Mouse Tumor Cells Research Articles

Tumoricidal Activity and Side Effects of Radiolabeled Anti-NCAM [131I]-Iodine-ERIC1 in Neuroblastoma-Bearing Mice.

Preliminary studies on a radioactive antibody against the neural cell adhesion molecule (NCAM) demonstrated a significant accumulation of [131I]I-ERIC1 in neuroblastoma tumor cells in mice. This study aims to validate the therapeutic efficacy and potential adverse effects of these radioactive immunoconjugates (RICs) in neuroblastoma-bearing mice. To determine the highest tolerated dose, healthy SCID mice received 1 to 22 MBq of [131I]I-ERIC1, with the survival time measured. Tumor response was evaluated by administering 0.8 to 22 MBq of [131I]I-ERIC1 to neuroblastoma-bearing mice and assessing tumor size and systemic toxicity through body weight, blood counts, and survival. It was observed that doses up to approximately 3 MBq per animal (150 MBq/kg) were well tolerated, whereas higher doses resulted in systemic toxicity and death. The neuroblastomas exhibited a dose-dependent response, with optimal therapeutic efficacy achieved at 1.8-2.5 MBq per animal (90-125 MBq/kg), significantly extending survival by a factor of five. The antibody ERIC1 is a promising vehicle for the transport of beta emitters into NCAM-positive tumor tissue. An optimal dosage of the [131I]I-ERIC1 antibody can be established with a balance of tumor-static effects and adverse effects, resulting in a marked extension of survival time.

Abstract C061: Loss of CaMK2B accelerates tumor formation and enhances metastatic competency in genetically engineered mouse models of PDAC

Abstract Background Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer- related deaths in the United States and is often not diagnosed until it has already metastasized. Our prior work established that calcium signaling pathways facilitate a pro-metastatic phenotype through the induction of an epithelial-to-mesenchymal transition (EMT) program in PDAC tumor cells, but the downstream signaling molecules mediating this phenotype have remained elusive. MethodsUsing a novel genetically engineered model of pancreatic cancer, we demonstrate that loss of Calcium/calmodulin-dependent kinase-II B (CaMK2B), a downstream effector kinase activated by calcium, enhances cellular plasticity, and increases metastasis. To this end, we generated a genetically engineered mouse model where Camk2b was knocked out in tumor cells in a lineage-labeled Kras- and p53-driven PDAC mouse model (herein KPCY-Camk2bcKO). Results Genetic deletion of Camk2b in the KPCY genetically engineered model accelerated tumor formation and dramatically reduced the overall median survival of KPCY- Camk2b cKO mice (78 days) relative to KPCY controls (136 days). Pathological and immunofluorescence analysis of KPCY-Camk2b cKO animals showed an increased number of poorly differentiated tumor regions and a higher metastatic burden, with >85% of KPCY- Camk2b cKO animals presenting with multi-focal metastases. Further analysis of tumor cells in KPCY-Camk2b cKO mice showed enhanced expression of markers of the highly aggressive squamous PDAC subtypes. Strikingly, Camk2b deletion combined with oncogenic Kras G12D (in the absence of p53 alterations), was sufficient to form lethal metastatic PDAC tumors, while age-matched control Kras G12D tumors with intact Camk2b only progressed to the acinar-to-ductal metaplasia (ADM) or Pancreatic Intraepithelial Neoplasia (PanIN) stage. Collectively, these results establish Camk2b loss as a new oncogenic and pro-metastatic mechanism in PDAC Conclusion This work demonstrates that Camk2b loss enhances tumor cell evolution and plasticity within PDAC to promote metastasis. In this context, we speculate that loss of Camk2b rewires calcium signaling to drive an aggressive subtype of PDAC with increased metastasis. Citation Format: Jessica Peura, Nikita Bhalerao, Calvin Johnson, Yamini Ogoti, Faith Keller, Emma Watson, Zhen Zhao, Jason Pitarresi. Loss of CaMK2B accelerates tumor formation and enhances metastatic competency in genetically engineered mouse models of PDAC [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C061.

Small Molecule Induces Time-Dependent Inhibition of Stat3 Dimerization and DNA-Binding Activity and Regresses Human Breast Tumor Xenografts.

Aberrantly-active signal transducer and activator of transcription (Stat)3 has a causal role in many human cancers and represents a validated anticancer drug target, though it has posed significant challenge to drug development. A new small molecule, JKB887, was identified through library screening and is predicted to interact with Lys591, Arg609 and Pro63 in the phospho-tyrosine (pTyr)-binding pocket of the Stat3 SH2 domain. JKB887 inhibited Stat3 DNA-binding activity in vitro in a time-dependent manner, with IC50 of 2.2-4.5 μM at 30-60-min incubation. It directly disrupted both the Stat3 binding to the cognate, high-affinity pTyr (pY) peptide, GpYLPQTV-NH2 in fluorescent polarization assay with IC50 of 3.5-5.5 μM at 60-90-min incubation, and to the IL-6 receptor/gp130 or Src in treated malignant cells. Treatment with JKB887 selectively blocked constitutive Stat3 phosphorylation, nuclear translocation and transcriptional activity, and Stat3-regulated gene expression, and decreased viable cell numbers, cell growth, colony formation, migration, and survival in human or mouse tumor cells. By contrast, JKB887 had minimal effects on Stat1, pErk1/2MAPK, pShc, pJAK2, or pSrc induction, or on cells that do not harbor aberrantly-active Stat3. Additionally, JKB887 inhibited growth of human breast cancer xenografts in mice. JKB887 is a Stat3-selective inhibitor with demonstrable antitumor effects against Stat3-dependent human cancers.

Structural characteristics and anti-tumor activity of alcohol-precipitated polysaccharides from Cordyceps militaris under different ethanol concentrations

Six Cordyceps militaris polysaccharides (named CMP-1, CMP-2, CMP-3, CMP-4, CMP-9, and CMP-A) were obtained by fractional alcohol precipitation. The experimental results showed that the six Cordyceps militaris polysaccharides had similar chemical composition and spectral features, and different molecular weights, monosaccharide compositions and anti-tumor activities. Purification of CMP-9 yielded the small molecule polysaccharide LMW-CMP (3.06 kDa). Structural experiments showed that LMW-CMP is an α-glucan with (1 → 4)-α-D-Glcp as the main chain and a glucose branched chain attached at the O-6 position. The results of cell experiments showed that LMW-CMP could effectively inhibit the growth and proliferation of HepG2 cells, activate the downstream NF-κB signaling pathway through the MAPK pathway to induce apoptosis of HepG2 cells, and block apoptosis at the G1 phase. Animal experiments showed that LMW-CMP inhibited the proliferation of tumor cells in H22 tumor-bearing mice by improving the state of immune organs, increasing the activity of immune cells and cytokine levels in the body, and regulating the distribution of lymphocyte subpopulations, with a tumor inhibition rate of 45.70 % (200 mg/kg).

The Wdr5-H3K4me3 Epigenetic Axis Regulates Pancreatic Tumor Immunogenicity and Immune Suppression.

The WDR5/MLL1-H3K4me3 epigenetic axis is often activated in both tumor cells and tumor-infiltrating immune cells to drive various cellular responses in the tumor microenvironment and has been extensively studied in hematopoietic cancer, but its respective functions in tumor cells and immune cells in the context of tumor growth regulation of solid tumor is still incompletely understood. We report here that WDR5 exhibits a higher expression level in human pancreatic tumor tissues compared with adjacent normal pancreas. Moreover, WDR5 expression is negatively correlated with patients' response to chemotherapy or immunotherapy in human colon cancer and melanoma. However, WDR5 expression is positively correlated with the HLA level in human cancer cells, and H3K4me3 enrichment is observed at the promoter region of the HLA-A, HLA-B, and HLA-C genes in pancreatic cancer cells. Using mouse tumor cell lines and in vivo tumor models, we determined that WDR5 deficiency or inhibition significantly represses MHC I expression in vitro and in vivo in pancreatic tumor cells. Mechanistically, we determine that WDR5 deficiency inhibits H3K4me3 deposition at the MHC I (H2K) promoter region to repress MHC I (H2K) transcription. On the other hand, WDR5 depletion leads to the effective downregulation of immune checkpoints and immunosuppressive cytokines, including TGFβ and IL6, in the pancreatic tumor microenvironments. Our data determine that WDR5 not only regulates tumor cell immunogenicity to suppress tumor growth but also activates immune suppressive pathways to promote tumor immune evasion. Selective activation of the WDR5-MHC I pathway and/or selective inhibition of the WDR5-immune checkpoint and WDR5-cytokine pathways should be considered in WDR5-based epigenetic cancer immunotherapy.

Targeting TNFRSF25 by agonistic antibodies and multimeric TL1A proteins co-stimulated CD8+ T cells and inhibited tumor growth

BackgroundTumor necrosis factor receptor superfamily 25 (TNFRSF25) is a T-cell co-stimulatory receptor. Expression of its ligand, TNF-like cytokine 1A (TL1A), on mouse tumor cells has been shown to promote tumor...

IL-33 stimulates the anticancer activities of eosinophils through extracellular vesicle-driven reprogramming of tumor cells

Immune cell-derived extracellular vesicles (EV) affect tumor progression and hold promise for therapeutic applications. Eosinophils are major effectors in Th2-related pathologies recently implied in cancer. Here, we evaluated the anti-tumor activities of eosinophil-derived EV following activation with the alarmin IL-33. We demonstrate that IL-33-activated mouse and human eosinophils produce higher quantities of EV with respect to eosinophils stimulated with IL-5. Following incorporation of EV from IL-33-activated eosinophils (Eo33-EV), but not EV from IL-5-treated eosinophils (Eo5-EV), mouse and human tumor cells increased the expression of cyclin-dependent kinase inhibitor (CDKI)-related genes resulting in cell cycle arrest in G0/G1, reduced proliferation and inhibited tumor spheroid formation. Moreover, tumor cells incorporating Eo33-EV acquired an epithelial-like phenotype characterized by E-Cadherin up-regulation, N-Cadherin downregulation, reduced cell elongation and migratory extent in vitro, and impaired capacity to metastasize to lungs when injected in syngeneic mice. RNA sequencing revealed distinct mRNA signatures in Eo33-EV and Eo5-EV with increased presence of tumor suppressor genes and enrichment in pathways related to epithelial phenotypes and negative regulation of cellular processes in Eo33-EV compared to Eo5-EV. Our studies underscore novel IL-33-stimulated anticancer activities of eosinophils through EV-mediated reprogramming of tumor cells opening perspectives on the use of eosinophil-derived EV in cancer therapy.

Targeting a STING agonist to perivascular macrophages in prostate tumors delays resistance to androgen deprivation therapy

BackgroundAndrogen deprivation therapy (ADT) is a front-line treatment for prostate cancer. In some men, their tumors can become refractory leading to the development of castration-resistant prostate cancer (CRPC). This causes...

Bioproduced Nanoparticles Deliver Multiple Cargoes via Targeted Tumor Therapy In Vivo.

This study recognized biologically produced gold nanoparticles (AuNPs) as multiple cargo carriers with a perspective of drug delivery into specialized tumor cells in vivo. Paclitaxel (PTX), transferrin, and antimiR-135b were conjugated with AuNPs and their uptake by mouse tumor cells in an induced breast cancer model was investigated. Each of the above-mentioned molecules was conjugated to the AuNPs separately as well as simultaneously, loading efficiency of each cargo was assessed, and performance of the final product (FP) was judged. After tumor induction in BALB/c mice, sub-IC50 doses of FP as well as control AuNPs, PTX, and phosphate buffered saline were administered in vivo. Round AuNPs were prepared using Fusarium oxysporum and exhibited a size of 13 ± 1.3 nm and a zeta potential of -35.8 ± 1.3 mV. The cytotoxicity of individual conjugates and FP were tested by MTT assay in breast tumor cells 4T1 and nontumor fibroblasts NIH/3T3 cells. The conjugation of individual molecules with AuNPs was confirmed, and FP (size of 54 ± 14 nm and zeta potential of -31.9 ± 2.08 mV) showed higher 4T1-specific toxicity in vitro when compared to control conjugates. After in vivo application of the FP, transmission electron microscopy analyses proved the presence of AuNPs in the tumor cells. Hematoxylin and eosin staining of the tumor tissue revealed that the FP group exhibited the highest amounts of inflammatory, necrotic, and apoptotic cells in contrast to the control groups. Finally, qPCR results showed that FP could transfect and suppress miR-135b expression in vivo, confirming the tumor-targeting properties of FP. The capacity of biologically produced gold nanoparticles to conjugate with multiple decorative molecules while retaining their stability and effective intracellular uptake makes them a promising alternative strategy superior to current drug carriers.

STEM-03. A NOVEL MOUSE MODEL OF CHOROID PLEXUS CARCINOMA UNRAVELS SEQUENTIAL DEDIFFERENTIATION OF HINDBRAIN CHOROID PLEXUS TISSUE AND REVEALS NEW THERAPEUTIC PROSPECTS

Abstract BACKGROUND Choroid Plexus tumors constitute 10-20% of brain tumors in the first year of life. Among those, Choroid Plexus Carcinomas (CPC) pose a significant challenge due to their aggressiveness, resulting in poor survival rates and long-term adverse effects stemming from intense therapeutic approaches. Although loss of p53 and Sonic hedgehog signaling have been implicated in CPC development, a deeper biological understanding is needed to expand mechanistic insights and advance targeted therapies. METHODS We generated a novel mouse model with a simultaneous loss of TP53 and overexpression of MYCN and Gli2 in central nervous system precursors (hGFAP-cre::P53Fl/Fl::lsl-MYCN::lsl-Gli2). Resulting tumors were histologically characterized and compared to human CPC. Moreover, spatial transcriptomic data were generated for molecular characterization. Finally, mouse tumor-derived cell lines were employed for differentiation analysis and therapeutic testing. RESULTS Examinations at different developmental stages revealed brain tumors in the choroid plexus as well as smaller lesions in the subcallosal cortex with a penetrance of 80% within 18 days. We observed a gradual dedifferentiation of hindbrain CP tissue from day 5 onwards, indicating a continuous developmental sequence corresponding with expanding tumor growth. The mouse model recapitulates early tumor development, aggressive and metastatic growth along with histological features of human tumors. Spatial transcriptomic analysis highlighted chromosomal aberrations as well as other features known from human CPCs and emphasized the disturbance of ciliary pathways in tumor development. In vitro studies revealed rapidly growing tumor cells with stem cell-like differentiation potential and high sensitivity to targeted therapies. CONCLUSION Through in-depth analysis, including multiple data types, we show that our novel CPC mouse model closely resembles human tumors. Our tumors reveal a strict pattern of dedifferentiation implying similar mechanisms in humans. Additionally, primary mouse tumor cells in culture facilitate further in vitro analysis, and newly generated spatial transcriptomic data enables further insights into tumor biology.

Chronic High-Salt Diet Activates Tumor-Initiating Stem Cells Leading to Breast Cancer Proliferation.

Several chronic inflammatory diseases have been linked to high-salt (HS) diets. Chronic inflammation is an established causative hallmark of cancer. However, a direct role of HS diets in tumorigenesis is yet to be defined. Previous orthotopic murine breast tumor studies have shown that short-term HS diets caused inhibition of tumor growth through the activation of cytotoxic adaptive immune responses. However, there have been experimental challenges in developing a viable chronic HS-diet-based murine tumor model. To address this, we have developed a novel chronic HS diet tumor model through the sequential passaging of tumor cells in mice under HS dietary conditions. Two orthotopic murine triple-negative breast cancer models, 4T1 tumor cells injected into BALB/c mice and Py230 tumor cells injected into C57Bl/6 mice, were utilized in our study. For the HS diet cohort, prior to orthotopic injection with tumor cells, the mice were kept on a 4% NaCl diet for 2 weeks. For the regular salt (RS) diet cohort, the mice were kept on a 1% NaCl diet. Following syngeneic cancer cell injection, tumors were allowed to grow for 28 days, following which they were collected to isolate immune cell-depleted cancer cells (passage 1, P1). The tumor cells from P1 were reinjected into the next set of non-tumor-bearing mice. This procedure was repeated for three cycles (P2-P4). In P1, compared to the RS diet cohort, we observed reduced tumor kinetics in both murine tumor models on the HS diet. In contrast, by P4, there was significantly higher tumor progression in the HS diet cohort over the RS diet cohort. Flow cytometry analysis demonstrated an 8-fold increase in tumor-initiating stem cells (TISCs) from P1 to P4 of the HS diet cohort, while there were no significant change in TISC frequency with sequential passaging in the RS diet cohort. Molecular studies showed enhanced expression of TGFβR2 and CD80 on TISCs isolated from the P4 HS diet cohort. In vitro studies demonstrated that TGFβ stimulation of these TISCs increased the cellular expression of CD80 molecules. Further, the chronic HS diet selectively induced the glycolytic metabolic phenotype over the mitochondrial oxidative phosphorylation phenotype in TISCs, which is needed for the production of metabolites during tumor cell differentiation and proliferation. The infiltrating CD8 and CD4 T-lymphocytes in P4 tumors demonstrated increased expression of the immune checkpoint inhibitor (ICI) CTLA4, a known binding partner of CD80, to cause immune exhaustion and pro-tumorigenic effects. Interestingly, anti-TGFβ monoclonal antibodies (mAbs) played a synergistic role in further enhancing the anti-tumor effect of anti-CTLA4 mAb. In summary, our findings demonstrated that chronic HS diet increased the frequency of TISCs in tumors leading to blunting of cytotoxic adaptive immune responses causing tumor proliferation. Furthermore, a combination of anti-TGFβ with current ICI-based immunotherapies could exert more favorable anti-cancer clinical outcomes.

In Vivo Labeling and Detection of Circulating Tumor Cells in Mice Using OTL38

PurposeWe recently developed an optical instrument to non-invasively detect fluorescently labeled circulating tumor cells (CTCs) in mice called ‘Diffuse in vivo Flow Cytometry’ (DiFC). OTL38 is a folate receptor (FR) targeted near-infrared (NIR) contrast agent that is FDA approved for use in fluorescence guided surgery of ovarian and lung cancer. In this work, we investigated the use OTL38 for in vivo labeling and detection of FR + CTCs with DiFC.ProceduresWe tested OTL38 labeling of FR + cancer cell lines (IGROV-1 and L1210A) as well as FR- MM.1S cells in suspensions of Human Peripheral Blood Mononuclear cells (PBMCs) in vitro. We also tested OTL38 labeling and NIR-DIFC detection of FR + L1210A cells in blood circulation in nude mice in vivo.Results62% of IGROV-1 and 83% of L1210A were labeled above non-specific background levels in suspensions of PBMCs in vitro compared to only 2% of FR- MM.1S cells. L1210A cells could be labeled with OTL38 directly in circulation in vivo and externally detected using NIR-DiFC in mice with low false positive detection rates.ConclusionsThis work shows the feasibility of labeling CTCs in vivo with OTL38 and detection with DiFC. Although further refinement of the DiFC instrument and signal processing algorithms and testing with other animal models is needed, this work may eventually pave the way for human use of DiFC.

Abstract LB217: Novel organoid models of lineage plasticity in castration resistant prostate cancer

Abstract The development of next-generation AR-targeted drugs, such as abiraterone and enzalutamide, has improved survival of patients with castration-resistant prostate cancer (CRPC). However, many patients eventually progress to therapy-resistant lethal prostate cancer. CRPC exhibits variant cellular states, including AR-pathway active prostate cancer (ARPC), AR activity-low prostate cancer (ARLPC), neuroendocrine prostate cancer (NEPC), amphicrine prostate cancer co-expressing AR and neuroendocrine genes (AMPC), and double-negative prostate cancer (DNPC) lacking both AR expression and neuroendocrine differentiation, indicating that lineage plasticity facilitates therapeutic resistance. While molecular characteristics of ARPC and NEPC are well described, other common forms of CRPC, such as DNPC which occurs in 20-25% of CRPC patients, remain poorly understood. Therefore, characterization of pre-clinical models of DNPC and identification of novel regulators of lineage plasticity in DNPC are urgent necessities for the development of effective treatment for lethal prostate cancer.In our studies, we have generated a new mouse model of CRPC in which Pten and Smad4 are deleted in distal luminal cells upon tamoxifen administration (Nkx3.1CreERT2/+; Ptenfl/fl; Smad4fl/fl; R26R-eYFP/+, NPS). We observed a molecular transition from ARPC to ARLPC and DNPC in the prostate tumors derived from NPS mice during tumor progression. Moreover, a combination of castration and enzalutamide treatment promoted a partial epithelial-mesenchymal transition (EMT) in DNPC. To identify the evolutionary trajectories of cancer progression and drivers of lineage plasticity in CRPC, we have established organoid lines from the prostate tumor cells of NPS mice. Single-cell RNA-sequencing (scRNA-seq) and marker validation analyses shown that these organoid lines display overt lineage plasticity, corresponding to ARPC, ARLPC, partial EMT-absent DNPC, and partial EMT-present DNPC. Orthotopic grafts derived from the established NPS organoid lines show consistent molecular phenotypes and confirm that AR-targeted therapies facilitate partial EMT in vivo. Furthermore, cross-species bioinformatic analyses using scRNA-seq datasets indicate that the established NPS organoid lines partially recapitulate the spectrum of lineage plasticity in human CRPC.In summary, we have established prostate cancer organoid lines from a novel mouse model of CRPC, which not only provide large and reproducible sources of two distinct forms of DNPC (partial EMT-absent DNPC and partial EMT-present DNPC) for molecular analyses, but also can capture the regulatory complexity of lineage plasticity in human CRPC. Therefore, NPS mice provide an excellent pre-clinical model of CRPC, especially DNPC, to identify novel regulators that drive lineage plasticity and to pursue assays for development of candidate drugs that can inhibit or even possibly convert therapy-resistant forms of CRPC to therapy-sensitive ones. Citation Format: Jinqiu Lu, Michael M. Shen. Novel organoid models of lineage plasticity in castration resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB217.

Mechanically stimulated osteocytes maintain tumor dormancy in bone metastasis of non-small cell lung cancer by releasing small extracellular vesicles

Although preclinical and clinical studies have shown that exercise can inhibit bone metastasis progression, the mechanism remains poorly understood. Here, we found that non-small cell lung cancer (NSCLC) cells adjacent to bone tissue had a much lower proliferative capacity than the surrounding tumor cells in patients and mice. Subsequently, it was demonstrated that osteocytes, sensing mechanical stimulation generated by exercise, inhibit NSCLC cell proliferation and sustain the dormancy thereof by releasing small extracellular vesicles with tumor suppressor micro-RNAs, such as miR-99b-3p. Furthermore, we evaluated the effects of mechanical loading and treadmill exercise on the bone metastasis progression of NSCLC in mice. As expected, mechanical loading of the tibia inhibited the bone metastasis progression of NSCLC. Notably, bone metastasis progression of NSCLC was inhibited by moderate exercise, and combinations with zoledronic acid had additive effects. Moreover, exercise preconditioning effectively suppressed bone metastasis progression. This study significantly advances the understanding of the mechanism underlying exercise-afforded protection against bone metastasis progression.

Mechanically stimulated osteocytes maintain tumor dormancy in bone metastasis of non-small cell lung cancer by releasing small extracellular vesicles.

Although preclinical and clinical studies have shown that exercise can inhibit bone metastasis progression, the mechanism remains poorly understood. Here, we found that non-small cell lung cancer (NSCLC) cells adjacent to bone tissue had a much lower proliferative capacity than the surrounding tumor cells in patients and mice. Subsequently, it was demonstrated that osteocytes, sensing mechanical stimulation generated by exercise, inhibit NSCLC cell proliferation and sustain the dormancy thereof by releasing small extracellular vesicles with tumor suppressor micro-RNAs, such as miR-99b-3p. Furthermore, we evaluated the effects of mechanical loading and treadmill exercise on the bone metastasis progression of NSCLC in mice. As expected, mechanical loading of the tibia inhibited the bone metastasis progression of NSCLC. Notably, bone metastasis progression of NSCLC was inhibited by moderate exercise, and combinations with zoledronic acid had additive effects. Moreover, exercise preconditioning effectively suppressed bone metastasis progression. This study significantly advances the understanding of the mechanism underlying exercise-afforded protection against bone metastasis progression.

The C-type lectin DCIR contributes to the immune response and pathogenesis of colorectal cancer

Development and progression of malignancies are accompanied and influenced by alterations in the surrounding immune microenvironment. Understanding the cellular and molecular interactions between immune cells and cancer cells has not only provided important fundamental insights into the disease, but has also led to the development of new immunotherapies. The C-type lectin Dendritic Cell ImmunoReceptor (DCIR) is primarily expressed by myeloid cells and is an important regulator of immune homeostasis, as demonstrated in various autoimmune, infectious and inflammatory contexts. Yet, the impact of DCIR on cancer development remains largely unknown. Analysis of available transcriptomic data of colorectal cancer (CRC) patients revealed that high DCIR gene expression is associated with improved patients’ survival, immunologically "hot" tumors and high immunologic constant of rejection, thus arguing for a protective and immunoregulatory role of DCIR in CRC. In line with these correlative data, we found that deficiency of DCIR1, the murine homologue of human DCIR, leads to the development of significantly larger tumors in an orthotopic murine model of CRC. This phenotype is accompanied by an altered phenotype of tumor-associated macrophages (TAMs) and a reduction in the percentage of activated effector CD4+ and CD8+ T cells in CRC tumors of DCIR1-deficient mice. Overall, our results show that DCIR promotes antitumor immunity in CRC, making it an attractive target for the future development of immunotherapies to fight the second deadliest cancer in the world.

Abstract 1538: Impact of C-reactive protein on the efficacy of immune checkpoint inhibitors in non-small cell lung cancer

Abstract Background: Immune checkpoint inhibitors (ICIs) therapy has achieved remarkable success in the treatment of non-small cell lung cancer (NSCLC). Clinical studies have suggested a correlation between C-reactive protein (CRP) levels and treatment efficacy, but it remains unclear whether CRP can directly impact the efficacy. Therefore, we investigated the imapct of CRP on the efficacy of ICIs in NSCLC. Methods: The tumor growth model was established in CRP knockout and wildtype mice by injecting LLC cells to evaluate the effect of CRP on tumor proliferation. The frequencies and phenotypes of macrophages and T cells in mouse tumors were detected by flow cytometry. The impact of CRP on macrophage polarization was evaluated using flow cytometry and IF, while its impact on T cell chemokines CCL5, CXCL9, and CXCL10 was analyzed by ELISA and qRT-PCR. mCRP and α-PD-1 were implemented in C57/BL6 mice injected with LLC cells to evaluate the effect of mCRP on tumor immunotherapy. The frequencies of T cells in mouse tumors were detected by flow cytometry. Expression of mCRP and infiltration of immune cells in human NSCLC tissues were analyzed using IHC. Results: We found that tumor progression was enhanced and the proportion of tumor-infiltrated M1 macrophages was decreased in CRP knockout mice. Using human PBMC-derived macrophage and RAW264.7 cell lines, we demonstrated that the monomeric form of CRP, known as mCRP, induced M1 polarization of macrophages, leading to increased secretion of CCL5, CXCL9, and CXCL10. In tumor bearing mice, mCRP treatment enhanced anti-tumor immunity and suppressed tumor progression by increasing CD4+ and CD8+ T cell recruitment. Surprisingly, the combined treatment of mCRP and α-PD-1 induced more significant tumor regression than α-PD-1 treatment alone. Additionally, high level of mCRP in NSCLC tissues is correlated with a more inflamed tumor microenvironment phenotype. Conclusion: mCRP can enhance the efficacy of immune checkpoint inhibitors in NSCLC by activating anti-tumor immunity. Citation Format: Wenyuan Li, Hui Guo. Impact of C-reactive protein on the efficacy of immune checkpoint inhibitors in non-small cell lung 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 1538.

Abstract 7503: Non-clinical study of circulating tumor cells in humanized mice: Post-xenograft effects in immunodeficient mice

Abstract Circulating tumor cells (CTCs) possess the potential to serve as innovative markers in clinical trials, contributing to the understanding of cancer metastasis mechanisms, diagnosis, prognosis, the development of personalized treatment strategies, and enabling the monitoring of treatment efficacy. NSG mice, which are a strain of immunodeficient mice frequently utilized as a non-clinical model for cancer research, exhibit diminished levels of natural killer (NK) cells and abnormal monocytes in their bloodstream. In a previous study, a positive correlation was observed between the duration of injection and the levels of white blood cells (WBC) in mice that were injected with various cancer cell lines derived from humans. To evaluate the correlation among the primary tumor and circulating tumor cells (CTCs), as well as the impact on immune cells, we assessed changes in immune cell composition, primary tumor size, and enumeration of CTCs in xenografted mice over a period of time. This investigation was carried out using CytoGen's Smart Biopsy™ systems. The results, which were obtained using equipment including CytoGen's Smart Biopsy™ Systems, showed that the distribution of white blood cell (WBC) components exhibited variations based on age, primary tumor burden, and circulating tumor cell (CTC) count following injection. A notable association was observed between the augmentation of immune cells and the quantity of circulating tumor cells (CTCs) present in the bloodstream. Therefore, alterations in immune cells may potentially impact the potential to affect the ability to influence the efficacy of cancer immunotherapy, metabolic therapy, and anti-metastatic therapy. When conducting non-clinical investigations with the objective of developing cancer treatment protocols, it is crucial to meticulously select humanized or immunodeficient mice that are appropriate for the study. Therefore, it is advisable to perform regular monitoring of murine blood samples in order to observe any variations in the counts of circulating tumor cells (CTCs), while considering a standardized blood volume per individual. In the immunodeficient mouse model, the existence of circulating tumor cells (CTCs) results in an increase in the quantity of cells present in the bloodstream. The observed rise in circulating tumor cells (CTCs) is found to be concurrent with the progression and development of the primary tumor. The consideration of this aspect is of utmost importance in the formulation of non-clinical studies aimed at the development of cancer treatment protocols. Citation Format: Sehyung Pak, Hajin Pak, Hee Jin Yoo, Sra Min, Hui Ji Kim, JaeYoon Lee, Min-Ji Song, Jaesung Choi, Aejin Jeong, Hanbyeol Kim, Jung Won Kim, Hai-Chon Lee. Non-clinical study of circulating tumor cells in humanized mice: Post-xenograft effects in immunodeficient mice [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 7503.

Abstract 6759: Antigen-pHLIP for tumor treatment

Abstract Targeted antigen delivery allows activation of the immune system to kill tumor cells. Among the immunogenic epitopes widely investigated is α-Gal, since humans exhibit specific anti-Gal reactivity. However, the repertoire of immunogenic epitopes could be significantly enhanced if therapeutic efficacy did not rely on the presence of natural antibodies, but instead relied on the production of anti-epitope endogenous antibodies induced by immunization against the selected epitope. Therefore, we designed and tested several HA-pHLIP agents, where the HA peptide (YPYDVPDYA) from the influenza virus was selected as an exogenous highly immunogenic epitope, since it is absent in the human genome, and a pH Low Insertion Peptide (pHLIP) was selected as the tumor targeting agent. HA peptides were attached to the N-termini of pHLIPs either directly or via PEG polymers. To enhance the overall binding affinity of HA-pHLIP to anti-HA antibodies, double headed HA-pHLIP agents were introduced, where two HA epitopes were linked to a single pHLIP peptide via PEG12 polymers. The pHLIP sequence was modified to ensure proper pKs of insertion into cell membranes. HA epitopes were targeted to cancer cells in mouse tumors, and remained exposed to the extracelullar space within tumors for about 24 hours. Double-headed HA-pHLIP treatments of imunized mice (a high titer of anti-HA antibodies was developed in mice after immunization with KLH-HA), bearing 4T1 triple negative or B16F10 MHC-I negative melanoma tumors resulted in a 55% reduction of tumor growth. Further reduction of tumor growth was impossible to achive, since all of the anti-HA antibodies in the blood were captured after 3 injections of HA-pHLIP and additional boosts would be required to restore the level of free anti-HA antibodies to induce a more significant therapeutic efficacy. Citation Format: Michael DuPont, Hannah Visca, Anna Moshnikova, Donald Engelman, Yana Reshetnyak, Oleg Andreev. Antigen-pHLIP for tumor treatment [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 6759.

Abstract 4002: Investigating CAR-T cell efficacy and activation in the disseminated NALM6-luc human B-cell acute lymphoblastic leukemia model

Abstract Introduction: Chimeric Antigen Receptor T (CAR-T) cell therapy has emerged as a promising approach for treating hematological malignancies, particularly B-cell acute lymphoblastic leukemia (B-ALL). This study aimed to delve into the activation dynamics and therapeutic efficacy of CD19 CAR-T cells in a disseminated NALM6-luc human B-ALL murine model. Experimental design: NALM6-Luc-mCh-Puro cells were implanted intravenously in female NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mice. Animals were treated with CD19 CAR-T cells alone and in combination with ibrutinib. The anti-tumor activity was assessed, and the persistence and activation of CAR-T cells in the blood were evaluated using flow cytometry. Additionally, ddPCR analysis was employed to quantify CAR copy numbers, providing insights into the T-cell persistence over time. Results: Treatment with CD19 CAR-T cells exhibited notable anti-cancer activity and that activity was enhanced in combination with ibrutinib, in line with other reports. The increased time to progression was noted as 69.2% for the CAR-T group and 138.4% for the combination of CAR-T and ibrutinib compared to control. Flow cytometry analysis showed that CAR-T cells persisted in the blood throughout the study. The mean CAR-T absolute cell count for both CAR-T and CAR-T plus ibrutinib treated groups increased from 2 cell/µL blood on Day 0 to 11 and 51 cells/µL of blood, respectively, by Day 39. The progressive increase of PD-1+ and LAG-3+ percentage cells correlates positively with tumor burden, indicating a dynamic link between biomarker upregulation and the presence of tumor cells in mice. ddPCR analysis revealed an initial CAR copy decrease in all groups, followed by gradual increase in tumor-bearing mice treated with CD19 CAR-T cells, with a dramatic increase observed by Day 39. Results from CAR-T treated and CAR-T plus ibrutinib treated groups were comparable, showing mean copy numbers per ng of DNA increasing from less than 1 on day 4 to 17.9 and 23.3, respectively, on day 39. Importantly, no changes were noted in non-tumor implanted mice, emphasizing the tumor dependency for CAR-T cell expansion. Conclusion: This study emphasizes the marked anti-cancer activity of CD19 CAR-T cells in the NALM6-Luc-mCh-Puro B-ALL murine model. Comprehensive analysis of CAR-T cell persistence and activation, including insights from ddPCR, provides a robust understanding of therapeutic response dynamics. The observed in vivo anti-cancer efficacy aligns with the persistence of CAR-T cells revealed by flow cytometry and the dynamic expansion captured through ddPCR analysis. Our results indicate ddPCR and flow cytometry as complementary and independent methods for assessing the systemic CAR-T cell persistence, contributing to optimizing therapy for B-cell acute lymphoblastic leukemia. Citation Format: Prashant Pandey, David Draper, Sheri Barnes, Yewei Xing, Derrik Germain, Lauren Kucharczyk, Roys Stacey. Investigating CAR-T cell efficacy and activation in the disseminated NALM6-luc human B-cell acute lymphoblastic leukemia model [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 4002.