Orthotopic Xenograft Research Articles

Senescent cells promote breast cancer cells motility by secreting GM-CSF and bFGF that activate the JNK signaling pathway

BackgroundCellular senescence can be induced in mammalian tissues by multiple stimuli, including aging, oncogene activation and loss of tumor suppressor genes, and various types of stresses. While senescence is a tumor suppressing mechanism when induced within premalignant or malignant tumor cells, senescent cells can promote cancer development through increased secretion of growth factors, cytokines, chemokines, extracellular matrix, and degradative enzymes, collectively known as senescence-associated secretory phenotype (SASP). Previous studies indicated that senescent cells, through SASP factors, stimulate tumor cell invasion that is a critical step in cancer cell metastasis.MethodsIn the current study, we investigated the effect of senescent cells on the motility of breast cancer cells, which is another key step in cancer cell metastasis. We analyzed the motility of breast cancer cells co-cultured with senescent cells in vitro and metastasis of the breast cancer cells co-injected with senescent cells in orthotopic xenograft models. We also delineated the signaling pathway mediating the effect of senescent cells on cancer cell motility.ResultsOur results indicate that senescent cells stimulated the migration of breast cancer cells through secretion of GM-CSF and bFGF, which in turn induced activation of the JNK pathway in cancer cells. More importantly, senescent cells promoted breast cancer metastasis, with a minimum effect on the primary tumor growth, in orthotopic xenograft mouse models.ConclusionsThese results have revealed an additional mechanism by which senescent cells promote tumor cell metastasis and tumor progression, and will potentially lead to identification of novel targets for cancer therapies that suppress metastasis, the major cause of cancer mortality.

EZH2 functional dichotomy in reactive oxygen species-stratified glioblastoma.

EZH2, well-known for its canonical methyltransferase activity in transcriptional repression in many cancers including glioblastoma (GBM), has an understudied non-canonical function critical for sustained tumor growth. Recent GBM consortial efforts reveal complex molecular heterogeneity for which therapeutic vulnerabilities correlated with subtype stratification remain relatively unexplored. Current enzymatic EZH2 inhibitors (EZH2inh) targeting its canonical SET domain show limited efficacy and lack durable response, suggesting that underlying differences in the non-canonical pathway may yield new knowledge. Here, we unveiled dual roles of the EZH2 CXC domain in therapeutically-distinct, reactive oxygen species (ROS)-stratified tumors. We analyzed differentially expressed genes between ROS classes by examining cis-regulatory elements as well as clustering of activities and pathways to identify EZH2 as the key mediator in ROS-stratified cohorts. Pull-down assays and CRISPR knockout of EZH2 domains were used to dissect the distinct functions of EZH2 in ROS-stratified GBM cells. The efficacy of NF-κB-inducing kinase inhibitor (NIKinh) and standard-of-care temozolomide was evaluated using orthotopic patient-derived GBM xenografts. In ROS(+) tumors, CXC-mediated co-interaction with RelB drives constitutive activation of non-canonical NF-κB2 signaling, sustaining the ROS(+) chemoresistant phenotype. In contrast, in ROS(-) subtypes, PRC2 methyltransferase activity represses canonical NF-κB. Addressing the lack of EZH2inh targeting its non-methyltransferase roles, we utilized a brain-penetrant NIKinh that disrupts EZH2-RelB binding, consequently prolonging survival in orthotopic ROS(+)-implanted mice. Our findings highlight the functional dichotomy of the EZH2 CXC domain in governing ROS-stratified therapeutic resistance, thereby advocating for the development of therapeutic approaches targeting its non-canonical activities and underscoring the significance of patient stratification methodologies.

7065 Eradication Of Metastatic ER-Positive Breast, Ovarian, Endometrial And Lung Cancer In Mouse Xenografts And Patient Derived Organoids

Abstract Disclosure: D.J. Shapiro: None. D. Duraki: None. S. Ghosh: None. J. Zhu: None. C. Mao: None. J. Kim: None. M. Jabeen: None. M.W. Boudreau: None. M.P. Mulligan: None. R. Romero: None. Y. Han: None. J. Zhang: None. E.R. Nelson: None. O. Olopade: None. G. Chang: None. P.J. Hergenrother: Advisory Board Member; Self; Systems Oncology. We described the tumor protective estrogen-ER activated anticipatory Unfolded Protein Response (a-UPR) pathway. Here we report a previously undescribed multistep pathway by which very rapid estrogen-ER activation of the a-UPR authorizes and regulates subsequent transcription of the estrogen-ER transcriptome. We repurposed the tumor protective a-UPR through identification and optimization of the small molecule ErSO and its family of agents. ErSO acts non-competitively with estrogen to induce lethal hyperactivation of the a-UPR. In orthotopic mouse xenografts containing wild type or mutant ER, ErSO often induced complete regression without recurrence of large primary breast tumors and of most lung, bone and liver metastases, near complete regression of normally lethal brain metastases and complete destruction of patient derived organoids (PDOs) in Matrigel. Six research teams in four locations have confirmed the remarkable effectiveness of ErSO in ER-positive breast cancer. We next evaluated ErSO in diverse ER containing cancers in which estrogen is not the primary driver of proliferation. ErSO often induced complete regression in multiple orthotopic xenograft models of primary and metastatic ovarian cancer. Using fresh ovarian cancer organoids immediately after removal from patients by paracentesis, ErSO destroyed the organoids from some patients with advanced stage III and stage IV disease. ErSO was effective in a mouse xenograft model of endometrial cancer and, surprisingly, even in ERalpha positive lung cancer. Our ongoing studies demonstrate ErSO induces complete, or near complete regression, of primary and metastatic lung cancer in mice. Studies of ErSO’s mechanism of action using genome-wide CRISPR screens with positive selection, and other techniques, unveil a novel death pathway in which ErSO activation of the a-UPR triggers rapid calcium release into the cell body. The calcium opens the plasma membrane TRPM4 sodium channel, leading to an influx of extracellular sodium. This swells the cells, resulting in osmotic stress that sustains lethal a-UPR activation. A little-studied cytoskeleton regulator we identified, FGD3, plays a pivotal role in whether the cells rupture their membranes, inducing necrotic cell death. Notably, medium from diverse cancer cells killed by ErSO-induced necrosis robustly activates human macrophage and induces their migration - potentially facilitating immunotherapy. These studies describe a pathway from a multiprotein ER-SRC-PLC complex, through the a-UPR, to a novel cell swelling and necrosis pathway, that we are exploiting to target diverse, therapeutically challenging, ER-positive human cancers. Presentation: 6/2/2024

Engineered extracellular vesicles for combinatorial TNBC therapy: SR-SIM-guided design achieves substantial drug dosage reduction

Triple negative breast cancer is an aggressive subtype of breast cancer that has no therapeutic targets, relies on chemotherapeutics for treatment, and is in dire need of novel therapeutic approaches for improved patient outcomes. Extracellular vesicles serve as intercellular communicators and have been proposed as ideal drug delivery vehicles. Here, extracellular vesicles were engineered with RNA nanotechnology to develop Triple negative breast cancer tumor inhibitors. Utilizing Super Resolved-Structured Illumination Microscopy, extracellular vesicles were optimized for precise Survivin siRNA conjugated to chemotherapeutics loading and CD44 aptamer ligand decoration, thereby enhancing specificity towards triple negative breast cancer cells. Conventional treatments typically employ chemotherapy drugs Gemcitabine and Paclitaxel at dosages on the order of mg/kg respectively, per injection (IV) in mice. In contrast, engineered extracellular vesicles encapsulating these drugs saw functional tumor growth inhibition at significantly reduced concentrations: 2.2 μg/kg for Gemcitabine or 5.6 μg/kg for Paclitaxel, in combination with 21.5 μg/kg Survivin-siRNA in mice. The result is a substantial decrease of chemotherapeutic dose required, by orders of magnitude, compared to standard regimens. In vivo and in vitro evaluations in a triple negative breast cancer orthotopic xenograft mouse model demonstrated the efficacy of this reduced dosage strategy, indicating potential for decreased chemotherapy-associated toxicity.

LSD1 and CoREST2 Potentiate STAT3 Activity to Promote Enteroendocrine Cell Differentiation in Mucinous Colorectal Cancer.

Neuroendocrine cells have been implicated in therapeutic resistance and worse overall survival in many cancer types. Mucinous colorectal cancer (mCRC) is uniquely enriched for enteroendocrine cells (EECs), the neuroendocrine cell of the normal colon epithelium, as compared to non-mCRC. Therefore, targeting EEC differentiation may have clinical value in mCRC. Here, single cell multi-omics uncovered epigenetic alterations that accompany EEC differentiation, identified STAT3 as a regulator of EEC specification, and discovered a rare cancer-specific cell type with enteric neuron-like characteristics. Furthermore, LSD1 and CoREST2 mediated STAT3 demethylation and enhanced STAT3 chromatin binding. Knockdown of CoREST2 in an orthotopic xenograft mouse model resulted in decreased primary tumor growth and lung metastases. Collectively, these results provide rationale for developing LSD1 inhibitors that target the interaction between LSD1 and STAT3 or CoREST2, which may improve clinical outcomes for patients with mCRC.

Bismuth-based mesoporous nanoball carrying sorafenib for synergistic photothermal and molecularly-targeted therapy in an orthotopic hepatocellular carcinoma xenograft mouse model

Sorafenib (SOR), a multi-kinase inhibitor for advanced hepatocellular carcinoma (HCC), has limited clinical application due to severe side effects and drug resistance. To overcome these challenges, we developed a bismuth-based nanomaterial (BOS) for thermal injury-assisted continuous targeted therapy in HCC. Initially, the mesoporous nanomaterial was loaded with SOR, forming the BOS@SOR nano-carrier system for drug delivery and controlled release. Notably, compared to targeted or photothermal therapy alone, the combination therapy using this nano-carrier system significantly impaired cell proliferation and increased apoptosis. In vivo efficacy evaluations demonstrated that BOS@SOR exhibited excellent biocompatibility, confirmed through hemolysis and biochemical analyses. Additionally, BOS@SOR enhanced contrast in computed tomography, aiding in the precise identification of HCC size and location. The photothermal therapeutic properties of bismuth further contributed to the synergistic anti-tumor activity of BOS@SOR, significantly reducing tumor growth in an orthotopic xenograft HCC model. Taken together, encapsulating SOR within a bismuth-based mesoporous nanomaterial creates a multifunctional and environmentally stable nanocomposite (BOS@SOR), enhancing the therapeutic effect of SOR and presenting an effective strategy for HCC treatment.

KDM1A/LSD1 inhibition enhances chemotherapy response in ovarian cancer.

Ovarian cancer (OCa) is the deadliest of all gynecological cancers. The standard treatment for OCa is platinum-based chemotherapy, such as carboplatin or cisplatin in combination with paclitaxel. Most patients are initially responsive to these treatments; however, nearly 90% will develop recurrence and inevitably succumb to chemotherapy-resistant disease. Recent studies have revealed that the epigenetic modifier lysine-specific histone demethylase 1A (KDM1A/LSD1) is highly overexpressed in OCa. However, the role of KDM1A in chemoresistance and whether its inhibition enhances chemotherapy response in OCa remains uncertain. Analysis of TCGA datasets revealed that KDM1A expression is high in patients who poorly respond to chemotherapy. Western blot analysis show that treatment with chemotherapy drugs cisplatin, carboplatin, and paclitaxel increased KDM1A expression in OCa cells. KDM1A knockdown (KD) or treatment with KDM1A inhibitors NCD38 and SP2509 sensitized established and patient-derived OCa cells to chemotherapy drugs in reducing cell viability and clonogenic survival and inducing apoptosis. Moreover, knockdown of KDM1A sensitized carboplatin-resistant A2780-CP70 cells to carboplatin treatment and paclitaxel-resistant SKOV3-TR cells to paclitaxel. RNA-seq analysis revealed that a combination of KDM1A-KD and cisplatin treatment resulted in the downregulation of genes related to epithelial-mesenchymal transition (EMT). Interestingly, cisplatin treatment increased a subset of NF-κB pathway genes, and KDM1A-KD or KDM1A inhibition reversed this effect. Importantly, KDM1A-KD, in combination with cisplatin, significantly reduced tumor growth compared to a single treatment in an orthotopic intrabursal OCa xenograft model. Collectively, these findings suggest that combination of KDM1A inhibitors with chemotherapy could be a promising therapeutic approach for the treatment of OCa.

Energy and endoplasmic reticulum stress induction by gold(III) dithiocarbamate and 2-deoxyglucose synergistically trigger cell death in breast cancer

The elusiveness of triple-negative breast cancer from targeted therapy has redirected focus towards exploiting the metabolic shortcomings of these highly metastatic subtypes of breast cancer. Cueing from the metabolic heterogeneity of TNBC and the exposition of the dual dependence of some TNBCs on OXPHOS and glycolysis for ATP, we herein report the efficacy of cotreatment of TNBCs with an OXPHOS inhibitor, 2a and 2DG, a potent glycolysis inhibitor. 2a-2DG cotreatment inhibited TNBC cell proliferation with IC50 of ∼5 to 36 times lower than that of 2a alone and over 5000 times lower than IC50 of 2DG alone. 2a-2DG cotreatment suppressed mitochondrial ATP production and significantly induced AMPK activation. Mechanistic studies revealed the distinct yet synergistic contributions of 2a and 2DG to the antiproliferative effect of the cotreatment. While 2a induced apoptotic cell death, 2DG sensitized TNBCs to the antiproliferative effects of 2a via endoplasmic reticulum stress induction. Strikingly, the combination of 2a-2DG ablated SUM159 tumors in an orthotopic xenograft mouse model. This study highlights the synergistic effect of a gold-based complex with 2DG and the potential benefit of multi-metabolic pathways targeting as an effective therapeutic strategy against TNBCs.

N-Acetyl-L-Cysteine (NAC) Blunts Axitinib-Related Adverse Effects in Preclinical Models of Glioblastoma.

Axitinib is a tyrosine kinase inhibitor characterized by a strong affinity for Vascular Endothelial Growth Factor Receptors (VEGFRs). It was approved in 2012 by Food and Drug Administration and European Medicines Agency as a second line treatment for advanced renal cell carcinoma and is currently under evaluation in clinical trial for the treatment of other cancers. Glioblastoma IDH-wild type (GBM) is a highly malignant brain tumor characterized by diffusely infiltrative growth pattern and by a prominent neo-angiogenesis. In GBM, axitinib has demonstrated a limited effectiveness as a monotherapy, while it was recently shown to significantly improve its efficacy in combination treatments. In preclinical models, axitinib has been reported to trigger cellular senescence both in tumor as well as in normal cells, through a mechanism involving intracellular reactive oxygen species (ROS) accumulation and activation of Ataxia Telangiectasia Mutated kinase (ATM). Limiting axitinib-dependent ROS increase by antioxidants prevents senescence specifically in normal cells, without affecting tumor cells. We used brain tumor xenografts obtained by engrafting Glioma Stem Cells (GSCs) into the brain of immunocompromised mice, to investigate the hypothesis that the antioxidant molecule N-Acetyl-L-Cysteine (NAC) might be used to reduce senescence-associated adverse effects of axitinib treatment without altering its anti-tumor activity. We demonstrate that the use of the antioxidant molecule N-Acetyl-Cysteine (NAC) in combination with axitinib stabilizes tumor microvessels in GBM tumor orthotopic xenografts, eventually resulting in vessel normalization, and protects liver vasculature from axitinib-dependent toxicity. Overall, we found that NAC co-treatment allows vessel normalization in brain tumor vessels and exerts a protective effect on liver vasculature, therefore minimizing axitinib-dependent toxicity.

Cabozantinib enhances CAIX specific CAR-T cells against renal cancer by improving effector functions and augmenting tumor immune microenvironment

Despite demonstrating promising outcomes in treating hematologic malignancies, the efficacy of chimeric antigen receptor-modified T (CAR-T) cell therapy remains limited when applied to solid tumors due to tumor immune microenvironment (TIME). Strategies to augment CAR-T cell efficacy against solid tumors have been investigated by ameliorating TIME to a certain extent. In this study, Cabozantinib was utilized in combination with CAR-T cells targeting carbonic anhydrase IX (CAIX) for the treatment of renal cancer. Our findings indicate that combination therapy with CAIX-CAR-T and Cabozantinib demonstrated synergistic efficacy against an orthotopic xenograft tumor model and a subcutaneous tumor model of renal cell carcinoma in mice. Mechanistically, it was observed that CAR-T cells combined with Cabozantinib led to an increase in the infiltration of tumor-infiltrating T cells, while reducing tumor-associated macrophages and M2 polarization. Additionally, Cabozantinib blocked the programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) axis by decreasing the expression of PD-L1 in tumor cells and PD-1 in T cells. Furthermore, Cabozantinib promoted CAR-T cell effector function and reduced T cell exhaustion. This combination therapy represents a novel approach to enhancing CAR-T cell efficacy against solid tumors and holds significant promise for advancing CAR-T cell therapy in clinical settings.

Fiber Optic-Mediated Type I Photodynamic Therapy of Brain Glioblastoma Based on an Aggregation-Induced Emission Photosensitizer.

Glioblastoma (GBM) is one of the most lethal human malignancies. The current standard-of-care is highly invasive with strong toxic side effects, leading to poor prognosis and high mortality. As a safe and effective clinical approach, photodynamic therapy (PDT) has emerged as a suitable option for GBM. Nevertheless, its implementation is significantly impeded by the limits of light penetration depth and the firm reliance on oxygen. To overcome these challenges, herein, a promising strategy that harnesses a modified optical fiber and less oxygen-dependent Type I aggregation-induced emission (AIE) photosensitizer (PS) is developed for the first time to realize in vivo GBM treatments. The proposed AIE PS, namely TTTMN, characterized by a highly twisted molecular architecture and a bulky spacer, exhibits enhanced near-infrared emission and strong production of hydroxyl and superoxide radicals at the aggregated state, thus affording efficient fluorescence imaging-guided PDT once formulated into nanoparticles. The inhibition of orthotopic and subcutaneous GBM xenografts provides compelling evidence of the treatment efficacy of Type I PDT irradiated through a tumor-inserted optical fiber. These findings highlight the substantially improved therapeutic outcomes achieved through fiber optic-mediated Type I PDT, positioning it as a promising therapeutic modality for GBM.

Copy number amplification-induced overexpression of lncRNA LOC101927668 facilitates colorectal cancer progression by recruiting hnRNPD to disrupt RBM47/p53/p21 signaling

BackgroundSomatic copy number alterations (SCNAs) are pivotal in cancer progression and patient prognosis. Dysregulated long non-coding RNAs (lncRNAs), modulated by SCNAs, significantly impact tumorigenesis, including colorectal cancer (CRC). Nonetheless, the functional significance of lncRNAs induced by SCNAs in CRC remains largely unexplored.MethodsThe dysregulated lncRNA LOC101927668, induced by copy number amplification, was identified through comprehensive bioinformatic analyses utilizing multidimensional data. Subsequent in situ hybridization was employed to ascertain the subcellular localization of LOC101927668, and gain- and loss-of-function experiments were conducted to elucidate its role in CRC progression. The downstream targets and signaling pathway influenced by LOC101927668 were identified and validated through a comprehensive approach, encompassing RNA sequencing, RT-qPCR, Western blot analysis, dual-luciferase reporter assay, evaluation of mRNA and protein degradation, and rescue experiments. Analysis of AU-rich elements (AREs) within the mRNA 3’ untranslated region (UTR) of the downstream target, along with exploration of putative ARE-binding proteins, was conducted. RNA pull-down, mass spectrometry, RNA immunoprecipitation, and dual-luciferase reporter assays were employed to elucidate potential interacting proteins of LOC101927668 and further delineate the regulatory mechanism between LOC101927668 and its downstream target. Moreover, subcutaneous xenograft and orthotopic liver xenograft tumor models were utilized to evaluate the in vivo impact of LOC101927668 on CRC cells and investigate its correlation with downstream targets.ResultsSignificantly overexpressed LOC101927668, driven by chr7p22.3-p14.3 amplification, was markedly correlated with unfavorable clinical outcomes in our CRC patient cohort, as well as in TCGA and GEO datasets. Moreover, we demonstrated that enforced expression of LOC101927668 significantly enhanced cell proliferation, migration, and invasion, while its depletion impeded these processes in a p53-dependent manner. Mechanistically, nucleus-localized LOC101927668 recruited hnRNPD and translocated to the cytoplasm, accelerating the destabilization of RBM47 mRNA, a transcription factor of p53. As a nucleocytoplasmic shuttling protein, hnRNPD mediated RBM47 destabilization by binding to the ARE motif within RBM47 3'UTR, thereby suppressing the p53 signaling pathway and facilitating CRC progression.ConclusionsThe overexpression of LOC101927668, driven by SCNAs, facilitates CRC proliferation and metastasis by recruiting hnRNPD, thus perturbing the RBM47/p53/p21 signaling pathway. These findings underscore the pivotal roles of LOC101927668 and highlight its therapeutic potential in anti-CRC interventions.

5-Azacytidine treatment inhibits the development of lung cancer models via epigenetic reprogramming and activation of cellular pathways with anti-tumor activity.

Non-small cell lung cancer (NSCLC) treatment is challenged by late detection and limited therapeutic options. Aberrant DNA methylation, a common epigenetic alteration in NSCLC, offers new therapeutic avenues. This study aims to evaluate the combined effects of 5-Azacytidine (5-Aza), an epigenetic modifier, and ionizing radiation (IR) on NSCLC, exploring the underlying molecular mechanisms and therapeutic potential. In this study, we examined the effects of 5-Aza combined with IR in both in vitro and in vivo models of NSCLC. Five human NSCLC cell lines were treated with 5-Aza and IR. Cell viability, colony formation, wound healing, and transwell migration assays were performed to assess treatment effects. Microarray and qPCR analyses were conducted to identify gene expression changes. Additionally, subcutaneous and orthotopic xenograft models were used to evaluate the treatment's efficacy in vivo. Treatment with 5-Aza and IR resulted in significant reductions in cell viability, colony formation, and migration in NSCLC cell lines. Microarray analysis revealed significant changes in gene expression, including the upregulation of apoptosis-related genes and the downregulation of cell proliferation-related genes. In vivo studies demonstrated a notable reduction in tumor growth and metastasis in both subcutaneous and orthotopic NSCLC models following 5-Aza and IR treatment. Histological and bioluminescent imaging confirmed the therapeutic effects of the combined treatment. The combination of 5-Aza and IR shows promise as an effective treatment for NSCLC, enhancing apoptosis and reducing tumor growth through epigenetic modulation.

Abstract A073: Desmoglein-2 is a regulator of pancreatic ductal adenocarcinoma progression

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with a dismal 5-year survival rate of <13%. We have discovered that desmoglein-2 (DSG2), a cell surface protein, is highly expressed on PDAC cells. In silico data indicate that elevated levels of DSG2 is associated with PDAC progression and poor patient survival. Immunohistochemistry (IHC) analysis of a tissue microarray of 302 patient samples showed that DSG2 was expressed by >90% of PDAC patients. We hypothesized that DSG2 is an under-appreciated contributor to PDAC progression and that DSG2 can be targeted. The main aims of this study were to: 1) investigate the role of DSG2 in PDAC cell function in vitro, 2) investigate the molecular biology underpinning the role of DSG2 in PDAC, and 3) to use murine PDAC tumor models to evaluate the contribution of DSG2 to cancer progression in vivo. Our in vitro data showed that reducing the expression of DSG2 (via small interfering RNA (siRNA)) significantly decreased PDAC cell proliferation, migration, and invasion. Moreover, signaling analysis of PDAC cells with or without DSG2 (via siRNA) using a reverse-phase protein array and cytokine array revealed that DSG2 modulates pro-tumorigenic and pro-metastatic cellular pathways, through reducing the effects of certain proteins. Particular alterations were observed in pathways involving gene regulation (e.g., beta-catenin), migration (e.g., epidermal growth factor receptor and integrin-beta1), and cytokine release (e.g., serpine-1). Next, in an orthotopic xenograft mouse model, BxPC-3 PDAC cells with a stable knockdown of DSG2 (via short-hairpin RNA) were injected into NSG (NOD scid gamma) mice, where we observed a significant reduction in tumor burden and liver metastasis when compared to control mice. IHC staining of tumor sections revealed that the DSG2 knockdown tumors contained reduced levels of collagen, tumor vasculature and cancer associated fibroblasts. Thus, suggesting that DSG2 also has a modulatory effect on the tumor microenvironment (TME). A similar reduction in tumor burden, cancer progression and changes to the TME were observed when a neutralizing anti-DSG2 monoclonal antibody was administered intraperitoneally twice a week at 5mg/kg to BxPC-3 tumor bearing mice. Finally, to investigate the immune cell landscape, we used an orthotopic syngeneic mouse model, whereby Dsg2 was knocked out of KPC (LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre) mouse PDAC cells via clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9. This mouse model also showed that loss of Dsg2 resulted in a significant reduction in tumor burden, cancer cell metastasis and changes to the TME. In summary, we have identified a potential new target for the treatment of PDAC, namely DSG2, and future experiments are pursuing clinical opportunities to improve PDAC patient survival. Citation Format: Charlie B Ffrench, Kay K Myo Min, Mark DeNichilo, Michaelia P Cockshell, Emma L Dorward, Emma J Thompson, Michael Ortiz, Michael S Samuel, Savio George Barreto, Claudine S Bonder. Desmoglein-2 is a regulator of pancreatic ductal adenocarcinoma progression [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 A073.

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.

PTPRZ1-targeting RNA CAR T cells exert antigen-specific and bystander antitumor activity in glioblastoma.

The great success of chimeric antigen receptor (CAR) T-cell therapy in the treatment of patients with B-cell malignancies has prompted its translation to solid tumors. In the case of glioblastoma (GBM), clinical trials have shown modest efficacy, but efforts to develop more effective anti-GBM CAR T cells are ongoing. In this study, we selected PTPRZ1 as a target for GBM treatment. We isolated six anti-human PTPRZ1 scFv from a human phage display library and produced 2nd generation CAR T cells in an RNA format. Patient-derived GBM PTPRZ1-knock-in cell lines were used to select the CAR construct that showed high cytotoxicity while consistently displaying high CAR expression (471_28z). CAR T cells incorporating 471_28z were able to release IFN-γ, IL-2, TNF-α, Granzyme B, IL-17A, IL-6, and soluble FasL, and displayed low tonic signaling. Additionally, they maintained an effector memory phenotype after in vitro killing. In addition, 471_28z CAR T cells displayed strong bystander killing against PTPRZ1-negative cell lines after pre-activation by PTPRZ1-positive tumor cells but did not kill antigen-negative non-tumor cells. In an orthotopic xenograft tumor model using NSG mice, a single dose of anti-PTPRZ1 CAR T cells significantly delayed tumor growth. Taken together, these results validate PTPRZ1 as a GBM target and prompt the clinical translation of anti-PTPRZ1 CAR T cells.

Three-dimensional analysis of mitochondria in a patient-derived xenograft model of triple negative breast cancer reveals mitochondrial network remodeling following chemotherapy treatments.

Mitochondria are hubs of metabolism and signaling and play an important role in tumorigenesis, therapeutic resistance, and metastasis in many cancer types. Various laboratory models of cancer demonstrate the extraordinary dynamics of mitochondrial structure, but little is known about the role of mitochondrial structure in resistance to anticancer therapy. We previously demonstrated the importance of mitochondrial structure and oxidative phosphorylation in the survival of chemotherapy-refractory triple negative breast cancer (TNBC) cells. As TNBC is a highly aggressive breast cancer subtype with few targeted therapy options, conventional chemotherapies remain the backbone of early TNBC treatment. Unfortunately, approximately 45% of TNBC patients retain substantial residual tumor burden following chemotherapy, associated with abysmal prognoses. Using an orthotopic patient-derived xenograft mouse model of human TNBC, we compared mitochondrial structures between treatment-naïve tumors and residual tumors after conventional chemotherapeutics were administered singly or in combination. We reconstructed 1,750 mitochondria in three dimensions from serial block-face scanning electron micrographs, providing unprecedented insights into the complexity and intra-tumoral heterogeneity of mitochondria in TNBC. Following exposure to carboplatin or docetaxel given individually, residual tumor mitochondria exhibited significant increases in mitochondrial complexity index, area, volume, perimeter, width, and length relative to treatment-naïve tumor mitochondria. In contrast, residual tumors exposed to those chemotherapies given in combination exhibited diminished mitochondrial structure changes. Further, we document extensive intra-tumoral heterogeneity of mitochondrial structure, especially prior to chemotherapeutic exposure. These results highlight the potential for structure-based monitoring of chemotherapeutic responses and reveal potential molecular mechanisms that underlie chemotherapeutic resistance in TNBC.

EGFR and EGFRvIII coopt host defense pathways, promoting progression in glioblastoma.

Co-amplification of EGFR and EGFRvIII, a tumor-specific truncation mutant of EGFR, represent hallmark genetic lesions in glioblastoma. We used phospho-proteomics, RNA-sequencing, TCGA data and glioblastoma cell culture and mouse models to study the signal transduction mediated by EGFR and EGFRvIII. We report that EGFR and EGFRvIII stimulate the innate immune defense receptor Toll-like Receptor 2 (TLR2); and that knockout of TLR2 dramatically improved survival in orthotopic glioblastoma xenografts. EGFR and EGFRvIII activated TLR2 in a ligand-independent manner, promoting tumor growth and immune evasion. We show that EGFR and EGFRvIII cooperate to activate the Rho-associated protein kinase ROCK2, which modulated malignant progression both by activating TLR2 and WNT signaling, and through remodeling the tumor microenvironment. Together, our findings show that EGFR and EGFRvIII cooperate to drive tumor progression through ROCK2 and downstream WNT-β-catenin/TLR2 signaling pathways.

Targeting stress induction of GRP78 by cardiac glycoside oleandrin dually suppresses cancer and COVID-19

BackgroundDespite recent therapeutic advances, combating cancer resistance remains a formidable challenge. The 78-kilodalton glucose-regulated protein (GRP78), a key stress-inducible endoplasmic reticulum (ER) chaperone, plays a crucial role in both cancer cell survival and stress adaptation. GRP78 is also upregulated during SARS-CoV-2 infection and acts as a critical host factor. Recently, we discovered cardiac glycosides (CGs) as novel suppressors of GRP78 stress induction through a high-throughput screen of clinically relevant compound libraries. This study aims to test the possibility that agents capable of blocking stress induction of GRP78 could dually suppress cancer and COVID-19.ResultsHere we report that oleandrin (OLN), is the most potent among the CGs in inhibiting acute stress induction of total GRP78, which also results in reduced cell surface and nuclear forms of GRP78 in stressed cells. The inhibition of stress induction of GRP78 is at the post-transcriptional level, independent of protein degradation and autophagy and may involve translational control as OLN blocks stress-induced loading of ribosomes onto GRP78 mRNAs. Moreover, the human Na+/K+-ATPase α3 isoform is critical for OLN suppression of GRP78 stress induction. OLN, in nanomolar range, enhances apoptosis, sensitizes colorectal cancer cells to chemotherapeutic agents, and reduces the viability of patient-derived colon cancer organoids. Likewise, OLN, suppresses GRP78 expression and impedes tumor growth in an orthotopic breast cancer xenograft model. Furthermore, OLN blocks infection by SARS-CoV-2 and its variants and enhances existing anti-viral therapies. Notably, GRP78 overexpression mitigates OLN-mediated cancer cell apoptotic onset and suppression of virus release.ConclusionOur findings validate GRP78 as a target of OLN anti-cancer and anti-viral activities. These proof-of-principle studies support further investigation of OLN as a readily accessible compound to dually combat cancer and COVID-19.

Abstract B053: Tumor-associated macrophages diminishes IL1RAP-targeting CAR-T cell therapy efficacy in Ewing sarcoma

Abstract Ewing sarcoma (EwS) is a pediatric malignancy of soft tissue and bone with a poor prognosis, especially in its metastatic stages. We have previously identified IL1RAP as a promising target for immunotherapies like chimeric antigen receptor (CAR) T cell therapy against EwS. However, CAR-T cells, despite their success in hematological cancers, often show limited efficacy against solid tumors. In orthotopic xenograft models of Ewing sarcoma (EwS) we have observed that CD11b+ CD206+ macrophages, known as tumor-associated macrophages (TAMs), surround the primary tumor. Treatment with IL1RAP-targeting CAR-T cells specific to EwS results in T cells localizing with these macrophages and failing to infiltrate the primary tumor. This study aims to characterize the impact of TAMs on CAR-T cell efficacy in EwS. We hypothesized that TAMs, polarized by Ewing sarcoma cells, suppress IL1RAP CAR-T cell activity. To model these interactions, we co-cultured EwS cells, macrophages, and CAR-T cells, performing luciferin-based in vitro cytotoxicity assays. THP-1 monocytes were differentiated into macrophages and polarized into M1 or M2 states using cytokines (LPS + IFN-y, IL-4 + IL-13), or differentiated into TAMs by co-culture with EwS cell lines. In vitro cytotoxicity assays were conducted using luciferase-expressing EwS target cells, polarized THP-1 macrophages, and IL1RAP CAR-T effector cells, with luminescence indicating EwS cell survival. We found that M1 macrophages did not affect CAR-T cell targeting of EwS cells, whereas M2 macrophages and TAMs significantly decreased specific lysis (p < 0.001). Conditioned media from polarized macrophages had no effect on CAR-T cell performance against EwS, suggesting that physical proximity or direct contact with TAMs is necessary to suppress CAR-T cell function. Western blot analysis of polarized THP-1 macrophages revealed that M2-polarized macrophages upregulated IL1RAP expression compared to M1 macrophages. Ongoing experiments aim to determine whether elevated IL1RAP expression in M2 macrophages redirects IL1RAP CAR-T cells away from EwS cells or if M2 macrophages mediate general suppression of CAR-T cell activity. Additionally, we are investigating whether THP-1-derived TAMs and primary macrophages also upregulate IL1RAP expression when polarized and how this affects syngeneic CAR-T cell performance. Our findings indicate that TAMs can influence the efficacy of IL1RAP-targeting CAR-T cells against EwS. Further investigation into the specific mechanisms responsible for this suppressive effect could enhance CAR-T therapy for Ewing sarcoma and potentially other solid tumors. Citation Format: Yue Zhou (Joe) Huang, Melanie Rouleu, Poul Sorensen. Tumor-associated macrophages diminishes IL1RAP-targeting CAR-T cell therapy efficacy in Ewing sarcoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pediatric Cancer Research; 2024 Sep 5-8; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl):Abstract nr B053.