Pancreatic Ductal Adenocarcinoma Growth Research Articles

Alcohol-induced C/EBP β-driven VIRMA decreases oxidative stress and promotes pancreatic ductal adenocarcinoma growth and metastasis via the m6A/YTHDF2/SLC43A2 pathway.

N6-methyladenosine (m6A) plays a role in the development of tumors. However, the specific role of VIRMA, an RNA methyltransferase, in pancreatic ductal adenocarcinoma (PDAC) remains unclear. This study shows that VIRMA expression is elevated in PDAC. Increased VIRMA levels promoted PDAC growth and spread, while reducing VIRMA expression slowed these processes. VIRMA facilitated SLC43A2 mRNA degradation through an m6A-YTHDF2 pathway. The resulting decrease in SLC43A2 reduced phenylalanine absorption and oxidative stress, further driving PDAC progression. Furthermore, alcohol increased C/EBP β expression, which bound to VIRMA's promoter, enhancing its transcription. These findings suggest a connection between alcohol consumption, m6A modifications, and phenylalanine absorption in PDAC progression, offering a new approach to combat this disease.

Halting Pancreatic Ductal Adenocarcinoma Progression and Metastasis by Neuron-Inhibitory Liposomes.

Pancreatic ductal adenocarcinoma (PDAC) remains an aggressive malignancy. The occurrence of perineural invasion is associated with neuropathic pain and poor prognosis of PDAC, underscoring the active participation of nerves and their potential as therapeutic targets. Lidocaine is a local anesthetic with antitumor properties in some tumors in the clinic. Nevertheless, its clinical application in PDAC is constrained by the insufficient tumor accumulation and potential neurovirulence associated with a high-dose regimen. Here, a tumor microenvironment-targeted and -responsive liposome was constructed to deliver lidocaine for restraining PDAC growth through single nerve regulation. By conjugation of a collagen binding peptide, the pH-responsive liposomes accumulate in the extracellular matrix. The released lidocaine selectively reduces neurite length and density, thereby indirectly halting the progression and metastasis of PDAC in an orthotopic mouse model without noticeable adverse effects. This study highlights the potential of anesthetic-based nanomodulation of crosstalk between nerve and tumor cells for PDAC treatment.

Cell polarity proteins promote macropinocytosis in response to metabolic stress

Macropinocytosis has emerged as a scavenging pathway that cancer cells exploit to survive in a nutrient-deprived microenvironment. Tumor cells are especially reliant on glutamine for their survival, and in pancreatic ductal adenocarcinoma (PDAC) cells, glutamine deficiency can enhance the stimulation of macropinocytosis. Here, we identify the atypical protein kinase C (aPKC) enzymes, PKCζ and PKCι, as regulators of macropinocytosis. In normal epithelial cells, aPKCs associate with the scaffold proteins Par3 and Par6 to regulate cell polarity, affecting several targets, including the Par1 kinases and we find that each of these proteins is required for macropinocytosis. Mechanistically, aPKCs are regulated by EGFR signaling or by the transcription factor CREM to promote the Par3 relocation to microtubules, facilitating macropinocytosis in a dynein-dependent manner. Importantly, cell fitness impairment caused by aPKC depletion is rescued by the restoration of macropinocytosis and aPKCs support PDAC growth in vivo. Our findings enhance our understanding of the mechanistic underpinnings that control macropinocytic uptake in the context of metabolic stress.

Abstract C022: Exercise reduces pancreatic tumor in a gut microbiome dependent manner

Abstract Preclinical studies suggest that aerobic exercise influences the tumor microenvironment by normalizing vasculature and reducing immunosuppression in Pancreatic Ductal Adenocarcinoma (PDAC). Gut microbes can influence PDAC progression by modulating metabolic and immune pathways. However, a knowledge gap remains regarding the role of the gut microbiome in the anti-tumor effects of exercise. We hypothesized that the exercise-induced anti-tumor effect in PDAC is regulated by gut microbiome. We compared the effect of treadmill running on growth of orthotopic PDAC in C57BL/6 mice from Taconic Biosciences (Tac) and Jackson Laboratories (Jax), which have different microbiomes. Tumor-bearing mice performed treadmill exercise (ex, 12 meters/minute (m/min) for 45 minutes (min) daily) or were non-exercised controls (no-ex). Exercise reduced tumor weight compared to no-ex controls in Jax (no-ex, 0.72±0.05 grams (g); ex, 0.54±0.04g; p=0.04) but not in Tac mice (no-ex, 0.72±0.05g; ex, 0.78±0.05g; p=0.47). Interestingly, in Tac mice treated with antibiotics (ATBx) ad libitum, treadmill exercise reduced tumor growth (no-ex, 0.74±0.04 g; ex, 0.53±0.03g; p= 0.006). Taken together, this data indicates that the anti-tumor effect of exercise is affected by gut microbiome. We considered potential mechanisms by which exercise suppresses tumor growth. Tumor infiltrating immune cells were measured by flow cytometry and immunohistochemistry. No significant differences in the tumor infiltrating immune cells were observed between no-ex and ex mice from Tac or Jax, regardless of ATBx, indicating that gut microbiome mediated anti-tumor effect is independent of immune pathways. Previous studies have demonstrated that exercise reduces tumor growth in an intensity dependent manner. Therefore, to determine exercise intensity as percentage of Peak Velocity (VPeak), exercise capacity (ExCap) test was performed. VPeak (m/min), time to exhaustion (min), and distance to exhaustion (m) were used as indicators for treadmill ExCap. Treadmill ExCap was significantly lower in tumor bearing Tac mice (24.86±3.55m/min, 12.56±1.79min, 217.17±31.02m) compared to Jax mice (30.50±3.81m/min; 16.58±2.07min; 320.15±40.02m; p=0.01). However, ATBx treatment did not change the treadmill ExCap in the Tac mice (25.50±3.19m/min; 12.62±1.58min; 209.26±26.16m; p=0.97) despite significantly changing the effect of exercise on tumor growth, indicating that ExCap may not regulate differences observed in the tumor weight. Overall, these results indicate that gut microbiome regulates anti-tumor effects of exercise, that are independent of tumor infiltrating immune cells or exercise intensity. Analysis of serum and tumor metabolites, 16s rRNAseq to evaluate microbial differences, and bulk RNAseq on tumors, is underway with the goal of identifying microbial-derived metabolites which mediate the anti-tumor effect of exercise. Understanding how the gut microbiome mediates the efficacy of exercise to suppress tumor growth will be critical for maximizing the benefits of exercise for patients with PDAC. Citation Format: Sumedha Pareek, Vidhi Chandra, Le Li, Hetal Patel, Truong Lam, Olivereen LeRoux, Haoyue Liu, Jonghae Lee, Florencia McAllister, Keri Schadler. Exercise reduces pancreatic tumor in a gut microbiome dependent manner [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C022.

Fibrolytic vaccination against ADAM12 reduces desmoplasia in preclinical pancreatic adenocarcinomas.

A hallmark feature of pancreatic ductal adenocarcinoma (PDAC) is massive intratumoral fibrosis, designated as desmoplasia. Desmoplasia is characterized by the expansion of cancer-associated fibroblasts (CAFs) and a massive increase in extracellular matrix (ECM). During fibrogenesis, distinct genes become reactivated specifically in fibroblasts, e.g., the disintegrin metalloprotease, ADAM12. Previous studies have shown that immunotherapeutic ablation of ADAM12+ cells reduces fibrosis in various organs. In preclinical mouse models of PDAC, we observe ADAM12 expression in CAFs as well as in tumor cells but not in healthy mouse pancreas. Therefore, we tested prophylactic and therapeutic vaccination against ADAM12 in murine PDAC and observed delayed tumor growth along with a reduction in CAFs and tumor desmoplasia. This is furthermore associated with vascular normalization and alleviated tumor hypoxia. The ADAM12 vaccine induces a redistribution of CD8+ T cells within the tumor and cytotoxic responses against ADAM12+ cells. In summary, vaccination against the endogenous fibroblast target ADAM12 effectively depletes CAFs, reduces desmoplasia and delays the growth of murine PDACs. These results provide proof-of-principle for the development of vaccination-based immunotherapies to treat tumor desmoplasia.

Pirfenidone antagonizes TGF-β1-mediated gabapentin resistance via reversal of desmoplasia and the ‘cold’ microenvironment in pancreatic cancer

Owing to the desmoplastic stroma constituted by cancer-associated fibroblasts (CAFs), few immune cells infiltrate the pancreatic ductal adenocarcinoma (PDAC). Gabapentin can impede the production of ketoacids by CAFs to support cancer cells. However, in our study, we discovered a dose-dependent increase in transforming growth factor β1 (TGF-β1) levels in cancer cells in response to gabapentin. This reverse increase of TGF-β1 contributes to 'Gabapentin-resistance', leading to the antitumor effects on PDAC cell lines are negatively negotiated in the presence of pancreatic stellate cells. Pirfenidone synergistically inhibited the growth and apoptosis resistance of PDAC when combined with Gabapentin. In a mouse orthotopic PDAC model, Fe3+-mediated coordination nanodrugs, which contain gabapentin, pirfenidone and the natural polyphenol (EGCG), efficiently promoted the infiltration of naïve CD8+ T cells (CD44lowCD62Lhigh) and the accumulation of inflammatory CAFs (α-SMAlowIL-6high). This led to a nearly two-fold increase in survival compared to the control. Furthermore, we identified a new subpopulation as Hmox1highiCAFs following treatment with our nanodrugs. Hmox1highiCAFs overexpressed the Cxcl10 receptor (Sdc4) and facilitated functional CD8+ T-cell infiltration through the Tnfsf9-Tnfrsf9 axis. Overall, our nanodrugs reshape the phenotype of CAFs and enhance functional CD8+ T-cell infiltration into tumors, holding the potential to be a safe and promising therapy for PDAC.

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.

Pancreatic cancer: new approaches to drug therapy.

Outcomes in pancreatic ductal adenocarcinoma (PDAC) remain poor due to a variety of biological, clinical, and societal factors. However, in recent years, PDAC has seen 1) increased precision of initial evaluation, 2) increased emphasis on supportive care, 3) deeper understanding of the translation biology of PDAC, especially as pertains to genomic alterations, and 4) foundational combination chemotherapy clinical trials across all disease stages. These advances have led to a wide range of new approaches to drug therapy for PDAC. Currently available drugs are showing added benefit, both by resequencing them with each other and also with respect to other therapeutic modalities. Molecular strategies are being developed to predict response to known therapeutic agents and to identify others. Additionally, a wide range of new drugs for PDAC are under development, including drugs which inhibit critical molecular pathways, drugs which attempt to capitalize on homologous repair deficiencies, immunotherapeutic approaches, antimetabolic agents, and drugs which attack the extracellular matrix which supports PDAC growth. These new approaches offer the promise of improved survival for future PDAC patients.

RCC1 regulation of subcellular protein localization via Ran GTPase drives pancreatic ductal adenocarcinoma growth

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy, with limited therapeutic options. Here, we evaluated the role of regulator of chromosome condensation 1 (RCC1) in PDAC. RCC1 functions as a guanine exchange factor for GTP-binding nuclear protein Ran (Ran) GTPase and is involved in nucleocytoplasmic transport. RCC1 RNA expression is elevated in PDAC tissues compared to normal pancreatic tissues and correlates with poor prognosis. RCC1 silencing by RNAi and CRISPR-Cas9 knockout (KO) results in reduced proliferation in 2-D and 3-D cell cultures. RCC1 knockdown (KD) reduced migration and clonogenicity, enhanced apoptosis, and altered cell cycle progression in human PDAC and murine cells from LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre (KPC) tumors. Mechanistically, RCC1 KO shows widespread transcriptomic alterations including regulation of PTK7, a co-receptor of the Wnt signaling pathway. RCC1 KD disrupted subcellular Ran localization and the Ran gradient. Nuclear and cytosolic proteomics revealed altered subcellular proteome localization in Rcc1 KD KPC-tumor-derived cells and several altered metabolic biosynthesis pathways. In vivo, RCC1 KO cells show reduced tumor growth potential when injected as sub-cutaneous xenografts. Finally, RCC1 KD sensitized PDAC cells to gemcitabine chemotherapy treatment. This study reveals the role of RCC1 in pancreatic cancer as a novel molecular vulnerability that could be exploited to enhance therapeutic response.

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

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

Abstract C043: Hyperinsulinemia promotes pancreatic cancer progression by altering tumor metabolism

Abstract Metabolic diseases, such as type 2 diabetes (T2D), insulin resistance, and obesity, often accompany pancreatic ductal adenocarcinoma (PDAC), and they are associated with reduced survival. Hyperinsulinemia is a common hallmark symptom shared by those disorders and is independently associated with reduced survival of PDAC patients. While it has been established that endogenous hyperinsulinemia accelerates PDAC initiation by promoting the formation of KRAS-driven pre-cancerous lesions, its role in the progression of established tumors remains poorly understood. This represents a major knowledge gap in our understanding of whether insulin needs to be monitored and controlled during PDAC treatment, as it is not typically considered in current treatment paradigms. We hypothesized that hyperinsulinemia promotes the progression of PDAC tumors. Using patient-derived PDAC organoids (PDOs) and a mouse model of metabolic disorders, we found that insulin may promote PDOs’ growth by reprogramming tumor metabolism. A High-fat diet (HFD) treatment that induces hyperinsulinemia, but not hyperglycemia in mice accelerated the growth of PDO-derived orthotopic xenografts. Importantly, the fasting insulin level showed a significant positive correlation with the endpoint tumor volume, suggesting that endogenous insulin may positively contribute to PDOs’ growth in vivo. To assess the direct effect of insulin on the growth and molecular profile of PDOs, we treated an early passage PDO line with different concentrations of insulin and glucose at physiologically relevant levels. We observed a ∼1.2-fold increase in cell number after 7 days of culture in high insulin (10 nM) conditions with high (15 mM) or physiological (6 mM) levels of glucose, relative to the low insulin control. Phosphoproteomic analysis demonstrated significantly greater PI3K/AKT/mTOR, but not RAF/MEK/ERK, activity under high insulin with high or physiological levels of glucose compared to the control, directing the investigation toward the metabolic effects of insulin. Consistently, unbiased proteomics profiling revealed that metabolic proteins were significantly enriched in both high insulin conditions, and interestingly insulin enriched different sets of proteins in various metabolic pathways depending on glucose levels. Together, our preliminary results suggest that hyperinsulinemia may enhance the growth and progression of PDAC by altering tumor metabolism to support cell growth. Further experiments are needed to functionally link the insulin-mediated metabolic changes with increased PDO growth, as well as testing the direct effect of endogenous insulin on PDAC cells in vivo. Citation Format: Jeffrey Lin, James D Johnson, David Schaeffer, Vincent Richard, Christoph Borchers, Janel L Kopp. Hyperinsulinemia promotes pancreatic cancer progression by altering tumor metabolism [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 C043.

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

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

Abstract C026: Concurrent inhibition of the RAS ERK-MAPK pathway and PIKfyve as a therapeutic strategy for pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized clinically by poor survival and mechanistically by KRAS- and autophagy-dependent growth. We and others previously demonstrated that inhibition of KRAS signaling via downstream inhibition of the RAF-MEK-ERK pathway enhanced autophagic flux and dependency of PDAC on autophagy. Furthermore, we demonstrated that concurrent treatment with the nonspecific autophagy inhibitor chloroquine (CQ) and ERK MAPK inhibitors synergistically blocked PDAC growth. These findings provided rationale for our initiation of Phase I/II clinical trials evaluating the combination of MEKi (binimetinib; NCT4132505) or ERKi (LY3214996; NCT04386057) with HCQ in PDAC. However, a limitation of this approach is that CQ/HCQ is limited in terms of specificity and potency. Thus, we aimed to identify alternative anti-autophagy strategies. We performed a CRISPR-Cas9 loss- of-function screen in PDAC cell lines that identified the lipid kinase PIKfyve as a growth- promoting gene. PIKfyve is a lipid kinase that is essential for the generation of PI(3,5)P2 and critical for the dynamic regulation of lysosomal recycling. Because PIKfyve has been implicated in regulation of autophagy in other cellular contexts, we evaluated the effects of PIKfyve inhibition on growth and autophagic flux in PDAC cell lines and tumors. We demonstrated that PIKfyve inhibition by the small molecule apilimod resulted in durable growth suppression, with much greater potency than CQ treatment. PIKfyve inhibition potently reduced autophagy as indicated by decreased autophagic flux and the robust accumulation of autophagy-related proteins. Additionally, PIKfyve inhibition resulted in the accumulation of LAMP1 positive vacuoles that exhibited impaired cargo degradation, likely due to a lack of required acidity. Next, we hypothesized that PIKfye inhibition would sensitize PDAC cells to RAS pathway inhibition. We demonstrated that PIKfyve inhibition blocked the compensatory increases in autophagic flux associated both with MEK inhibition and with direct RAS inhibition. Accordingly, combined inhibition of PIKfyve and either the RAS ERK-MAPK pathway or RAS itself showed robust growth suppression across a panel of KRAS-mutant PDAC models. Growth suppression was due, in part, to potentiated cell cycle arrest and induction of apoptosis following loss of IAP proteins. These findings implicate PIKfyve as an effective anti-autophagy target when paired with RAS or ERK-MAPK pathway inhibition in pre-clinical models of PDAC. Citation Format: Jonathan M DeLiberty, Mallory K Roach, Clint A Stalnecker, Ryan Robb, Elyse G Schechter, Noah L Pieper, Runying Yang, Scott Bang, Khalilah E Taylor, Kristina Drizyte-Miller, John P Morris IV, Channing J Der, Adrienne D Cox, Kirsten L Bryant. Concurrent inhibition of the RAS ERK-MAPK pathway and PIKfyve as a therapeutic strategy for 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 C026.

SREBP-Dependent Regulation of Lipid Homeostasis Is Required for Progression and Growth of Pancreatic Ductal Adenocarcinoma.

Our findings demonstrate that SREBP pathway activation is a critical part of the metabolic reprogramming that occurs in PDAC development and progression. Therefore, targeting the SREBP pathway has significant therapeutic potential.

KHSRP Stabilizes m6A-Modified Transcripts to Activate FAK Signaling and Promote Pancreatic Ductal Adenocarcinoma Progression.

N 6-Methyladenosine (m6A) is the most prevalent RNA modification and is associated with various biological processes. Proteins that function as readers and writers of m6A modifications have been shown to play critical roles in human malignancies. Here, we identified KH-type splicing regulatory protein (KHSRP) as an m6A binding protein that contributes to the progression of pancreatic ductal adenocarcinoma (PDAC). High KHSRP levels were detected in PDAC and predicted poor patient survival. KHSRP deficiency suppressed PDAC growth and metastasis in vivo. Mechanistically, KHSRP recognized and stabilized FAK pathway mRNAs, including MET, ITGAV, and ITGB1, in an m6A-dependent manner, which led to activation of downstream FAK signaling that promoted PDAC progression. Targeting KHSRP with a PROTAC showed promising tumor suppressive effects in mouse models, leading to prolonged survival. Together, these findings indicate that KHSRP mediates FAK pathway activation in an m6A-dependent manner to support PDAC growth and metastasis, highlighting the potential of KHSRP as a therapeutic target in pancreatic cancer. Significance: KHSRP is a m6A-binding protein that stabilizes expression of FAK pathway mRNAs and that can be targeted to suppress FAK signaling and curb pancreatic ductal adenocarcinoma progression.

Interaction between MED12 and ΔNp63 activates basal identity in pancreatic ductal adenocarcinoma.

The presence of basal lineage characteristics signifies hyperaggressive human adenocarcinomas of the breast, bladder and pancreas. However, the biochemical mechanisms that maintain this aberrant cell state are poorly understood. Here we performed marker-based genetic screens in search of factors needed to maintain basal identity in pancreatic ductal adenocarcinoma (PDAC). This approach revealed MED12 as a powerful regulator of the basal cell state in this disease. Using biochemical reconstitution and epigenomics, we show that MED12 carries out this function by bridging the transcription factor ΔNp63, a known master regulator of the basal lineage, with the Mediator complex to activate lineage-specific enhancer elements. Consistent with this finding, the growth of basal-like PDAC is hypersensitive to MED12 loss when compared to PDAC cells lacking basal characteristics. Taken together, our genetic screens have revealed a biochemical interaction that sustains basal identity in human cancer, which could serve as a target for tumor lineage-directed therapeutics.

Establishment of a Transplantation Model of PDAC-Derived Liver Metastases

BackgroundThe highly metastatic nature of pancreatic ductal adenocarcinoma (PDAC) and the difficulty to achieve favorable patient outcomes emphasize the need for novel therapeutic solutions. For preclinical evaluations, genetically engineered mouse models are often used to mimic human PDAC but frequently fail to replicate synchronous development and metastatic spread. This study aimed to develop a transplantation model to achieve synchronous and homogenous PDAC growth with controlled metastatic patterns in the liver.MethodsTo generate an orthotopic PDAC model, the DT6606 cell line was injected into the pancreas head of C57BL/6 mice, and their survival was monitored over time. To generate a heterotopic transplantation model, growing doses of three PDAC cell lines (DT6606, DT6606lm, and K8484) were injected into the portal vein of mice. Magnetic resonance imaging (MRI) was used to monitor metastatic progression, and histologic analysis was performed.ResultsOrthotopically injected mice succumbed to the tumor within an 11-week period (average survival time, 78.2 ± 4.45 days). Post-mortem examinations failed to identify liver metastasis. In the intraportal model, 2 × 105 DT6606 cells resulted in an absence of liver metastases by day 21, whereas 5 × 104 DT6606lm cells and 7 × 104 K8484 cells resulted in steady metastatic growth. Higher doses caused significant metastatic liver involvement. The use of K8484 cells ensured the growth of tumors closely resembling the histopathologic characteristics of human PDAC.ConclusionsThis report details the authors’ efforts to establish an “optimal” murine model for inducing metastatic PDAC, which is critical for advancing our understanding of the disease and developing more effective treatments.

Physical Activity Decreases Inflammation and Delays the Development of Obesity-Associated Pancreatic Ductal Adenocarcinoma.

Obesity is a risk factor for pancreatic ductal adenocarcinoma (PDAC), a deadly disease with limited preventive strategies. Lifestyle interventions to decrease obesity represent a potential approach to prevent obesity-associated PDAC. In this study, we examined whether decreasing obesity through physical activity (PA) and/or dietary changes could decrease inflammation in humans and prevent obesity-associated PDAC in mice. Comparison of circulating inflammatory-associated cytokines in subjects (overweight and obese) before and after a PA intervention revealed PA lowered systemic inflammatory cytokines. Mice with pancreatic-specific inducible KrasG12D expression were exposed to PA and/or dietary interventions during and after obesity-associated cancer initiation. In mice with concurrent diet-induced obesity and KrasG12D expression, the PA intervention led to lower weight gain, suppressed systemic inflammation, delayed tumor progression, and decreased proinflammatory signals in the adipose tissue. However, these benefits were not as evident when obesity preceded pancreatic KrasG12D expression. Combining PA with diet-induced weight loss (DI-WL) delayed obesity-associated PDAC progression in the genetically engineered mouse model, but neither PA alone nor combined with DI-WL or chemotherapy prevented PDAC tumor growth in orthotopic PDAC models regardless of obesity status. PA led to the upregulation of Il15ra in adipose tissue. Adipose-specific overexpression of Il15 slowed PDAC growth but only in nonobese mice. Overall, our study suggests that PA alone or combined with DI-WL can reduce inflammation and delay obesity-associated PDAC development or progression. Lifestyle interventions that prevent or manage obesity or therapies that target weight loss-related molecular pathways could prevent progression of PDAC. Significance: Physical activity reduces inflammation and induces changes to adipose-related signaling to suppress pancreatic cancer, supporting the potential of obesity management strategies to reduce the risk of developing pancreatic cancer. See related commentary by Sogunro and Muzumdar, p. 2935.

FBXO32 Stimulates Protein Synthesis to Drive Pancreatic Cancer Progression and Metastasis.

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer-related death worldwide, primarily due to its rapid progression. The current treatment options for PDAC are limited, and a better understanding of the underlying mechanisms responsible for PDAC progression is required to identify improved therapeutic strategies. In this study, we identified FBXO32 as an oncogenic driver in PDAC. FBXO32 was aberrantly upregulated in PDAC, and high FBXO32 expression was significantly associated with an unfavorable prognosis in patients with PDAC. FRG1 deficiency promoted FBXO32 upregulation in PDAC. FBXO32 promoted cell migration and invasion in vitro and tumor growth and metastasis in vivo. Mechanistically, FBXO32 directly interacted with eEF1A1 and promoted its polyubiquitination at the K273 site, leading to enhanced activity of eEF1A1 and increased protein synthesis in PDAC cells. Moreover, FBXO32-catalyzed eEF1A1 ubiquitination boosted the translation of ITGB5 mRNA and activated focal adhesion kinase (FAK) signaling, thereby facilitating focal adhesion assembly and driving PDAC progression. Importantly, interfering with the FBXO32-eEF1A1 axis or pharmaceutical inhibition of FAK by defactinib, an FDA-approved FAK inhibitor, substantially inhibited PDAC growth and metastasis driven by aberrantly activated FBXO32-eEF1A1 signaling. Overall, this study uncovers a mechanism by which PDAC cells rely on FBXO32-mediated eEF1A1 activation to drive progression and metastasis. FBXO32 may serve as a promising biomarker for selecting eligible patients with PDAC for treatment with defactinib. Significance: FBXO32 upregulation in pancreatic cancer induced by FRG1 deficiency increases eEF1A1 activity to promote ITGB5 translation and stimulate FAK signaling, driving cancer progression and sensitizing tumors to the FAK inhibitor defactinib.

Driver Mutations in Pancreatic Cancer and Opportunities for Targeted Therapy.

Pancreatic cancer is the sixth leading cause of cancer-related mortality globally. As the most common form of pancreatic cancer, pancreatic ductal adenocarcinoma (PDAC) represents up to 95% of all pancreatic cancer cases, accounting for more than 300,000 deaths annually. Due to the lack of early diagnoses and the high refractory response to the currently available treatments, PDAC has a very poor prognosis, with a 5-year overall survival rate of less than 10%. Targeted therapy and immunotherapy are highly effective and have been used for the treatment of many types of cancer; however, they offer limited benefits in pancreatic cancer patients due to tumor-intrinsic and extrinsic factors that culminate in drug resistance. The identification of key factors responsible for PDAC growth and resistance to different treatments is highly valuable in developing new effective therapeutic strategies. In this review, we discuss some molecules which promote PDAC initiation and progression, and their potential as targets for PDAC treatment. We also evaluate the challenges associated with patient outcomes in clinical trials and implications for future research.