Body piercing

Background: Pancreatic ductal adeno-carcinoma (PDAC) ranks among the most lethal of human malignancies. We have demonstrated that ATDC is overexpressed in PDAC and promotes pancreatic cancer growth by activation of Wnt/β-catenin signaling (Cancer Cell, 2009). However, the role of ATDC during PDAC initiation and progression is incompletely understood. Hence, we developed a new transgenic mouse model to evaluate the impact of ATDC overexpression on PDAC formation. Methods: To genetically engineer a mouse ubiquitously overexpressing ATDC, a Flag-ATDC construct was subcloned into a pCAGGS vector containing a CMV enhancer/chicken β-actin (CAG) promoter. ATDC mice were bred onto a FVB/n background. Mice were genotyped by multiplex PCR. ATDC, β-catenin, Zeb1 and PTEN were measured by immunohistochemical staining. Results: ATDC overexpression resulted in acinar atypia with a long latency but was not sufficient to induce pancreatic intraepithelial neoplasia (PanIN) formation. We then analyzed the impact of ATDC overexpression in the context of KrasG12D by crossing of ATDC mice with LSL-KrasG12D;p48-Cre (KC) mice to generate ATDC;LSL-KrasG12D;p48-Cre (AKC) triple transgenic mice. KC mice developed PanINs with a long latency, and PDAC was not observed until mice reached an age of 15 months or greater. However, ATDC overexpression combined with KrasG12D accelerated PanIN progression and resulted in the development of invasive and widely metastatic PDAC with a high penetrance. 45% of AKC (0% KC) mice exhibited PanIN2or 3 as early as 2 months of age. 85% of AKC mice at 6-8 months of age developed highly invasive and metastatic PDAC, whereas none of the age-matched KC mice displayed those lesions. The evolution of PDAC in AKC mice recapitulated the histopathological manifestations of human PDAC, possessing a proliferative stromal component (Ki67 and collagen positive) and glandular architecture (CK19 and E cadherin positive) with a propensity for some tumors to advance to a poorly differentiated state (CK19, E cadherin and mucin negative). ATDC and β-catenin were upregulated in these primary and metastatic PDAC lesions. Furthermore, epithelial-to-mesenchymal transition (EMT) markers, ZEB1 and vimentin, were significantly upregulated in invasive PDAC and liver metastasis from AKC mice. In 2 separate cell lines developed from the AKC primary tumors, increased ATDC expression was found to not only correlate with upregulated β-catenin signaling and expression of the EMT markers ZEB1 and vimentin, but also loss of PTEN expression. Downregulation of PTEN expression by ATDC was determined to be due to ATDC-mediated methylation of the PTEN promoter. Loss of PTEN expression was observed in pancreatic tumors arising in the AKC mice. Conclusions: Here we demonstrate that ATDC, when coupled with oncogenic Kras, accelerates PanIN progression and the development of invasive pancreatic cancer that mimics human PDAC. ATDC may mediate these effects by alterations in the β-catenin and PTEN signaling pathways. This novel mouse model provides a platform for an improved understanding the pathogenesis of PDAC and for development of targeted treatment strategies. Citation Format: Lidong Wang, Huibin Yang, Filip Bednar, Yaqing Zhang, Jacob Leflein, Taylor Detzler, Gina M. Ney, Marina Pasca di Magliano, Diane M. Simeone. ATDC synergizes with oncogenic Kras to induce invasive pancreatic adeno-carcinoma in transgenic mice. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Progress and Challenges; Jun 18-21, 2012; Lake Tahoe, NV. Philadelphia (PA): AACR; Cancer Res 2012;72(12 Suppl):Abstract nr B49.

Protein phosphatase 2A (PP2A) is a major serine-threonine phosphatase that regulates many cellular pathways including KRAS, whose oncogenic mutation is prevalent in 95% of patients with Pancreatic Ductal Adenocarcinoma (PDAC). Previous research has identified a decrease in global PP2A activity and an increase in the expression PP2A inhibitors in PDAC cell lines, suggesting that suppression of PP2A activity may be pertinent in PDAC maintenance. Importantly, PP2A has low mutation rates in PDAC, making it a viable target for therapeutic reactivation. While PP2A has been shown to have global tumor suppressive capabilities, the regulation of specific pathways by PP2A can be altered based on PP2A holoenzyme composition. Therefore, there is a critical need to understand the mechanisms by which oncogenic KRAS can affect PP2A function and differential substrate targeting in PDAC. The PP2A holoenzyme consists of 3 subunits: the scaffolding subunit (A), the catalytic subunit (C), and the regulatory subunit (B). There are 16 different B subunits that can be incorporated into the PP2A holoenzyme that are responsible for substrate specificity. The B56α subunit of PP2A has been shown to negatively regulate cellular transformation and has decreased expression in aggressive subtypes of PDAC, indicating that suppression of this subunit may aid in PDAC tumorgenicity. Our research aims to investigate the mechanisms by which PP2A-B56α is regulated downstream of oncogenic KRAS and how suppression of B56α impacts the initiation and progression of PDAC. In order to determine how oncogenic KRAS alters the dynamics of PP2A-B56α and overall PP2A activity we utilized tet-inducible KRASG12D cell lines to allow direct manipulation of KRAS mutational activation. Using this system, we have identified time dependent alterations in cancerous inhibitor of PP2A (CIP2A) following induction of KRASG12D expression, indicating that PP2A suppression may be an early event in PDAC initiation. Consistent with this hypothesis, we characterized changes in the acceleration of PDAC formation in vivo using the Ptf1a-Cre; LSL-KRASG12D (KC) genetic mouse model combined with a B56α hypomorph model (KCBhm/hm). Our data show that the loss of B56α accelerates PDAC initiation, with an increase in pancreatic precursor lesion (PanIN) number and a decrease in healthy acinar area. Similar results were seen in an ex vivo acinar-to-ductal metaplasia assay, suggesting that B56α alters pancreatic cellular plasticity in a cell-autonomous manner. Future studies will investigate how mutant KRAS expression effects overall PP2A phosphatase activity, holoenzyme formation, and sequestration of B56α by endogenous inhibitors to further understand how suppression of PP2A-B56α contributes to development of PDAC. Together, these studies identify PP2A as a critical regulator of KRAS-induced cellular plasticity and support therapeutic reactivation of PP2A as a novel therapeutic strategy in PDAC patients. Citation Format: Samantha L. Tinsley, Rebecca A. Shelley, Mary C. Thoma, Goutham Narla, Rosalie C. Sears, Brittany A. Allen-Petersen. The role of PP2A-B56α in acinar-to-ductal metaplasia and initiation of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PR-008.

Fascin Is Regulated by Slug, Promotes Progression of Pancreatic Cancer in Mice, and Is Associated With Patient Outcomes

We have identified regulators of G protein signaling (Rgs8 and Rgs16) as a new class of tumor suppressor genes in a mouse model of pancreatic ductal adenocarcinoma (PDA). PDA is the 3rd leading cause of cancer related deaths in the United States. Kras mutations (e.g. KrasG12D) are associated with over 90% of human PDA and are an early event in the multistep process leading to PDA. Kras can be activated by protein kinase and G-Protein Coupled Receptor (GPCR) signaling. Rgs proteins regulate GPCR signaling by accelerating the GTPase activity of Gq- and Gi class alpha subunits. Activating alleles of Gq that are resistant to Rgs inhibition are associated with PDA in humans. We found Rgs8 and Rgs16 are in vivo reporters of Kras activity in pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and PDA progression (DMM 8, 2015). Rgs8 and Rgs16 are expressed in PanIN and IPMN, precursors of PDA, in KC mice (LSL-KrasG12D; p48::Cre). To test if Rgs8-16 function as tumor suppressor genes, we crossed the Rgs8-16 double knockout into KC (termed KCR8-16) mice. Compared to KC, PDA initiates earlier, is more aggressive, and KCR8-16 mice die earlier. Our study suggests that Rgs8 and Rgs16 control Kras-dependent PDA initiation and progression. Note: This abstract was not presented at the meeting. Citation Format: Shreoshi Pal Choudhuri, Yalda Zolghadri, Luke Mascarenhas, Ozhan Ocal, Thomas Wilkie. Rgs8 and Rgs16 are tumor suppressor genes in mouse pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5518. doi:10.1158/1538-7445.AM2017-5518

We have collectively been spoiled by the astounding clinical benefit of antimicrobials. Much like the discovery and use of penicillin to eradicate once deadly infections, we continue to desperately search for the next “magic bullet” to kill cancer while sparing the non‐transformed cells. Greater appreciation for the molecular intricacies of malignancy has resulted in dedicated pursuit of cancer genomics and large‐scale informatics to identify “drugable” targets within the cancer cell itself. However, studies at the bench elucidating a dynamic relationship between tumor and microenvironment have become more common and demonstrate promise for novel therapeutic intervention.

<div>Abstract<p>Perturbation of cell polarity is a hallmark of pancreatic ductal adenocarcinoma (PDAC) progression. Scribble (SCRIB) is a well-characterized polarity regulator that has diverse roles in the pathogenesis of human neoplasms. To investigate the impact of SCRIB deficiency in PDAC development and progression, <i>Scrib</i> expression was genetically ablated in well-established mouse models of PDAC. <i>Scrib</i> loss in combination with <i>Kras</i><sup><i>G12D</i></sup> did not influence development of pancreatic intraepithelial neoplasms in mice. However, <i>Scrib</i> deletion cooperated with <i>Kras</i><sup><i>G12D</i></sup> and concomitant <i>Trp53</i> heterozygous deletion to promote invasive PDAC and metastatic dissemination, leading to reduced overall survival. Immunohistochemical and transcriptome analyses revealed that <i>Scrib</i>-null tumors display a pronounced reduction of collagen content and an abundance of cancer-associated fibroblasts (CAF). Mechanistically, IL1α levels were reduced in <i>Scrib</i>-deficient tumors, and <i>Scrib</i> knockdown downregulated IL1α in mouse PDAC organoids (mPDO), which impaired CAF activation. Furthermore, <i>Scrib</i> loss increased YAP activation in mPDOs and established PDAC cell lines, enhancing cell survival. Clinically, SCRIB expression was decreased in human PDAC, and SCRIB mislocalization was associated with poorer patient outcome. These results indicate that SCRIB deficiency enhances cancer cell survival and remodels the tumor microenvironment to accelerate PDAC development and progression, establishing the tumor suppressor function of SCRIB in advanced pancreatic cancer.</p><p> <b>Significance:</b> SCRIB loss promotes invasive pancreatic cancer development via both cell-autonomous and non–cell-autonomous processes and is associated with poorer outcomes, denoting SCRIB as a tumor suppressor and potential biomarker for the prediction of recurrence.</p></div>

Carcinogenesis of pancreatic ductal adenocarcinoma (PDAC) has been well studied using genetically engineered mouse (GEM) models with abnormalities in activation of both RAS and E2 factor (E2F)-which is associated with the Rb-E2F pathway, and dysfunction of p53-which is associated with the transformed 3T3 cell double minute 2 (MDM2)-p53 pathway. Catastrophic progression of the malignancy is one of unique manifestation, which has not been recapitulated in the GEMs to study underlined mechanisms, while we have recently reported a new GEM developing PDAC to die in 3 weeks after birth due to the catastrophic progression [Yamaguchi T. et al, J Pathol. 2014; 234(2):228-138]. The GEM had the specific expression of SV40 tsA58 large T antigen (tsTAg) to inhibit p53 and Rb family molecules (Rb1, Rbl1 and Rbl2) on pancreas with the expression of oncogenic Kras (KrasG12D) by Pdx1 promoter-mediated Cre-loxP recombination. In this study, we sought to determine if the induced tsTAg on pancreatic epithelial cells with constitutive KrasG12D expression are enough to develop PDAC and catastrophic manifestation, by the generation of a new GEM based on Cre-loxP recombination and Tet-On system. In the GEM, KrasG12D constitutively expresses on pancreatic epithelial cells after the Cre-loxP recombination under the control Pdx1 promoter, while tsTAg expression can be regulated by Tet-On system after the recombination by Pdx1 promoter. Any of the mice did not developed PDAC within 6 month, but all of the mice developed PDAC by Dox administration in within 1 week and died by the progression of PDAC within 3 weeks after the start.The rapid progression and development of PDAC appeared to be associated with the stronger tsTAg expression depending on reverse tetracycline trans-activator. These results demonstrated that KrasG12D driven PDAC carcinogenesis was promoted by the presence of tsTAg expression, resulting in production of PDAC cells with aggressive growth. In conclusion, our established new mouse model can contribute to increase knowledge about catastrophic PDAC. Citation Format: Takashi Yamaguchi, Sanae K. Ikehara, Hayao Nakanishi, Yuzuru Ikehara. Genetically engineered mouse models of catastrophic pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 822. doi:10.1158/1538-7445.AM2015-822

Ubiquitously transcribed tetratricopeptide repeat on chromosome X (UTX), also known as lysine (K)-specific demethylase 6A (KDM6A), functions as a tumor suppressor gene or oncogene depending on the tumor type and context. However, its tumor-suppressive mechanisms remain largely unknown. Here, we investigated the clinical significance and biological effects of UTX expression in pancreatic ductal adenocarcinoma (PDA) and determined the potential mechanisms of its dysregulation. UTX expression and its association with clinicopathologic characteristics of PDA patients were analyzed using immunohistochemistry. UTX mRNA and protein expression and their regulation in PDA cell lines were measured using quantitative polymerase chain reaction and Western blot analyses. The biological functions of UTX in PDA cell growth, migration, and invasion were determined using gain- and loss-of-function assays with both in vitro and in vivo animal models. UTX expression was reduced in human PDA cell lines and specimens. Low UTX expression was associated with poor differentiation and prognosis in PDA. Forced UTX expression inhibited PDA proliferation, migration, and invasion in vitro and PDA growth and metastasis in vivo, whereas knockdown of UTX expression did the opposite. Mechanistically, UTX expression was trans-activated by GATA6 activation. GATA6-mediated PDA progression could be blocked, at least partially, by silencing UTX expression. In conclusion, loss of GATA6-mediated UTX expression was evident in human PDA and restored UTX expression suppressed PDA growth and metastasis. Thus, UTX is a tumor suppressor in PDA and may serve as a prognostic biomarker and therapeutic target.

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal types of cancer. Despite major advances in defining the molecular mutations driving PDAC, this disease remains universally lethal with an overall 5-year survival rate of only about 7–8%. Genetic alterations in PDAC are exemplified by four critical genes (KRAS, TP53, CDKN2A, and SMAD4) that are frequently mutated. Among these, KRAS mutation ranges from 88% to 100% in several studies. Hippo signaling is an evolutionarily conserved network that plays a key role in normal organ development and tissue regeneration. Its core consists of the serine/threonine kinases mammalian sterile 20-like kinase 1 and 2 (MST1/2) and large tumor suppressor 1 and 2. Interestingly, pancreas-specific MST1/2 double knockout mice have been reported to display a decreased pancreas mass. Many of the genes involved in the Hippo signaling pathway are recognized as tumor suppressors, while the Hippo transducers Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) are identified as oncogenes. By dephosphorylation, YAP and TAZ accumulate in the nucleus and interact with transcription factors such as TEA domain transcription factor-1, 2, 3, and 4. Dysregulation of Hippo signaling and activation of YAP/TAZ have been recognized in a variety of human solid cancers, including PDAC. Recent studies have elucidated that YAP/TAZ play a crucial role in the induction of acinar-to-ductal metaplasia, an initial step in the progression to PDAC, in genetically engineered mouse models. YAP and TAZ also play a key role in the development of PDAC by both KRAS-dependent and KRAS-independent bypass mechanisms. YAP/TAZ have become extensively studied in PDAC and their biological importance during the development and progression of PDAC has been uncovered. In this review, we summarize the biological significance of a dysregulated Hippo signaling pathway or activated YAP/TAZ in PDAC and propose a role for YAP/TAZ as a therapeutic target.

Tumor heterogeneity - resulting from genetic and epigenetic alterations acquired during tumor progression - is a critical driver of phenotypic diversity in most cancers. A lethal consequence of tumor heterogeneity is the acquisition of metastatic traits by tumor cells, leading to poor clinical outcomes. This remains a major problem in pancreatic ductal adenocarcinoma (PDAC), which continues to have the worst prognosis of any major cancer type. While most cases of PDAC present with metastatic disease at the time of diagnosis, the patterns and burden of metastasis can vary widely, with some patients exhibiting a limited metastatic burden while others have more extensive spread, which impacts clinical outcomes. However, the biological and functional differences that drive metastatic heterogeneity are poorly understood. One barrier to understanding metastatic heterogeneity has been a paucity of model systems that capture this natural variation and allow for direct assessment of paired primary tumors and metastases. We previously developed an autochthonous model of PDAC – the KPCX model – that employs multiplexed fluorescence-based labeling to track the contribution of multiple distinct tumor populations to metastasis. Importantly, this technique allows for ascertainment of primary-metastatic lineage relationships in vivo, so that primary tumor clones with substantial metastatic potential can be distinguished with those having poor metastatic potential. To understand the factors underlying differences in metastatic potential, we analyzed paired primary tumors and metastases in the KPCX model and from a cohort of 398 PDAC patients. Genomic and transcriptomic analysis of murine and human metastatic PDAC revealed an association between the highly metastatic state and gene amplification or transcriptional upregulation of MYC and its transcriptional targets. Functional assessments showed that MYC promotes metastasis by recruiting tumor associated macrophages (TAMs), leading to greater bloodstream intravasation. Consistent with these findings, metastatic progression in human PDAC was also associated of MYC signaling pathways and enrichment for MYC amplification in metastasis. Collectively, these results implicate MYC activity as a major determinant of metastatic burden and heterogeneity in advanced PDA. Citation Format: Ravikanth Maddipati, Robert J. Norgard, Timour Baslan, Komal S. Rathi, Amy Zhang, Pichai Raman, Max D. Wengyn, Taiji Yamazoe, Jinyang Li, David Balli, Michael J. LaRiviere, Ian W. Folkert, Ian D. Millstein, Jonathan Bermeo, Erica L. Carpenter, Scott Lowe, Christine Iacobuzio-Donahue, Faiyaz Notta, Ben Z. Stanger. MYC Influences metastatic heterogeneity in pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-053.

Background: Cancer immunotherapies can lead to durable and sometimes curative responses in patients with otherwise treatment-refractory disease, and as such have revolutionized our approach to cancer therapy. Still, there are many roadblocks that must be overcome to make immunotherapies effective across a broader spectrum of patients and cancer types. Immune checkpoint blockade (ICB) therapies that are effective in some malignancies through reactivation of cytotoxic T cell immunity have failed in immunologically “cold” tumors such as pancreatic ductal adenocarcinoma (PDAC) due to poor T cell infiltration and weak antigen presentation necessary for effective anti-tumor T cell responses. We and others have demonstrated that induction of cellular senescence and the senescence associated secretory phenotype (SASP), which leads to production of immunomodulatory cytokines, chemokines, and growth factors, can be a powerful way to not only enhance T cell infiltration into tumors but also reactivate a different type of innate, antigen-independent Natural Killer (NK) cell immunity that can mediate tumor control. Recently, we found that a combination of two RAS pathway targeting therapies- the MEK inhibitor trametinib and CDK4/6 inhibitor palbociclib (T/P)- could induce senescence in genetically engineered mouse models of KRAS mutant lung adenocarcinoma and PDAC (Ruscetti*, Leibold*, Bott* et al. Science 2018; Ruscetti*, Morris*, Mezzadra* et al. Cell 2020). Strikingly, whereas therapy-induced senescence led to NK cell-mediated tumor regressions and long-term survival benefit in KRAS mutant lung cancer, it had little effect on NK cell immunity and tumor progression in PDAC. Here we set out to understand how the pancreas tumor microenvironment (TME) suppresses NK immunity and develop strategies to harness NK cell surveillance for immunotherapy in PDAC. Results and Discussion: We took advantage of genetically similar Kras mutant, p53 altered PDAC and lung cancer cell lines that could be transplanted into different organs of C57BL/6 mice to study whether and how the pancreas TME may impact senescence-driven immune responses. Syngeneic KRAS mutant lung and PDAC tumor cells transplanted into the pancreas of C57BL/6 mice displayed transcriptional repression and reduced chromatin accessibility of SASP transcriptional activators (NF-KB, IRFs) and factors necessary for NK cell activity (IL-15, IL-18) and chemotaxis (CCL2, CCL7, CCL8, CXCL9, CXCL10) following T/P-induced senescence, and did not undergo anti-tumor NK immune surveillance as compared to tumors propagated in the lungs and liver. Transcriptomic analysis identified induction of EZH2 and epigenetic repression of its targets, including key SASP factors and regulators, specifically in tumor cells grown in the pancreas TME. Genetic or pharmacological inhibition of EZH2 enhanced proinflammatory SASP signaling and resulted in NK cell migration and anti-tumor cytotoxicity in murine and human PDAC lines and transplanted and genetically engineered PDAC mouse models. Remarkably, tumor-intrinsic EZH2 knockdown in combination with T/P treatment led to complete tumor regressions in some PDAC-bearing mice that were reversed following NK cell depletion or suppression of key SASP factors. Pharmacological inhibition of EZH2 methyltransferase activity also enhanced NK cell infiltration and tumor control following therapy-induced senescence in transplanted and genetically engineered PDAC mouse models. Importantly, we found that an EZH2 repression signature was associated with enhanced NK cell infiltration and SASP induction in human PDAC patient samples. These results demonstrate that EZH2 mediates transcriptional repression of the proinflammatory SASP in the pancreas TME, and that EZH2 blockade in combination with senescence-inducing therapies could be a powerful means to reactivate absent NK cell surveillance in PDAC to achieve immune-mediated tumor responses. In the future we plan to test these therapeutic interventions in combination with anti-PD-1/PD-L1 ICB therapy as a means to further activate both NK and T cell immunity to fully eradicate pancreatic cancer. This work highlights the importance of understanding the impact of the resident tumor microenvironment on anti-tumor immune responses to come up with new paradigms to potentiate immunotherapy in this and other immunologically “cold” tumor settings that are historically unresponsive to ICB therapy. Citation Format: Marcus Ruscetti. Modulating cellular senescence to reinstate natural killer cell immunity for pancreatic cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr SY24-03.

Background and Introduction: Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease with limited treatment options. There is an urgent need for the identification of novel therapeutic targets for PDAC. The transport of molecular cargo between the nucleus and cytoplasm, facilitated by Ran-GTPase, is a critical process that dividing cells rely on to maintain their growth. Elevated nuclear Ran-GTP levels are produced by the activity of the Ran guanine nucleotide exchange factor (GEF) known as Regulator of Chromosome Condensation 1 (RCC1), which is found in the nucleus bound to chromatin. This creates a Ran-GTP gradient across the nuclear membrane, which maintains proper directional transport of proteins and RNA. To sustain proliferative signaling, cancer cells become reliant on high rates of nucleocytoplasmic transport through dysregulation of transport machinery. Methods: We examined the role of RCC1 in the biology of PDAC. The impact of RCC1 modulation on PDAC growth was evaluated using RNA interference and CRISPR-Cas9 in vitro and in vivo using PDAC cell lines and LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre (KPC) tumor-derived cells. The broader impact of RCC1 silencing on PDAC-sustaining signaling was evaluated through RNA-sequencing and proteomics. Results: Transcriptomic sequencing of PDAC tissue (n=5,071) as well as analysis of publicly available data from the TCGA, CPTAC and GTEx revealed that RCC1 expression is higher in PDAC tissues compared to normal pancreas. Moreover, PDAC patients with higher RCC1 expression were more likely to have poorer outcomes. RCC1 silencing by RNAi and CRISPR-Cas9 resulted in reduced proliferation in 2D and 3D cultures and attenuated tumor growth in vivo. RCC1 KD decreased migration and colony formation, enhanced apoptosis, and altered the cell cycle in human and KPC mouse PDAC cells. Subcutaneous RCC1 KO cell line-derived xenografts show arrested growth. Subcellular Ran distribution was disrupted upon RCC1 KO, suggesting that nuclear Ran concentration is important for PDAC proliferation. Nuclear and cytosolic proteomic analysis revealed altered subcellular proteome in RCC1 KD KPC tumor-derived cells. Altered cytoplasmic protein pathways include several metabolic pathways, PI3K-AKT, and Hedgehog signaling. Nuclear enriched pathways include cell cycle, mitosis, metabolic processes, and RNA processing. RNA-seq of RCC1 KO cells showed widespread transcriptional alterations. Upstream of RCC1, c-MYC activates the RCC1-RAN axis, and RCC1 KO cells show differential sensitivity to c-MYC inhibitors. Finally, RCC1 KD resulted in the sensitization of PDAC cells to Gemcitabine. Molecular characterization of conditional Rcc1fl/fl KO transgenic model to study the role of RCC1 in PDAC in vivo is ongoing. Conclusions: Overall, our results show that RCC1 is involved in the regulation of PDAC growth and is a potential target for therapy. Citation Format: Sahar F. Bannoura, Husain Y. Khan, Amro Aboukameel, Md Hafiz Uddin, Rund Nimri, Eliza Beal, Seongho Kim, Mohammed Najeeb Al Hallak, Bassel El-Rayes, Philip A. Philip, Boris Pasche, Ramzi Mohammad, Asfar S. Azmi. Regulator of chromosome condensation 1 (RCC1) as a novel therapeutic target in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5587.

<div>Abstract<p>Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy, with most patients facing an adverse clinical outcome. Aberrant Notch pathway activation has been implicated in the initiation and progression of PDAC, specifically the aggressive phenotype of the disease. We used a panel of human PDAC cell lines as well as patient-derived PDAC xenografts to determine whether pharmacologic targeting of Notch pathway could inhibit PDAC growth and potentiate gemcitabine sensitivity. MRK-003, a potent and selective γ-secretase inhibitor, treatment resulted in the downregulation of nuclear Notch1 intracellular domain, inhibition of anchorage-independent growth, and reduction of tumor-initiating cells capable of extensive self-renewal. Pretreatment of PDAC cells with MRK-003 in cell culture significantly inhibited the subsequent engraftment in immunocompromised mice. MRK-003 monotherapy significantly blocked tumor growth in 5 of 9 (56%) PDAC xenografts. A combination of MRK-003 and gemcitabine showed enhanced antitumor effects compared with gemcitabine in 4 of 9 (44%) PDAC xenografts, reduced tumor cell proliferation, and induced both apoptosis and intratumoral necrosis. Gene expression analysis of untreated tumors indicated that upregulation of NF-κB pathway components was predictive of sensitivity to MRK-003, whereas upregulation in B-cell receptor signaling and nuclear factor erythroid-derived 2-like 2 pathway correlated with response to the combination of MRK-003 with gemcitabine. Our findings strengthen the rationale for small-molecule inhibition of Notch signaling as a therapeutic strategy in PDAC. <i>Mol Cancer Ther; 11(9); 1999–2009. ©2012 AACR</i>.</p></div>

Disruption of C1galt1 Gene Promotes Development and Metastasis of Pancreatic Adenocarcinomas in Mice

Background: Pancreatic ductal adenocarcinoma (PDAC) remains the 4th most deadly cancer in the US. Current chemotherapeutic regimens poorly control PDAC progression and no approved immunotherapeutic options currently exist. PDAC incidence and progression are increased by obesity, which promotes a potently protumor PDAC microenvironment characterized by inflammation, fibrosis, and immunosuppression. β Hydroxy β Methylbutyrate, found to be safe and well-tolerated in clinical trials over many years, blunts cancer cachexia; however it has not been tested in PDAC. Further, the role of HMB in modifying existing therapies has been understudied. We sought to determine if HMB treatment would alter therapeutic response of lean and obese mice to gemcitabine or anti-PD1 immunotherapy. Methods: Lean and obese C57BL/6 mice were treated with HMB alone or in combination with gemcitabine or anti-PD1 immunotherapy following subcutaneous injection of Panc02 PDAC cells. In addition, bone marrow-derived macrophages (BMDM) were treated with HMB in vitro with or without LPS. Tumor/macrophage transcriptomic analysis, followed by gene set enrichment analysis and enrichment mapping identified transcriptional responses. CIBERSORTx determined microenvironment immune cell composition. Results: a) HMB reduces obesity-associated PDAC progression; b) HMB treatment and gemcitabine together suppress PDAC growth in obese mice; c) HMB mitigates PDAC immunosuppression and promotes tumor immune surveillance; d) HMB enhances the efficacy of anti-PD1 immunotherapy; e) HMB promotes M1 polarization of BMDM. Conclusion: Overall, HMB evokes antitumor immune responses in the context of pro-inflammatory stimuli such as obesity or immunotherapy. Moreover, HMB promotes immune surveillance in PDAC, synergizing with both cytotoxic chemotherapy and immunotherapy. HMB has been found to be safe and well tolerated in clinical trials for many years. Hence, HMB-induced suppression of PDAC tumor growth and promotion of immune surveillance may offer significant synergy with chemotherapies or immunotherapies in PDAC. This research was supported by R35CA197627 to S. Hursting. Citation Format: Michael F. Coleman, Kristyn A. Liu, Suhas K. Etigunta, Alex J. Pfeil, Xiaohu Tang, Salvador Fabela, Laura M. Lashinger, Zhengrong Cui, Stephen D. Hursting. β Hydroxy β Methylbutyrate synergizes with cytotoxic chemotherapy and immunotherapy in a mouse model of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3151.