Primary Tumor Growth Research Articles

Abstract B013: Investigation of a novel lncRNA, TROLL-9, in breast cancer formation and progression

Abstract Breast cancer (BC) is the most diagnosed cancer and the second leading cancer-related cause of mortality among women in the US. Despite advances in treatment, BC remains a challenge due to its metastatic potential. The most aggressive BC subtype, triple negative (TN), often harbors mutations in the tumor suppressor gene, p53. One of the effects of mutant p53 involves the inhibition of the tumor and metastatic suppressive functions of TAp63, a p53 family member. Loss of TAp63 leads to the formation of metastatic mammary adenocarcinomas in mice, in part through the regulation of a group of nine long non-coding RNAs (lncRNAs), that we identified and named TAp63 regulated oncogenic lncRNAs (TROLLs). We previously characterized two TROLLs, TROLL-2 and TROLL-3, as markers of tumor progression in multiple cancer types via the activation of the AKT pathway. Currently we are investigating the role of another member, TROLL-9. To investigate the biological role of TROLL-9, we performed in vivo experiments using preclinical mouse models. Specifically, MCF-DCIS, MCF-CA1D, and MDA-MB-231 triple negative breast cancer (TNBC) cells constitutively expressing TROLL-9 were generated and utilized for two mouse models: orthotopic xenografts for primary tumor growth and spontaneous metastasis. The former was designed to identify the potential role of TROLL-9 in tumor formation, whereas the latter involved the resection of a primary tumor and monitoring for metastases via bioluminescence imaging. Notably, TROLL-9 overexpression led to increased formation of lung and livers metastases in all these models, suggesting a role for TROLL-9 in the metastatic cascade. In order to elucidate the mechanism of function of TROLL-9, two complementary approaches were used. Firstly, pulldown using MS2-TRAP followed by mass spectrometry (MS) was performed and led to the identification of putative protein interactors. In parallel, Laser Capture Microscopy (LCM) of the lung metastases followed by RNA-sequencing was used to assess for any gene expression changes due to TROLL-9 overexpression. Integration of the two datasets is currently being performed to unveil the network of genes and proteins perturbed by TROLL-9. Furthermore, to understand the relevance in BC patients, TROLL-9 expression levels were analyzed in the TCGA BC dataset. Interestingly, differences in TROLL-9 levels across BC subtypes were observed, thus supporting its putative role in TNBC. Overall, our data suggest a role for TROLL-9 in BC progression. Our findings provide evidence for further characterizing its mechanism of function as a potential therapeutic target for the treatment of invasive BC, particularly TNBC harboring TP53 mutations. Citation Format: Avani A Deshpande, Marco Napoli, John H Lockhart, Christina L Carr, Jaden R Baldwin, Elsa R Flores. Investigation of a novel lncRNA, TROLL-9, in breast cancer formation and progression [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr B013.

Modeling Lymphoma Angiogenesis, Lymphangiogenesis, and Vessel Co-Option, and the Effects of Inhibition of Lymphoma–Vessel Interactions with an αCD20-EndoP125A Antibody Fusion Protein

Lymphoma growth, progression, and dissemination require tumor cell interaction with supporting vessels and are facilitated through tumor-promoted angiogenesis, lymphangiogenesis, and/or lymphoma vessel co-option. Vessel co-option has been shown to be responsible for tumor initiation, metastasis, and resistance to anti-angiogenic treatment but is largely uncharacterized in the setting of lymphoma. We developed an in vitro model to study lymphoma–vessel interactions and found that mantle cell lymphoma (MCL) cells co-cultured on Matrigel with human umbilical vein (HUVEC) or human lymphatic (HLEC) endothelial cells migrate to and anneal with newly formed capillary-like (CLS) or lymphatic-like (LLS) structures, consistent with lymphoma–vessel co-option. To inhibit this interaction, we constructed an antibody fusion protein, αCD20-EndoP125A, linking mutant anti-angiogenic endostatin (EndoP125A) to an αCD20-IgG1-targeting antibody. αCD20-EndoP125A inhibited both CLS and LLS formation, as well as MCL migration and vessel co-option. Lymphoma vessel co-option requires cell migration, which is regulated by chemokine–chemokine receptor interactions. CXCL12 and its receptor, CXCR4, are highly expressed by both endothelial cells forming CLS and by MCL cells during vessel co-option. αCD20-EndoP125A suppressed expression of both CXCL12 and CXCR4, which were required to facilitate CLS assembly and vessel co-option. We also tested αCD20-EndoP125A effects in vivo using an aggressive murine B cell lymphoma model, 38c13-hCD20, which demonstrated rapid growth and dissemination to tumor-draining lymph nodes (TDLNs) and the spleen, lung, and brain. The pattern of lymphoma distribution and growth within the lung was consistent with vessel co-option. As predicted by our in vitro model, αCD20-EndoP125A treatment inhibited primary tumor growth, angiogenesis, and lymphangiogenesis, and markedly reduced the number of circulating tumor cells and lymphoma dissemination to TDLNs and the lungs, spleen, and brain. αCD20-EndoP125A inhibited lymphoma vessel co-option within the lung. Marked inhibition of MCL primary tumor growth and dissemination were also seen using an MCL xenograft model. The ability of αCD20-EndoP125A to inhibit angiogenesis, lymphangiogenesis, and lymphoma vessel co-option provides a novel therapeutic approach for inhibition of lymphoma progression and dissemination.

Obesity, white adipose tissue and cancer.

White adipose tissue (WAT) is crucial for whole-body energy homeostasis and plays an important role in metabolic and hormonal regulation. While healthy WAT undergoes controlled expansion and contraction to meet the body's requirements, dysfunctional WAT in conditions like obesity is characterized by excessive tissue expansion, alterations in lipid homeostasis, inflammation, hypoxia, and fibrosis. Obesity is strongly associated with an increased risk of numerous cancers, with obesity-induced WAT dysfunction influencing cancer development through various mechanisms involving both systemic and local interactions between adipose tissue and tumors. Unhealthy obese WAT affects circulating levels of free fatty acids and factors like leptin, adiponectin, and insulin, altering systemic lipid metabolism and inducing inflammation that supports tumor growth. Similar mechanisms are observed locally in an adipose-rich tumor microenvironment (TME), where WATcells can also trigger extracellular matrix remodeling, thereby enhancing the TME's ability to promote tumor growth. Moreover, tumors reciprocally interact with WAT, creating a bidirectional communication that further enhances tumorigenesis. This review focuses on the complex interplay between obesity, WAT dysfunction, and primary tumor growth, highlighting potential targets for therapeutic intervention.

The role of glycolysis in tumorigenesis: From biological aspects to therapeutic opportunities

Glycolytic metabolism generates energy and intermediates for biomass production. Tumor-associated glycolysis is upregulated compared to normal tissues in response to tumor cell-autonomous or non-autonomous stimuli. The consequences of this upregulation are twofold. First, the metabolic effects of glycolysis become predominant over those mediated by oxidative metabolism. Second, overexpressed components of the glycolytic pathway (i.e. enzymes or metabolites) acquire new functions unrelated to their metabolic effects and which are referred to as “moonlighting” functions. These functions include induction of mutations and other tumor-initiating events, effects on cancer stem cells, induction of increased expression and/or activity of oncoproteins, epigenetic and transcriptional modifications, bypassing of senescence and induction of proliferation, promotion of DNA damage repair and prevention of DNA damage, antiapoptotic effects, inhibition of drug influx or increase of drug efflux. Upregulated metabolic functions and acquisition of new, non-metabolic functions lead to biological effects that support tumorigenesis: promotion of tumor initiation, stimulation of tumor cell proliferation and primary tumor growth, induction of epithelial-mesenchymal transition, autophagy and metastasis, immunosuppressive effects, induction of drug resistance and effects on tumor accessory cells. These effects have negative consequences on the prognosis of tumor patients. On these grounds, it does not come to surprise that tumor-associated glycolysis has become a target of interest in antitumor drug discovery. So far, however, clinical results with glycolysis inhibitors have fallen short of expectations. In this review we propose approaches that may allow to bypass some of the difficulties that have been encountered so far with the therapeutic use of glycolysis inhibitors.

Caerin 1.1 and 1.9 peptides halt B16 melanoma metastatic tumours via expanding cDC1 and reprogramming tumour macrophages

BackgroundCancer immunotherapy, particularly immune checkpoint inhibitors (ICBs) such as anti-PD-1 antibodies, has revolutionised cancer treatment, although response rates vary among patients. Previous studies have demonstrated that caerin 1.1 and 1.9, host-defence peptides from the Australian tree frog, enhance the effectiveness of anti-PD-1 and therapeutic vaccines in a murine TC-1 model by activating tumour-associated macrophages intratumorally.MethodsWe employed a murine B16 melanoma model to investigate the therapeutic potential of caerin 1.1 and 1.9 in combination with anti-CD47 and a therapeutic vaccine (triple therapy, TT). Tumour growth of caerin-injected primary tumours and distant metastatic tumours was assessed, and survival analysis conducted. Single-cell RNA sequencing (scRNAseq) of CD45+ cells isolated from distant tumours was performed to elucidate changes in the tumour microenvironment induced by TT.ResultsThe TT treatment significantly reduced tumour volumes on the treated side compared to untreated and control groups, with notable effects observed by Day 21. Survival analysis indicated extended survival in mice receiving TT, both on the treated and distant sides. scRNAseq revealed a notable expansion of conventional type 1 dendritic cells (cDC1s) and CD4+CD8+ T cells in the TT group. Tumour-associated macrophages in the TT group shifted toward a more immune-responsive M1 phenotype, with enhanced communication observed between cDC1s and CD8+ and CD4+CD25+ T cells. Additionally, TT downregulated M2-like macrophage marker genes, particularly in MHCIIhi and tissue-resident macrophages, suppressing Cd68 and Arg1 expression across all macrophage types. Differential gene expression analysis highlighted pathway alterations, including upregulation of oxidative phosphorylation and MYC target V1 in Arg1hi macrophages, and activation of pro-inflammatory pathways in MHCIIhi and tissue-resident macrophages.ConclusionOur findings suggest that caerin 1.1 and 1.9, combined with immunotherapy, effectively modulate the tumour microenvironment in primary and secondary tumours, leading to reduced tumour growth and enhanced systemic immunity. Further investigation into these mechanisms could pave the way for improved combination therapies in advanced melanoma treatment.

HSP90 N-terminal inhibition promotes mitochondria-derived vesicles related metastasis by reducing TFEB transcription via decreased HSP90AA1-HCFC1 interaction in liver cancer

ABSTRACT Cancer cells compensate with increasing mitochondria-derived vesicles (MDVs) to maintain mitochondrial homeostasis, when canonical MAP1LC3B/LC3B (microtubule associated protein 1 light chain 3 beta)-mediated mitophagy is lacking. MDVs promote the transport of mitochondrial components into extracellular vesicles (EVs) and induce tumor metastasis. Although HSP90 (heat shock protein 90) chaperones hundreds of client proteins and its inhibitors suppress tumors, HSP90 inhibitors-related chemotherapy is associated with unexpected metastasis. Herein, we find that HSP90 inhibitor causes mitochondrial damage but stimulates the low LC3-induced MDVs and the release of MDVs-derived EVs. However, why LC3 decreases and what is the transcriptional regulatory mechanism of MDVs formation under HSP90 inhibition remain unknown. Because TFEB (transcription factor EB) is the most important mitophagy transcription factor, and the HSP90 client HCFC1 (host cell factor C1) regulates TFEB transcription, there should be a hidden connection between TFEB, HCFC1 and HSP90 in MDVs formation. Our results support the idea that HSP90 N-terminal inhibition reduces TFEB transcription via decreased HSP90AA1-HCFC1 interaction, which prevents HCFC1 from binding to the TFEB proximal promoter region. Decreased TFEB transcription and consequently reduced LC3, ultimately promoted MDVs formation. Blocking MDVs formation with the microtubule inhibitor nocodazole (NOC) activates the HCFC1-TFEB-LC3 axis, weakens HSP90 inhibitors-induced MDVs and the release of MDVs-derived EVs, inhibits the growth of tumor cell spheres and primary liver tumors, and reduces the extravasation of cancer cells to secondary metastatic sites. Taken together, these data suggest that combination therapy should be used to reduce the metastatic risk of low TFEB-triggered-MDVs formation caused by HSP90 inhibitors.

Enhanced Tumor Immunotherapy by Triple Amplification Effects of Nanomedicine on the STING Signaling Pathway in Dendritic Cells.

Insufficient activation of stimulator of interferon genes (STING) signaling pathway in tumor-associated dendritic cells limits the efficiency of tumor immunotherapy. Herein, the "three-in-one" IAHA-LaP/siPTPN6 NPs containing lanthanum ions (La3+), cGAMP, and PTPN6 siRNA are developed for triple amplification of the STING pathway. In vitro results demonstrate that La3+ significantly promotes cGAMP-mediated activation of the STING pathway by enhancing the phosphorylation of STING, TBK1, IRF3, and NF-κB p65. Moreover, the IAHA-LaP/siPTPN6 NPs further significantly enhance the phosphorylation of STING and NF-κB p65 and augment K63-linked ubiquitination of STING protein via siPTPN6-mediated downregulation of SHP-1 protein. Furthermore, NPs improve the secretion of IFNβ (2.4-fold), IL-6 (1.5-fold), and TNF-α (1.4-fold), thereby promoting DCs maturation compared to the mixture of La3+ and cGAMP. In vivo results show that the IAHA-LaP/siPTPN6 NPs remarkably inhibit primary tumor growth by increasing the percentage of mature DCs in tumor-draining lymph nodes, polarizing M2/M1 phenotype in TME, and promoting the infiltration of CD8+T cells into tumors. Moreover, these NPs dramatically prevent the growth of distal tumor by inducing systemic anti-tumor immunity and generating a long-term anti-tumor memory for protection against tumor recurrence in mice bearing bilateral B16F10. These IAHA-LaP/siPTPN6 NPs may offer a promising platform for robust anti-tumor immune responses.

Autophagy activator-loaded bicomponent peptide nanocarriers for phototherapy-triggered immunity enhancement against metastatic breast cancer

Mild autophagy accompanied with immunogenic cell death (ICD) effect destructs immune-associated antigens, weakening the immune response against tumor growth. To address this dilemma, we develop a peptide-based bicomponent nanocarrier with encapsulation of a cellular hyperautophagy activator (STF-62247) for near-infrared (NIR) photo/immunotherapy to eliminate primary and metastatic breast tumors. The electrostatic-driven nanodrug (PPNPs@STF) with active-targeting and efficient endosomal escape can induce specific ICD effect upon NIR laser irradiation, and trigger autophagy to a mild activation state. Notably, the simultaneously released STF-62247 precisely promotes autophagy to an overactivated state, resulting in autophagic death of tumor cells and further boosting ICD-related antigen presentation. More importantly, the combined photo/immunotherapy of PPNPs@STF not only inhibits tumor cell proliferation, but also promotes dendritic cells (DCs)-associated immune response. In 4 T1 tumor-bearing mice, PPNPs@STF effectively inhibits growth of primary and distant tumors, and suppresses lung metastasis with a minimized side effect. This study provides a hyperautophagy activator-assisted strategy that can enhance ICD-based antitumor immune response for the treatment of metastatic breast cancer.

Dual-Activatable Nano-Immunomodulator for NIR-II Fluorescence Imaging-Guided Precision Cancer Photodynamic Immunotherapy.

Photodynamic immunotherapy which combines photodynamic therapy with immunotherapy has become an important and effective method for the treatment of cancer. However, most cancer photodynamic immunotherapeutic systems are not able to achieve precise release of immunomodulators, resulting in systemic side effects and poor patient outcomes. Herein, a dual-activatable nano-immunomodulator (DIR NP), which both its photodynamic effect and agonist release can be activated under specific stimuli, is reported for precision cancer photodynamic immunotherapy. The DIR NP is self-assembled from an R848-conjugated amphiphilic polymer (mPEG-TK-R848) and a hydrophobic oxidized bovine serum albumin (BSA-SOH)-conjugatable photosensitizer (DIR). DIR NPs may generate a small amount of 1O2 under 808nm laser irradiation, leading to the cleavage of thioketal (TK) moiety and release of R848 and DIR. The released DIR may conjugate with tumor-overexpressed BSA-SOH, improving its photodynamic efficiency and NIR-II fluorescence signal. Such photodynamic efficiency improvement may further enhance the release of cargoes upon irradiation. The activated photodynamic effect induces immunogenic cell death (ICD) to release immune factors and R848 can enhance the maturation of dendritic cells for inhibiting the growth of both primary and distant tumors and eliminating lung metastasis. Therefore, this study provides a dual-activatable intelligent nano-immunomodulator for precise regulation of tumor photodynamic immunotherapy.

Simple theranostics nanoagent for precision suppression of tumor growth and metastasis: A traditional fermented product having a novel functional breakthrough

Biomass-based nanoagents constitute a focal point in the clinical development of tumor nanotheranostics, characterized by their high biocompatibility, biodegradability, controllability, and sustainability. However, achieving satisfactory nanoagents with biological safety and high theranostic efficacy for clinical translation remains a significant challenge. Herein, based on the design concept of medicine food homology, we developed a simple, mass-produced theranostics nanoagent (HSAVMn@CM NA) using Shanxi aged vinegar (SAV) as the raw material, enabling second near-infrared fluorescence/photoacoustic (NIR-II FL/PA) imaging-guided photo/catalytic/chemodynamic synergistic tumor therapy. A novel strategy involving the hydrolysis of SAV (HSAV) via the hydrolysis-acidification method has been developed to enhance NIR-II FL imaging performance. The HSAVMn@CM NAs have improved tumor-targeted efficiency through biomimetic modification of tumor membranes. Guided by NIR-II FL/PA dual-modal imaging, the HSAVMn@CM NAs achieve targeted photothermal/photodynamic synergistic phototherapy. Notably, the employment of a single laser source for simultaneous photothermal/photodynamic therapy has led to an enhancement in the efficacy of phototherapy. Moreover, the HSAVMn@CM NAs effectively chelated Zn2+ ions within the tumor microenvironment, to inhibit matrix metalloproteinase 2/9 (MMP 2/9) activity, thereby synergistically suppressing primary tumor growth and metastasis. Taken together, this research provides a novel design strategy for biomass-based nanoagents with potential clinical translation in precise tumor theranostics.

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.

A NIR-II Organic Dendrimer with Superb Photothermal Performance Based on Electron-Donor Iteration for Photothermal Immunotherapy.

Organic photothermal materials have attracted extensive attention due to their designable molecular structure, tunable excited-state properties, and excellent biocompatibility, however, the development of near-infrared II (NIR-II) absorbingorganic photothermal materials with high photothermal conversion efficiency (PTCE) and molar extinction coefficient (ɛ) remains challenging. Herein, a novel "electron-donor iteration" strategy is proposed to construct organic photothermal dendrimers (CR-DPA-T, CR-(DPA)2-T and CR-(DPA)3-T) with donor-π-acceptor-π-donor (D-π-A-π-D) features and diradical characteristics. Owing to the enhanced D-A effect and intramolecular motions, their absorption and photothermal capacity increase as the generation grows. Surprisingly, an excellent photothermal performance (ɛ1064 ×PTCE1064) with a superb value of 2.85×104 in the NIR-II region is achieved for CR-(DPA)3-T nanoparticles (CR-(DPA)3-T NPs) compared to most reported counterparts. Besides, CR-(DPA)3-T NPs exhibit superior antitumor efficacy by the synergistic effect of photothermal therapy (PTT)and immunotherapy, efficiently inhibiting the growth of both primary and distant tumors. To the best knowledge, organic photothermal dendrimer is for the first time reported, and a universal donor engineering strategy is offered to develop NIR-II-absorbing organic photothermal materials for photothermal immunotherapy.

Association of Granulocyte Colony-Stimulating Factor Treatment with Risk of Brain Metastasis in Advanced Stage Breast Cancer.

The routine use of granulocyte colony-stimulating factor (GCSF) is not recommended for the prevention or treatment of chemotherapy-induced neutropenia or febrile neutropenia because risks associated with certain types of cancers, distant organ metastases, and primary tumor growth cannot be excluded. We examined the association between GCSF use and the incidence of brain metastasis (BM), as well as BM-free survival (BMFS). This retrospective cohort study included 121 stage IV breast cancer patients without confirmed BM at the time of diagnosis and who received at least one course of systematic chemotherapy or target therapy at a tertiary teaching hospital between 1 January 2014 and 31 December 2022. The effect of GCSF use on BM was assessed with other confounding factors in Cox regression analyses. In this retrospective cohort, patients who received GCSF treatment had a significantly higher incidence of BM than those who did not (34.9% vs. 13.8%, p = 0.011). Univariate Cox regression analysis showed that GCSF use, menopause status, hormone treatment, HER2 treatment, cumulative dosage, dosage density, and neutropenia were independent risk factors for BMFS (p < 0.05). GCSF users had a higher risk of BM (adjusted HR: 2.538; 95% CI: 1.127-5.716, p = 0.025) than nonusers. BM risk was significantly associated with those with neutropenia (RR: 1.84, 95% CI: 1.21, 2.80) but not with those without neutropenia (RR: 0.59, 95% CI: 0.41-0.84, Interaction p-value < 0.05). The higher the dose density of GCSF, the higher the risk compared with those who do not use GCSF (p for trend < 0.01). These preliminary results suggest that GCSF is associated with BM in patients with stage IV breast cancer who did not have BM at initial diagnosis. Further comprehensively designed large-scale observational studies are needed to confirm our preliminary results.

7076 Inhibiting Oxidosqualene Cyclase, An Enzyme In The Cholesterol Biosynthetic Pathway, Suppresses Lung Metastasis Of Triple-Negative Breast Cancer Cells

Abstract Disclosure: Y. Liang: None. S.M. Hyder: None. Triple-negative breast cancers (TNBC) lack ER, PR and Her2neu proteins that are commonly targeted in breast cancer therapies. As a consequence, women who suffer from TNBC have poor prognosis and limited treatment options, and are usually administered toxic, non-specific chemotherapeutic agents. Drug-resistance almost always occurs, leading to tumor metastasis, the main cause of patient death. New non-toxic therapeutic strategies to control metastasis of TNBC are urgently needed. Cholesterol is an essential structural and functional component of cell membranes that is necessary for the growth of both primary tumors and metastatic colonies that reside in distant organs. Therefore, inhibiting cholesterol production is an attractive therapeutic strategy. Treatment with statins, a class of cholesterol biosynthesis inhibitors that target HMGCoA-reductase, is associated with certain undesirable side effects; consequently, we targeted oxidosqualene cyclase (OSC), an enzyme that occurs downstream of HMGCoA-reductase in the cholesterol biosynthetic pathway, to disrupt tumor metastasis. Potent small molecule inhibitors of OSC have been identified. RO 48-8071 (4′-[6-(allylmethylamino)hexyloxy]-4-bromo-2′-fluorobenzophenone fumarate) (RO), has emerged as a useful chemotherapeutic agent for treating several forms of primary tumors. We developed a mouse model for studying lung metastasis using a MDA-MB-231 variant (LM2) TNBC cell line obtained from Dr. Massagué (Memorial Sloan-Kettering Cancer Center). These are aggressive cells, and injection of only 2 X 105 cells produces detectable lung metastatic colonies in approximately 4-6 weeks. We inoculated female nu/nu mice, 5-6 weeks old, with 2 X 105 MDA-MB-231/LM2 cells in 0.1 ml DMEM/F12 medium without serum via tail vein. Five days after tumor cell inoculation animals received 20 mg/kg (n=6), 40 mg/kg (n=7) RO (ip) or vehicle alone (n=7) every other day for two weeks. Animals were then sacrificed, and both lungs harvested and immediately fixed in Bouin’s fixative. Metastatic colonies on the lung surface were identified and counted under a dissecting microscope. Our study showed that RO effectively reduced lung metastasis without affecting animal weight. Compared with 56 + 7 colonies (Mean ± SEM) in controls given vehicle alone, RO significantly reduced lung metastatic colonies to 28 ± 5 in animals exposed to 20 mg/kg and 6 ± 1 in 40 mg/kg treated animals (p&amp;lt;0.05, ANOVA). Reduction in number of colonies in 40 mg/kg group was also significantly different from colonies counted in 20 mg/kg treated animals. Our study is the first to demonstrate that disruption of cholesterol biosynthesis in a model of human TNBC leads to reduced metastasis in lungs. Further studies will determine mechanisms through which RO suppresses TNBC metastasis to the lungs. Supported by Zalk Missouri Professor Endowment Funds. Presentation: 6/3/2024

7076 Inhibiting Oxidosqualene Cyclase, an Enzyme in the Cholesterol Biosynthetic Pathway, Suppresses Lung Metastasis of Triple-negative Breast Cancer Cells

Abstract Disclosure: Y. Liang: None. S.M. Hyder: None. Triple-negative breast cancers (TNBC) lack ER, PR and Her2neu proteins that are commonly targeted in breast cancer therapies. As a consequence, women who suffer from TNBC have poor prognosis and limited treatment options, and are usually administered toxic, non-specific chemotherapeutic agents. Drug-resistance almost always occurs, leading to tumor metastasis, the main cause of patient death. New non-toxic therapeutic strategies to control metastasis of TNBC are urgently needed. Cholesterol is an essential structural and functional component of cell membranes that is necessary for the growth of both primary tumors and metastatic colonies that reside in distant organs. Therefore, inhibiting cholesterol production is an attractive therapeutic strategy. Treatment with statins, a class of cholesterol biosynthesis inhibitors that target HMGCoA-reductase, is associated with certain undesirable side effects; consequently, we targeted oxidosqualene cyclase (OSC), an enzyme that occurs downstream of HMGCoA-reductase in the cholesterol biosynthetic pathway, to disrupt tumor metastasis. Potent small molecule inhibitors of OSC have been identified. RO 48-8071 (4′-[6-(allylmethylamino)hexyloxy]-4-bromo-2′-fluorobenzophenone fumarate) (RO), has emerged as a useful chemotherapeutic agent for treating several forms of primary tumors. We developed a mouse model for studying lung metastasis using a MDA-MB-231 variant (LM2) TNBC cell line obtained from Dr. Massagué (Memorial Sloan-Kettering Cancer Center). These are aggressive cells, and injection of only 2 X 10[5] cells produces detectable lung metastatic colonies in approximately 4-6 weeks. We inoculated female nu/nu mice, 5-6 weeks old, with 2 X 10[5] MDA-MB-231/LM2 cells in 0.1 ml DMEM/F12 medium without serum via tail vein. Five days after tumor cell inoculation animals received 20 mg/kg (n=6), 40 mg/kg (n=7) RO (ip) or vehicle alone (n=7) every other day for two weeks. Animals were then sacrificed, and both lungs harvested and immediately fixed in Bouin’s fixative. Metastatic colonies on the lung surface were identified and counted under a dissecting microscope. Our study showed that RO effectively reduced lung metastasis without affecting animal weight. Compared with 56 + 7 colonies (Mean ± SEM) in controls given vehicle alone, RO significantly reduced lung metastatic colonies to 28 ± 5 in animals exposed to 20 mg/kg and 6 ± 1 in 40 mg/kg treated animals (p&amp;lt;0.05, ANOVA). Reduction in number of colonies in 40 mg/kg group was also significantly different from colonies counted in 20 mg/kg treated animals. Our study is the first to demonstrate that disruption of cholesterol biosynthesis in a model of human TNBC leads to reduced metastasis in lungs. Further studies will determine mechanisms through which RO suppresses TNBC metastasis to the lungs. Supported by Zalk Missouri Professor Endowment Funds. Presentation: 6/3/2024

An Exogenous Ketone Ester Slows Tumor Progression in Murine Breast and Renal Cancer Models.

Ketone esters (KEs) exhibit promise as anti-cancer agents but their impact on spontaneous metastases remains poorly understood. Although consumption of a ketogenic diet (KD) that is low in carbohydrates and high in fats can lead to KE production in vivo, the restrictive composition of KDs may diminish adherence in cancer patients. We investigated the effects of an exogenous ketone ester-supplemented (eKET), carbohydrate-replete diet on tumor growth, metastasis, and underlying mechanisms in orthotopic models of metastatic breast (4T1-Luc) and renal (Renca-Luc) carcinomas. Mice were randomized to diet after tumor challenge. Administration of KEs did not alter tumor cell growth in vitro. However, in mice, our eKET diet increased circulating β-hydroxybutyrate and inhibited primary tumor growth and lung metastasis in both models. Body composition analysis illustrated the overall safety of eKET diet use, although it was associated with a loss of fat mass in mice with renal tumors. Immunogenetic profiling revealed divergent intratumoral eKET-related changes by tumor type. In mammary tumors, Wnt and TGFβ pathways were downregulated, whereas in renal tumors, genes related to hypoxia and DNA damage repair were downregulated. Thus, our eKET diet exerts potent antitumor and antimetastatic effects in both breast and renal cancer models, albeit with different modes of action and physiologic effects. Its potential as an adjuvant dietary approach for patients with diverse cancer types should be explored further.

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.

High-grade serous ovarian cancer development and anti-PD-1 resistance is driven by IRE1α activity in neutrophils

ABSTRACT High-grade serious ovarian cancer (HGSOC) is an aggressive malignancy that remains refractory to current immunotherapies. While advanced stage disease has been extensively studied, the cellular and molecular mechanisms that promote early immune escape in HGSOC remain largely unexplored. Here, we report that primary HGSO tumors program neutrophils to inhibit T cell anti-tumor function by activating the endoplasmic reticulum (ER) stress sensor IRE1α. We found that intratumoral neutrophils exhibited overactivation of ER stress response markers compared with their counterparts at non-tumor sites. Selective deletion of IRE1α in neutrophils delayed primary ovarian tumor growth and extended the survival of mice with HGSOC by enabling early T cell-mediated tumor control. Notably, loss of IRE1α in neutrophils sensitized tumor-bearing mice to PD-1 blockade, inducing HGSOC regression and long-term survival in ~ 50% of the treated hosts. Hence, neutrophil-intrinsic IRE1α facilitates early adaptive immune escape in HGSOC and targeting this ER stress sensor might be used to unleash endogenous and immunotherapy-elicited immunity that controls metastatic disease.

Multi-Metallic Nanosheets Reshaping Immunosuppressive Tumor Microenvironment through Augmenting cGAS-STING Innate Activation and Adaptive Immune Responses for Cancer Immunotherapy.

The highly immunosuppressive tumor microenvironment (TME) restricts the efficient activation of immune responses. To restore the surveillance of the immune system for robust activation, vast efforts are devoted to normalizing the TME. Here, a manganese-doped layered double hydroxide (Mn-LDH) is developed for potent anti-tumor immunity by reversing TME. Mn-LDH is synthesized via a one-step hydrothermal method. In addition to the inherent proton neutralization capacity of LDH, the introduction of manganese oxide endows LDH with an additional ability to produce oxygen. Mn-LDH effectively releases Mn2+ and Mg2+ upon exposure to TME with high levels of H+ and H2O2, which activates synthase-stimulator of interferon genes pathway and maintains the cytotoxicity of CD8+ T cells respectively, achieving a cascade-like role in innate and adaptive immunity. The locally administered Mn-LDH facilitated a "hot" network consisting of mature dendritic cells, M1-phenotype macrophages, as well as cytotoxic and helper T cells, significantly inhibiting the growth of primary and distal tumors. Moreover, the photothermal conversion capacity of Mn-LDH sparks more robust therapeutic effects in large established tumor models with a single administration and irradiation. Overall, this study guides the rational design of TME-modulating immunotherapeutics for robust immune activation, providing a clinical candidate for next-generation cancer immunotherapy.

Injectable hydrogel assisted formation of hydroxyl radical generating bioreactor enables photothermally enhanced chemodynamic and immunotherapy

Photothermal therapy and chemodynamic therapy (CDT), two recently invented cancer treatments, have shown to be effective in potentiating immunotherapy through causing immunogenic cancer cell death. The rational integration of these two therapeutic modalities poses a formidable challenge in eliciting robust immunotherapy. Herein, an injectable hydrogel based bioreactor comprising of glucose oxidase (GOx), copper sulfide (CuS) nanoparticles, and poly (ethylene glycol) double acrylate (PEGDA) is prepared to potentiate immune checkpoint blockade (ICB) therapy. GOx can in situ convert glucose to hydrogen peroxide (H2O2) and gluconic acid, the latter of which further promotes the decomposition of H2O2 to hydroxyl radicals by creating an acidic microenvironment to benefit the pH-dependent Fenton-like catalytic reaction of Cu+, particularly in synergizing with near infrared (NIR) light exposure. Such catalytic couple of GOx and CuS together with NIR light exposure is efficient in inducing immunogenic cancer cell death. Additionally, GOx reprogrammed tumor immunosuppressive microenvironment by reducing lactate levels. Upon being fixed inside tumors with PEGDA hydrogel, such in situ formed bioreactor effectively suppresses the growth of 4T1 orthotopic murine breast cancers in Balb/c mice together with 808 nm laser exposure. Furthermore, such bioreactor enabled photothermally enhanced CDT could also synergize with anti-PD-L1 immunotherapy to more effectively suppress the growth of primary tumors and distant tumors. This study highlights that such NIR light and reactive oxygen species dual responsive bioreactor is robust to potentiate ICB immunotherapy.