S4 Primers for quantitative PCR

DNA motif analysis

Pancreatic ductal adenocarcinoma (PDAC) is the most lethal common malignancy, with little improvement in patient outcomes over the past decades. Recently, subtypes of pancreatic cancer with different prognoses have been elaborated; however, the inability to model these subtypes has precluded mechanistic investigation of their origins. Here, we present a xenotransplantation model of PDAC in which neoplasms originate from patient-derived organoids injected directly into murine pancreatic ducts. Our model enables distinction of the two main PDAC subtypes: intraepithelial neoplasms from this model progress in an indolent or invasive manner representing the classical or basal-like subtypes of PDAC, respectively. Parameters that influence PDAC subtype specification in this intraductal model include cell plasticity and hyperactivation of the RAS pathway. Finally, through intratumoral dissection and the direct manipulation of RAS gene dosage, we identify a suite of RAS-regulated secreted and membrane-bound proteins that may represent potential candidates for therapeutic intervention in patients with PDAC.Significance:Accurate modeling of the molecular subtypes of pancreatic cancer is crucial to facilitate the generation of effective therapies. We report the development of an intraductal organoid transplantation model of pancreatic cancer that models the progressive switching of subtypes, and identify stochastic and RAS-driven mechanisms that determine subtype specification.See related commentary by Pickering and Morton, p. 1448.This article is highlighted in the In This Issue feature, p. 1426

Confocal z-stack imaging of immunofluorescent (IF) images of mStrawberry-hT3 grafts 4 weeks after IGO transplantation

Supplementary Figure legends

Activating KRAS mutations are found in nearly all cases of pancreatic ductal adenocarcinoma (PDAC), yet effective clinical targeting of oncogenic KRAS remains elusive. Understanding of KRAS-dependent PDAC-promoting pathways could lead to the identification of vulnerabilities and the development of new treatments. We show that oncogenic KRAS induces BNIP3L/NIX expression and a selective mitophagy program that restricts glucose flux to the mitochondria and enhances redox capacity. Loss of Nix restores functional mitochondria to cells, increasing demands for NADPH reducing power and decreasing proliferation in glucose-limited conditions. Nix deletion markedly delays progression of pancreatic cancer and improves survival in a murine (KPC) model of PDAC. Although conditional Nix ablation in vivo initially results in the accumulation of mitochondria, mitochondrial content eventually normalizes via increased mitochondrial clearance programs, and pancreatic intraepithelial neoplasia (PanIN) lesions progress to PDAC. We identify the KRAS–NIX mitophagy program as a novel driver of glycolysis, redox robustness, and disease progression in PDAC.Significance:NIX-mediated mitophagy is a new oncogenic KRAS effector pathway that suppresses functional mitochondrial content to stimulate cell proliferation and augment redox homeostasis. This pathway promotes the progression of PanIN to PDAC and represents a new dependency in pancreatic cancer.This article is highlighted in the In This Issue feature, p. 1143

Supplementary Figures S1-S8

Supplementary Figure S1 shows the data quality and clustering metrics of the human PDAC single cell transcriptomes, Supplementary Figure S2 shows the distribution of sub-clusters of cells throughout the human dataset, Supplementary Figure S3 shows pathway analysis in human PDAC iCAFs and myCAFs, Supplementary Figure S4 shows the data quality and clustering metrics of the KPC mouse PDAC single cell transcriptomes, Supplementary Figure S5 shows pathway analysis in different KPC CAFs, Supplementary Figure S6 shows that Podoplanin is a pan-fibroblast marker in murine PDAC, Supplementary Figure S7 shows the validation of apCAFs in human PDAC, Supplementary Figure S8 shows the characterization of apCAFs in KPC and orthotopic transplantation models

Method Used to Define the Thresholds for Fast- and Slow-Progressing IGO-Derived Tumors

SFigure1

Purpose:Napabucasin (2-acetylfuro-1,4-naphthoquinone or BBI-608) is a small molecule currently being clinically evaluated in various cancer types. It has mostly been recognized for its ability to inhibit STAT3 signaling. However, based on its chemical structure, we hypothesized that napabucasin is a substrate for intracellular oxidoreductases and therefore may exert its anticancer effect through redox cycling, resulting in reactive oxygen species (ROS) production and cell death.Experimental Design:Binding of napabucasin to NAD(P)H:quinone oxidoreductase-1 (NQO1), and other oxidoreductases, was measured. Pancreatic cancer cell lines were treated with napabucasin, and cell survival, ROS generation, DNA damage, transcriptomic changes, and alterations in STAT3 activation were assayed in vitro and in vivo. Genetic knockout or pharmacologic inhibition with dicoumarol was used to evaluate the dependency on NQO1.Results:Napabucasin was found to bind with high affinity to NQO1 and to a lesser degree to cytochrome P450 oxidoreductase (POR). Treatment resulted in marked induction of ROS and DNA damage with an NQO1- and ROS-dependent decrease in STAT3 phosphorylation. Differential cytotoxic effects were observed, where NQO1-expressing cells generating cytotoxic levels of ROS at low napabucasin concentrations were more sensitive. Cells with low or no baseline NQO1 expression also produced ROS in response to napabucasin, albeit to a lesser extent, through the one-electron reductase POR.Conclusions:Napabucasin is bioactivated by NQO1, and to a lesser degree by POR, resulting in futile redox cycling and ROS generation. The increased ROS levels result in DNA damage and multiple intracellular changes, one of which is a reduction in STAT3 phosphorylation.

Supplementary Figures 1,2,3,4,5,6,7

Purpose:KRAS is mutated in the majority of pancreatic ductal adenocarcinoma. MAPK and PI3K-AKT are primary KRAS effector pathways, but combined MAPK and PI3K inhibition has not been demonstrated to be clinically effective to date. We explore the resistance mechanisms uniquely employed by malignant cells.Experimental Design:We evaluated the expression and activation of receptor tyrosine kinases in response to combined MEK and AKT inhibition in KPC mice and pancreatic ductal organoids. In addition, we sought to determine the therapeutic efficacy of targeting resistance pathways induced by MEK and AKT inhibition in order to identify malignant-specific vulnerabilities.Results:Combined MEK and AKT inhibition modestly extended the survival of KPC mice and increased Egfr and ErbB2 phosphorylation levels. Tumor organoids, but not their normal counterparts, exhibited elevated phosphorylation of ERBB2 and ERBB3 after MEK and AKT blockade. A pan-ERBB inhibitor synergized with MEK and AKT blockade in human PDA organoids, whereas this was not observed for the EGFR inhibitor erlotinib. Combined MEK and ERBB inhibitor treatment of human organoid orthotopic xenografts was sufficient to cause tumor regression in short-term intervention studies.Conclusions:Analyses of normal and tumor pancreatic organoids revealed the importance of ERBB activation during MEK and AKT blockade primarily in the malignant cultures. The lack of ERBB hyperactivation in normal organoids suggests a larger therapeutic index. In our models, pan-ERBB inhibition was synergistic with dual inhibition of MEK and AKT, and the combination of a pan-ERBB inhibitor with MEK antagonists showed the highest activity both in vitro and in vivo.

Supp Figure legends

Supplementary Figures 1-3

Table listing the differentially expressed genes between napabucasin treated cells compared to DMSO as vehicle control

Supplementary Figure Legends

Purpose:Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease characterized by an extensive fibroinflammatory stroma, which includes abundant cancer-associated fibroblast (CAF) populations. PDAC CAFs are heterogeneous, but the nature of this heterogeneity is incompletely understood. The Hedgehog pathway functions in PDAC in a paracrine manner, with ligands secreted by cancer cells signaling to stromal cells in the microenvironment. Previous reports investigating the role of Hedgehog signaling in PDAC have been contradictory, with Hedgehog signaling alternately proposed to promote or restrict tumor growth. In light of the newly discovered CAF heterogeneity, we investigated how Hedgehog pathway inhibition reprograms the PDAC microenvironment.Experimental Design:We used a combination of pharmacologic inhibition, gain- and loss-of-function genetic experiments, cytometry by time-of-flight, and single-cell RNA sequencing to study the roles of Hedgehog signaling in PDAC.Results:We found that Hedgehog signaling is uniquely activated in fibroblasts and differentially elevated in myofibroblastic CAFs (myCAF) compared with inflammatory CAFs (iCAF). Sonic Hedgehog overexpression promotes tumor growth, while Hedgehog pathway inhibition with the smoothened antagonist, LDE225, impairs tumor growth. Furthermore, Hedgehog pathway inhibition reduces myCAF numbers and increases iCAF numbers, which correlates with a decrease in cytotoxic T cells and an expansion in regulatory T cells, consistent with increased immunosuppression.Conclusions:Hedgehog pathway inhibition alters fibroblast composition and immune infiltration in the pancreatic cancer microenvironment.

ERI-type molecular sieves (SSZ-98, UZM-12, ERI-type zeolite, SAPO-17) are synthesized with varying Si/Al = 5–9 and Si/T-atoms = 0.034–0.12 using several organic structure-directing agents (OSDAs), and evaluated as catalysts for the methanol-to-olefins (MTO) reaction. SAPO-34 (Si/T-atoms = 0.089) and SSZ-13 (Si/Al = 15) are also prepared and tested for comparison. The ERI-type zeolites gave improved ethylene-to-propylene ratios (E/P = 1.1–1.9) over SSZ-13 (E/P = 0.82) and SAPO-34 (E/P = 0.85). The SAPO-17 samples produced an E/P of 0.7–1.1 and a generally high C₄+ fraction. The differences observed in the olefins product distributions between the zeolites with low framework Si/Al (E/P > 1.5) and SAPO-17 with low Si/T-atom < 0.1 (E/P ≤ 1 and high C₄+) are the result of slower maturation of aromatic hydrocarbon-pool (HP) species and the presence of aromatics with bulky alkyl-groups (C₃-C₄) in the SAPO-17 samples. The rapid formation of cyclic intermediates and the shift in their composition towards less-methylated ((CH₃)_(n≤4)) methylbenzenes and methylnaphthalenes are found to be key to enhancing the ethylene selectivity in ERI-type molecular sieves.

Engineered systems designed to remove CO2from the atmosphere need better adsorbents. Here, we report on zeolite-based adsorbents for the capture of low-concentration CO2. Synthetic zeolites with the mordenite (MOR)-type framework topology physisorb CO2from low concentrations with fast kinetics, low heat of adsorption, and high capacity. The MOR-type zeolites can have a CO2capacity of up to 1.15 and 1.05 mmol/g for adsorption from 400 ppm CO2at 30 °C, measured by volumetric and gravimetric methods, respectively. A structure–performance study demonstrates that Na+cations in the O33 site located in the side-pocket of the MOR-type framework, that is accessed through a ring of eight tetrahedral atoms (either Si4+or Al3+: eight-membered ring [8MR]), is the primary site for the CO2uptake at low concentrations. The presence of N2and O2shows negligible impact on CO2adsorption in MOR-type zeolites, and the capacity increases to ∼2.0 mmol/g at subambient temperatures. By using a series of zeolites with variable topologies, we found the size of the confining pore space to be important for the adsorption of trace CO2. The results obtained here show that the MOR-type zeolites have a number of desirable features for the capture of CO2at low concentrations.

Pancreatic ductal adenocarcinoma (PDA) samples reveal extensive cellular heterogeneity. Using single-cell RNA sequencing, we uncover multiple tumor cell populations distinguished by their differentiation state and associated with different stages of tumor progression in a mouse model of PDA. We identify Spdef as a factor required for tumorigenesis in pancreatic cancer cells of epithelial and mucinous nature. By comparative analysis of cell differentiation states in mice and humans, we find that the Spdef program is highly expressed by human PDAs of the classical subtype. Mouse and human PDA cells expressing elevated levels of Spdef are dependent upon this transcription factor for tumor progression in vivo. The tumor-promoting function of Spdef is recapitulated by two Spdef target genes that regulate protein folding and endoplasmic reticulum activity, Agr2 and Ern2/Ire1β. These findings offer insights into the factors controlling differentiation states in PDA and identify new vulnerabilities in the most common subtype of pancreatic cancer.

742 Background: Current biomarkers offer modest predictive capacity for drug sensitivity testing in pancreatic cancer. Patient-specific pharmacotyping offers the potential for a more direct, personalized prediction model. Recently, an implantable microdevice was developed to facilitate in situ multi-agent pharmacotyping and has since entered clinical trials in multiple cancer types, but had not yet been tested in pancreatic cancer. Here we evaluated the use of a microdosing device (microdevice) in a mouse xenotransplant model of pancreatic cancer as proof of principle to inform future translation to the clinic. Methods: A microdevice consists of a cylindrical frame and 18 wells embedded with standard chemotherapy agents (5 FU, gemcitabine, SN 38, paclitaxel, oxaliplatin), a non-toxic polyethylene glycol (PEG) matrix as control, and doxorubicin, the auto-fluorescent properties of which allow us to determine the distance of drug diffusion for each tumor. Devices were implanted into murine xenotransplanted human organoids (hM1A and hM1E Table 1). Microdevices retrieved at 4h, 8h, and 24h post-implantation together with tumors were fixed in 10% formalin. The tissue was embedded in paraffin and sectioned parallel to the device. A distance-dependent drug diffusion rate and concentration profiles with doxorubicin were evaluated. Co-immunohistochemistry (IHC) for cleaved caspase-3 (CC3), gamma H2AX (apoptosis markers), and human mitochondria (human cancer cell marker) was performed in the area of drug diffusion to determine the cytotoxic effects of chemotherapy. Results: 15 animals were enrolled in the experiment with 100% postoperative survival. One device per animal was placed, and all devices were successfully retrieved. Microdevice insertion and exposure to PEG had no effect on tumor integrity. At 250-350µm from the well, we observed intensity from doxorubicin, suggesting drug diffusion. The signal on differential response to drugs was detected as early as 4 hours. Conclusions: Utilization of implantable microdevice to predictcancer drug sensitivity is feasible in organoid transplantation animal models of pancreatic cancer. Future work is needed to expand this model to other cancer drugs and biomarkers to evaluate the cancer drug sensitivity and to test the feasibility of this model to study the effects of chemotherapy on the tumor microenvironment. [Table: see text]

BackgroundPancreatic ductal adenocarcinoma (PDAC) is one of the deadliest tumors owing to its robust desmoplasia, low immunogenicity, and recruitment of cancer-conditioned, immunoregulatory myeloid cells. These features strongly limit the success of immunotherapy as a single agent, thereby suggesting the need for the development of a multitargeted approach. The goal is to foster T lymphocyte infiltration within the tumor landscape and neutralize cancer-triggered immune suppression, to enhance the therapeutic effectiveness of immune-based treatments, such as anticancer adoptive cell therapy (ACT).MethodsWe examined the contribution of immunosuppressive myeloid cells expressing arginase 1 and nitric oxide synthase 2 in building up a reactive nitrogen species (RNS)-dependent chemical barrier and shaping the PDAC immune landscape. We examined the impact of pharmacological RNS interference on overcoming the recruitment and immunosuppressive activity of tumor-expanded myeloid cells, which render pancreatic cancers resistant to immunotherapy.ResultsPDAC progression is marked by a stepwise infiltration of myeloid cells, which enforces a highly immunosuppressive microenvironment through the uncontrolled metabolism of L-arginine by arginase 1 and inducible nitric oxide synthase activity, resulting in the production of large amounts of reactive oxygen and nitrogen species. The extensive accumulation of myeloid suppressing cells and nitrated tyrosines (nitrotyrosine, N-Ty) establishes an RNS-dependent chemical barrier that impairs tumor infiltration by T lymphocytes and restricts the efficacy of adoptive immunotherapy. A pharmacological treatment with AT38 ([3-(aminocarbonyl)furoxan-4-yl]methyl salicylate) reprograms the tumor microenvironment from protumoral to antitumoral, which supports T lymphocyte entrance within the tumor core and aids the efficacy of ACT with telomerase-specific cytotoxic T lymphocytes.ConclusionsTumor microenvironment reprogramming by ablating aberrant RNS production bypasses the current limits of immunotherapy in PDAC by overcoming immune resistance.