KRAS-mutant Pancreatic Cancer Research Articles

Deciphering molecular crosstalk mechanisms between skeletal muscle atrophy and KRAS-mutant pancreatic cancer: a literature review

Deciphering molecular crosstalk mechanisms between skeletal muscle atrophy and KRAS-mutant pancreatic cancer: a literature review

Intercellular TIMP-1-CD63 signaling directs the evolution of immune escape and metastasis in KRAS-mutated pancreatic cancer cells

Background and aimsOncogenic KRAS mutations are present in approximately 90% of pancreatic ductal adenocarcinoma (PDAC). However, Kras mutation alone is insufficient to transform precancerous cells into metastatic PDAC. This study investigates how KRAS-mutated epithelial cells acquire the capacity to escape senescence or even immune clearance, thereby progressing to advanced PDAC.MethodsSingle-cell RNA sequencing and analysis of primary PDAC tumors were conducted. Genetically engineered pancreas-specific Kras-mutated, dual specificity phosphatase-2 (Dusp2) knockout mouse models were established. Human and mouse primary pancreatic cancer cell lines were used for in vitro assessment of cancer characteristics. Tumor progression was studied via pancreas orthotopic and portal vein injection in the immune-competent mice. Clinical relevance was validated by digital spatial transcriptomic analysis of PDAC tumors.ResultsKras mutation induces the formation of pancreatic intraepithelial neoplasia (PanIN), these lesions also exhibit significant apoptotic signals. Single-cell RNA sequencing identified a subset of ERKactiveDUSP2low cells continuing to expand from early to advanced stage PDAC. In vitro and in vivo studies reveal that early infiltrating macrophage-derived tissue inhibitor of metallopeptidase 1 (TIMP-1) is the key factor in maintaining the ERKactiveDUSP2low cell population in a CD63-dependent manner. The ERKactiveDUSP2low cancer cells further exacerbate macrophage-mediated cancer malignancy, including loss of epithelial trait, increased lymphangiogenesis, and immune escape. Digital spatial profiling analysis of PDAC samples demonstrates the colocalization of TIMP-1high macrophages and CD63high cancer cells. The presence of TIMP-1high macrophages and CD63high epithelial cells correlates with poor prognosis in PDAC.ConclusionsOur study reveals the vicious cycle between early infiltrating macrophages and pancreatic cancer cells, providing a mechanistic insight into the dynamic regulation directing pancreatic cancer progression.

TMOD3 accelerated resistance to immunotherapy in KRAS-mutated pancreatic cancer through promoting autophagy-dependent degradation of ASCL4

The high prevalence of KRAS mutations in pancreatic cancer (PC) is widely acknowledged and results in the resistance of targeted ferroptosis therapy and immunotherapy. Herein, via a CRISPR/Cas9 library screen, the effects of ferroptosis agonists were increased in KRAS-mutant PC cells upon knockout of tropomodulin 3 (TMOD3), while these effects were not observed in KRAS-wild-type cells. Increased levels of TMOD3 were found in PC tissues, particularly in those with KRAS mutations. The increase in TMOD3 expression was facilitated by KRAS via the ETS transcription factor ELK1. Liquid chromatography-mass spectrometry (LC/MS) showed that TMOD3 increased acyl-CoA synthetase long chain family member 4 (ACSL4) protein expression and fatty acid metabolism. Mechanistically, TMOD3 promoted F-actin polymerization, thereby facilitating the fusion of autophagosomes with lysosomes, increasing the degradation of the ACSL4 protein, and augmenting the ferroptosis-inducing effects of RSL3. These effects of TMOD3 were counteracted by the administration of cytochalasin, the removal of the α2 domain of TMOD3, or the introduction of a mutation at S71. Cangrelor, an FDA-approved drug, can target TMOD3. In a mouse model, the suppression of TMOD3 using cangrelor or gene silencing technology resulted in increased infiltration of CD8+ T cells into tumor tissues with KRAS mutations and exhibited a synergistic effect with the PD-1 antibody. In conclusion, TMOD3 was found to inhibit ferroptosis and induced the resistance to PD-1 antibody by facilitating the fusion of autophagosomes and lysosomes through the promotion of F-actin polymerization in KRAS-mutant PC. TMOD3 was identified as a novel target for PC therapy.

Endosomal Trafficking Bypassed by the RAB5B-CD109 Interplay Promotes Axonogenesis in KRAS-Mutant Pancreatic Cancer.

Perineural invasion (PNI) represents a unique biological feature associated with poor prognosis in pancreatic ductal adenocarcinoma (PDAC), especially in the presence of KRAS mutations. Extracellular vesicle (EV)-packaged circular RNAs (circRNAs) function as essential mediators of tumor microenvironment communication, triggering PDAC cell invasion and distant metastasis. However, the regulatory mechanisms of EV-packaged circRNAs in the PNI of KRAS-mutant PDAC have not yet been elucidated. Herein, a KRASG12D mutation-responsive EV-packaged circRNA, circPNIT, which positively correlated with PNI in PDAC patients is identified. Functionally, KRASG12D PDAC-derived EV-packaged circPNIT promoted axonogenesis and PNI both in vitro and in vivo. Mechanistically, the circPNIT-mediated Rab5B-CD109 interplay bypassed traditional endosomal trafficking to anchor Rab5B to the lipid rafts of multivesicular bodies and packaged circPNIT into CD109+ EVs. Subsequently, CD109+ EVs delivered circPNIT to neurons by binding to TRPV1 and facilitating DSCAML1 transcription-induced axonogenesis, which in turn enhanced the PNI by activating the GFRα1/RET pathway. Importantly, circPNIT-loaded CD109+ EVs are established to dramatically promote PNI in a KRASG12D/+ Trp53R172H/+ Pdx-1-Cre mouse model. Collectively, the findings highlight the mechanism underlying how EV-packaged circRNAs mediate the PNI of KRAS-mutant PDAC cells through the Rab5B endosomal bypass, identifying circPNIT as an effective target for the treatment of neuro-metastatic PDAC.

Targeting KRAS-mutant pancreatic cancer through simultaneous inhibition of KRAS, MEK, and JAK2.

The Kirsten rat sarcoma (KRAS) oncogene was considered "undruggable" until the development of sotorasib, a KRASG12C selective inhibitor that shows favorable effects against lung cancers. MRTX1133, a novel KRASG12D inhibitor, has shown promising results in basic research, although its effects against pancreatic cancer are limited when used alone. Therefore, there is an urgent need to identify effective drugs that can be used in combination with KRAS inhibitors. In this study, we found that administration of the KRAS inhibitors sotorasib or MRTX1133 upregulated STAT3 phosphorylation and reactivated ERK through a feedback reaction. The addition of the MEK inhibitor trametinib and the JAK2 inhibitor fedratinib successfully reversed this effect and resulted in significant growth inhibition in vitro and in vivo. Analyses of sotorasib- and MRTX1133-resistant cells showed that trametinib plus fedratinib reversed the resistance to sotorasib or MRTX1133. These findings suggest that the JAK2-mediated pathway and reactivation of the MAPK pathway may play key roles in resistance to KRAS inhibitors in pancreatic cancers. Accordingly, simultaneous inhibition of KRAS, MEK, and JAK2 could be an innovative therapeutic strategy against KRAS-mutant pancreatic cancer.

Crosstalk between FTH1 and PYCR1 dysregulates proline metabolism and mediates cell growth in KRAS-mutant pancreatic cancer cells.

Ferritin, comprising heavy (FTH1) and light (FTL) chains, is the main iron storage protein, and pancreatic cancer patients exhibit elevated serum ferritin levels. Specifically, higher ferritin levels are correlated with poorer pancreatic ductal adenocarcinoma (PDAC) prognosis; however, the underlying mechanism and metabolic programming of ferritin involved in KRAS-mutant PDAC progression remain unclear. Here, we observed a direct correlation between FTH1 expression and cell viability and clonogenicity in KRAS-mutant PDAC cell lines as well as with in vivo tumor growth through the control of proline metabolism. Our investigation highlights the intricate relationship between FTH1 and pyrroline-5-carboxylate reductase 1 (PYCR1), a crucial mitochondrial enzyme facilitating the glutamate-to-proline conversion, underscoring its impact on proline metabolic imbalance in KRAS-mutant PDAC. This regulation is further reversed by miR-5000-3p, whose dysregulation results in the disruption of proline metabolism, thereby accentuating the progression of KRAS-mutant PDAC. Additionally, our study demonstrated that deferasirox, an oral iron chelator, significantly diminishes cell viability and tumor growth in KRAS-mutant PDAC by targeting FTH1-mediated pathways and altering the PYCR1/PRODH expression ratio. These findings underscore the novel role of FTH1 in proline metabolism and its potential as a target for PDAC therapy development.

Abstract IA-05: Targeting KRAS for pancreatic cancer treatment

Abstract The approval of clinically effective inhibitors for KRAS G12C mutant non-small cell lung cancers in 2021 and 2022 marks a significant milestone in anti-KRAS oncogene drug discovery. This success has fueled intense efforts to develop inhibitors targeting additional KRAS mutations. However, primary and treatment-associated acquired resistance limit the depth and duration of efficacy of KRAS G12C selective and likely other KRAS inhibitors. Thus, a major challenge moving forward will be the elucidation of mechanisms of resistance to then guide development of effective combination anti-KRAS therapies. Recent studies have begun to identify mechanisms of acquired resistance, where most involve alterations in components in the RAS signaling network that then cause reactivation of KRAS effector signaling that bypass drug activity. Our studies have established the critical role of reactivation of the RAF-MEK-ERK mitogen activated protein kinase cascade, and the ERK target MYC, in driving resistance in KRAS-mutant pancreatic cancer. To fully understand how aberrant ERK and MYC activation overcomes KRAS inhibitor response, we have established a comprehensive molecular portrait of ERK- and MYC-dependent activities. We have also identified YAP/TAZ-TEAD activation as a mechanism of acquired resistance and have characterized KEAP1 loss as a mechanism of primary resistance. Together, these studies have identified drug combination strategies that enhance KRAS inhibitor activity. Progress in these and other studies will be presented. Citation Format: Channing J. Der. Targeting KRAS for pancreatic cancer treatment [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-05.

Determining the ERK-regulated phosphoproteome driving KRAS-mutant cancer.

To delineate the mechanisms by which the ERK1 and ERK2 mitogen-activated protein kinases support mutant KRAS-driven cancer growth, we determined the ERK-dependent phosphoproteome in KRAS-mutant pancreatic cancer. We determined that ERK1 and ERK2 share near-identical signaling and transforming outputs and that the KRAS-regulated phosphoproteome is driven nearly completely by ERK. We identified 4666 ERK-dependent phosphosites on 2123 proteins, of which 79 and 66%, respectively, were not previously associated with ERK, substantially expanding the depth and breadth of ERK-dependent phosphorylation events and revealing a considerably more complex function for ERK in cancer. We established that ERK controls a highly dynamic and complex phosphoproteome that converges on cyclin-dependent kinase regulation and RAS homolog guanosine triphosphatase function (RHO GTPase). Our findings establish the most comprehensive molecular portrait and mechanisms by which ERK drives KRAS-dependent pancreatic cancer growth.

Mediator kinase inhibition impedes transcriptional plasticity and prevents resistance to ERK/MAPK-targeted therapy in KRAS-mutant cancers

Acquired resistance remains a major challenge for therapies targeting oncogene activated pathways. KRAS is the most frequently mutated oncogene in human cancers, yet strategies targeting its downstream signaling kinases have failed to produce durable treatment responses. Here, we developed multiple models of acquired resistance to dual-mechanism ERK/MAPK inhibitors across KRAS-mutant pancreatic, colorectal, and lung cancers, and then probed the long-term events enabling survival against this class of drugs. These studies revealed that resistance emerges secondary to large-scale transcriptional adaptations that are diverse and cell line-specific. Transcriptional reprogramming extends beyond the well-established early response, and instead represents a dynamic, evolved process that is refined to attain a stably resistant phenotype. Mechanistic and translational studies reveal that resistance to dual-mechanism ERK/MAPK inhibition is broadly susceptible to manipulation of the epigenetic machinery, and that Mediator kinase, in particular, can be co-targeted at a bottleneck point to prevent diverse, cell line-specific resistance programs.

ZDHHC20-mediated S-palmitoylation of YTHDF3 stabilizes MYC mRNA to promote pancreatic cancer progression

Post-translational modifications of proteins in malignant transformation and tumor maintenance of pancreatic ductal adenocarcinoma (PDAC) in the context of KRAS signaling remain poorly understood. Here, we use the KPC mouse model to examine the effect of palmitoylation on pancreatic cancer progression. ZDHHC20, upregulated by KRAS, is abnormally overexpressed and associated with poor prognosis in patients with pancreatic cancer. Dysregulation of ZDHHC20 promotes pancreatic cancer progression in a palmitoylation-dependent manner. ZDHHC20 inhibits the chaperone-mediated autophagic degradation of YTHDF3 through S-palmitoylation of Cys474, which can result in abnormal accumulation of the oncogenic product MYC and thereby promote the malignant phenotypes of cancer cells. Further, we design a biologically active YTHDF3-derived peptide to competitively inhibit YTHDF3 palmitoylation mediated by ZDHHC20, which in turn downregulates MYC expression and inhibits the progression of KRAS mutant pancreatic cancer. Thus, these findings highlight the therapeutic potential of targeting the ZDHHC20–YTHDF3–MYC signaling axis in pancreatic cancer.

Metabolomic Approach to Identify Potential Biomarkers in KRAS-Mutant Pancreatic Cancer Cells.

Pancreatic cancer is characterized by its high mortality rate and limited treatment options, often driven by oncogenic RAS mutations. In this study, we investigated the metabolomic profiles of pancreatic cancer cells based on their KRAS genetic status. Utilizing both KRAS-wildtype BxPC3 and KRAS-mutant PANC1 cell lines, we identified 195 metabolites differentially altered by KRAS status through untargeted metabolomics. Principal component analysis and hierarchical condition trees revealed distinct separation between KRAS-wildtype and KRAS-mutant cells. Metabolite set enrichment analysis highlighted significant pathways such as homocysteine degradation and taurine and hypotaurine metabolism. Additionally, lipid enrichment analysis identified pathways including fatty acyl glycosides and sphingoid bases. Mapping of identified metabolites to KEGG pathways identified nine significant metabolic pathways associated with KRAS status, indicating diverse metabolic alterations in pancreatic cancer cells. Furthermore, we explored the impact of TRPML1 inhibition on the metabolomic profile of KRAS-mutant pancreatic cancer cells. TRPML1 inhibition using ML-SI1 significantly altered the metabolomic profile, leading to distinct separation between vehicle-treated and ML-SI1-treated PANC1 cells. Metabolite set enrichment analysis revealed enriched pathways such as arginine and proline metabolism, and mapping to KEGG pathways identified 17 significant metabolic pathways associated with TRPML1 inhibition. Interestingly, some metabolites identified in PANC1 compared to BxPC3 were oppositely regulated by TRPML1 inhibition, suggesting their potential as biomarkers for KRAS-mutant cancer cells. Overall, our findings shed light on the distinct metabolite changes induced by both KRAS status and TRPML1 inhibition in pancreatic cancer cells, providing insights into potential therapeutic targets and biomarkers for this deadly disease.

RAS-RAF-miR-296-3p signaling axis increases Rad18 expression to augment radioresistance in pancreatic and thyroid cancers

Oncogenic RAS and RAF signaling has been implicated in contributing to radioresistance in pancreatic and thyroid cancers. In this study, we sought to better clarify molecular mechanisms contributing to this effect. We discovered that miRNA 296-3p (miR-296-3p) is significantly correlated with radiosensitivity in a panel of pancreatic cancer cells, and miR-296-3p is highly expressed in normal cells, but low in cancer cell lines. Elevated expression of miR-296-3p increases radiosensitization while decreasing the expression of the DNA repair enzyme RAD18 in both pancreatic and thyroid cancer cells. RAD18 is overexpressed in both pancreatic and thyroid tumors compared to matched normal controls, and high expression of RAD18 in tumors is associated with poor prognostic features. Modulating the expression of mutant KRAS in pancreatic cancer cells or mutant BRAF in thyroid cancer cells demonstrates a tight regulation of RAD18 expression in both cancer types. Depletion of RAD18 results in DNA damage and radiation-induced cell death. Importantly, RAD18 depletion in combination with radiotherapy results in marked and sustained tumor regression in KRAS mutant pancreatic cancer orthotopic tumors and BRAF mutant thyroid heterotopic tumors. Overall, our findings identify a novel coordinated RAS/RAF-miR-296-3p-RAD18 signaling network in pancreatic and thyroid cancer cells, which leads to enhanced radioresistance.

STAT3 is a genetic modifier of TGF-beta induced EMT in KRAS mutant pancreatic cancer.

Oncogenic mutations in KRAS are among the most common in cancer. Classical models suggest that loss of epithelial characteristics and the acquisition of mesenchymal traits are associated with cancer aggressiveness and therapy resistance. However, the mechanistic link between these phenotypes and mutant KRAS biology remains to be established. Here, we identify STAT3 as a genetic modifier of TGF-beta-induced epithelial to mesenchymal transition. Gene expression profiling of pancreatic cancer cells identifies more than 200 genes commonly regulated by STAT3 and oncogenic KRAS. Functional classification of the STAT3-responsive program reveals its major role in tumor maintenance and epithelial homeostasis. The signatures of STAT3-activated cell states can be projected onto human KRAS mutant tumors, suggesting that they faithfully reflect characteristics of human disease. These observations have implications for therapeutic intervention and tumor aggressiveness.

STAT3 is a genetic modifier of TGF-beta induced EMT in KRAS mutant pancreatic cancer

Oncogenic mutations in KRAS are among the most common in cancer. Classical models suggest that loss of epithelial characteristics and the acquisition of mesenchymal traits are associated with cancer aggressiveness and therapy resistance. However, the mechanistic link between these phenotypes and mutant KRAS biology remains to be established. Here, we identify STAT3 as a genetic modifier of TGF-beta-induced epithelial to mesenchymal transition. Gene expression profiling of pancreatic cancer cells identifies more than 200 genes commonly regulated by STAT3 and oncogenic KRAS. Functional classification of the STAT3-responsive program reveals its major role in tumor maintenance and epithelial homeostasis. The signatures of STAT3-activated cell states can be projected onto human KRAS mutant tumors, suggesting that they faithfully reflect characteristics of human disease. These observations have implications for therapeutic intervention and tumor aggressiveness.

Abstract 7223: A triplet therapeutic strategy targeting MEK, BCL-XL, and EGFR, for KRAS-mutant pancreatic ductal adenocarcinoma

Abstract KRAS mutations drive over 90% of pancreatic cancers, but KRAS has been proven difficult to target. Downstream of KRAS, MEK inhibition in combination with BCL-XL inhibition is synthetically lethal and an effective treatment for gynecologic, but not colorectal malignancies. Like colorectal cancer, pancreatic cancer often exhibits aberrant HER/EGFR activity. We hypothesized that a triplicate regimen targeting MEK, BCL-XL, and EGFR/HER would be effective for pancreatic cancer. Trametinib (MEK inhibitor), Afatinib (pan-EGFR/HER inhibitor), and Navitoclax (BCL-XL inhibitor); or DT2216 (a BCL-XL/BCL-1 proteolysis targeting chimera, PROTAC) were explored using various combinatorial strategies. These drug combinations were tested using four primary human pancreatic cancer cell lines using live cell imaging (Incucyte) and an in vivo murine model. Group comparisons were analyzed using one-way ANOVAs, and adjusted p-values <0.05 were considered significant. We observed that no single-agent treatments were effective. MEK inhibition plus anti-BCL-XL (Trametinib + Navitoclax or Trametinib + DT2216) demonstrated efficacy in one of the four cell lines. We noted synergistic effects on reduced cell growth and increased cell death when EGFR/HER inhibition was included by the administration of Afatinib. The triplet combination resulted in synergistic effects in three of four cell lines with Navitoclax and four of four cell lines with DT2216 (q<0.05). This effect was confirmed with DT2216 inhibition of BCL-XL in an in-vivo murine model. In conclusion, our study shows that a combinatory strategy targeting MEK, BCL-XL, and pan-EGFR/HER receptor kinase shows significant synergistic effects in pancreatic cancer. Clinical trials that assess the efficacy and safety of this strategy for patients with KRAS-mutant pancreatic cancer are warranted. Our data also suggests that novel KRAS inhibitors as monotherapy are likely to fail. Citation Format: Gerik W. Tushoski-Alemán, Alexandra J. Crespin, Chibeze J. Oguejiofor, Jordan A. McKean, Kelly M. Herremans, Thomas J. George, Carmen J. Allegra, Steven J. Hughes, Song Han. A triplet therapeutic strategy targeting MEK, BCL-XL, and EGFR, for KRAS-mutant 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 7223.

Abstract 5912: Rational design of a small-molecule inhibitor targeting the allosteric site of sos1 in oncogenic k-ras pancreatic cancer

Abstract Oncogenic Kras signaling is a key therapeutic target in human cancers. Ras activation is catalyzed by guanine nucleotide exchange factors (GEFs), of which SOS1 is a major player that transduces receptor tyrosine kinase signaling to Ras. In addition to recently devised oncogenic Kras targeting small molecule inhibitors, disrupting the catalytic interaction between Ras and SOS1 has emerged as an attractive therapeutic strategy in working synergistically with Kras inhibitors and overcoming resistance. Previous studies have demonstrated an active “feed forward” loop of active Kras binding to the allosteric site of SOS1 that further stimulates SOS1 catalytic activation of wild type H/N/Kras, which is required for oncogenic Kras driven tumorigenesis. Here we have developed a rational approach that combines virtual screening with experimental screening to identify small molecule inhibitors that target the allosteric site of SOS1 to suppress oncogenic Kras mediated SOS1-regulated wild-type Ras activities. Unlike SOS1 catalytic site inhibitors which can have significant toxicity due to their ability to inhibit normal Ras signaling function, the lead SOS1 allosteric inhibitors developed in our laboratory binds to the allosteric site of SOS1 and blocks active Ras interaction with SOS1: we found these inhibitors can competitively suppresses SOS1-Ras interaction at the SOS1 allosteric site and dose-dependently inhibits the feed-forward SOS1 GEF activity. Mutagenesis and structure-activity relationship studies mapped the site of action to the SOS1 allosteric site, and preliminarily defined the chemical moieties in the inhibitor essential for the activity. The inhibitor showed dose-dependent and selective efficacy in inhibiting WT Ras activity, downstream signaling activities, and associated cell proliferation in KRAS mutation cells but not KRAS wild-type cells. Compared to the SOS1 catalytic inhibitor, BI3406, our inhibitors showed better selectivity for KRAS mutant pancreatic cancer cells vs. WT KRAS cells. These studies establish a proof of principle for the rational design of small molecule inhibitors targeting an oncogenic Kras specific allosteric site of SOS1 and provide a novel therapeutic concept to target KRAS-driven tumors more effectively. Citation Format: Xin Duan, Chris R Evelyn, Jacek Biesiada, James F Johnson, William L. Seibel, Jaroslaw Meller, Yi Zheng. Rational design of a small-molecule inhibitor targeting the allosteric site of sos1 in oncogenic k-ras pancreatic cancer [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 5912.

Abstract 4588: Combination of MTA-cooperative PRMT5 inhibitor and direct mutant-selective KRAS inhibitors as a novel therapeutic approach for MTAP-deficient pancreatic cancer

Abstract KRAS is mutationally activated in 95% of pancreatic ductal adenocarcinoma (PDAC) patients. Direct KRAS inhibitors are under intense preclinical and clinical development, with two KRASG12C mutant-selective inhibitors (G12Ci) now approved. However, treatment-associated resistance to KRAS inhibitors has been reported in the clinic highlighting an urgent need to identify both additional therapeutic targets and novel combination treatment strategies with KRAS inhibitors. To that end, we performed a CRISPR/Cas9 loss-of-function screen using a library targeting ~2,500 druggable genes in KRASG12C/D-mutant PDAC cell lines. We identified multiple genes that were essential for PDAC cell growth and selected PRMT5, a protein arginine methyltransferase, to assess as a novel therapeutic target for pancreatic cancer. We found that suppression of PRMT5 activity using two distinct first-generation clinical candidate small molecule inhibitors (JNJ-64619178 and GSK3326595) demonstrated single agent activity and reduced PDAC cell growth. We further assessed a mechanistically distinct MTA-cooperative clinical candidate PRMT5 inhibitor, MRTX1719, that is selective for MTAP-deleted tumors, which occur in ~25% of PDAC patients. We determined that MRTX1719 exhibited low nanomolar GI50 activities in MTAP-deficient but not MTAP wild-type KRAS-mutant cell lines. Unexpectedly, PDAC cells treated with MRTX1719 exhibited a paradoxical activation of ERK, suggesting that combined inhibition of PRMT5 and KRAS might be therapeutically advantageous. In support of our hypothesis, we demonstrated that combination treatment with MRTX1719 and mutant selective KRAS inhibitors (G12Ci/MRTX849 and G12Di/MRTX1133) further sensitized KRASG12C/D-mutant PDAC cells to KRAS inhibition in short- and long-term growth assays as well as in vivo xenograft studies. Our ongoing studies are evaluating the consequences of co-targeting PRMT5 and KRAS on gene expression changes using RNA-Seq and cancer cell signaling pathways using RPPA analyses. In summary, our data support concurrent inhibition of PRMT5 and KRAS as a promising therapeutic strategy for MTAP-deficient KRAS-mutant pancreatic cancer. Citation Format: Kristina Drizyte-Miller, Wen-Hsuan Chang, Andrew M. Waters, Clint A. Stalnecker, Junning Wang, Andrew J. Aguirre, Adrienne D. Cox, Channing J. Der. Combination of MTA-cooperative PRMT5 inhibitor and direct mutant-selective KRAS inhibitors as a novel therapeutic approach for MTAP-deficient pancreatic cancer [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 4588.

Exploring KRAS-mutant pancreatic ductal adenocarcinoma: a model validation study.

Pancreatic ductal adenocarcinoma (PDAC) has the highest mortality rate among all solid tumors. Tumorigenesis is promoted by the oncogene KRAS, and KRAS mutations are prevalent in patients with PDAC. Therefore, a comprehensive understanding of the interactions between KRAS mutations and PDAC may expediate the development of therapeutic strategies for reversing the progression of malignant tumors. Our study aims at establishing and validating a prediction model of KRAS mutations in patients with PDAC based on survival analysis and mRNA expression. A total of 184 and 412 patients with PDAC from The Cancer Genome Atlas (TCGA) database and the International Cancer Genome Consortium (ICGC), respectively, were included in the study. After tumor mutation profile and copy number variation (CNV) analyses, we established and validated a prediction model of KRAS mutations, based on survival analysis and mRNA expression, that contained seven genes: CSTF2, FAF2, KIF20B, AKR1A1, APOM, KRT6C, and CD70. We confirmed that the model has a good predictive ability for the prognosis of overall survival (OS) in patients with KRAS-mutated PDAC. Then, we analyzed differential biological pathways, especially the ferroptosis pathway, through principal component analysis, pathway enrichment analysis, Gene Ontology (GO) enrichment analysis, and gene set enrichment analysis (GSEA), with which patients were classified into low- or high-risk groups. Pathway enrichment results revealed enrichment in the cytokine-cytokine receptor interaction, metabolism of xenobiotics by cytochrome P450, and viral protein interaction with cytokine and cytokine receptor pathways. Most of the enriched pathways are metabolic pathways predominantly enriched by downregulated genes, suggesting numerous downregulated metabolic pathways in the high-risk group. Subsequent tumor immune infiltration analysis indicated that neutrophil infiltration, resting CD4 memory T cells, and resting natural killer (NK) cells correlated with the risk score. After verifying that the seven gene expression levels in different KRAS-mutated pancreatic cancer cell lines were similar to that in the model, we screened potential drugs related to the risk score. This study established, analyzed, and validated a model for predicting the prognosis of PDAC based on risk stratification according to KRAS mutations, and identified differential pathways and highly effective drugs.

Discovery of Novel PDEδ Autophagic Degraders: A Case Study of Autophagy-Tethering Compound (ATTEC).

The autophagy-tethering compound (ATTEC) technology has emerged as a promising strategy for targeted protein degradation (TPD). Here, we report the discovery of the first generation of PDEδ autophagic degraders using an ATTEC approach. The most promising compound 12c exhibited potent PDEδ binding affinity and efficiently induced PDEδ degradation in a concentration-dependent manner. Mechanistic studies confirmed that compound 12c reduced the PDEδ protein level through lysosome-mediated autophagy without affecting the PDEδ mRNA expression. Importantly, compound 12c was much more effective in suppressing the growth in KRAS mutant pancreatic cancer cells than the corresponding PDEδ inhibitor. Taken together, this study expands the application scope of the ATTEC approach and highlights the effectiveness of the PDEδ autophagic degradation strategy in antitumor drug discovery.

Dual Inhibition of KRASG12D and Pan-ERBB Is Synergistic in Pancreatic Ductal Adenocarcinoma.

KRAS-mutant pancreatic cancer models, including KRAS inhibitor-resistant models, show exquisite sensitivity to combined pan-ERBB and KRAS targeting, which provides the rationale for testing this drug combination in clinical trials.