PANC-1 Cells Research Articles

The long non-coding RNA NEAT1 contributes to aberrant STAT3 signaling in pancreatic cancer and is regulated by a metalloprotease-disintegrin ADAM8/miR-181a-5p axis.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers and several studies demonstrate that STAT3 has critical roles throughout the course of PDAC pathogenesis. TCGA, microarray, and immunohistochemistry data from a PDAC cohort were used for clinical analyses. Panc89 cells with ADAM8 knockout, re-expression of ADAM8 mutants, and Panc1 cells overexpressing ADAM8 were generated. Gene expression analyses of ADAM8, STAT3, long non-coding (lnc) RNA NEAT1, miR-181a-5p and ICAM1 were performed by quantitative PCR. Subcellular fractionation quantified NEAT1 expression in cytoplasm and nucleus of PDAC cell lines. Cell proliferation, scratch, and invasion assays were performed to detect growth rate, migration and invasion capabilities of cells. Gain and loss of function experiments were carried out to investigate the biological effects of lncRNA NEAT1 and miR-181a-5p on PDAC cells and downstream genes. Dual-luciferase reporter gene assay determined interaction and binding sites of miR-181a-5p in lncRNA NEAT1. Pull down assays, RNA binding protein immunoprecipitation (RIP), and ubiquitination assays explored the molecular interaction between lncRNA NEAT1 and STAT3. High ADAM8 expression causes aberrant STAT3 signaling in PDAC cells and is positively correlated with NEAT1 expression. NEAT1 binding to STAT3 was confirmed and prevents STAT3 degradation in the proteasome as increased degradation of STAT3 was observed in ADAM8 knockout cells and cells treated with bortezomib. Furthermore, miRNA-181a-5p regulates NEAT1 expression by direct binding to the NEAT1 promoter. ADAM8 regulates intracellular STAT3 levels via miR-181a-5p and NEAT1 in pancreatic cancer.

Differential regulation of expression of the protein kinases DYRK1A and DYRK1B in cancer cells

The protein kinases DYRK1A and DYRK1B are pivotal regulators of cell cycle progression by promoting cell cycle exit into quiescence. DYRK1B appears to play a more important role in cancer cell quiescence than DYRK1A, as evidenced by its overexpression or copy number variations in human tumour samples. Nonetheless, the stimuli driving DYRK1B upregulation and the potential divergence in expression patterns between DYRK1A and DYRK1B remain largely elusive. In the present study, we scrutinized the regulatory pathways modulating DYRK1B expression relative to DYRK1A in PANC-1 and A549 cancer cell lines across varying conditions. Serum deprivation, pharmacological mTOR inhibition and increased cell density resulted in the differential upregulation of DYRK1B compared to DYRK1A. We then aimed to assess the role of protein kinases MST1 and MST2, which are key transmitters of cell density dependent effects. Unexpectedly, exposure to the MST1/2 inhibitor XMU-MP-1 resulted in increased DYRK1B levels in A549 cells. Further investigation into the off-target effects of XMU-MP-1 unveiled the inhibition of Aurora kinases (AURKA and AURKB) as a potential causative factor. Consistently, AURK inhibitors VX-680 (tozasertib), MLN8237 (alisertib), AZD1152-HQPA (barasertib) resulted in the upregulation of DYRK1B expression in A549 cells. In summary, our findings indicate that the expression of DYRK1A and DYRK1B is differentially regulated in cancer cells and reveal that the kinase inhibitor XMU-MP-1 increases DYRK1B expression likely through off target inhibition of Aurora kinases.

Efficacy of photodynamic therapy using 5-aminolevulinic acid-induced photosensitization is enhanced in pancreatic cancer cells with acquired drug resistance

The use of 5-aminolevulinic acid (ALA) as a precursor for protoporphyrin IX (PpIX) is an established photosensitization strategy for photodynamic therapy (PDT) and fluorescence guided surgery. Ongoing studies are focused on identifying approaches to enhance PpIX accumulation as well as to identify tumor sub-types associated with high PpIX accumulation. In this study, we investigated PpIX accumulation and PDT treatment response with respect to nodule size in 3D cultures of pancreatic cancer cells (Panc1) and a derivative subline (Panc1OR), which has acquired drug resistance and exhibits increased epithelial mesenchymal transition. In monolayer and 3D culture dose response studies the Panc1OR cells exhibit significantly higher cell killing at lower light doses than the drug naïve cells. Panc1OR also exhibits increased PpIX accumulation. Further analysis of cell killing efficiency per molecule of intracellular PpIX indicates that the drug resistant cells are intrinsically more responsive to PDT. Additional investigation using exogenous delivery of PpIX also shows higher cell killing in drug resistant cells, under conditions which achieve approximately the same intracellular PpIX. Overall these results are significant as they demonstrate that this example of drug-resistant cells associated with aggressive disease progression and poor clinical outcomes, show increased sensitivity to ALA-PDT.

Honey Targets Ribosome Biogenesis Components to Suppress the Growth of Human Pancreatic Cancer Cells

Pancreatic cancer (PanCa) is one of the deadliest cancers, with limited therapeutic response. Various molecular oncogenic events, including dysregulation of ribosome biogenesis, are linked to the induction, progression, and metastasis of PanCa. Thus, the discovery of new therapies suppressing these oncogenic events and ribosome biogenesis could be a novel therapeutic approach for the prevention and treatment of PanCa. The current study was designed to investigate the anti-cancer effect of honey against PanCa. Our results indicated that honey markedly inhibited the growth and invasive characteristics of pancreatic cancer cells by suppressing the mRNA expression and protein levels of key components of ribosome biogenesis, including RNA Pol-I subunits (RPA194 and RPA135) along with its transcriptional regulators, i.e., UBTF and c-Myc. Honey also induced nucleolar stress in PanCa cells by reducing the expression of various nucleolar proteins (NCL, FBL, and NPM). Honey-mediated regulation on ribosome biogenesis components and nucleolar organization-associated proteins significantly arrested the cell cycle in the G2M phase and induced apoptosis in PanCa cells. These results, for the first time, demonstrated that honey, being a natural remedy, has the potential to induce apoptosis and inhibit the growth and metastatic phenotypes of PanCa by targeting ribosome biogenesis.

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.

Adipose tissue-derived extracellular vesicles from obese mice suppressed splenocyte-mediated pancreatic cancer cell death.

Obesity is a risk factor for pancreatic cancer and negatively contributes to the immune system. However, the mechanisms by which obesity mediates these actions are still poorly understood. Recent studies have demonstrated that extracellular vesicles (EVs) are key mediators of communication between cells and may influence various aspects of cancer progression. We aim to explore the influence of EVs derived from adipose tissue of obese mice on cytokine production within the interactions between cancer cells and immune cells. We isolated EVs from the adipose tissue of both C57BL6/J mice and Ob/Ob mice. Subsequently, we treated EVs with Panc02 cells, the murine ductal pancreatic cancer cell line, which were co-cultured with splenocytes. Viability and SMAD4 gene expression were examined in Panc02 cells, and cytokine concentrations of IL-6, IL-4, IL-12, and IL-12p70 were measured in the cultured medium. Interestingly, we observed a significant reduction in splenocyte-mediated Panc02 cell death when treated with EVs derived from the adipose tissue of Ob/Ob mice, compared to those from C57BL6/J mice. Additionally, EVs from Ob/Ob mice-derived adipose tissue significantly increased the levels of IL-4, IL-2, and IL-12p70 in the culture media of Panc02 cells co-cultured with splenocytes, compared to EVs from C57BL6/J mice-derived adipose tissue. Adipose tissue-derived EVs from obese mice suppressed splenocyte-mediated Panc02 cell death and upregulated IL-4, IL-2, and IL-12p70 in cultured medium.

Dronedarone hydrochloride (DH) induces pancreatic cancer cell death by triggering mtDNA-mediated pyroptosis

Pancreatic cancer is one of the leading causes of cancer-associated mortality, with a poor treatment approach. Previous study has shown that inducing pyroptosis in pancreatic ductal adenocarcinoma (PDAC) slows the growth of PDACs, implying that pyroptosis inducers are potentially effective for PDAC therapy. Here, we found that Dronedarone hydrochloride (DH), an antiarrhythmic drug, induces pyroptosis in pancreatic cancer cells and inhibits PDAC development in mice. In PANC-1 cells, DH caused cell death in a dosage- and time-dependent manner, with only pyroptosis inhibitors and GSDMD silencing rescuing the cell death, indicating that DH triggered GSDMD-dependent pyroptosis. Further work revealed that DH increased mitochondrial stresses and caused mitochondrial DNA (mtDNA) leakage, activating the cytosolic STING-cGAS and pyroptosis pathways. Finally, we assessed the anti-cancer effects of DH in a pancreatic cancer mouse model and found that DH treatment suppressed pancreatic tumor development in vivo. Collectively, our investigation demonstrates that DH triggers pyroptosis in PDAC and proposes its potential effects on anti-PDAC growth.

Curcumin-loaded emulsome nanoparticles induces apoptosis through p53 signaling pathway in pancreatic cancer cell line PANC-1

Pancreatic cancer is a global health problem with a poor prognosis, limited treatment options and low survival rates of patients. Thus, the exploration of novel treatment approaches is crucial. Curcumin shows promise in pancreatic cancer. Curcumin has anticancer properties promoting apoptosis through the p53 pathway. However, adverse effects and low bioavailability are curcumin's main drawbacks and its delivery by nanoparticles could improve its effectiveness as a treatment option. Curcumin-loaded emulsome nanoparticles (CurEm) have shown promise in colorectal, hepatocellular, and prostate cancers. This study aims to evaluate the anticancer potential of CurEm in pancreatic cancer cell line PANC-1. The cytotoxic effects of CurEm on PANC-1 cells show cytotoxicity in dose and time-dependent manner. The selected dose 30 μM CurEm resulted spheroidal morphology in PANC-1 cells and colony forming and scratch assay conducted demonstrated significant growth inhibition and decrease in migration ability, respectively. Cell cycle analysis shows that CurEm induces G2/M arrest in PANC-1 cells. CurEm-treated PANC-1 cells showed a significant increase in p53 and Caspase 3 genes, while a significant decrease in Bcl-2 genes compared to untreated group. Western blot results showed parallel results to qPCR analysis for Bcl-2 protein levels. Interestingly, we saw low p53 protein levels in CurEm-treated PANC-1 cells. These findings shed light on the potential of CurEm as an effective and stable therapeutic approach for pancreatic cancer.

Folate-Functionalized Chitosan-PLGA Nanoparticles: A Novel approach for targeted osthole delivery in pancreatic cancer

Efficient drug delivery systems targeting cancer cells are crucial for enhancing cancer therapy. In this study, we developed PLGA nanoparticles coated with folate-conjugated chitosan (osthole-PLGA-NPs/CS-FA) to deliver osthole to cancer cells and investigated its inhibitory and molecular signaling mechanisms in the PANC-1 pancreatic cancer cell line. Field emission scanning electron microscopy (FESEM) revealed that osthole-PLGA-NPs/CS-FA had a spherical structure with a uniform size distribution. Dynamic light scattering (DLS) analysis showed an average size of 171.76 nm, a dispersion index 0.26, and a surface charge of + 33.08 mV, indicating stability and uniform dispersion. Fourier-transform infrared (FTIR) spectrum analysis confirmed the successful incorporation of osthole into the PLGA nanoparticles, with an encapsulation efficiency of 93.12 %. These physicochemical properties suggest efficient cellular uptake and targeted delivery. The antioxidant potential of osthole-PLGA-NPs/CS-FA was evaluated using the ABTS assay, showing concentration-dependent inhibition of free radicals with an IC50 value of 172.95 μg/mL. The anticancer properties were assessed using the MTT assay, demonstrating a significant and concentration-dependent cytotoxic effect on PANC-1 cells (IC50 = 31.2 μg/mL) with minimal impact on normal human foreskin fibroblast (HFF) cells. DAPI staining and flow cytometry analyses confirmed a concentration-dependent increase in apoptosis in PANC-1 cells. The nanoparticles induced upregulation of Bax and downregulation of Bcl2, indicating activation of the intrinsic mitochondrial apoptotic pathway. The anti-angiogenic activity of osthole-PLGA-NPs/CS-FA was evaluated using the chick chorioallantoic membrane (CAM) assay. The results showed significant inhibition of angiogenesis in a concentration-dependent manner, starting at 40 μg/mL and increasing up to 120 μg/mL. In conclusion, osthole-PLGA-NPs/CS-FA nanoparticles exhibit promising potential for targeted pancreatic cancer therapy by enhancing cellular uptake, inducing apoptosis, and inhibiting angiogenesis.

Blocking M2-Like Macrophage Polarization Using Decoy Oligodeoxynucleotide-Based Gene Therapy Prevents Immune Evasion for Pancreatic Cancer Treatment.

M2-like macrophages exhibit immunosuppressive activity and promote pancreatic cancer progression. Reactive oxygen species (ROS) affect macrophage polarization; however, the mechanism remains unclear. This study aimed to elucidate the underlying molecular basis and design a gene therapy to inhibit M2-like polarization. Microarray analysis and immunofluorescence staining were performed in M1-like and M2-like macrophages to ascertain the expression of CYBB, a major intracellular ROS source. Coculture assay and syngeneic orthotopic pancreatic cancer mice models were used to study the mechanism of M2-like skewing. Decoy oligodeoxynucleotides (ODNs) were designed to manipulate CYBB transcription to inhibit M2-like polarization and control tumor growth. Lipopolysaccharide treatment polarized U937 cells to M1-like macrophages in which CYBB expression was increased. In contrast, coculture with PANC-1 cells induced M2-like polarization in U937 cells with CYBB downregulation. High CD204 M2-like expression in combination with low CYBB expression was associated with the worst prognosis in patients with pancreatic cancer. STAT6 and HDAC2 in U937 cells were activated by cancer cell-derived IL4 after coculture and then bound to the CYBB promoter to repress CYBB expression, resulting in M2-like polarization. Diphenyleneiodonium, 8λ³-iodatricyclo[7.4.0.02,⁷]trideca-1(13),2,4,6,9,11-hexaen-8-ylium chloride that inhibits ROS production could block this action. Knockdown of STAT6 and HDAC2 also inhibited M2-like polarization and maintained the M1-like phenotype of U937 cells after coculture. Decoy ODNs interrupting the binding of STAT6 to the CYBB promoter counteracted M2-like polarization and tumor growth and triggered antitumor immunity in vivo. Gene therapy using STAT6-CYBB decoy ODNs can inhibit M2-like polarization, representing a potential therapeutic tool for pancreatic cancer.

Further Probing the Properties of a Unique Sponge-derived Alkaloid Through the Isolation of a New (-)-(5E)-(8R)-(14Z)-Mycothiazole Analogue.

Scale-up isolation of (+)-(5Z)-(8S)-(14Z)-mycothiazole (1) from Vanuatu specimens of C. mycofijiensis to semisynthesize (+)-(5Z)-(8S)-8-O-acetyl-(14Z)-mycothiazole (2) revealed a new diastereomer, (-)-(5E)-(8R)-(14Z)-mycothiazole (4). The structure of 4 was determined using HRMS, NMR, and comparing optical rotation to (-)-(5Z)-(8R)-(14Z)-mycothiazole (3) and 2. The maximum tolerated dose of 2 in mice was 0.1 mg/kg. The IC50 of 4 in PANC-1 and HepG2 cancer cell lines was 111.6 and 115.0 nM. Evaluation of 4 in C. elegans showed similar oxygen consumption compared to 1-2, and all compounds significantly increased the lifespan. The Z orientation at Δ5,6 is crucial for picomolar cytotoxicity but not for mitochondrial inhibition.

Growing Desmoplastic Three-Dimensional Pancreatic Cancer Spheroids from Co-Culture.

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers with a 5-year survival rate of <12%. The biggest barrier to therapy is the dense desmoplastic extracellular matrix (ECM) that surrounds the tumor and reduces vascularization, generally termed desmoplasia. A variety of drug combinations and formulations have been tested to treat the cancer, and although many of them show success pre-clinically, they fail clinically. It, therefore, becomes important to have a clinically relevant model available that can predict the response of the tumor to therapy. This model has been previously validated against resected clinical tumors. Here a simple protocol to grow desmoplastic three-dimensional (3D)-coculture spheroids is described that can naturally generating a robust ECM and do not require any external matrix sources or scaffold to support their growth. Briefly human pancreatic stellate cells (HPaSteC) and PANC-1 cells are used to prepare a suspension containing the cells in a 1:2 ratio, respectively. The cells are plated in a poly-HEMA coated, 96-well low attachment U-well plate. The plate is centrifuged to allow the cells to form an initial pellet. The plate is stored in the incubator at 37 °C with 5% CO2, and media is replaced every 3 days. Plates can be imaged at designated intervals to measure spheroid volume. Following 14 days of culture, mature desmoplastic spheroids are formed (i.e. average volume of 0.048 + 0.012 mm3(451 µm x 462.84 µm)) and can be utilized for experimental therapy assessment. Mature ECM components include collagen-I, hyaluronic acid, fibronectin, and laminin.

Systematic Evaluation of Affinity Enrichment Methods for O-GlcNAc Proteomics.

O-Linked β-N-acetylglucosamine (O-GlcNAc) modification (i.e., O-GlcNAcylation) on proteins plays critical roles in the regulation of diverse biological processes. However, protein O-GlcNAcylation analysis, especially at a large scale, has been a challenge. So far, a number of enrichment materials and methods have been developed for site-specific O-GlcNAc proteomics in different biological settings. Despite the presence of multiple methods, their performance for the O-GlcNAc proteomics is largely unclear. In this work, by using the lysates of PANC-1 cells (a pancreatic cancer cell line), we provided a head-to-head comparison of three affinity enrichment methods and materials (i.e., antibody, lectin AANL6, and an OGA mutant) for site-specific O-GlcNAc proteomics. The enriched peptides were analyzed by HCD product-dependent EThcD (i.e., HCD-pd-EThcD) mass spectrometry. The resulting data files were processed by three different data analysis packages (i.e., Sequest HT, Byonic, and FragPipe). Our data suggest that each method captures a subpopulation of the O-GlcNAc proteins. Besides the enrichment methods, we also observe complementarity between the different data analysis tools. Thus, combining different approaches holds promise for enhanced coverage of O-GlcNAc proteomics.

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.

G3BP2 promotes tumor progression and gemcitabine resistance in PDAC via regulating PDIA3-DKC1-hENT in a stress granules-dependent manner.

Pancreatic ductal adenocarcinoma (PDAC) is distinguished by its aggressive malignancy, limited treatment avenues and a tendency towards chemotherapy resistance, underscoring the critical need for advanced research to uncover new therapeutic approaches. Stress granules (SGs) that is implicated in cellular self-protection mechanism, along with its associated family molecules have shown pro-cancer effects and are closely related to tumor chemotherapy resistance. In this study we investigated the relationship between Ras GTPase-activating protein-binding proteins 2 (G3BP2), a core component of SGs, and the malignancy of PDAC as well as its resistance to the chemotherapy drug gemcitabine. Analyzing TCGA dataset revealed that the expression of G3BP1 and G3BP2 was significantly upregulated in PDAC compared with adjacent normal pancreatic tissues, and the high expression of G3BP2 rather than G3BP1 was significantly associated with poorer overall survival (OS) in PDAC patients. We demonstrated that knockdown of G3BP2 inhibited the proliferation and invasion of PANC-1 and CFPAC-1 cells in vitro and in vivo. By analyzing the differentially expressed genes in G3BP2 knockdown and overexpressed PANC-1 cells, we identified DKC1 that was associated with RNA stability and regulation as the target of G3BP2. We demonstrated that G3BP2 bound to PDIA3 mRNA and recruited them into SGs, increasing the stability of PDIA3 mRNA and attenuating its translation efficiency, thereby promoting DKC1 expression. Furthermore, DKC1 could bind to hENT mRNA and inhibited its expression, which enhanced gemcitabine resistance of PDAC. Therefore, we propose a novel mechanism wherein G3BP2 facilitates PDAC's resistance to chemotherapy by modulating PDIA3-DKC1-hENT in a SGs-dependent way, suggesting G3BP2 SGs a protentional therapeutic target for the treatment in PDAC.

Human bone marrow mesenchymal stem cell-derived exosomes loaded with gemcitabine inhibit pancreatic cancer cell proliferation by enhancing apoptosis.

Pancreatic cancer remains one of the most lethal malignancies, and has limited effective treatment. Gemcitabine (GEM), a chemotherapeutic agent, is commonly used for clinical treatment of pancreatic cancer, but it has characteristics of low drug delivery efficiency and significant side effects. The study tested the hypothesis that human bone marrow mesenchymal stem cell (MSC)-derived exosomes loaded with GEM (Exo-GEM) would have a higher cytotoxicity against human pancreatic cancer cells by enhancing their apoptosis. To investigate the cytotoxicity of MSC-derived Exo-GEM against pancreatic cancer cells in vitro. Exosomes were isolated from MSCs and characterized by transmission electron microscopy and nanoparticle tracking analysis. Exo-GEM through electroporation, sonication, or incubation, and the loading efficiency was evaluated. The cytotoxicity of Exo-GEM or GEM alone against human pancreatic cancer Panc-1 and MiaPaca-2 cells was assessed by MTT and flow cytometry assays. The isolated exosomes had an average size of 76.7 nm. The encapsulation efficacy and loading efficiency of GEM by electroporation and sonication were similar and significantly better than incubation. The cytotoxicity of Exo-GEM against pancreatic cancer cells was stronger than free GEM and treatment with 0.02 μM Exo-GEM significantly reduced the viability of both Panc-1 and MiaPaca-2 cells. Moreover, Exo-GEM enhanced the frequency of GEM-induced apoptosis in both cell lines. Human bone marrow MSC-derived Exo-GEM have a potent cytotoxicity against human pancreatic cancer cells by enhancing their apoptosis, offering a promising drug delivery system for improving therapeutic outcomes.

Abstract A077: The role of RhoV in basal-like pancreatic cancer

Abstract Background Pancreatic ductal adenocarcinoma is a devastating disease lacking targeted therapy. Basal-like pancreatic cancer is a tumor subtype with a worse clinical outcome than other subtypes. These cancers are characterized by the expression of basal keratins and mesenchymal markers. However, the genes that drive the basal-like phenotype are poorly understood. Ras homolog family member V (RhoV) is one of the Rho GTPases, and it has been demonstrated to drive the progression of lung and breast cancers. The current study aims to reveal the role of RhoV in basal-like pancreatic cancer. Design RhoV, p63, and CK5/6 were stained in sequential sections by immunohistochemistry. Expression of RhoV in pancreatic cancer and cell lines was reanalyzed based on the data from ProteinAtlas and Broad Insitute DepMap Portal. Basal cell line, BxPC3, and non-basal cell line, Panc1 were selected for functional evaluation based on their differentiated RhoV expression. RhoV gene was overexpressed and knocked down using the CRISPR/gRNA-based Lentiviral system, followed by sphere formation, colony formation, migration, and invasion assays. Results RhoV, p63, and CK5/6 were expressed in the same histologic location of basal pancreatic cancer. The gene expression level of RhoV was co-expressed with p63 (a classic basal marker) in four pancreatic cancer cell lines (broadinstitute.org). Knockout of RhoV by three runs of gRNAs in BxPC3 cells all significantly attenuated tumor sphere formation with less colony formation as compared to mock knockout. Overexpression of RhoV in non-basal-like cells, Panc 1, significantly increased the size of sphere formation, numbers of colony formation, and p38 activation compared to EV control. Cell migration and invasion assays showed the same RhoV-dependent migration and invasion in corresponding cells. Panc1 cells with RhoV knockout significantly generated smaller tumor xenografts in immunodeficient mice and RhoV overexpression led to larger tumor sizes. Conclusion Finding the driver of the basal-like phenotype helps to reveal the pathophysiology of the basal-like subtype of pancreatic cancer and facilitates the identification of new targets for therapeutic purposes. Our preliminary results indicated that RhoV, a small G protein from the Rho family of GTPases, played essential roles in tumor proliferation and progression, by activating the p38 signaling pathway. Further study will be focused on revealing Rhov's downstream pathways and exploring the role of RhoV in apoptosis/cell cycle, cell metabolism, autophagy, etc. in basel-like pancreatic cancer. Citation Format: Shang Wu, Jia Feng, Selina Gao, Ting Wang, Zebang Li, Yifei Liu, Chiung-Kuei Huang, Shaolei Lu. The role of RhoV in basal-like pancreatic cancer [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 A077.

Abstract A070: Time-Dependent Oxidation and Aggregation of Vimentin upon Binding by β-lap Induced Immunogenic Cell Death

Abstract β-lapachone (β-lap) has been demonstrated as an NAD(P)H:quinone oxidoreductase1 (NQO1) bioactivatable compound. It initiated a futile redox cycle catalyzed by NQO1, resulting in reactive oxygen species (ROS) generation, with consumption of the reductive NAD(P)H. After a 4-h pulse of sufficiently lethal dose of β-lap, high levels of ROS diffused into nuclei to induce tumor-selective DNA damage and programmed necrosis in cancers overexpressing NQO1. Recently, our experiments showed that prolonged low dose β-lap administration exerted significant and NQO1 independent antitumor efficacy in mouse models with no overt signs of toxicity. Thus, we synthesized a photoactive β-lap probe to identify the molecular target of β-lap. Vimentin, a major constituent of the intermediate filament family of proteins, was identified as the direct binding target of β-lap. Vimentin was highly upregulated in multiple cancers including PDAC, and was a binding partner of β-lap with a dissociation constant at micromolar levels. Ligand binding assays in Panc1 cells employing β-lap as a specific competitor showed that vimentin was bound by β-lap-probe in a β-lap-competitive manner, and further confirmed that the in vivobinding target of β-lap was vimentin. Moreover, it was manifested that endogenous vimentin mRNA levels directly correlated with sensitivity to prolonged exposure of β-lap in a panel of pancreatic cancer cell lines, and knockout of vimentin in Panc1 cells markedly decreased lethality after prolonged exposure of β-lap. Mechanistically, we revealed that β-lap bound to vimentin and induced disulfide bonds that participated in disulfide cross-linking between a pair of vimentin dimers in a concentration and time dependent manner, forming vimentin oligomers of approximately 150 kDa. Prolonged exposure of β-lap promoted the disruption of filament architecture and vimentin degradation, ultimately resulting in cell death. In addition, the cell death by targeting vimentin exhibited a more inflammatory condition and enhanced DC activation. Together, our findings unveiled an unknown molecular target for β-lap and provided valuable insights into its mechanism of action. Targeting vimentin also presented a new strategy that inhibited the tumor growth and synergized with immunotherapy to disrupt immune evasion and reduce immune suppression against pancreatic cancers. Citation Format: Feng Qian, Lei Dou, Kaixin Wang, Yi Xia, Zhidong Chen, Yumeng Zu, Shuang Xi. Time-Dependent Oxidation and Aggregation of Vimentin upon Binding by β-lap Induced Immunogenic Cell Death [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 A070.

Abstract A079: SB-216 inhibits oncogenic beta-tubulin subtypes in PDAC

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies, with only 12% of patients living longer than five years after diagnosis. Recent studies have shown that inhibiting microtubule dynamics may be a promising therapeutic avenue for treating patients with this cancer. Microtubules are critical in cancer cell growth and division, as well as intracellular cytoskeletal support and internal trafficking. In PDAC, βIII- and βIVb-tubulin are highly upregulated in contrast to normal pancreas cells. Decreased expression of βIII- and βIVb-tubulin, through silencing or inhibition, correlates with reduced PDAC cell growth, tumorigenic potential, metastases in xenograft models, and chemoresistance. We hypothesized that a novel colchicine binding site beta-tubulin inhibitor, SB-216, will decrease cell growth while also decreasing the expression of oncogenic βIII- and βIVb-tubulin. To examine the anti-proliferative effects, PDCL110, a PDAC patient-derived cell line, cells were seeded (6,000 cells/well), and after 24 hours, treated with 0.1% DMSO (control), 2 nM, 5 nM, 10 nM, or 15 nM SB-216. Plates were analyzed on the IncuCyte Live-Cell Analysis System for six days, where phase contrast images of confluency were captured every four hours. To characterize the mRNA expression of βIII- and βIVb-tubulin, Panc-1 and PDCL110 cells were treated with 0.1% DMSO and 5 nM SB-216 for 48 hours. Next, total RNA was extracted using a TRIzol reagent. cDNAs were prepared using the SYBR Green RNA Reverse Transcription kit, and mRNA expression of beta-tubulin isotypes was quantified using the QuantStudio Real-Time PCR system. The expression of tubulin isotypes was normalized with the internal control ACTIN. Cell growth curves illustrated a significant (p&amp;lt;0.006) decrease in proliferation after 48 hours of treatment at all tested concentrations of SB-216. After 72 hours, cell growth inhibition became more significant (p&amp;lt;0.0001) in a dose-dependent manner. SB-216 treatment of a commercially available PDAC cell line (Panc-1) led to decreased mRNA expression of TUBB3 (class βIII, p&amp;lt;0.05) and TUBB4B (class βIVb, p&amp;lt;0.05) compared to DMSO control. Similarly, TUBB4B expression was significantly (p&amp;lt;0.05) decreased in the PDCL110 cells upon SB-216 treatment. These results enhance our confidence in utilizing SB-216 as a therapeutic agent against PDAC. Future studies are directed at elucidating the effects of SB-216 on metastases, chemoresistance, and mitochondrial function. Through an improved understanding of the mechanisms behind microtubule inhibition, we can meet the urgent clinical need of finding targeted treatments for this complex cancer. Citation Format: Lauren C Gattie, Chun Cai, Rui Wang, Wei Li, Evan Glazer. SB-216 inhibits oncogenic beta-tubulin subtypes in PDAC [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 A079.

Abstract C055: Unraveling pancreatic cancer susceptibility at 5p15.33: Functional characterization of a novel VNTR element

Abstract Genome-wide association studies (GWAS) have identified independent signals at 5p15.33 across numerous cancers, with protective alleles for one cancer often conferring risk for another. Many of these associations are thought to act via allele-specific alterations in the cis- regulation of target genes. Transcriptomic analyses in multiple tissue types implicate two plausible target genes: TERT and CLPTM1L. However, the mechanisms linking cancer susceptibility alleles to their presumed target genes, along with the observed antagonistic pleiotropy between different cancers remain elusive. With this in mind, we employed a comprehensive approach, integrating statistical fine-mapping of GWAS summary statistics with massively parallel reporter assays (MPRA) and a densely tiled CRISPRi screen performed across eight cell lines, representative of four distinct cancers associated with 5p15.33 alleles – pancreatic, melanoma, lung, and bladder cancer. Integrative screening identified up to 30 variants across multiple signals in the locus with putative allele-specific transcriptional activity. Furthermore, a variable number tandem repeat (VNTR) in intron 9 of CLPTM1L emerged as a potent transcriptional enhancer in CRISPRi screening. Leveraging PacBio sequencing, VNTR alleles of European ancestry samples from the 1000 Genomes Project were genotyped and found to be highly polymorphic, with longer VNTRs linked to the haplotype tagged by rs31490-A (risk increasing for pancreatic cancer). Subsequent imputation into a pancreatic cancer GWAS of 9,040 cases and 12,496 controls revealed an association between longer VNTRs and risk of pancreatic cancer (OR for VNTR in the 75th percentile = 1.17, 95% CI = 1.13-1.22, P = 2.21x10-12). The significance of the association for the lead SNP rs31490 after conditioning on the VNTR genotype dropped to P= 2.20x10-5, suggesting that VNTR alleles merit consideration as part of the credible variant set for pancreatic cancer. Targeted CRISPRi assays suggested VNTR-mediated cis-regulation of both TERT and CLPTM1L in PANC-1 and MIA PaCa-2 pancreatic cancer cell lines, while dual luciferase reporter assays in the same cell lines revealed that VNTR enhancer activity is mediated by Hippo pathway transcription factors. In ongoing experiments, we aim to expand on luciferase reporter assays and DNA-protein binding assays in relevant cell lines with the aim of not only deciphering how longer VNTRs differentially exert their transcriptional effects compared to shorter alleles but also characterizing the divergent directions of effect between different cancer types. These findings underscore the proposition that pancreatic cancer susceptibility at the 5p15.33 locus may be mediated by both SNPs and an uncharted class of variants, yet to be characterized in the post-GWAS landscape. Citation Format: Aidan O'Brien, Hyunkyung Kong, Minal Patel, Katelyn E Connelly, Mai Xu, Irene Collins, Jun Zhong, Jason Hoskins, Michelle Ho, Brenen Papenburg, Mark M Iles, Matthew H Law, Maria-Teresa Landi, Rachael Stolzenber- Solomon, Brian M Wolpin, Alison P Klein, Nick Orr, Stephen J Chanock, Sara Lindström, Marc-Henri Stern, Ludmila Prokunina-Olsson, Jieyon Choi, Kevin M Brown, Laufey T Amundadottir. Unraveling pancreatic cancer susceptibility at 5p15.33: Functional characterization of a novel VNTR element [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 C055.