Alter Tumor Growth Research Articles

Abstract 161: Myocardial Infarction Accelerates Melanoma Tumor Progression

Adult survivors of cancer are at increased risk of cardiovascular disease (CVD). Indeed, while CVD emerges as the second leading cause of death in recovering cancer patients, cross-disease communication remains poorly understood. We previously demonstrated that myocardial infarction (MI) accelerates breast cancer tumor growth and cancer-specific mortality in mice and humans. However, whether MI alters tumor growth of other cancer types and impacts metastasis is not known. To assess these gaps, we examined the effect of acute MI, induced by ligation of the left anterior descending (LAD) coronary artery, in syngeneic C57BL6 mouse models of primary and metastatic melanoma. Compared to sham surgery, LAD ligation resulted in a two-fold increase in tumor growth in both the B16 and YUMM melanoma models. Notably, tumor burden significantly correlated with the size of the infarct, suggesting a direct relationship between injury signal activation and disease progression. Analysis of the intratumoral immune cell landscape by flow cytometry revealed an enrichment of immunosuppressive CD4 + FoxP3 + T regulatory cells after MI, and systemic depletion of FoxP3 + cells attenuated MI-induced tumor growth. Finally, histological analysis and magnetic resonance imaging revealed an increase in the number and size of metastatic foci in the liver after MI compared to sham. Our data suggest that MI dampens antitumor immunity and reorganizes the tumor microenvironment to exacerbate tumor progression via infiltration of immunosuppressive FoxP3 + T cells. Collectively, these findings of deleterious cross-disease communication underscore the importance of implementing strategies that mitigate CVD risk in cancer patients.

Vascular Endothelial Growth Factor (VEGF) and Its Role in the Progression and Development of Breast Tumor

Breast cancer is the most common type of cancer in women and is widely known. Angiogenesis is the process through which new blood vessels develop from the body's current vascular system. It is essential for tumor growth, invasiveness, and metastasis, and so plays a pivotal role in the development of carcinoma. Proteolytic and proangiogenic catalyst activators and inhibitors regulate angiogenesis in a hierarchical fashion. The angiogenic process is largely under the direction of VEGF. In a select number of malignant tumors, the VEGF gene is overexpressed. The function of VEGF in angiogenesis has been the subject of intensive study in recent years. In breast cancer patients, VEGF plasma levels are highly predictive of tumor growth and survival. Several VEGF gene polymorphisms, have been identified to affect gene expression level in prior investigations. Epidemiological studies have linked polymorphisms in the VEGF gene to altered cancer risk, tumor growth, and metastasis. Previous research on VEGF polymorphism to evaluate the association between genes and breast cancer susceptibility was scant. The current review discusses the role of VEGF in the progression of breast cancer in addition to its promising usage as a predictive marker for breast cancer.

Abstract 3981: Immune targeting progesterone receptor in hormone receptor positive breast cancer

Abstract Background: Hormone receptor positive (HR⁺) breast cancer (BC) is a subtype of BC that is characterized by expression of estrogen receptor (ER) and progesterone receptor (PR). A cornerstone treatment for this subtype of BC is endocrine inhibition therapy (EIT), in which estrogen and ER are suppressed using antagonists to suppress tumor growth. However, patients eventually obtain resistance to EIT. Metastatic HR⁺BC is the deadliest form of BC, with no cure. Current therapies currently only utilize the ER-axis, with no PR-targeted therapies. Little is known about the role of PR in these BCs, but we have found evidence for an immunosuppressive role for PR in HR⁺BC. Yet, it is unclear how PR mediates immunosuppression and if this axis can be therapeutically targeted. We hypothesized that PR confers local immunosuppression through the stimulation of immunosuppressive transcriptional activity and that we can immunologically target this axis using a PR vaccine. Experimental methods: To assess the immune impact of PR, we expressed the isoforms of PR (A, B and A+B) in mouse mammary cancer cells and assessed their capacity to elicit PR signaling. We assessed the impact of PR expression on T cell activity in targeting PR⁺ mammary tumors that express GFP, along with using GFP-specific JEDI CD8⁺ T cells. We explored the ability of PR to protect against GFP xenoantigen immune responses by engrafting PR⁺ mammary cells into immune competent and deficient mice. Lastly, we engineered 1st generation adenoviral vectors encoding mouse and human PR and utilized two antiprogestins (Mifepristone and Onapristone) in vivo. Using our vectors, we vaccinated BALB/c in the footpad and assessed PR-specific immunity using IFNγ ELISPOT. Results: Using PR signaling reporters, we found canonical PR signaling activity in the absence of progesterone (P4) by PR-A and in the presence of P4 by PR-B, but the most profound activation of PR signaling was seen through combined expression of PR-A and B. While expression of these genes did not confer striking cytotoxic T cell resistance in vitro, combination of PR-A+PR-B in 67NR cells permitted successful tumor engraftment in immune competent mice, despite xenoantigen expression. GFP expression did not alter tumor growth in immunodeficient mice, suggesting a key role in modulating local anti-tumor immunity. The use of either Mifepristone or Onapristone significantly suppressed tumor engraftment in immune competent mice in vivo. We found that an Ad-PR vaccine could elicit T cell responses against human PR-specific epitopes, a potential step towards immune targeting these BCs. Conclusions: We found that murine PR-A and PR-B can confer robust P4 signaling that is linked to an immunosuppressive phenotype in vivo. We developed a PR vaccine that elicited PR-specific T cell responses in vivo. We are currently examining the mechanisms that underlie PR-mediated immunosuppression and exploring the potential of PR vaccines in HR⁺BC. Citation Format: Andrea E. Wilson, Junping Wei, Gangjun Lei, Xiao-Yi Yang, Cong-Xiao Liu, Melissa Gajda, Tao Wang, Christy Hagan, Zachary C. Hartman. Immune targeting progesterone receptor in hormone receptor positive breast 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 3981.

Cancer-associated adipocytes in the ovarian cancer microenvironment.

The tumor microenvironment (TME) plays a critical role in high energy metabolism during tumorigenesis, progression and metastasis. Among them, adipocytes, as an important component of the TME, can transform into cancer-associated adipocytes (CAAs) through dedifferentiation via interactions with tumor cells. These CAAs provide nutrients, growth factors, cytokines and metabolites to the tumor and later transdifferentiate into other stromal cells at a later stage to alter tumor growth, metastasis and the drug response and ultimately influence the treatment and prognosis of ovarian cancer. This review outlines the physiological functions of CAAs and discusses the progress in the use of CAAs as therapeutic targets in ovarian cancer.

Protein kinase C delta regulates mononuclear phagocytes and hinders response to immunotherapy in cancer.

Mononuclear phagocytes (MPs) play a crucial role in tissue homeostasis; however, MPs also contribute to tumor progression and resistance to immune checkpoint blockade (ICB). Targeting MPs could be an effective strategy to enhance ICB efficacy. We report that protein kinase C delta (PKCδ), a serine/threonine kinase, is abundantly expressed by MPs in human and mouse tumors. PKCδ-/- mice displayed reduced tumor progression compared to wild types, with increased response to anti-PD-1. Tumors from PKCδ-/- mice demonstrated TH1-skewed immune response including increased antigen presentation and T cell activation. Depletion of MPs in vivo altered tumor growth in control but not PKCδ-/- mice. Coinjection of PKCδ-/- M2-like macrophages with cancer cells into wild-type mice markedly delayed tumor growth and significantly increased intratumoral T cell activation compared to PKCδ+/+ controls. PKCδ deficiency reprogrammed MPs by activating type I and type II interferon signaling. Thus, PKCδ might be targeted to reprogram MPs to augment ICB efficacy.

Abstract A072: Ghrelin deletion reduces mammary tumor growth and enhances response to immunotherapy

Abstract Ghrelin is a peptide hormone, primarily produced in the stomach, best known for its role as a regulator of nutrient sensing, appetite, and meal initiation. However, increasing evidence supports a more complex and nuanced role for ghrelin in a diverse array of biological processes, including cancer. Ghrelin’s effects on breast cancer development and progression are not clear, as the literature detailing its effects is conflicting. Several studies in breast cancer survivors have concluded that higher expression of ghrelin is correlated with better recurrence-free and breast cancer-specific survival. However, additional clinical and foundational science studies have suggested greater complexity for ghrelin’s role in breast cancer development as a splice variant of ghrelin, namely In1-ghrelin, is associated with increased tumor proliferation and reduced disease-free survival of breast cancer patients. Thus, the current study sought to determine the effects of ghrelin deletion within mammary tumor cells (67NR) on subsequent tumor growth. Specifically, we hypothesized that ghrelin deletion would significantly alter tumor growth. Adult female mice received bilateral orthotopic injections of the nonmetastatic murine breast carcinoma cell line 67NR or one of two CRISPR generated ghrelin deleted cell lines 1G9 or 2G2 (derived from the 67NR cell line). Ghrelin deletion significantly reduced tumor volume and tumor mass by ~60% and ~55%, respectively. Additionally, ghrelin deletion significantly increased median survival duration by ~30%. When examining changes within the tumor microenvironment we observed a significant increase in macrophage colonization in ghrelin knockouts relative to the parental 67NR tumors. Notably, the percent F4/80 staining within the tumor positively correlated with length of survival. To determine the role of these F4/80 cells on tumor progression, we ablated these macrophages by feeding chow containing the colony stimulating factor receptor 1 inhibitor, PLX5622, for the entirety of the study. Ablating macrophages significantly increased tumor volume and tumor mass and rendered the previous beneficial effects of ghrelin deletion null, suggesting that the positive effects of ghrelin deletion may be due to actions on macrophages. Lastly, because of the increased macrophage infiltration within ghrelin knockout tumors, we sought to determine their repose to an immunotherapy targeting macrophages, namely anti-CD47. Notably, ghrelin deleted tumors displayed a positive response to the immunotherapy and further reduction in tumor growth (~80% reduction in tumor volume compared to 67NR tumors). Whereas, 67NR tumors were unresponsive to the immunotherapy. These data add to the literature detailing the complex effects of ghrelin on tumor growth and suggest that ghrelin may be a druggable target to slow tumor development. Citation Format: William H Walker II, Brittany D Elliott, Claire O Kisamore, Randy J Nelson, A. Courtney DeVries. Ghrelin deletion reduces mammary tumor growth and enhances response to immunotherapy [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A072.

Multi-Functional Regulation by YAP/TAZ Signaling Networks in Tumor Progression and Metastasis.

The Hippo pathway transcriptional co-activators, YES-associated protein (YAP) and Transcriptional Co-Activator with PDZ Binding Motif (TAZ), have both been linked to tumor progression and metastasis. These two proteins possess overlapping and distinct functions, and their activities lead to the expression of genes involved in multiple cellular processes, including cell proliferation, survival, and migration. The dysregulation of YAP/TAZ-dependent cellular processes can result in altered tumor growth and metastasis. In addition to their well-documented roles in the regulation of cancer cell growth, survival, migration, and invasion, the YAP/TAZ-dependent signaling pathways have been more recently implicated in cellular processes that promote metastasis and therapy resistance in several solid tumor types. This review highlights the role of YAP/TAZ signaling networks in the regulation of tumor cell plasticity mediated by hybrid and reversible epithelial-mesenchymal transition (EMT) states, and the promotion of cancer stem cell/progenitor phenotypes. Mechanistically, YAP and TAZ regulate these cellular processes by targeting transcriptional networks. In this review, we detail recently uncovered mechanisms whereby YAP and TAZ mediate tumor growth, metastasis, and therapy resistance, and discuss new therapeutic strategies to target YAP/TAZ function in various solid tumor types. Understanding the distinct and overlapping roles of YAP and TAZ in multiple cellular processes that promote tumor progression to metastasis is expected to enable the identification of effective therapies to treat solid tumors through the hyper-activation of YAP and TAZ.

Investigating the Potential of Cuboidal Nanometals as Protein Subunit Vaccine Carriers In Vivo

AbstractMetal nanoparticles (NPs) are suggested as a vaccine delivery platform. At present, there is limited description of cuboidal Ag nanocubes (AgNCs; nonporous) and Au nanocages (AuNCs; porous) as a protein carrier for vaccination. Here, the intrinsic protein binding ability of AgNC and AuNC is first investigated, using ovalbumin (OVA) as a model antigen, to determine its suitability as a vaccine carrier. Next, the effect of AgNCs and AuNCs on bone‐marrow‐derived dendritic cells (BMDCs) is assessed in vitro. Finally, in vivo humoral and cellular immune responses of AgNC–OVA and AuNC–OVA following intramuscular immunization and their prophylactic effects in B16F10‐OVA mice tumor model are investigated. In terms of OVA loading efficiency, AgNCs are superior to AuNCs. Both nanomaterials are found not to induce BMDC maturation at subtoxic doses. After administration of nanovaccines, serum immunoglobulin G (IgG) responses are comparable between groups. However, there are slight alterations in relative frequencies of lymphocyte subpopulations, with AgNC–OVA‐immunized mice exhibiting lower memory T cells and reduced B cell and T follicular helper cell populations in spleen. Overall, AgNC–OVA and AuNC–OVA immunizations do not alter tumor growth. This study characterizes the intrinsic immunomodulatory properties of AgNCs and AuNCs, as protein subunit vaccine carriers.

Tumor-localized catalases can fail to alter tumor growth and transcriptional profiles in subcutaneous syngeneic mouse tumor models

Catalase is an antioxidant enzyme that catalyzes the rapid conversion of hydrogen peroxide to water and oxygen. Use of catalase as a cancer therapeutic has been proposed to reduce oxidative stress and hypoxia in the tumor microenvironment, both activities which are hypothesized to reduce tumor growth. Furthermore, exposing murine tumors to exogenous catalase was previously reported to have therapeutic benefit. We studied the therapeutic effect of tumor-localized catalases with the aim to further elucidate the mechanism of action. To do this, we engineered two approaches to maximize intratumoral catalase exposure: 1) an injected extracellular catalase with enhanced tumor retention, and 2) tumor cell lines that over-express intracellular catalase. Both approaches were characterized for functionality and tested for therapeutic efficacy and mechanism in 4T1 and CT26 murine syngeneic tumor models. The injected catalase was confirmed to have enzyme activity >30,000 U/mg and was retained at the injection site for more than one week in vivo. The engineered cell lines exhibited increased catalase activity and antioxidant capacity, with catalase over-expression that was maintained for at least one week after gene expression was induced in vivo. We did not observe a significant difference in tumor growth or survival between catalase-treated and untreated mice when either approach was used. Finally, bulk RNA sequencing of tumors was performed, comparing the gene expression of catalase-treated and untreated tumors. Gene expression analysis revealed very few differentially expressed genes as a result of exposure to catalase and notably, we did not observe changes consistent with an altered state of hypoxia or oxidative stress. In conclusion, we observe that sustained intratumoral catalase neither has therapeutic benefit nor triggers significant differential expression of genes associated with the anticipated therapeutic mechanism in the subcutaneous syngeneic tumor models used. Given the lack of effect observed, we propose that further development of catalase as a cancer therapeutic should take these findings into consideration.

Non-Canonical Activin A Signaling Stimulates Context-Dependent and Cellular-Specific Outcomes in CRC to Promote Tumor Cell Migration and Immune Tolerance.

We have shown that activin A (activin), a TGF-β superfamily member, has pro-metastatic effects in colorectal cancer (CRC). In lung cancer, activin activates pro-metastatic pathways to enhance tumor cell survival and migration while augmenting CD4+ to CD8+ communications to promote cytotoxicity. Here, we hypothesized that activin exerts cell-specific effects in the tumor microenvironment (TME) of CRC to promote anti-tumoral activity of immune cells and the pro-metastatic behavior of tumor cells in a cell-specific and context-dependent manner. We generated an Smad4 epithelial cell specific knockout (Smad4-/-) which was crossed with TS4-Cre mice to identify SMAD-specific changes in CRC. We also performed IHC and digital spatial profiling (DSP) of tissue microarrays (TMAs) obtained from 1055 stage II and III CRC patients in the QUASAR 2 clinical trial. We transfected the CRC cells to reduce their activin production and injected them into mice with intermittent tumor measurements to determine how cancer-derived activin alters tumor growth in vivo. In vivo, Smad4-/- mice displayed elevated colonic activin and pAKT expression and increased mortality. IHC analysis of the TMA samples revealed increased activin was required for TGF-β-associated improved outcomes in CRC. DSP analysis identified that activin co-localization in the stroma was coupled with increases in T-cell exhaustion markers, activation markers of antigen presenting cells (APCs), and effectors of the PI3K/AKT pathway. Activin-stimulated PI3K-dependent CRC transwell migration, and the in vivo loss of activin lead to smaller CRC tumors. Taken together, activin is a targetable, highly context-dependent molecule with effects on CRC growth, migration, and TME immune plasticity.

Anti‑tumor effects of an aqueous extract of Eckloniacava in BALB/cKorl syngeneic mice using colon carcinoma CT26 cells.

Eckloniacava (E.cava) is well known as one of edible alga that contains various unique polyphenols. The anti‑tumor activity of an aqueous extract of E.cava (AEC) against colon carcinoma was evaluated by analyzing the alterations in tumor growth, histopathological structure and molecular mechanisms in CT26 tumor‑bearing BALB/cKorl syngeneic mice after administrating AEC for five weeks. AEC contained high total phenolic contents and demonstrated significant scavenging activity against 2,2‑diphenyl‑1‑picrylhydrazyl radicals. Marked anti‑tumor effects were demonstrated in the AEC‑treated CT26 cells. In the invivo syngeneic model, the AEC treatment decreased the volume and weight of CT26 tumors, and expanded the necrotic region in the hematoxylin and eosin stained tumor sections. The inhibitory effects of AEC on tumor growth were reflected by the increased level of apoptotic proteins, inhibition of cell proliferation, suppression of metastasis ability and increase in tumor‑suppressing activity in CT26 tumor‑bearing BALB/cKorl syngeneic mice. The potential function of phlorotannin (PT), one of the primary active compounds in AEC, was demonstrated by the increased cytotoxicity, apoptosis and suppression of cell proliferation in PT‑treated CT26 cells. Overall, the results of the present study provide novel scientific evidence that AEC can suppress the growth of CT26 colon cancer by activating apoptosis, suppressing cell proliferation, inhibiting cell migration and enhancing the tumor‑suppressing activity.

Investigating the potential of silver nanocubes and gold nanocages as protein subunit vaccine carriers

Abstract Metal nanoparticles have been exploited as vaccine delivery platforms for various diseases. In particular, Ag and Au NPs of different size and shape have been shown to promote delivery of antigens and act as efficient adjuvants. Yet, there is limited description of cuboidal Ag nanocubes (AgNCs) and Au nanocages (AuNCs) as antigen carriers for vaccination. Here, we first investigated the intrinsic protein binding ability of AgNCs and AuNCs, using ovalbumin (OVA) as a model. Next, the effect of AgNCs and AuNCs on bone marrow-derived dendritic cells (BMDCs) in terms of cytotoxicity and maturation was assessed. Finally, we investigated humoral and cellular immune responses of AgNCs-OVA and AuNCs-OVA following intramuscular immunization and their prophylactic effects in B16F10-OVA mice tumor model. In terms of OVA loading efficiency, AgNCs were more potent than AuNCs, despite their non-porous form. Both cubic nanomaterials were found not to induce BMDCs maturation in vitro or DCs maturation in spleen. Following the administration of nanovaccine doses, serum IgG responses were comparable between groups. However, there were significant alterations in relative frequencies of lymphocyte sub-populations. Overall, AgNCs-OVA and AuNCs-OVA immunization via intramuscular route did not alter tumour growth. This study has demonstrated the intrinsic immunomodulatory properties of AgNCs and AuNCs, preceding their potential use as nanocarriers. Supported by grants from British Council (Newton Fund, 337313), Wellcome Trust (WT103913), and TUBITAK.

MP20-06 ATORVASTATIN WITH DEGARELIX MODULATES TUMOR PROLIFERATION AND THE PROSTATE TUMOR IMMUNE ENVIRONMENT IN A Myc-CaP/AS MURINE MODEL

You have accessJournal of UrologyCME1 Apr 2023MP20-06 ATORVASTATIN WITH DEGARELIX MODULATES TUMOR PROLIFERATION AND THE PROSTATE TUMOR IMMUNE ENVIRONMENT IN A Myc-CaP/AS MURINE MODEL Ashanda Esdaille, Bing Yang, Tanaya Purohit, Kayla Bahr, Ali Ghasemzadeh, Dagna Sheerar, Douglas McNeel, and David Jarrard Ashanda EsdailleAshanda Esdaille More articles by this author , Bing YangBing Yang More articles by this author , Tanaya PurohitTanaya Purohit More articles by this author , Kayla BahrKayla Bahr More articles by this author , Ali GhasemzadehAli Ghasemzadeh More articles by this author , Dagna SheerarDagna Sheerar More articles by this author , Douglas McNeelDouglas McNeel More articles by this author , and David JarrardDavid Jarrard More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003245.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Androgen deprivation therapy (ADT) exerts immunomodulatory effects and induces a unique phenotypic response that accumulating data suggests may be improved with the addition of standard medications. Prior studies have shown that ADT and metformin or statins improves oncologic outcomes versus ADT alone. We hypothesize that these outcomes may be due to the effects of statins and ADT in immune and prostate tumor modulation. We aim to investigate whether Atorvastatin±ADT alters tumor growth, proliferation, apoptosis and the immune infiltrate within myc-CaP/AS murine models. METHODS: FVB/NJ, immunocompetent mice were injected subcutaneously with 1x106 Myc-CaP/AS cells. Treatment was initiated at an average tumor volume of 400mm3. Groups were randomized into short term (5 days post ADT) and long term (10 days post) for a total of 8 mice per group per time period. Mice were injected i.p. with: 1) 5µg/g Atorvastatin, q2 days x 3 doses OR q2 days x 5 doses AND/OR 2) Degarelix 25µg/g x 1 dose OR 3) PBS i.p. for controls. Immunohistochemical staining, followed by flow cytometry, was performed using single cell suspensions of harvested tumors. Western blots were performed to assess expression of PCNA and CC3. RESULTS: ADT + Atorvastatin treated tumors had the greatest decrease in volume (Figure 1). Tumor volume differences were present between post-treatment Atorvastatin vs control (p=0.029) and post-treatment Degarelix +Atorvastatin vs control (p=0.018). On flow cytometric analysis, Atorvastatin-treated tumors had the greatest CD8 T-cell expansion over time. MDSC expression decreased significantly over time for ADT and ADT + Atorvastatin-treated tumors. Early ADT and ADT + Atorvastatin decreased tumor proliferation and late Atorvastatin increased apoptosis in myc-CaP/AS tumors. CONCLUSIONS: Atorvastatin+ADT combination therapy decreased tumor volume and tumor proliferation when compared to ADT or statin drug alone. Atorvastatin alone increased CD8 T-cell presence, important for cell death, and in combination with ADT, decreased MDSC expression, which impedes cancer cell death. Demonstrating synergy between androgen deprivation and immunomodulatory agents has to potential to shift the treatment paradigm in patients with high-risk prostate cancer. Source of Funding: AUA/UCF Grant# 017-822959 © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e277 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ashanda Esdaille More articles by this author Bing Yang More articles by this author Tanaya Purohit More articles by this author Kayla Bahr More articles by this author Ali Ghasemzadeh More articles by this author Dagna Sheerar More articles by this author Douglas McNeel More articles by this author David Jarrard More articles by this author Expand All Advertisement PDF downloadLoading ...

Caloric Restriction Ketogenic Diets (KR) Enhance Radiotherapy Responses in Lung Cancer Xenografts

<h3>Purpose/Objective(s)</h3> Dietary interventions can change metabolite levels in the tumor microenvironment, which might then affect cancer cell metabolism to alter tumor growth. Caloric restriction (CR) and ketogenic diet (KD) are often thought to limit tumor progression. <h3>Materials/Methods</h3> Mice bearing Lewis Lung Carcinoma xenografts were randomly divided into ad libitum diet group (AL), radiation group (RT), KR diet group (KR), or KR + RT group (KT). Mice in KR and KT group were fed a KR (KetoCal 4:1 fats: proteins+carbohydrates; 70% of total energy). Mice in RT and KT group were treated with radiation (4Gy*3f). Mice weights, tumor size, blood ketone levels and survival were monitored. <h3>Results</h3> Blood ketone levels were significantly higher for the mice consuming a KR diet compared to standard diet (3.2 mmol/L vs 0.8 mmol/L at week 3, P < .001). Some mice with KR diet lost a significant amount of weight (10%ཞ15% of starting weight) by the end of the treatment. The KR diets combined with radiation resulted in slower tumor growth in Lewis Lung Carcinoma xenografts and longer survival time (P < 0.05), relative to radiation alone. The KR diet also slowed tumor growth and prolonged survival (P < 0.05), relative to control. Hematological and pathological examinations indicated that the KR diet was safe and well tolerated, and no significant cardiac, hepatic and renal toxicity was observed. <h3>Conclusion</h3> Blood ketone levels were significantly higher for the mice consuming a KR diet compared to standard diet (3.2 mmol/L vs 0.8 mmol/L at week 3, P < .001). Some mice with KR diet lost a significant amount of weight (10%ཞ15% of starting weight) by the end of the treatment. The KR diets combined with radiation resulted in slower tumor growth in Lewis Lung Carcinoma xenografts and longer survival time (P < 0.05), relative to radiation alone. The KR diet also slowed tumor growth and prolonged survival (P < 0.05), relative to control. Hematological and pathological examinations indicated that the KR diet was safe and well tolerated, and no significant cardiac, hepatic and renal toxicity was observed.

Myeloperoxidase alters tumor growth in vitro and in vivo

Myeloperoxidase alters tumor growth in vitro and in vivo

ICAM-1 on Breast Cancer Cells Suppresses Lung Metastasis but Is Dispensable for Tumor Growth and Killing by Cytotoxic T Cells.

Breast tumors and their derived circulating cancer cells express the leukocyte β2 integrin ligand Intercellular adhesion molecule 1 (ICAM-1). We found that elevated ICAM-1 expression in breast cancer cells results in a favorable outcome and prolonged survival of breast cancer patients. We therefore assessed the direct in vivo contribution of ICAM-1 expressed by breast cancer cells to breast tumorigenesis and lung metastasis in syngeneic immunocompetent mice hosts using spontaneous and experimental models of the lung metastasis of the C57BL/6-derived E0771 cell line, a luminal B breast cancer subtype. Notably, the presence of ICAM-1 on E0771 did not alter tumor growth or the leukocyte composition in the tumor microenvironment. Interestingly, the elimination of Tregs led to the rapid killing of primary tumor cells independently of tumor ICAM-1 expression. The in vivo elimination of a primary E0771 tumor expressing the ovalbumin (OVA) model neoantigen by the OVA-specific OVA-tcr-I mice (OT-I) transgenic cytotoxic T lymphocytes (CTLs) also took place normally in the absence of ICAM-1 expression by E0771 breast cancer target cells. The whole lung imaging of these cells by light sheet microscopy (LSM) revealed that both Wild type (WT)- and ICAM-1-deficient E0771 cells were equally disseminated from resected tumors and accumulated inside the lung vasculature at similar magnitudes. ICAM-1-deficient breast cancer cells developed, however, much larger metastatic lesions than their control counterparts. Strikingly, the vast majority of these cells gave rise to intravascular tumor colonies both in spontaneous and experimental metastasis models. In the latter model, ICAM-1 expressing E0771- but not their ICAM-1-deficient counterparts were highly susceptible to elimination by neutrophils adoptively transferred from E0771 tumor-bearing donor mice. Ex vivo, neutrophils derived from tumor-bearing mice also killed cultured E0771 cells via ICAM-1-dependent interactions. Collectively, our results are a first indication that ICAM-1 expressed by metastatic breast cancer cells that expand inside the lung vasculature is involved in innate rather than in adaptive cancer cell killing. This is also a first indication that the breast tumor expression of ICAM-1 is not required for CTL-mediated killing but can function as a suppressor of intravascular breast cancer metastasis to lungs.

Abstract 254: Dietary fish oil and aspirin to augment anti-PD-1 immunotherapy in metastatic melanoma

Abstract Introduction: First line anti-PD-1 immune checkpoint inhibition (αPD-1 ICI) induces objective responses in less than 50% of metastatic melanoma patients. Aspirin (ASA) use is associated with improved responsiveness to ICI, with inhibition of myeloid-induced immunosuppression in the tumor microenvironment (TME) a purported mechanism. Cyclooxygenase modulators ASA (pharmacologic inhibitor) and dietary fish oil (FO, substrate) shift myeloid and T cell populations to anti-inflammatory, pro-resolution phenotypes in immunity and cancer. Methods: C57-BL6/J mice were injected with YUMM 1.7 melanoma in the flank. Mice were fed control chow and water (CTL) or omega-3 rich (FO) chow (10% w/w, 30%kcal/kcal), given ASA in drinking water (600 ug/mL), or FO/ASA combined (COMBO) starting 12 days post tumor implantation, the same day as starting intraperitoneal αPD1 or IgG2a vehicle (q3-4 days). An alternative cohort received pre-αPD-1 treatment ASA and FO starting day 7. Tumors were assessed for growth, harvested, and characterized via flow cytometry on day 32. Results: When diets and water were started concurrent with αPD-1/IgG2a, FO decreased tumor volume vs. CTL for both vehicle (28%) and αPD-1 (27%) treatments; ASA and COMBO (p = 0.0501) did not. Compared to CTL, FO and COMBO increased monocytes (CD45+, CD11b+, Ly6C+, Ly6G-) and PD-L1+ monocytes in the TME with no effect on tumor associated macrophages (TAMS); ASA decreased the percent of Arginase 1+, CD206+ TAMs. ASA increased PD1+ CD8 T cells, while COMBO increased CD4 and CD8 T cells including LAG3+ and PD1+ CD8 T cells. When diets and water were started on day 7, FO + αPD-1 decreased tumor volume (21%) vs. αPD-1 controls; ASA and COMBO did not. Compared to CTL, FO and COMBO similarly altered immune populations as above, with FO additionally increasing total CD3+ T-cells, PD-L1+ CD4 T cells, and PD-1+ CD8 T cells; COMBO increased dendritic cells (CD11c+, MHCII+, F4/80-). TAMS were not assessed. Results significant (p&amp;lt; 0.05) by ANOVA or t-test unless specified. Food eaten, water imbibed, and weight did not vary between groups. Conclusions: Dietary fish oil impaired in vivo melanoma tumor growth with and without αPD-1 ICI despite increases in classically deleterious monocyte populations, while aspirin decreased M2-like macrophages in the TME without alterations in tumor growth. Modulation of the cyclooxygenase axis may be a cost-effective method to skew TME immune populations to favor αPD-1 immunotherapy responses in metastatic melanoma. Citation Format: Alexander C. Chacon, Shuyang S. Qin, Alexa D. Melucci, Katherine M. Jackson, Paul R. Burchard, Yatee A. Dave, Rachel Jewell, Brian A. Belt, William Tabayoyong, David C. Linehan, Peter A. Prieto. Dietary fish oil and aspirin to augment anti-PD-1 immunotherapy in metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 254.

Caloric restriction ketogenic diets (KR) in relation to radiotherapy responses in lung cancer xenografts

e20528 Background: Dietary interventions can change metabolite levels in the tumour microenvironment, which might then affect cancer cell metabolism to alter tumour growth. Caloric restriction (CR) and ketogenic diet (KD) are often thought to limit tumour progression. The current study tests the hypothesis that caloric restriction ketogenic diets (KR) enhance radiotherapy responses in lung cancer xenografts. Methods: Mice bearing Lewis Lung Carcinoma xenografts were randomly divided into ad libitum diet group (AL), radiation group (RT), KR diet group (KR), or KR + RT group (KT). Mice in KR and KT group were fed a KR (KetoCal 4:1 fats: proteins+carbohydrates;70% of total energy). Mice in RT and KT group were treated with radiation (4Gy*3f). Mice weights, tumor size, blood ketone levels and survival were monitored. Results: Blood ketone levels were significantly higher for the mice consuming a KR diet compared to standard diet (3.2 mmol/L vs 0.8 mmol/L at week 3, P &lt; .001). Some mice with KR diet lost a significant amount of weight (10%～15% of starting weight) by the end of the treatment.The KR diets combined with radiation resulted in slower tumor growth in Lewis Lung Carcinoma xenografts and longer survival time (P &lt; 0.05), relative to radiation alone. The KR diet also slowed tumor growth and prolonged survival (P &lt; 0.05), relative to control. Hematological and pathological examinations indicated that the KR diet was safe and well tolerated, and no significant cardiac, hepatic and renal toxicity was observed. Conclusions: These results showed that a KR diet enhanced radiotherapy responses in lung cancer xenografts. Further studies are needed to address the mechanism of this diet intervention.

Abstract P5-12-10: A commensal’s exopolysaccharide inhibits breast cancer proliferation in vitro but promotes tumor growth in vivo

Abstract Background: Recent decades have started to realize the importance of the microbiome in cancer initiation, progression and response to therapy. Recent findings suggest that both the local and distal microbiome may influence tumor growth. Although many studies focused on the gut microbiome, the breast itself also possesses a unique microbiome which differs between healthy and breast cancer patients, and between tumor subtypes. However, it is poorly understood whether these bacteria in the gut or the breast microenvironment may interact with breast cancer cells and if that interaction alters tumor growth. Bacteria produce metabolites and other signaling molecules to alter the host’s response. We have identified and purified an exopolysaccharide (EPS) produced by the commensal bacterium Bacillus subtilis, which was shown to act directly on the host’s innate immune cells to protect against various inflammatory diseases. This study aims to investigate if, and how the bacterial product (EPS) alters proliferation and tumor growth of breast cancer cells.Methods: Cell proliferation of bulk cells was conducted on PBS or EPS treated breast cancer cells (T47D, MDA-MB-468, MDA-MB-453, HCC1428, BT549, MDA-MB-231, ZR-75-30, and MCF-7) using trypan blue exclusion and the XTT assay. Flow cytometry was used to assess apoptosis with Annexin V, and cell cycle progression with propidium iodide. Cancer stem cell survival was assessed using the mammosphere forming assay. CRISPR/Cas9-mediated knockout of the Toll-like-receptor 4 (TLR4) was used to assess the requirement of TLR4 signaling on EPS-mediated phenotypes. RNA-sequencing was performed on both EPS-sensitive and resistant breast cancer cell lines after treatment with PBS or EPS for 20 hours. T47D xenografts studies were performed in vivo using EPS pretreatment and continual treatment via i.p. injection.Results: EPS inhibited proliferation of some breast cancer cell lines (T47D, MDA-MB-468, MDA-MB-453, HCC1428) in a concentration dependent manner while having little effect on others (BT549, MDA-MB-231, ZR-75-30, MCF7). EPS acted via distinct mechanisms depending on the cell line, increasing apoptosis in MDA-MB-468 cells while inducing G0/G1 cell cycle arrest in T47D cells. Although EPS directly inhibited bulk cell proliferation, the cancer stem cell population of T47D cells was increased by EPS. EPS is known to require TLR4 signaling to modulate immune cells. CRISPR/Cas9 knockout of TLR4 demonstrated that it was not required for EPS-mediated inhibition of T47D breast cancer cells, suggesting a novel mechanism of action in this cell line. RNA-sequence analysis showed that EPS altered interferon signaling and cell cycle progression pathways. Interferon signaling activates the STAT family of transcription factors, and western blots confirmed that 3h of EPS treatment induced STAT1 phosphorylation and p21 accumulation, indicating that EPS activated this pathway. Contrary to in vitro proliferation data, in vivo results showed that EPS-treated cells formed significantly larger tumors compared to PBS controls (273mg vs 59mg). The slope of tumor growth was also significantly faster in the EPS-treated group. Conclusions: These findings demonstrated the multifacet of EPS’s effect on breast cancer cells. EPS inhibits the proliferation of certain breast cancer cells in vitro, possibly via activation of STAT1 and p21 signaling, but also increases survival of cancer stem cells and promotes more aggressive tumor growth in vivo. This highlights the complexity of the influence of commensal bacteria on breast cancer growth, which can be highly context-dependent. Deeper understanding of this complex interplay between the host-microbe-tumor will be vital to the development of novel bacterial strategies in the future. Citation Format: Mai Rachel Nguyen, Katherine L Knight, Clodia Osipo. A commensal’s exopolysaccharide inhibits breast cancer proliferation in vitro but promotes tumor growth in vivo [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-12-10.

Insulin-like Growth Factor-1 Influences Prostate Cancer Cell Growth and Invasion through an Integrin α3, α5, αV, and β1 Dependent Mechanism.

Simple SummaryInsulin-like growth factor-1 (IGF-1) is a growth hormone and is implicated in prostate cancer progression. Most prostate cancers begin in an androgen-dependent state so that androgen deprivation therapy results in improved clinical outcome. However, some cancerous cells may survive androgen deprivation, growing into therapy-resistant, androgen-independent prostate cancer. The present study investigated the influence of IGF-1 on tumor growth and migration properties using androgen-dependent LNCaP and VCaP and androgen-independent PC3 and DU145 prostate cancer cells. Stimulation with IGF-1 activated growth in all cell lines. There were changes in transmembrane receptors (integrins) that bind cells to each other and changes in focal adhesion kinase that controls cell motility. Intracellular Akt/mTOR signaling, regulating cell division, was also activated. Thus, it seems that prostate cancer progression is controlled by a fine-tuned network between IGF-1-driven integrin-FAK signaling and the Akt-mTOR pathway. Concerted targeting of both pathways may, therefore, help prevent cancer dissemination.Insulin-like growth factor-1 (IGF-1)-related signaling is associated with prostate cancer progression. Links were explored between IGF-1 and expression of integrin adhesion receptors to evaluate relevance for growth and migration. Androgen-resistant PC3 and DU145 and androgen-sensitive LNCaP and VCaP prostate cancer cells were stimulated with IGF-1 and tumor growth (all cell lines), adhesion and chemotaxis (PC3, DU145) were determined. Evaluation of Akt/mTOR-related proteins, focal adhesion kinase (FAK) and integrin α and β subtype expression followed. Akt knock-down was used to investigate its influence on integrin expression, while FAK blockade served to evaluate its influence on mTOR signaling. Integrin knock-down served to investigate its influence on tumor growth and chemotaxis. Stimulation with IGF-1 activated growth in PC3, DU145, and VCaP cells, and altered adhesion and chemotactic properties of DU145 and PC3 cells. This was associated with time-dependent alterations of the integrins α3, α5, αV, and β1, FAK phosphorylation and Akt/mTOR signaling. Integrin blockade or integrin knock-down in DU145 and PC3 cells altered tumor growth, adhesion, and chemotaxis. Akt knock-down (DU145 cells) cancelled the effect of IGF-1 on α3, α5, and αV integrins, whereas FAK blockade cancelled the effect of IGF-1 on mTOR signaling (DU145 cells). Prostate cancer growth and invasion are thus controlled by a fine-tuned network between IGF-1 driven integrin-FAK signaling and the Akt-mTOR pathway. Concerted targeting of integrin subtypes along with Akt-mTOR signaling could, therefore, open options to prevent progressive dissemination of prostate cancer.