Mouse Model Of Cancer Research Articles

Study of metal organic framework with siRNA for overcoming matrix barrierin breast cancer

Objective: This study aimed to develop a new delivery strategy that utilized metal organic framework (MOF) loaded with small-interfering RNA (siRNA) targeting ITGAV to overcome tumor matrix barrier, and thus enhance drug penetration and immune accessibility in breast cancer. Methods: MOF@siITGAV particles were constructed and characterized. The uptake of MOF@siITGAV in breast cancer cell line 4T1 was observed by the cellular uptake assay. The toxicity of MOF@siITGAV was detected by cell counting kit 8 (CCK-8). The blank control group, naked siITGAV group and MOF@siITGAV group were set. Real-time fluorescent quantitative polymerase chain reaction (RT-qPCR) and Western blot were used to detect the expressions of ITGAV. The level of transforming growth factor β1 (TGF-β1) in the cell culture medium was detected by enzyme-linked immunosorbent assay (ELISA). The penetration of MOF@siITGAV in 4T1 cells was tested by constructing 3D spheroids. Mouse models of triple negative breast cancer were established. The effect of MOF@siITGAV on the growth of transplanted tumors and main organs was verified. Imminohistochemical (IHC) was used to test the expression of collagen and CD8. Results: MOF@siITGAV particles were constructed with sizes of (198.0±3.3) nm and zeta potential of -(20.2±0.4) mV. MOF@siITGAV could be engulfed by 4T1 cells and triggered to release siRNA. Compared to the blank control group, the expression of ITGAV in the MOF@siITGAV group [(46.5±11.3)%] and the naked siITGAV group [(109.9±19.0)%] was lower. TGF-β1 in the cell culture medium of the blank control group, naked siITGAV group, and MOF@siITGAV group was (474.5±34.4) pg/ml, (437.2±16.5) pg/ml, and (388.4±14.4) pg/ml, respectively. MOF@siITGAV could better penetrate into 4T1 spheroids and exhibit no obvious toxicity. The cell viability was (99.7±3.5)%, (98.2±5.2)%, (97.3±6.6)%, (92.1±8.1)%, and (92.4±4.1)%, respectively, after MOF@siITGAV treatment with the concentration of 0, 10, 20, 40, 80, and 160 μg/ml, respectively, for 24 h. The tumor growth in the MOF@siITGAV group was suppressed significantly. After 15-day treatment, the tumor volume of the MOF@siITGAV group was (135.3±41.9) mm3, smaller than that of the blank control group [(691.1±193.0) mm3] (P=0.025). The expression of collagen and the number of CD8 positive cells of the MOF@siITGAV group were lower than those of the other two groups. No significant abnormalities were observed in the main organs of mice. Conclusions: Targeting the integrinαv on the surface of cancer cells could destroy extracellular matrix, improve drug delivery, and increase immune infiltration.

Abstract A011: Bladder cancerization is linked to epithelial basalization and is reversed by EGF inhibition

Abstract Introduction: Epithelial changes can extend beyond the boundaries of an incipient tumor, leading to cancer recurrence even after effective excision of the primary tumor. This ‘field cancerization’ and consequent high recurrence rate is especially pronounced in bladder cancer. The purpose of this study is to characterize the urothelium in the context of ‘field cancerization’ in a mouse model of bladder cancer as well as in patients with bladder cancer and to determine if reversal of the field effect will prevent tumor formation. Results: We investigated field cancerization by single cell transcriptomics (scRNA-Seq) in a murine (male FVB mice) bladder carcinogenesis model using N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) and found that prior to overt tumor formation urothelial cells throughout the entire bladder take on a strongly basal phenotype, characterized by reduced expression of differentiation markers (i.e. Upk1a, Upk2, and Upk3a) and increased expression of basal markers (i.e. Krt14, Krt6a, Krt5). Using monocle, we applied single cells from a BBN treated mouse bladder library to a pseudotime trajectory generated from a control mouse bladder library in order to unbiasedly characterize urothelial differentiation in the non-tumor urothelium of BBN treated mouse bladders. scRNA-Seq analysis of non-tumor urothelium from bladder cancer patients revealed a similar ‘basalization’ among non-tumor urothelial cells. In order to apply our single cell findings to bulk RNA-seq data, we developed a basal index from differentially expressed genes in basal clusters versus non-basal clusters from healthy control human urothelium single cell libraries, and we applied this basal index to non-tumor bladder samples from the The Cancer Genome Atlas (TCGA). We found that among a small subset of patients with paired tumor and non-tumor urothelium in the bladder TCGA dataset, the basal index, when applied to the non-tumor urothelium, was prognostic of survival. Finally, we found that basalization in BBN treated mice could be reversed pharmacologically by epidermal growth factor (EGF) pathway antagonism using erlotinib and trametinib and that over a 4-month time course this reversal dramatically decreased tumor incidence and improved survival, suggesting a new, more effective approach using mechanism-based cancer drugs for the prevention of bladder cancer recurrence in patients. Conclusions: The non-tumor urothelium in BBN treated mouse bladders, prior to overt tumor formation, demonstrates a basal phenotype which we characterize with scRNA-Seq and pseudotime analysis. Similarly, in patients with bladder cancer we observe that the non-tumor urothelium also takes on a basal phenotype. This ‘basalization’ of the non-tumor urothelium may potentially be prognostic, and pharmacologic reversal of the basal phenotype in the non-tumor urothelium using EGF pathway inhibitors prevents tumors in BBN treated mice. Citation Format: Aaron M. Kershner, Kris B. Prado, Bernhard M. Kiss, Karim Mrouj, Lolita Penland, Wan-Jin Lu, Jiyun Choi, Edward Diaz, Rovin Lachmansingh, Bertha Chen, Chia-Sui Kao, Joseph C. Liao, Philip A. Beachy. Bladder cancerization is linked to epithelial basalization and is reversed by EGF inhibition [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr A011.

Abstract A010: Cancer associated fibroblast dependency in a novel immunocompetent mouse model of bladder cancer

Abstract Introduction: The relationship between genotype and phenotype in targeted therapy has proven to be crucial for the successful use of most kinase inhibitors. In bladder cancer, the PI3K/AKT/mTOR pathway is widely activated by mutation but untargeted. Our study focuses on developing an immunocompetent, CRISPR-edited bladder cancer mouse model that mirrors common PI3K/AKT/mTOR pathway mutations. We established effective genotype-kinase inhibitor pairings using CRISPR-edited organoids and cancer associated fibroblasts (CAFs) to create a pro-tumorigenic environment in vivo. Methods and Results: Urothelial cells were isolated from the bladder of Rosa26 Lox-Stop-Lox-Cas9/GFP transgenic mice and grown as organoids in matrigel. These organoids were co-edited for Trp53 and Rb1 KO, and further editing of the Pten gene resulted in a nine-fold increase in sensitivity to the kinase inhibitor ipatasertib. Despite successful initial engraftment into mouse bladder, these edited cells regressed before tumor formation, and subcutaneous injection did not yield subcutaneous tumors. An alternate model featuring a 9p21 deletion with Trp53 KO also displayed similar regression post-engraftment into bladder or subcutaneous injections. However, co-injection with a previously established CAF line subcutaneously yielded palpable subcutaneous tumors that enlarged for 12 weeks. We then established a BBN bladder-tumor-derived CAF line, leading to the formation of tumors with squamous differentiation upon intramural co-injection with edited organoids. These models displayed immune-excluded architecture and a predominance of M2 over M1 macrophages. We also aimed to enhance the model's adaptability by introducing common PI3K/AKT/mTOR mutations, specifically TSC1/TSC2 KO, and Pik3ca hotspots, into our 9p21/Trp53 KO model. While TSC1/TSC2 KO lines exhibited elevated P-S6K signaling, they displayed resistance to Torin 1, Voxtalisib, and Everolimus—kinase inhibitors targeting mTORC1/2. In parallel, we employed CRISPR-mediated homologous recombination to successfully introduce a Pik3ca H1047R hotspot into the 9p21/Trp53 KO genotype, as evidenced by increased Phosphorylation of AKT compared to wild-type 9p21/Trp53 KO cell lines. This genotype resulted in approximately 80-fold selective increased sensitivity to pictilisib, a PI3K inhibitor compared to Pik3ca WT control. Conclusions: In this model, CAFs were required for successful engraftment of tumors into the bladder wall or subcutaneously. BUTU is a customizable model of bladder cancer and is suitable for direct targeting by kinase inhibitors while providing a platform for understanding the genotype-phenotype relationship in bladder cancer. We hope to use it as a tool to develop preclinical evidence on which to base precision medicine clinical trials. Citation Format: Philip H. Abbosh, Henkel Valentine. Cancer associated fibroblast dependency in a novel immunocompetent mouse model of bladder cancer [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr A010.

Abstract PR006: EG-70 (detalimogene voraplasmid), a novel, non-viral intravesical gene therapy for BCG-unresponsive non-muscle-invasive bladder cancer: Preclinical characterization and translation into the clinic

Abstract Background: EG-70 (detalimogene voraplasmid) is a novel, investigational, non-integrating, non-viral gene therapy specifically engineered to elicit local stimulation of anti-tumor immune response in the bladder and to drive durable efficacy in patients with BCG-unresponsive high-risk non-muscle-invasive bladder cancer (NMIBC), while mitigating the risk of systemic toxicities from immune stimulation. Previous preclinical data indicate that intravesical instillation (IVI) of EG-70 results in local expression of transgene products in murine and non-human primate models. Here we describe the latest preclinical data to support the mechanism of action of EG-70 and Phase 1 clinical study results for EG-70 in the treatment of BCG-unresponsive NMIBC. Methods: Preclinical: A murine surrogate formulation of EG-70 (mEG-70) was administered locally to the bladder by IVI in C57BL/6 mice. Efficacy was assessed in a luciferase-expressing MB49 model of orthotopic bladder cancer. Following confirmation of cancer cell implantation by in vivo imaging, mice received two weekly IVIs of mEG-70. Immune profiling was evaluated by assessing protein expression levels and cell compositions (via MSD, flow cytometry, and immunohistochemistry). Immune cell depletion studies were conducted using specific antibodies directed against CD4 or CD8 antigen to assess T-cell contribution to efficacy. Clinical: In a Phase 1/2 study in high-risk BCG-unresponsive NMIBC with carcinoma in situ (CIS) (LEGEND; NCT04752722), EG-70 was assessed in four separate dose groups. Results: Preclinical: In a mouse model of orthotopic bladder cancer, IVI of mEG-70 caused striking remodeling of the tumor microenvironment from an immunosuppressive phenotype to a pro-inflammatory milieu supportive of tumor clearance. This was demonstrated by a significant decrease in myeloid cells and IL-4 cytokine levels, an increase in NK-cells and T-cells, and an increase in pro-inflammatory cytokines in tumor tissue. Accordingly, administration of mEG-70 was associated with marked reduction in tumor burden and significant improvement of survival. The anti-tumor response was largely immune-mediated as demonstrated by the critical role of T-cells, durable clearance of tumors, and protection against subsequent tumorigenic re-challenge, both locally in the bladder as well as distally, after flank implantation. Clinical: Results from the Phase 1 portion of the LEGEND study show that IVI of EG-70 was well-tolerated in patients with high-risk BCG-unresponsive NMIBC with CIS across all dose levels, with an overall complete response rate of 73%. Conclusions: The latest preclinical findings demonstrate that EG-70 has the potential to deliver immunostimulatory payloads locally to the bladder. The mechanism of action described preclinically has been translated into the clinic, in the Phase 1 portion of the LEGEND study in patients with BCG-unresponsive NMIBC with CIS. Citation Format: Marie-Line Goulet, Shauna M Dauphinee, Daniel Veilleux, Kristine S Louis, David Lazure, Sarah Stevenson, Darius Bilimoria, Fazmina Zamzameer, Ximin Chen, Sébastien Sublemontier, Sahar Amirkhani, Carlos Fleet, Richard Bryce, Matthew Bui, Shreyas Joshi, Susan J. Kalota, Anthony Cheung, James Sullivan. EG-70 (detalimogene voraplasmid), a novel, non-viral intravesical gene therapy for BCG-unresponsive non-muscle-invasive bladder cancer: Preclinical characterization and translation into the clinic [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr PR006.

Active Targeting Hyaluronan Conjugated Nanoprobe for Magnetic Particle Imaging and Near-Infrared Fluorescence Imaging of Breast Cancer and Lung Metastasis.

A major contributing cause to breast cancer related death is metastasis. Moreover, breast cancer metastasis often shows little symptoms until a large area of the organs is occupied by metastatic cancer cells. Breast cancer multimodal imaging is attractive since it integrates advantages from several modalities, enabling more accurate cancer detection. Glycoprotein CD44 is overexpressed on most breast cancer cells and is the primary cell surface receptor for hyaluronan (HA). To facilitate breast cancer diagnosis, we report an indocyanine green (ICG) and HA conjugated iron oxide nanoparticle (NP-ICG-HA), which enabled active targeting to breast cancer by HA-CD44 interaction and detected metastasis with magnetic particle imaging (MPI) and near-infrared fluorescence imaging (NIR-FI). When evaluated in a transgenic breast cancer mouse model, NP-ICG-HA enabled the detection of multiple breast tumors in MPI and NIR-FI, providing more comprehensive images and a diagnosis of breast cancer. Furthermore, NP-ICG-HAs were evaluated in a lung metastasis model. Upon NP-ICG-HA administration, MPI showed clear signals in the lungs, indicating the tumor sites. This is the first time that HA-based NPs have enabled MPI of cancer. NP-ICG-HAs are an attractive platform for noninvasive detection of primary breast cancer and lung metastasis.

Protein-nanoparticle co-assembly supraparticles for drug delivery: Ultrahigh drug loading and colloidal stability, and instant and complete lysosomal drug release

Two frequent problems hindering clinical translation of nanomedicine are low drug loading and low colloidal stability. Previous efforts to achieve ultrahigh drug loading (>30 %) introduce new hurdles, including lower colloidal stability and others, for clinical translation. Herein, we report a new class of drug nano-carriers based on our recent finding in protein-nanoparticle co-assembly supraparticle (PNCAS), with both ultrahigh drug loading (58 % for doxorubicin, i.e., DOX) and ultrahigh colloidal stability (no significant change in hydrodynamic size after one year). We further show that our PNCAS-based drug nano-carrier possesses a built-in environment-responsive drug release feature: once in lysosomes, the loaded drug molecules are released instantly (<1 min) and completely (∼100 %). Our PNCAS-based drug delivery system is spontaneously formed by simple mixing of hydrophobic nanoparticles, albumin and drugs. Several issues related to industrial production are studied. The ultrahigh drug loading and stability of DOX-loaded PNCAS enabled the delivery of an exceptionally high dose of DOX into a mouse model of breast cancer, yielding high efficacy and no observed toxicity. With further developments, our PNCAS-based delivery systems could serve as a platform technology to meet the multiple requirements of clinical translation of nanomedicines.

Digital droplet PCR analysis of organoids generated from mouse mammary tumors demonstrates proof-of-concept capture of tumor heterogeneity

Breast cancer metastases exhibit many different genetic alterations, including copy number amplifications (CNA). CNA are genetic alterations that are increasingly becoming relevant to breast oncology clinical practice. Here we identify CNA in metastatic breast tumor samples using publicly available datasets and characterize their expression and function using a metastatic mouse model of breast cancer. Our findings demonstrate that our organoid generation can be implemented to study clinically relevant features that reflect the genetic heterogeneity of individual tumors.

Macrophage PET imaging in mouse models of cardiovascular disease and cancer with an apolipoprotein-inspired radiotracer

Macrophages are key inflammatory mediators in many pathological conditions, including cardiovascular disease (CVD) and cancer, the leading causes of morbidity and mortality worldwide. This makes macrophage burden a valuable diagnostic marker and several strategies to monitor these cells have been reported. However, such strategies are often high-priced, non-specific, invasive, and/or not quantitative. Here, we developed a positron emission tomography (PET) radiotracer based on apolipoprotein A1 (ApoA1), the main protein component of high-density lipoprotein (HDL), which has an inherent affinity for macrophages. We radiolabeled an ApoA1-mimetic peptide (mA1) with zirconium-89 (89Zr) to generate a lipoprotein-avid PET probe (89Zr-mA1). We first characterized 89Zr-mA1’s affinity for lipoproteins in vitro by size exclusion chromatography. To study 89Zr-mA1’s in vivo behavior and interaction with endogenous lipoproteins, we performed extensive studies in wildtype C57BL/6 and Apoe-/- hypercholesterolemic mice. Subsequently, we used in vivo PET imaging to study macrophages in melanoma and myocardial infarction using mouse models. The tracer’s cell specificity was assessed by histology and mass cytometry (CyTOF). Our data show that 89Zr-mA1 associates with lipoproteins in vitro. This is in line with our in vivo experiments, in which we observed longer 89Zr-mA1 circulation times in hypercholesterolemic mice compared to C57BL/6 controls. 89Zr-mA1 displayed a tissue distribution profile similar to ApoA1 and HDL, with high kidney and liver uptake as well as substantial signal in the bone marrow and spleen. The tracer also accumulated in tumors of melanoma-bearing mice and in the ischemic myocardium of infarcted animals. In these sites, CyTOF analyses revealed that natZr-mA1 was predominantly taken up by macrophages. Our results demonstrate that 89Zr-mA1 associates with lipoproteins and hence accumulates in macrophages in vivo. 89Zr-mA1’s high uptake in these cells makes it a promising radiotracer for non-invasively and quantitatively studying conditions characterized by marked changes in macrophage burden.

Synergistic antitumor activity by dual blockade of CCR1 and CXCR2 expressed on myeloid cells within the tumor microenvironment.

Chemokine signaling within the tumor microenvironment can promote tumor progression. Although CCR1 and CXCR2 on myeloid cells could be involved in tumor progression, it remains elusive what effect would be observed if both of those are blocked. We employed two syngeneic colorectal cancer mouse models: a transplanted tumor model and a liver metastasis model. We generated double-knockout mice for CCR1 and CXCR2, and performed bone marrow (BM) transfer experiments in which sub-lethally irradiated wild-type mice were reconstituted with BM from either wild-type, Ccr1-/-, Cxcr2-/- or Ccr1-/-Cxcr2-/- mice. Myeloid cells that express MMP2, MMP9 and VEGF were accumulated around both types of tumors through CCR1- and CXCR2-mediated pathways. Mice reconstituted with Ccr1-/-Cxcr2-/- BM exhibited the strongest suppression of tumor growth and liver metastasis compared with other three groups. Depletion of CCR1+CXCR2+ myeloid cells led to a higher frequency of CD8+ T cells, whereas the numbers of Ly6G+ neutrophils, FOXP3+ Treg cells and CD31+ endothelial cells were significantly decreased. Furthermore, treatment with a neutralizing anti-CCR1 mAb to mice reconstituted with Cxcr2-/- BM significantly suppressed tumor growth and liver metastasis. Dual blockade of CCR1 and CXCR2 pathways in myeloid cells could be an effective therapy against colorectal cancer.

Expanded ROS Generation and Hypoxia Reversal: Excipient-free Self-assembled Nanotheranostics for Enhanced Cancer Photodynamic Immunotherapy.

The efficacy of photodynamic therapy (PDT)-related cancer therapies is significantly restricted by two irreconcilable obstacles, i.e., low reactive oxygen species (ROS) generation capability and hypoxia which constrains the immune response. Herein, we developed a self-assembled clinical photosensitizer indocyanine green (ICG) and the HSP90 inhibitor 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG) nanoparticles (ISDN) without any excipient. We discovered that the hydrophobic interaction forces between ICG and 17-DMAG promote the photostability of ICG and its intersystem crossing process (ISC), thereby improving the ROS quantum yield from 0.112 to 0.46. Augmented ROS generation enhances PDT efficacy and further enhances immunogenic cell death (ICD) effects. 17-DMAG inhibits the HSP90/HIF-1α axis to dramatically reverse the immunosuppressive tumor microenvironment caused by PDT-aggravated hypoxia. In a mouse model of pancreatic cancer, ISDN markedly improve cytotoxic T lymphocyte infiltration and MHC I and MHC II activation, demonstrating the superior ICD effects in situ tumor and the powerful systematic antitumor immunity generation, eventually achieving vigorous antitumor and recurrence resistance. This study proposes an unsophisticated and versatile strategy to significantly improve PDT efficacy for enhancing systemic antitumor immunity and potentially extending it to multiple cancers. This article is protected by copyright. All rights reserved.

Combining EHMT and PARP Inhibition: A Strategy to Diminish Therapy-Resistant Ovarian Cancer Tumor Growth while Stimulating Immune Activation.

Despite the success of Poly-ADP-ribose polymerase inhibitors (PARPi) in the clinic, high rates of resistance to PARPi presents a challenge in the treatment of ovarian cancer, thus it is imperative to find therapeutic strategies to combat PARPi resistance. Here, we demonstrate that inhibition of epigenetic modifiers Euchromatic histone lysine methyltransferases 1/2 (EHMT1/2) reduces the growth of multiple PARPi-resistant ovarian cancer cell lines and tumor growth in a PARPi-resistant mouse model of ovarian cancer. We found that combinatory EHMT and PARP inhibition increases immunostimulatory dsRNA formation and elicits several immune signaling pathways in vitro. Using epigenomic profiling and transcriptomics, we found that EHMT2 is bound to transposable elements, and that EHMT inhibition leads to genome-wide epigenetic and transcriptional derepression of transposable elements. We validated EHMT-mediated activation of immune signaling and upregulation of transposable element transcripts in patient-derived, therapy-naïve, primary ovarian tumors, suggesting potential efficacy in PARPi-sensitive disease as well. Importantly, using multispectral immunohistochemistry, we discovered that combinatory therapy increased CD8 T cell activity in the tumor microenvironment of the same patient-derived tissues. In a PARPi-resistant syngeneic murine model, EHMT and PARP inhibition combination inhibited tumor progression and increased Granzyme B+ cells in the tumor. Together, our results provide evidence that combinatory EHMT and PARP inhibition stimulates a cell autologous immune response in vitro, is an effective therapy to reduce PARPi resistant ovarian tumor growth in vivo, and promotes anti-tumor immunity activity in the tumor microenvironment of patient-derived ex vivo tissues of ovarian cancer.

Erlotinib suppresses tumorigenesis in a mouse model of colitis-associated cancer

Colitis-associated cancer (CAC) in inflammatory bowel diseases exhibits more aggressive behavior than sporadic colorectal cancer; however, the molecular mechanisms remain unclear. No definitive preventative agent against CAC is currently established in the clinical setting. We investigated the molecular mechanisms of CAC in the azoxymethane/dextran sulfate sodium (AOM/DSS) mouse model and assessed the antitumor efficacy of erlotinib, a small molecule inhibitor of the epidermal growth factor receptor (EGFR). Erlotinib premixed with AIN-93 G diet at 70 or 140 parts per million (ppm) inhibited tumor multiplicity significantly by 96%, with ∼60% of the treated mice exhibiting zero polyps at 12 weeks. Bulk RNA-sequencing revealed more than a thousand significant gene alterations in the colons of AOM/DSS-treated mice, with KEGG enrichment analysis highlighting 46 signaling pathways in CAC development. Erlotinib altered several signaling pathways and rescued 40 key genes dysregulated in CAC, including those involved in the Hippo and Wnt signaling. These findings suggest that the clinically-used antitumor agent erlotinib might be repurposed for suppression of CAC, and that further studies are warranted on the crosstalk between dysregulated Wnt and EGFR signaling in the corresponding patient population.

MOTS-c is an effective target for treating cancer-induced bone pain through the induction of AMPK-mediated mitochondrial biogenesis.

Bone cancer pain (BCP), due to cancer bone metastasis and bone destruction, is a common symptom of tumors, including breast, prostate, and lung tumors. Patients often experience severe pain without effective treatment. Here, using a mouse model of bone cancer, we report that MOTS-c, a novel mitochondrial-derived peptide, confers remarkable protection against cancer pain and bone destruction. Briefly, we find that the plasma level of endogenous MOTS-c is significantly lower in the BCP group than in the sham group. Accordingly, intraperitoneal administration of MOTS-c robustly attenuates bone cancer-induced pain. These effects are blocked by compound C, an AMPK inhibitor. Furthermore, MOTS-c treatment significantly enhances AMPKα 1/2 phosphorylation. Interestingly, mechanical studies indicate that at the spinal cord level, MOTS-c relieves pain by restoring mitochondrial biogenesis, suppressing microglial activation, and decreasing the production of inflammatory factors, which directly contribute to neuronal modulation. However, in the periphery, MOTS-c protects against local bone destruction by modulating osteoclast and immune cell function in the tumor microenvironment, providing long-term relief from cancer pain. Additionally, we find that chronic administration of MOTS-c has little effect on liver, renal, lipid or cardiac function in mice. In conclusion, MOTS-c improves BCP through peripheral and central synergistic effects on nociceptors, immune cells, and osteoclasts, providing a pharmacological and biological rationale for the development of mitochondrial peptide-based therapeutic agents for cancer-induced pain.

CYRI-B mediated macropinocytosis drives metastasis via lysophosphatidic acid receptor uptake.

Pancreatic ductal adenocarcinoma carries a dismal prognosis, with high rates of metastasis and few treatment options. Hyperactivation of KRAS in almost all tumours drives RAC1 activation, conferring enhanced migratory and proliferative capacity as well as macropinocytosis. Macropinocytosis is well understood as a nutrient scavenging mechanism, but little is known about its functions in trafficking of signaling receptors. We find that CYRI-B is highly expressed in pancreatic tumours in a mouse model of KRAS and p53-driven pancreatic cancer. Deletion of Cyrib (the gene encoding CYRI-B protein) accelerates tumourigenesis, leading to enhanced ERK and JNK-induced proliferation in precancerous lesions, indicating a potential role as a buffer of RAC1 hyperactivation in early stages. However, as disease progresses, loss of CYRI-B inhibits metastasis. CYRI-B depleted tumour cells show reduced chemotactic responses to lysophosphatidic acid, a major driver of tumour spread, due to impaired macropinocytic uptake of the lysophosphatidic acid receptor-1. Overall, we implicate CYRI-B as a mediator of growth and signaling in pancreatic cancer, providing new insights into pathways controlling metastasis.

A novel NIR fluorescent probe for enhanced β-galactosidase detection and tumor imaging in ovarian cancer models

The advancement of biological imaging techniques critically depends on the development of novel near-infrared (NIR) fluorescent probes. In this study, we introduce a designed NIR fluorescent probe, NRO-βgal, which exhibits a unique off–on response mechanism to β-galactosidase (β-gal). Emitting a fluorescence peak at a wavelength of 670 nm, NRO-βgal showcases a significant Stokes shift of 85 nm, which is indicative of its efficient energy transfer and minimized background interference. The probe achieves a remarkably low in vitro detection limit of 0.2 U/L and demonstrates a rapid response within 10 min, thereby underscoring its exceptional sensitivity, selectivity, and operational swiftness. Such superior analytical performance broadens the horizon for its application in intricate biological imaging studies. To validate the practical utility of NRO-βgal in bio-imaging, we employed ovarian cancer cell and mouse models, where the probe's efficacy in accurately delineating tumor cells was examined. The results affirm NRO-βgal's capability to provide sharp, high-contrast images of tumor regions, thereby significantly enhancing the precision of surgical tumor resection. Furthermore, the probe's potential for real-time monitoring of enzymatic activity in living tissues underscores its utility as a powerful tool for diagnostics in oncology and beyond.

Spatial transcriptomics reveals the interplay between cancer and immune cells directed by MXene quantum dots

Nanomedicine plays an essential role in the development of tumor treatment modalities. However, tumors have a complex structure that includes a variety of immune cell types, which, along with tumor cells, comprise the heterogeneous tumor microenvironment (TME). Although nanoparticles that overcome the limitations of other classical therapeutics and navigate heterogeneous biological barriers have been developed, many unknown players within the TME still exist. The role of immune cell populations and signaling pathways in the TME, which can affect the nanoparticle distribution in the tumor or the overall outcome of nanotherapeutic treatments, are poorly described. In this study, we used spatial transcriptomics to determine in situ gene expression and identified immune cells, other than tumor-associated macrophages, that play vital roles following nanoparticle exposure. In this proof-of-concept study, a recently explored type of nanoparticle, Ti3C2Tx MXene quantum dots (MQDs), with a single particle diameter of ≤10 nm, were administered to orthotopic breast cancer model mice. Thanks to their red-emitting fluorescence properties, we could track the distribution of MQDs in the tumor. Whole-transcriptome analysis and immunofluorescence staining suggested that the heterogeneous distribution of MQDs results in different tumor and immune cell responses in situ. We observed a more tumor-suppressive phenotype at tumor regions with high MQD accumulation compared to regions with decreased MQD accumulation or naïve tumors. Based on pathway analysis and cell deconvolution, we also identified other immune cell types altered by MQDs, including B cells and neutrophils. Specifically, the application of MQDs recruited and activated B cells and resulted in neutrophil degranulation and NETosis in vivo. Using spatial transcriptomics technology, we defined the fundamental molecular and cellular changes that occur in situ in the TME following MQD administration. Future spatial omics studies involving different nanoparticles with other material characteristics will help design more effective nanotherapeutics.

CCR5 antagonist maraviroc alleviates doxorubicin-induced neuroinflammation and neurobehavioral deficiency by regulating NF-κB/NLRP3 signaling in a breast cancer mouse model

The chemotherapeutic agent Doxorubicin (DOX) is known to cause chemotherapy-induced cognitive impairment (CICI). Maraviroc, a potent C–C chemokine receptor 5 (CCR5) antagonist, shows neuroprotective properties, while its role in CICI remains unclear. This study determined the therapeutic potential of maraviroc on CICI. Adult C57BL/6J mice with implanted breast cancer cells received four weekly intraperitoneal injections of saline (Control group), 5 mg/kg DOX (DOX group), 10 mg/kg maraviroc (MVC group), or 5 mg/kg DOX with 10 mg/kg maraviroc (DOX + MVC group). The Morris Water Maze (MWM) was used for neurobehavioural test. Western blot analysis and immunofluorescence were used to evaluate the expressions of inflammatory markers, apoptosis-related proteins, and synaptic-related proteins. The volume and weight of tumor were also evaluated after treatments. DOX treatment significantly increased chemokines (CCL3, CCL4) and inflammatory cytokines (IL-1β, TNF-α) in tumor-bearing mice hippocampus. While maraviroc administration reduced hippocampal proinflammatory factors compared to the DOX group. Furthermore, it also lowered apoptosis markers, restored synaptic proteins levels, and inhibited the NF-κB/NLRP3 pathway. Accordingly, maraviroc treatment significantly improved DOX-induced neurobehavioural impairments as evidenced by an increased number of platform crossings and percentage of target quadrant time in the MWM test. Additionally, when combined with DOX, maraviroc had additional inhibitory effects on tumor growth. These findings suggest that maraviroc can mitigate DOX-induced CICI by suppressing elevated proinflammatory chemokines and cytokines through the NF-κB/NLRP3 pathway, potentially offering an anti-tumor benefit. This research presents a promising therapeutic approach for DOX-induced CICI, enhancing the safety and efficacy of cancer treatments.

Abstract PO1-25-08: Evaluating the role of CDK4/6 inhibition on STAT3 activation in a transgenic mouse model of HER2-positive breast cancer

Abstract Background: The human epidermal growth factor receptor 2 (HER2) is a receptor tyrosine kinase overexpressed in approximately 20-25% of breast cancers with varying biological differences according to hormone receptor (HR) positive status. Combination of chemotherapy with dual HER2 blockade and endocrine therapy (adjuvant) or CDK4/6 inhibitor (CDK4/6i) therapy (metastatic) is standard of care for HER2-positive/HR-positive breast cancer. However, de-escalation of chemotherapy remains of significant interest given associated toxicities and, as a result, alternative therapeutic strategies are needed. One such strategy is targeting the signal transducer and activator of transcription 3 (STAT3) which is constitutively activated in the HER-2 positive setting. Moreover, there is preclinical evidence to suggest that phosphorylated STAT3 (pSTAT3) induces overexpression of cyclin D1 (CCND1), which along with CDK4 may mediate resistance to targeted therapy for HER2-positive breast cancer. However, it is unclear if pSTAT3 plays a significant role in tumorigenesis or the development of resistance to therapy in HER2-positive disease. We aim to evaluate the effect of CDK4/6i therapy with palbociclib on tumor growth in an inducible transgenic HER2-positive mouse model and the impact on pSTAT3 and cyclin D1 levels. Methods: Using an inducible transgenic mouse mammary tumor virus (MMTV) model of HER2-positive breast cancer, we evaluated STAT3 phosphorylation in tumors driven by HER2 expression in addition to the impact of CDK4/6 inhibition with palbociclib on tumorigenesis and pSTAT3 activation. To model tumor recurrence, doxycycline was withdrawn from tumor bearing mice and tumor regression was observed. Subsequently, the mice developed recurrent mammary tumors. Given recurrent tumors in this model are driven by a HER2-independent mechanism, we examined expression of cell cycle proteins together with STAT3 phosphorylation to determine association with recurrence. Result: In addition to expressing HER2, the primary tumors expressed estrogen receptor (ERα), Rb, cyclin D1, and CDK4/6 proteins. STAT3 phosphorylation was also observed. Treatment with palbociclib decreased Rb phosphorylation and decreased tumor growth compared to vehicle treated mice (%TGI 79.37% after 21 days). Furthermore, pSTAT3 levels were not altered with palbociclib therapy. When recurrent tumors were analyzed, they lacked HER2 expression but expressed cyclin D1 and CDK4/6 supporting that tumor growth is driven by cyclin D1/CDK4 pathway. Recurrent tumors also demonstrated pSTAT3 despite lack of HER2 expression suggesting that STAT3 phosphorylation in the recurrent tumors is mediated by an alternative mechanism, potentially the CDK4/6 pathway. Conclusion: We demonstrate STAT3 activation in a mouse model of HER2 driven breast cancer and show persistent activation in recurrent tumors lacking HER2 expression rendering them resistant to HER2-targeted therapy. We also demonstrate the anti-tumor effect of palbociclib in primary tumors with HER2-dependent proliferation. Taken together, our findings suggest that pSTAT3 is a viable therapeutic target and provides the rationale for combination therapy with CDK4/6 inhibition using palbociclib and STAT3 inhibition with a novel STAT3 inhibitor in HER2-positive breast cancer. This therapeutic approach may represent a potential chemotherapy de-escalation strategy. Citation Format: Taiwo Adesoye, Linjie Luo, Tuyen Bui, Serena Kim, Hannah Wingate, Debu Tripathy, Kelly Hunt, Khandan Keyomarsi. Evaluating the role of CDK4/6 inhibition on STAT3 activation in a transgenic mouse model of HER2-positive breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-25-08.

Abstract ED03-01: Breaking the Obesity-Breast Cancer Link: Comparing Diet, Drug and Surgical Approaches

Abstract The prevalence of obesity, an established risk and progression factor for at least 15 types of cancer (including breast cancer), continues to rise in the US and many other countries. Lifestyle approaches to weight loss have proven challenging for most people to maintain, and bariatric surgery, while effective, is expensive and has numerous adverse effects. The recent availability of highly effective incretin therapies for weight loss raises several key questions that we will address, including: i) do these agents drive weight loss in obese female mice?; ii) do they reverse obesity-induced metabolic dysregulation?; iii) can they reverse obesity-driven cancer?; iv) how heterogeneous is the response to these agents? We will report our study of the effects of extended (13 weeks) tirzepatide (TZP, a dual GLP1R/GIPR agonist) treatment in obese female mice on weight loss, metabolic hormones, and mammary tumor growth. We found that—similar to reports in the literature using male mice—obese female mice lost &amp;gt;20% body weight by 4 weeks of TZP treatment. Moreover, TZP-induced weight loss was maintained through 13 weeks of treatment by progressively escalating the dose up to 40 nmol/kg. Congruent with reports in male rodents and humans, we found the majority of weight loss in female mice was attributed to loss of adipose tissue, rather than lean mass. The effects of TZP on body weight and composition were associated with reversal of obesity-induced changes in glycemic control and circulating levels of metabolic hormones, particularly leptin, insulin, and IGF-1. TZP also significantly reversed the protumor effects of obesity in our murine E0771 orthotopic transplant model of TNBC.Furthermore, daily 30% calorie restriction, which we previously reported has strong weight loss-inducing, metabolic reprogramming and anticancer effects in multiple mouse models of breast and other cancers, reversed body weight, adiposity, and TNBC tumor growth and altered metabolic hormones to a greater extent than all groups studied, including the never-obese control mice and TZP-treated mice. Citation Format: S. Hursting. Breaking the Obesity-Breast Cancer Link: Comparing Diet, Drug and Surgical Approaches [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr ED03-01.

Abstract PO5-24-12: IRX5010, a Highly Selective RARγ Nuclear Receptor Agonist Compound Inhibits In Vivo Growth of Murine EMT-6 Triple Negative Breast Cancer and Human JIMT-1Her2+ Breast Cancer By Induction of Tumor-Infiltrating Effector Memory T-cells

Abstract Research Objectives and Rationale: Previously, RARγ agonism has been shown to play an essential role in CD8 T-cell-mediated immunity to infectious pathogens. However, we found no previous reports on effects of RARγ agonists on in vivo tumor growth of triple negative or Her2+ breast cancers. Here we explored whether RARγ could play a critical role in T-cell-mediated immunity in these breast cancers, using potent highly selective novel RARγ agonist compounds. Experimental methods and results: We synthesized and screened compounds for selective transactivation of RAR γ in reporter assays. Three highly potent compounds, demonstrating highly selective RARγ transactivation at less than one nanomolar concentrations, were selected for further evaluation of potential anti-cancer activities in vitro. None of the three evaluated compounds demonstrated significant inhibitory effects on in vitro growth of EMT-6 triple negative breast cancer cells at concentrations of 20-100 millimolar, indicating that the three compounds have insignificant direct inhibitory effects on EMT-6 cancer cell growth in vitro. We then examined the effects of one of the compounds in vivo in a syngeneic mouse model of EMT-6 triple negative breast cancer. Treatment with the most potent of the three compounds, IRX5010, demonstrated dose response inhibition of in vivo growth of EMT-6 tumors. Inhibition of tumor growth at day 17 relative to vehicle was 59% and 69% respectively in mice treated with IRX5010 at 10 or 25 mg/kg/day. A cohort treated with 50 mg/kg/day was sacrificed early on day 12 due to excessive weight loss and deaths of some of the animals. This cohort experienced a 73% inhibition of tumor growth relative to vehicle. Gross necropsies of animals in the 25 and 50 mg/kg/day dose groups did not show observable pathologic findings in any major organ. Flow cytometry was performed on freshly excised tumors on the day of termination of the in-life portion of the study in the 10 and 25 mg/kg/day dose groups. Tumors from mice treated with IRX5010 had increased intratumoral numbers of Total CD45+ cells; Total CD3+, Total CD4+, and Total CD8+ T-cells per mg of tumor tissue, relative to vehicle controls. IRX5010 treated mice also had increased intratumoral CD4+IL-17+ T-helper cells; and increased CD4+CD62L- and CD8+CD62L- T-effector memory T-cells per mg of tumor tissue relative to vehicle-treated control mice. We also conducted an experiment of treatment with IRX5010 in mice transplanted with human immune cells (to provide a human immune system) to examine its effects on xenografted human Her2+ JIMT-1 cancer cells. In this model, treatment with IRX5010 at 10 mg/kg/day resulted in a 17% inhibition of tumor growth relative to vehicle control over 26 days of treatment. Flow cytometric analysis showed that tumors from the IRX5010 treated mice contained increased numbers per mg of tumor tissue of intratumoral human CD8+ T-cells, most of which were CD8+ CD7- CD45RA+ terminally differentiated effector memory phenotype T-cells. Conclusions: Treatment with IRX5010, a potent and highly selective RARγ nuclear receptor agonist compound demonstrated substantial treatment effects relative to vehicle control on inhibition of growth of murine triple negative breast cancer in vivo, despite having essentially no growth inhibitory effect on these cells in vitro. Treatment of xenografted human Her2+ tumors in mice with humanized immune systems resulted in a moderate inhibition of Her2+ breast cancer growth relative to vehicle controls. In both models, treatment with IRX5010 induced tumor infiltrating T-lymphocytes of largely effector memory phenotypes, demonstrating an effect on the tumor immune microenvironment. These data identify RARγ and RARγ agonists as a new treatment target and novel treatment modality for breast cancers, especially for the highly unmet need for new and better treatments for triple negative breast cancer. Citation Format: Martin Sanders, Mary Topalovski, Vidyasagar Vuligonda. IRX5010, a Highly Selective RARγ Nuclear Receptor Agonist Compound Inhibits In Vivo Growth of Murine EMT-6 Triple Negative Breast Cancer and Human JIMT-1Her2+ Breast Cancer By Induction of Tumor-Infiltrating Effector Memory T-cells [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-24-12.