Pro-tumorigenic Effects Research Articles

Abstract 331: Mitochondrial transfer from astrocytes drives glioblastoma tumorigenicity

Abstract Mitochondrial transfer in the central nervous system occurs from astrocytes to neurons in stroke. Mitochondrial exchange has also been reported among tumor cells in glioblastoma (GBM), the most common primary brain tumor. However, the role of mitochondrial transfer from non-neoplastic cells in the surrounding microenvironment to GBM remains poorly understood. We hypothesized that mitochondrial transfer from these non-neoplastic to GBM cells supports tumor metabolism and growth. Using transgenic mice expressing fluorophore-tagged mitochondria, we found that ~50% of orthotopically-implanted mouse GBM cells acquire host mitochondria. Brain-resident cells, mainly astrocytes, but not infiltrating immune cells were the primary mitochondrial donors in vivo and in vitro. Mitochondrial transfer also occurred from immortalized human astrocytes to a broad array of patient-derived xenograft (PDX) models of GBM in vitro at rates of 15-35%. GBM cells that acquired mitochondria expressed higher levels of the ATP-synthase subunit ATP5A and produced more ATP, while metabolomics revealed upregulated amino acid metabolism in recipient cells. In vivo, mouse GBM cells that acquired mitochondria were more likely to be in G2/M proliferative cell cycle phases. We observed a similar effect in PDX that acquired astrocyte mitochondria from co-cultures in vitro. To mechanistically link increased proliferation specifically to mitochondrial transfer, we isolated astrocyte mitochondria by differential centrifugation and found that addition and uptake of cell-free mitochondria in human GBM cells recapitulated the increased proliferation. Using sorted mouse and human GBM cells with/without astrocyte mitochondrial acquisition, we further found that mitochondrial transfer promoted in vitro self-renewal and in vivo tumorigenicity, leading to significant reduction in survival and increased penetrance in orthotopic GBM models. Transfer in mouse and human systems was contact-dependent and was abrogated by physical separation of donor and recipient cells by transwell inserts. We visualized contact-dependent transfer across actin-based intercellular connections consistent with previously reported microtubes. We confirmed the critical role of actin and the actin-associated protein, growth-associated protein 43 (GAP43) in facilitating mitochondrial transfer by showing that pharmacologic inhibition and genetic knockdown (respectively) significantly decreased the rate of mitochondrial transfer. Taken together, mitochondrial transfer comprises a fundamental, protumorigenic mechanism of GBM, enhancing metabolic activity and driving tumor cell proliferation. Further elucidating the molecular machinery regulating astrocyte mitochondrial transfer and its downstream protumorigenic effects will lead to therapeutic opportunities targeting this understudied tumor microenvironment interaction. Citation Format: Dionysios C. Watson, Defne Bayik, Simon Storevik, Shannon S. Moreino, Samuel S. Sprowls, Gauravi Deshpande, Palavalasa Sravya, Costas A. Lyssiotis, Daniel R. Wahl, Hrvoje Miletic, Justin D. Lathia. Mitochondrial transfer from astrocytes drives glioblastoma tumorigenicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 331.

Abstract 5129: Neutrophil extracellular traps induced by surgical stress regulate cancer metabolism leading to tumor growth

Abstract Introduction: Surgery is a crucial intervention to cure malignancies. However, evidence shows that the surgical insult and its accompanying immune response can enhance tumor growth and metastasis. Neutrophil Extracellular Traps (NETs) released systemically during surgical stress were previously shown to contribute to this process. In fact, to generate increased energy demands required for growth and metastasis, cancer cells in a stressful microenvironment need an adaptive mechanism where metabolic reprogramming to fatty acid (FA) oxidation has been emerging as an important process. Here, we aim to explore the direct effects of surgical NETs in regulating cancer cell metabolism leading to tumor growth and metastasis. Methods: For the indolent tumor model, C57BL/6 mice were injected with a small number of LLC-1 (Lewis Lung Cancer-1) cells subcutaneously (SQ) and a group was subjected to laparotomy for 30 mins, with or without intraperitoneal DNAse (NET inhibitor) injection perioperatively. Tumor growth was then followed for 4 weeks. For the tumor metastasis model, LLC-1 cells were injected SQ and allowed to grow for 3 weeks before resection with or without perioperative DNAse. Tumor metastasis to the lungs was assessed after 3 weeks. In vitro experiments on LLC-1 and MC-38 (murine colon adenocarcinoma) cancer cells were performed using NETs released from neutrophils freshly isolated from mice bone marrow and stimulated with Phorbol myristate acetate (PMA). Results: For the indolent tumor model, injection of cancer cells did not lead to any significant tumor growth after 4 weeks unless mice underwent surgical stress via laparotomy. Treatment with DNAse significantly reversed their growth. For the tumor metastasis model, tumor resection alone led to significant lung metastasis, but DNAse treatment during resection or resection in PAD-4 KO mice (unable to form NETs) led to significantly less metastatic burden. Furthermore, in vitro treatment of cancer cells with NETs lead to significant cell proliferation, relatively more under hypoxic and serum conditions. This was paralleled with a significant increase in fluorescently labeled FA uptake into cancer cells as detected by flow cytometry, as well as a significant upregulation of gene expression of FA transport proteins and oxidation enzymes. Conclusion: Surgical stress can promote tumor growth and metastasis through cancer cell metabolic reprogramming induced by systemically released NETs. We hope that elucidating the molecular mechanism behind this process can help in finding therapeutics to prevent the protumorigenic effects of surgical stress. Citation Format: Tony Haykal, Ruiqi Yang, Celine Tohme, Ronghua Wang, David Geller, Christof Kaltenmeier, Hamza Yazdani, Samer Tohme. Neutrophil extracellular traps induced by surgical stress regulate cancer metabolism leading to tumor growth. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5129.

Abstract 2536: Intracellular Ctla4 overexpression promotes melanoma progression and metastasis

Abstract Cytotoxic T Lymphocyte Antigen 4 (CTLA4) expressed on the surface of T cells is an important immunotherapeutic target in many cancers, including melanoma. However, we previously found highly upregulated expression of CTLA4 in BRAF/NRAS-mutant human melanoma cell lines and tissues. Although CTLA4 is almost entirely expressed intracellularly in melanoma cells, its intracellular functions have remained elusive. Ectopic expression of Ctla4 (Ctla4-ee) in mouse melanoma cell lines significantly promoted lung colonization in syngeneic mice as well as in immunocompromised mice, suggesting that Ctla4 had pro-tumorigenic effects independent of its extracellular immune checkpoint function. Proteomics analysis identified apoptosis to be a major affected pathway and we found that Ctla4 ectopic-expressing mouse melanoma cells (B2905-Ctla4-ee) were significantly resistant to doxorubicin-induced apoptosis as compared to empty vector (EV) controls. In a reciprocal experiment, knocking out CTLA4 in the Hs936T human melanoma cells, that exhibit high endogenous CTLA4 expression, showed significantly increased apoptosis than the parental cells. Moreover, significant upregulation of anti-apoptotic proteins (Bnip3, Birc6, Pak1, Mcl-1, Survivin, Rac1/Cdc42, Bcl-2, and Bnip3l) and downregulation of pro-apoptotic proteins (p53 and Bad) were observed in CTLA4-ee cells as compared to EV controls. CTLA4-ee cells also showed significantly higher invasion in Matrigel-coated Transwell assay. Interestingly, we also found that CTLA4 translocated to mitochondria, where it downregulated oxidative phosphorylation and increased glycolysis. These findings lead us to hypothesize that CTLA4 plays a significant role in regulating apoptosis and mitochondrial metabolic functions, leading to the promotion of melanoma progression and metastasis. Citation Format: Hasan Raza Kazmi, Xuan Mo, Bo Zhou, Sarah Preston Alp, Scott Gross, Hassaan Wajeeh, Carmen Merali, John Elrod, Jonathan Soboloff, Salim Merali, M. Raza Zaidi. Intracellular Ctla4 overexpression promotes melanoma progression and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2536.

Abstract 5956: Tumor-infiltrating neutrophil progenitors impair homologous DNA repair and promote sensitivity to PARP-inhibition

Abstract Tumor evolution is one of the major mechanisms responsible for acquiring therapy-resistant and more aggressive cancer clones. Whether the tumor microenvironment through immune-mediated mechanisms might promote the development of more aggressive cancer types is crucial for the identification of additional therapeutical opportunities. Here, we identified a novel subset of tumor-infiltrating neutrophils, defined as tumor-associated neutrophil progenitors (NePs). These NePs are enriched in highly proliferative hormone-dependent breast cancers and impair DNA repair capacity. Mechanistically, succinate secreted by tumor-associated NePs inhibits homologous recombination, promoting error-prone DNA repair through non-homologous end-joining regulated by PARP-1. Consequently, breast cancer cells acquire genomic instability, resulting in tumor progression and resistance to endocrine therapies. Selective inhibition of these pathways induces increased tumor cell kill in vitro and in vivo. Intra-tumor NePs score correlates with copy number alterations in highly proliferative hormone-dependent tumors from breast cancer patients. Treatment with PARP-1 inhibitors counteract the pro-tumorigenic effect of these neutrophils and reverses endocrine resistance. Citation Format: Arianna Calcinotto. Tumor-infiltrating neutrophil progenitors impair homologous DNA repair and promote sensitivity to PARP-inhibition. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5956.

Abstract 3654: Olaparib combined with entinostat exerts differential effects on tumor-associated macrophages in tumors compared to ascites in syngeneic HR-proficient murine models of ovarian cancer

Abstract Poly ADP ribose inhibitors (PARPi) are most effective in ovarian cancer tumors with homologous recombination (HR) deficiency. Our group has shown that histone deacetylase inhibitors (HDACi) sensitize HR proficient ovarian cancer cells to PARPi. Our current efforts are directed towards understanding how this therapeutic regimen alters tumor-associated macrophages (TAMs) in murine models of high grade serous ovarian cancer. To investigate the effects of Ola combined with Ent, we used HR-proficient ID8 P53 wild-type and ID8 P53−/− syngeneic murine models. Mice were randomized into 4 groups: control, Ola, Ent and Ola+Ent. Mice (Ent and Ola+Ent) were pre-treated with 15 mg/kg entinostat or vehicle (Ola and Ola+Ent) for one week via oral gavage and then treated with vehicle/Ent/Ola (100 mg/kg)/Ola+Ent for two weeks. Mice were sacrificed 24 h after the last dose to harvest tumors and ascites. Tumors were processed for histology to determine cell proliferation (Ki67) and immune cell markers (CCL2, M1 and M2-like macrophages). Ascites fluid was processed for flow cytometric analysis of immune cells. Tumors from parental ID8 P53 wild type mice showed significantly lower cell proliferation marker Ki67 (P<0.05), higher anti-tumorigenic M1-like CCL2 (P<0.05), and lower pro-tumorigenic M2-like mannose receptor (P<0.05) in Ent and Ola+Ent groups compared to vehicle and Ola. Ascites showed no significant change in anti-tumorigenic M1-like macrophages, but significantly increased pro-tumorigenic M2-like macrophages (P<0.005). ID8 P53−/− mice tumors showed significantly lower Ki-67 (P<0.05) in Ola+Ent group compared to vehicle and mono-treatments. Ascites showed no significant change in total macrophage or pro-tumorigenic M2-like macrophages, but a significant decrease in anti-tumorigenic M1-like macrophages in Ent and Ola+Ent groups compared to vehicle. To summarize, in HR proficient ID8 P53 wildtype and ID8 P53−/− syngeneic mouse models, Ola and Ent treatment exerted anti-tumorigenic effects in tumors but potentially pro-tumorigenic effects in ascites. In conclusion, concomitant targeting of tumor TAMs and ascites TAMs may be a therapeutic regimen to investigate in the future. Citation Format: Vijayalaxmi G. Gupta, Tyler Woodard, Simona Miceska, Bisiyao Fashemi, Sangappa Chadchan, Wendy Zhang, Katherine Roby, Andrew Wilson, Fiona Yull, Marta Crispens, Sumanta Naik, Asya Smimov, Christina Stallings, Dineo Khabele. Olaparib combined with entinostat exerts differential effects on tumor-associated macrophages in tumors compared to ascites in syngeneic HR-proficient murine models of ovarian cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3654.

Abstract 3600: MET-mediated STING activation regulates EMT and NF-ΚB pathway in non-small cell lung cancer

Abstract The cyclic GAMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway is known to have anti-tumor activity by activating the innate immune response against cytosolic double-stranded DNA (dsDNA). The regulating mechanism of STING remains unclear, and a pro-tumorigenic effect of STING pathway was recently reported. In this study, we investigated the expression of STING by MET and a novel role of the STING pathway in non-small cell lung cancer (NSCLC). The Cancer Genome Atlas (TCGA) and Cancer Cell Line Encyclopedia (CCLE) analysis showed that cGAS/STING pathway is enriched and STING expression is higher in MET-overexpressing tumors. Western blot for NSCLC cells and immunohistochemistry for NSCLC tumor tissues showed positive correlation between MET and STING expression in NSCLC cells. MET-overexpression and a MET agonist (HGF) treatment increased STING expression and CXCL10 and IFNβ expression and secretion, whereas MET-knockdown and a MET inhibitor (capmatinib) treatment decreased STING expression in NSCLC cells. In MET-positive and STING-positive cells, a STING agonist (poly-dAdT and diABZI) treatment led to increased activation of STING signaling pathway. In EBC-1 cells, MET knockdown decreased STING expression and STING-agonist-induced STING-pathway activation and cytokine production. To further investigate the role STING in NSCLC, EBC-1 cells were transfected with STING siRNA and submitted to RNS-seq. Gene set enrichment analysis revealed that several pathways were affected by STING expression. Epithelial-mesenchymal transition (EMT) and TNFα-signaling via NF-κB signaling were significantly downregulated in STING-knockdowned cells. In vitro experiments using EBC-1 cells, STING overexpression increased SLUG and TWIST1 expression and migration of cells, whereas STING knockdown decreased SLUG and TWIST1 expression and migration of cells. In summary, this study demonstrated that MET and STING expression were positively correlated with each other in NSCLC and MET overexpression increased STING expression and subsequent activation upon STING agonist stimulation. In addition, STING contributed to EMT in NSCLC. Citation Format: Seungchan Mun, Bogyeong Han, HyunKyung Ahn, Jaemoon Koh, Sehui Kim, DooHyun Chung, YoonKyung Jeon. MET-mediated STING activation regulates EMT and NF-ΚB pathway in non-small cell lung cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3600.

The Pro-Tumorigenic Role of Chemotherapy-Induced Extracellular HSP70 from Breast Cancer Cells via Intratumoral Macrophages

Tumor-associated macrophages (TAMs) contribute to tumor progression and chemoresistance; it is therefore important to clarify the altered functions of macrophages following chemotherapy. While extracellular heat shock protein (HSP) 70 is associated with therapeutic resistance, the effects of HSP70 on TAMs remain largely unknown. Here, we conducted in vitro experiments and immunohistochemistry in 116 breast carcinoma specimens to determine whether the secretion of HSP70 from breast cancer cells following chemotherapy affects macrophage function. It was revealed that the interaction of epirubicin (EPI)-exposed breast cancer cells with macrophages enhanced tumor progression, and EPI promoted the secretion of extracellular HSP70 from breast cancer cells. The expression of pro-tumorigenic macrophage marker CD163 was decreased in macrophages treated with a conditioned medium (CM) from HSP70-silenced breast cancer cells. Breast cancer cells treated with CM from HSP70-silenced breast cancer cells showed decreased expression of transforming growth factor (TGF)-β, and the pro-tumorigenic effects of macrophages were impaired when TGF-β signaling was inhibited. Immunohistochemistry demonstrated that HSP70 served as a poor prognostic factor in conjunction with macrophage infiltration. It was therefore concluded that extracellular HSP70 levels increased following chemotherapy and enhanced the pro-tumorigenic effects of TAMs, either directly or indirectly, by regulating TGF-β expression in breast cancer cells.

A multidimensional pan-cancer analysis of DCAF13 and its protumorigenic effect in lung adenocarcinoma.

DCAF13 is a substrate recognition protein in the ubiquitin-proteasome system with oncogenic effects in several malignant tumors. However, it is unclear that the relationship between DCAF13 expression pattern and prognosis across different cancer types. Also unknown is the biological function or effects on the immune microenvironment of DCAF13. In this study, we parsed multiple public databases to explore the potential tumorigenic actions of DCAF13, including correlations with prognosis, microsatellite instability (MSI), tumor mutational burden (TMB), immune checkpoint genes, immune cell infiltration, and immunotherapy response in pan-cancer. Moreover, we validated DCAF13 expression in a tissue microarray by immunohistochemistry and investigate its effects in vitro and in vivo. The results showed that DCAF13 was upregulated in 17 cancer types and correlated with poor prognosis in many cancers. Also, the correlation between DCAF13 and TMB was found in 14 cancers as well as MSI in nine. The expression level of DCAF13 was found to be notably correlated with immune cell infiltration, showing a negative correlation with CD4 T cell infiltration and a positive correlation with neutrophil infiltration. The oncogene DCAF13 expression was shown to have a positive correlation with CD274 or ADORA2A and negative correlation with VSIR, TNFRSF4, or TNFRSF14 across large subsets of human cancers. Finally, we observed that DCAF13 was highly expressed in a tissue microarray of lung cancer. In immunocompromised mouse models, xenograft growth of human lung cancer cells was significantly inhibited by DCAF13 knockdown. Our results highlighted the value of DCAF13 as a promising independent predictor of poor prognosis through numerous biological processes. High DCAF13 expression often predicts suppressive immune microenvironment and immunotherapy resistance in a pan-cancer context.

Investigating the Effects of Chordoma Cell-Derived Exosomes on the Tumorigenicity of Nucleus Pulposus Cells.

Objective Interaction of tumor cells with the surrounding environment is essential for tumor growth and progression that eventually leads to metastasis. Growing evidence shows that extracellular vesicles also known as exosomes play a crucial role in signaling between the tumor and its microenvironment. Tumor-derived exosomes have generally protumorigenic effects such as metastasis, hypoxia, angiogenesis, and epithelial-mesenchymal transition. Methods In this study, exosomes were isolated from a chordoma cell line, MUG-Chor1, and characterized subsequently. The number of exosomes was determined and introduced into the healthy nucleus pulposus (NP) cells for 140 days. The protumorigenic effects of a chordoma cell line-derived exosomes that initiate the tumorigenesis on NP cells were investigated. The impact of tumor-derived exosomes on various cellular events including cell cycle, migration, proliferation, apoptosis, and viability has been studied by treating NP cells with chordoma cell-line-derived exosomes cells. Results Upon treatment with exosomes, the NP cells not only gained a chordoma-like morphology but also molecular characteristics such as alterations in the levels of certain gene expressions. The migratory and angiogenic capabilities of NP cells increased after treatment with chordoma-derived exosomes. Conclusion Based on our findings, we can conclude that exosomes carry information from tumor cells and may exert tumorigenic effects on nontumorous cells.

The Role of Mesenchymal Stem Cells and Exosomes in Tumor Development and Targeted Antitumor Therapies.

Mesenchymal stem cells (MSCs) can be isolated from various tissues in adults and differentiated into cells of the osteoblasts, adipocytes, chondrocytes, and myocytes. Recruitments of MSCs towards tumors have a crucial contribution to tumor development. However, the role of MSCs in the tumor microenvironment is uncertain. In addition, due to its tropism to the tumor and low immunogenic properties, more and more pieces of evidence indicate that MSCs may be an ideal carrier for antitumor biologics such as cytokines, chemotherapeutic agents, and oncolytic viruses. Here, we review the existing knowledge on the anti- and protumorigenic effect of MSCs and their extracellular vesicles and exosomes, the role of MSCs, and their extracellular vesicles and exosomes as antitumor vectors.

The Potential of Senescence as a Target for Developing Anticancer Therapy.

Senescence occurs in response to various stimuli. Senescence has attracted attention because of its potential use in anticancer therapy as it plays a tumor-suppressive role. It also promotes tumorigeneses and therapeutic resistance. Since senescence can induce therapeutic resistance, targeting senescence may help to overcome therapeutic resistance. This review provides the mechanisms of senescence induction and the roles of the senescence-associated secretory phenotype (SASP) in various life processes, including therapeutic resistance and tumorigenesis. The SASP exerts pro-tumorigenic or antitumorigenic effects in a context-dependent manner. This review also discusses the roles of autophagy, histone deacetylases (HDACs), and microRNAs in senescence. Many reports have suggested that targeting HDACs or miRNAs could induce senescence, which, in turn, could enhance the effects of current anticancer drugs. This review presents the view that senescence induction is a powerful method of inhibiting cancer cell proliferation.

The divergent role of the GM-CSF/GM-CSFR signaling pathway in cholangiocarcinoma and pancreatic ductal adenocarcinoma.

736 Background: The granulocyte-macrophage colony-stimulating factor ligand and receptor (GM-CSF/GM-CSFR) pathway plays a multifaceted role in the setting of cancer, exerting an anti-tumorigenic or pro-tumorigenic effect depending on GM-CSF expression. In previous work, we and others have shown increased GM-CSF expression to correlate with poor prognosis in patients with cholangiocarcinoma (CCA) and pancreatic ductal adenocarcinoma (PDAC). We also demonstrated how GM-CSF neutralization leads to reduced tumor size in murine CCA models, in part due to inhibition of alternative macrophage polarization. Here, we explore the impact of blocking GM-CSFR signaling in CCA and PDAC, two immunologically cold tumors with poor prognoses. Methods: Immunohistochemistry (IHC) and digital quantification of staining was performed on tissue from a human PDAC and CCA databank. Murine F4/80+ bone marrow-derived macrophages were cultured in tumor-conditioned media (TCM) derived from PDAC (KP2) or CCA (URCCA4.3) cell lines, with and without anti-GM-CSFR antibody. Quantitative real time PCR (qRT-PCR) analysis was performed for gene expression. URCCA4.3 and a luciferase-labeled PDAC (KCKO) cell line were orthotopically implanted into Bc/BIL3 knockout (KO) mice which lack GM-CSFR and C57BL/6 mice. Mice implanted with URCCA4.3 were enrolled into vehicle or gemcitabine treatment groups. Mice implanted with KCKO were untreated. Tumor growth was monitored by ultrasonography or bioluminescence imaging. Results: Digital analysis of IHC staining for GM-CSFR in human PDAC tumors revealed low expression to be associated with improved overall survival (OS) and greater number of days to recurrence, while high levels were associated with worse OS and fewer days to recurrence (p<0.01). In addition, human CCA specimens had greater GM-CSFR expression compared to normal uninvolved liver (p<0.01). qRT-PCR analysis of RNA from bone marrow-derived macrophages exposed to either CCA or PDAC TCM demonstrated lower expression of genes associated with alternative macrophage polarization ( Arg1, Cd274, Pdcd1lg2) and chronic inflammation ( Ccl2, Ccl17, Irf4) (all p<0.01) in response to GM-CSFR blockade. GM-CSFR KO mice implanted with URCCA4.3 demonstrated no differences in tumor growth with or without chemotherapy, compared to wild-type controls. Similarly, KO mice implanted with an immunogenic PDAC cell line (KCKO) had no differences in tumor size compared to wild-type controls. Conclusions: GM-CSFR expression is prognostic in the setting of PDAC and elevated in human CCA compared to normal liver. In vitro, GM-CSFR blockade downregulated pro-tumor genes associated with immunosuppression and inflammation. However, complete disruption of GM-CSFR signaling reversed the efficacy generated with GM-CSF ligand neutralization, suggesting some signaling is required for inducing anti-tumor immune responses.

Long-term exposure to house dust mites accelerates lung cancer development in mice

BackgroundIndividuals with certain chronic inflammatory lung diseases have a higher risk of developing lung cancer (LC). However, the underlying mechanisms remain largely unknown. Here, we hypothesized that chronic exposure to house dust mites (HDM), a common indoor aeroallergen associated with the development of asthma, accelerates LC development through the induction of chronic lung inflammation (CLI). MethodsThe effects of HDM and heat-inactivated HDM (HI-HDM) extracts were evaluated in two preclinical mouse models of LC (a chemically-induced model using the carcinogen urethane and a genetically-driven model with oncogenic KrasG12D activation in lung epithelial cells) and on murine macrophages in vitro. Pharmacological blockade or genetic deletion of the Nod-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome, caspase-1, interleukin-1β (IL-1β), and C–C motif chemokine ligand 2 (CCL2) or treatment with an inhaled corticosteroid (ICS) was used to uncover the pro-tumorigenic effect of HDM. ResultsChronic intranasal (i.n) instillation of HDM accelerated LC development in the two mouse models. Mechanistically, HDM caused a particular subtype of CLI, in which the NLRP3/IL-1β signaling pathway is chronically activated in macrophages, and made the lung microenvironment conducive to tumor development. The tumor-promoting effect of HDM was significantly decreased by heat treatment of the HDM extract and was inhibited by NLRP3, IL-1β, and CCL2 neutralization, or ICS treatment.ConclusionsCollectively, these data indicate that long-term exposure to HDM can accelerate lung tumorigenesis in susceptible hosts (e.g., mice and potentially humans exposed to lung carcinogens or genetically predisposed to develop LC).

Single-cell RNA sequencing reveals the suppressive effect of PPP1R15A inhibitor Sephin1 in antitumor immunity

Protein phosphatase 1 regulatory subunit 15A (PPP1R15A) is an important factor in the integrated stress response (ISR) in mammals and may play a crucial role in tumorigenesis. In our studies, we found an inhibitor of PPP1R15A, Sephin1, plays a protumorigenic role in mouse tumor models. By analyzing the single-cell transcriptome data of the mouse tumor models, we found that in C57BL/6 mice, Sephin1 treatment could lead to higher levels of ISR activity and lower levels of antitumor immune activities. Specifically, Sephin1 treatment caused reductions in antitumor immune cell types and lower expression levels of cytotoxicity-related genes. In addition, Tcell receptor (TCR) repertoire analysis demonstrated that the clonal expansion of tumor-specific Tcells was inhibited by Sephin1. A special TCR+ macrophage subtype in tumor was identified to be significantly depleted upon Sephin1 treatment, implying its key antitumor role. These results suggest that PPP1R15A has the potential to be an effective target for tumor therapy.

Ethnic disparities in the immune microenvironment of triple negative breast cancer and its role in therapeutic outcomes.

In 2020, newly diagnosed breast cancer (BC) cases surpassed that of lung cancer among women, making it the most common female cancer globally. In spite of recent increases in incidence rates, mortality due to BC has declined since 1989. These declines have been attributed to advancements in treatment modalities as well as increased mammography surveillance. Despite these advances, African American (AA) women are 40% more likely to die from BC than Caucasian women. Multifactorial etiology has been implicated in the disparity of BC mortality rates among AA women. As an example, AA women have a disproportionate incidence of triple negative breast cancer (TNBC), which has a poor prognosis and marginal treatment options. Increasingly, the tumor microenvironment (TME) has gained relevance as it relates to primary tumor progression, metastasis and treatment possibilities. The treatment outcomes or pathological complete response (pCR) in TNBC among AA women are affected by differences in TME. The TME of AA women exhibit several variances in acellular and cellular components associated with pro-tumorigenic effects. For example, increased levels of the adipocyte-related hormone, resistin, the pro-inflammatory cytokine, IL-6, and the CC chemokine, CCL2, within the TME of AA women gives rise to an increased density of M2 macrophages, also known as tumor-associated macrophages. Elevated levels of vascular endothelial growth factor in the TME of AA women increase the vascular density or vascularity, which facilitate aggressive tumor growth and metastasis. Furthermore, a pro-tumorigenic TME is supported by increased levels of the CXC chemokine, CXCL12 that results in the recruitment of regulatory T lymphocytes (Tregs ). Due to these and other differences in the TME of AA women, precision oncology can target specific aspects of the TME that may contribute to a poorer prognosis. In addition to the discrepancies in the TME, AA women face socio-economic barriers that limit their ability to access state-of-the-art, novel therapies against metastatic TNBC. In this review, we will provide a brief overview of the tumor immune microenvironment, immune-based treatment options for TNBC and their potential to decrease health disparities due to ethnicity.

The Role οf Ion Channels in the Development and Progression of Prostate Cancer.

Ion channels have major regulatory functions in living cells. Apart from their role in ion transport, they are responsible for cellular electrogenesis and excitability, and may also regulate tissue homeostasis. Although cancer is not officially classified as a channelopathy, it has been increasingly recognized that ion channel aberrations play an important role in virtually all cancer types. Ion channels can exert pro-tumorigenic activities due to genetic or epigenetic alterations, or as a response to molecular signals, such as growth factors, hormones, etc. Increasing evidence suggests that ion channels and pumps play a critical role in the regulation of prostate cancer cell proliferation, apoptosis evasion, migration, epithelial-to-mesenchymal transition, and angiogenesis. There is also evidence suggesting that ion channels might play a role in treatment failure in patients with prostate cancer. Hence, they represent promising targets for diagnosis, staging, and treatment, and their effects may be of particular significance for specific patient populations, including those undergoing anesthesia and surgery. In this article, the role of major types of ion channels involved in the development and progression of prostate cancer are reviewed. Identifying the underlying molecular mechanisms of the pro-tumorigenic effects of ion channels may potentially inform the development of novel therapeutic strategies to counter this malignancy.

Disabled-2 (DAB2): A Key Regulator of Anti- and Pro-Tumorigenic Pathways.

Disabled-2 (DAB2), a key adaptor protein in clathrin mediated endocytosis, is implicated in the regulation of key signalling pathways involved in homeostasis, cell positioning and epithelial to mesenchymal transition (EMT). It was initially identified as a tumour suppressor implicated in the initiation of ovarian cancer, but was subsequently linked to many other cancer types. DAB2 contains key functional domains which allow it to negatively regulate key signalling pathways including the mitogen activated protein kinase (MAPK), wingless/integrated (Wnt) and transforming growth factor beta (TGFβ) pathways. Loss of DAB2 is primarily associated with activation of these pathways and tumour progression, however this review also explores studies which demonstrate the complex nature of DAB2 function with pro-tumorigenic effects. A recent strong interest in microRNAs (miRNA) in cancer has identified DAB2 as a common target. This has reignited an interest in DAB2 research in cancer. Transcriptomics of tumour associated macrophages (TAMs) has also identified a pro-metastatic role of DAB2 in the tumour microenvironment. This review will cover the broad depth literature on the tumour suppressor role of DAB2, highlighting its complex relationships with different pathways. Furthermore, it will explore recent findings which suggest DAB2 has a more complex role in cancer than initially thought.

Interferon-gamma signaling promotes melanoma progression and metastasis.

Interferon-gamma (IFNG) has long been regarded as the flag-bearer for the anti-cancer immunosurveillance mechanisms. However, relatively recent studies have suggested a dual role of IFNG, albeit there is no direct experimental evidence for its potential pro-tumor functions. Here we provide in vivo evidence that treatment of mouse melanoma cell lines with Ifng enhances their tumorigenicity and metastasis in lung colonization allograft assays performed in immunocompetent syngeneic host mice, but not in immunocompromised host mice. We also show that this enhancement is dependent on downstream signaling via Stat1 but not Stat3, suggesting an oncogenic function of Stat1 in melanoma. The experimental results suggest that melanoma cell-specific Ifng signaling modulates the tumor microenvironment and its pro-tumorigenic effects are partially dependent on the γδ T cells, as Ifng-enhanced tumorigenesis was inhibited in the TCR-δ knockout mice. Overall, these results show that Ifng signaling may have tumor-promoting effects in melanoma by modulating the immune cell composition of the tumor microenvironment.

Abstract A020: Exploring the effects of resveratrol on the gut microbiome in high fat diet-fed BRAFV600E mutant mice

Abstract The polyphenol resveratrol, widely known for its cancer protective activities has been shown to protect against the pro-tumorigenic effects induced by high-fat diets (HFD) in mouse models of colorectal cancer (CRC). Although, the mechanisms of actions of this compound in humans still remain elusive, recent studies suggest its effects may be mediated partly through its interaction with the gut microbiota. Here we sought to determine the changes induced by HFD on the intestinal microbiome and the impact of resveratrol supplementation on these alterations in a mouse model of BRAFV600E mutant CRC. BRAFV600E; BRAFWT (wild-type) mice were randomised into 8 groups and fed either a standard diet or HFD supplemented with low or high-dose of resveratrol (0.7mg/kg/day and 14mg/kg/day, respectively) for 6-weeks. The mouse faecal microbial profile was then assessed by targeting the V3-V4 area of the bacterial 16S rRNA gene. Consumption of HFD was associated with significant alternations in the gut microbiome composition in both BRAFV600E and BRAFWT based on beta-diversity analysis (PADONIS<0.05). HFD increased the Firmicutes and Clostridia abundance in BRAFWT compared to animals on a standard diet (P<0.01, P<0.008 respectively), while in BRAFV600E mice, alterations were observed in lower taxonomic levels including the enrichment of Faecalibaculum (P<0.02) and growth inhibition of Lactobacillus johnsonhii (P<0.05). High-dose resveratrol resulted in significant differences in the microbial composition compared to HFD-treated group in the BRAFV600E mice (PADONIS<0.05) but not in BRAFWT . Resveratrol administration did not counteract the HF-induced taxonomic changes but high-dose resveratrol changed Muribaculum, and UBA181 genera abundances in BRAFV600E mice (P<0.001 and P<0.05 respectively) compared to HF-treated mice. Low dose resveratrol had no significant effects on bacterial abundance in both BRAFV600E and BRAFWT mice. It was also observed that BRAFV600E mutation influenced the gut microbiome independently of diet based on beta and alpha-diversity (PADONIS<0.05, PChao1<0.05 respectively). Resveratrol administration modified the gut microbiota composition of BRAFV600E mice but did not completely reverse the HFD-induced changes indicating that alternative mechanisms may contribute to the protective effects of resveratrol in this mouse model. Citation Format: Despoina Theofanous, Hong Cai, Karen Brown. Exploring the effects of resveratrol on the gut microbiome in high fat diet-fed BRAFV600E mutant mice [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A020.

Candida tropicalis induces NLRP3 inflammasome activation via glycogen metabolism-dependent glycolysis and JAK-STAT1 signaling pathway in myeloid-derived suppressor cells to promote colorectal carcinogenesis.

Our previous studies showed that Candida tropicalis promoted colorectal cancer (CRC) by activating the function of MDSCs. However, underlying molecular mechanisms remains to be further investigated. In the present study, we indicated that C. tropicalis induced NLRP3 inflammasome activation through Dectin-3 in myeloid-derived suppressor cells (MDSCs). Mechanistically, we identified that C. tropicalis significantly enhanced the levels of glycolysis dependent on glycogen metabolism in MDSCs, which was required for NLRP3 inflammasome activation. C. tropicalis-induced NLRP3 inflammasome activation of MDSCs required the first priming signal and the second activation signal. For one thing, C. tropicalis promoted transcription of Nlrp3, Pro-caspase-1 and IL-1β genes through activation of JAK-STAT1 signaling pathway. For another, mtROS as the second activation signal mediated C. tropicalis-induced activation of NLRP3 inflammasome. Pharmacological inhibition of NLRP3 inflammasome activation abolished the pro-tumorigenic effect of C. tropicalis in an AOM/DSS-induced CAC mice model and significantly reduced C. tropicalis-promoted infiltration of MDSCs in colon tumors. Finally, in human CRC samples, the expression of STAT1, p-STAT1 and NLRP3 was elevated in MDSCs infiltrated by CRC. Collectively, these findings shed light on a previously unidentified mechanism by which C. tropicalis induces NLRP3 inflammasome activation in MDSCs to contribute to the progression of CRC. And STAT1-NLRP3 axis might represent a prospective therapeutic target for the treatment of CRC.