Anticancer Immune Response Research Articles

Lactate Transporters Modulate Stromal Cell Remodeling in Myeloproliferative Neoplasms (MPN)

Introduction. Philadelphia-negative myeloproliferative neoplasms (MPNs) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The diagnostic approach proposed by the World Health Organization (WHO) uses clinical features, bone marrow (BM) morphology, karyotype and molecular genetic tests to classify MPN subtypes. The BM morphology includes cellularity, erythropoiesis, and neutrophil granulopoiesis in context with specific features of megakaryocytes as well as the BM fiber content, especially in early-stage myelofibrosis that present with thrombocytosis and clinically mimic ET. Since alteration of hematopoiesis is constantly associated with profound modifications of the bone marrow (BM), we hypothesize that CD34+ cells from PMF can actively produce lactate and thus rewiring metabolism of immune cells and mesenchymal stromal cells (MSCs). In turn, this could favor immune evasion and remodeling of BM niche. Methods.Cell proliferation was assessed in vitro on primary MSCs, HS-5 cell line, and PBMC cells. Protein expression was performed by Western blot and immunofluorescence assay. The NCBI GEO database was used to select transcriptome datasets and to analyze gene expression in PMF patients. Cytokine detections were performed by Multiplex immunobead assay technology. An adult TPO-mimetic-induced PMF Zebrafish model was used for in vivo evaluation. An immunohistology assay was performed in MPN BM biopsies. Results.CD34+ cells from PMF patients significantly upregulated the lactate monocarboxylate transporters (MCT-1 and -4) compared to healthy CD34+ cells. Consistently, lactate concentration was higher in PMF sera compared to healthy controls. Since PMF patients showed an increased percentage of circulating immunosuppressive cells such as G- and M-MDSC and Treg, we incubated healthy peripheral blood mononucleated cells (PBMNCs) with PMF sera in the presence or absence of MCT1inhibitor (AZD3965) to evaluate the role of lactate in the expansion of these immunological subsets. We found an expansion of both Treg and M-MDSCs, which was reverted after blocking of circulating lactate by AZD3965. In order to study the effect of lactate in BM remodeling, we treated in vitro healthy MSCs with lactate (20 mM) for 24h. Interestingly, lactate induced a modification of extracellular matrix organization, as demonstrated by increased reticulin and collagen deposition and metalloproteases (MMP9, MMP2). Moreover, lactate increased calcium deposit and soluble osteogenic molecular signals (i.e. osteoprotegerin, osteonectin). These results also were obtained after incubation with PMF sera and were reverted after AZD3965 treatment. Since it has been demonstrated the role of cancer-associated fibroblast (CAF) in cancer development through ECM remodeling, we next evaluated the expression of CAF markers in MSCs after lactate exposure. α-SMA, FAP1, and TGFβ were found upregulated and this effect was reverted by AZD3965. Finally, we further confirmed these results in a Zebrafish animal model of PMF. Interestingly, in Zebrafish model we observed a reduction of MCT4 expression that was confirmed in the PBMNCs of the PMF patients. Conclusions. Inhibition of lactate metabolism may represent a strategy to inhibit cancer cells and contribute to restoring the anti-cancer immune response. Therefore, lactate metabolism may represent a promising target to counteract inflammation, osteosclerosis, and fibrosis in PMF patients.

Neutralizing tumor-related inflammation and reprogramming of cancer-associated fibroblasts by Curcumin in breast cancer therapy

Tumor-associated inflammation plays a vital role in cancer progression. Among the various stromal cells, cancer-associated fibroblasts are promising targets for cancer therapy. Several reports have indicated potent anti-inflammatory effects attributed to Curcumin. This study aimed to investigate whether inhibiting the inflammatory function of cancer-associated fibroblasts (CAFs) with Curcumin can restore anticancer immune responses. CAFs were isolated from breast cancer tissues, treated with Curcumin, and co-cultured with patients' PBMCs to evaluate gene expression and cytokine production alterations. Blood and breast tumor tissue samples were obtained from 12 breast cancer patients with stage II/III invasive ductal carcinoma. Fibroblast Activation Protein (FAP) + CAFs were extracted from tumor tissue, treated with 10 μM Curcumin, and co-cultured with corresponding PBMCs. The expression of smooth muscle actin-alpha (α-SMA), Cyclooxygenase-2(COX-2), production of PGE2, and immune cell cytokines were evaluated using Real-Time PCR and ELISA, respectively. Analyzes showed that treatment with Curcumin decreased the expression of genes α-SMA and COX-2 and the production of PGE2 in CAFs. In PBMCs co-cultured with Curcumin-treated CAFs, the expression of FoxP3 decreased along with the production of TGF-β, IL-10, and IL-4. An increase in IFN-γ production was observed that followed by increased T-bet expression. According to our results, Curcumin could reprogram the pro-tumor phenotype of CAFs and increase the anti-tumor phenotype in PBMCs. Thus, CAFs, as a component of the tumor microenvironment, are a suitable target for combination immunotherapies of breast cancer.

STING-driven activation of T cells: relevance for the adoptive cell therapy of cancer

Adoptive cell therapy (ACT) can successfully treat hema-topoietic cancers but lacks efficacy against solid tumors. This is due to insufficient T cell infiltration, high tumor heterogeneity, frequent antigen loss with subsequent tumor escape, and the immunosup-pressive tumor microenvironment (TME). Alternative methods to boost the anticancer efficacy of adoptively transferred cells are ac-tively pursued. Among adjuvants that are utilized to stimulate anti-cancer immune responses, ligands of the stimulator of interferon genes (STING) pathway have received increasing attention. STING activation can trigger dendritic cell (DC) activation and endogenous immune responses, thereby preventing tumor escape. Activation of the STING pathway in the context of ACT was accordingly associated with improved T cell trafficking and persistence in the TME com-bined with the reduced presence of immunosuppressive cells. Re-cent findings also suggest cell-intrinsic effects of STING ligands on T cells. Activation of the STING signaling pathway was in this regard shown to enhance effector functions of CD4+ and CD8+ T cells, sug-gesting that the STING signaling could be exploited to harness T cell anticancer functions. In this review, we will discuss how the STING signaling can be used to enhance the anticancer efficacy of ACT.

The Tautomerase Activity of Tumor Exosomal MIF Promotes Pancreatic Cancer Progression by Modulating MDSC Differentiation.

Pancreatic cancer is a deadly disease that is largely resistant to immunotherapy, in part because of the accumulation of immunosuppressive cells in the tumor microenvironment (TME). Much evidence suggests that tumor-derived exosomes (TDE) contribute to the immunosuppressive activity mediated by myeloid-derived suppressor cells (MDSC) within the pancreatic cancer TME. However, the underlying mechanisms remain elusive. Herein, we report that macrophage migration inhibitory factor (MIF) in TDEs has a key role in inducing MDSC formation in pancreatic cancer. We identified MIF in both human and murine pancreatic cancer-derived exosomes. Upon specific shRNA-mediated knockdown of MIF, the ability of pancreatic cancer-derived exosomes to promote MDSC differentiation was abrogated. This phenotype was rescued by reexpression of the wild-type form of MIF rather than a tautomerase-null mutant or a thiol-protein oxidoreductase-null mutant, indicating that both MIF enzyme activity sites play a role in exosome-induced MDSC formation in pancreatic cancer. RNA sequencing data indicated that MIF tautomerase regulated the expression of genes required for MDSC differentiation, recruitment, and activation. We therefore developed a MIF tautomerase inhibitor, IPG1576. The inhibitor effectively inhibited exosome-induced MDSC differentiation in vitro and reduced tumor growth in an orthotopic pancreatic cancer model, which was associated with decreased numbers of MDSCs and increased infiltration of CD8+ T cells in the TME. Collectively, our findings highlight a pivotal role for MIF in exosome-induced MDSC differentiation in pancreatic cancer and underscore the potential of MIF tautomerase inhibitors to reverse the immunosuppressive pancreatic cancer microenvironment, thereby augmenting anticancer immune responses.

Transport Barriers Influence the Activation of Anti-Tumor Immunity: A Systems Biology Analysis.

Effective anti-cancer immune responses require activation of one or more naïve T cells. If the correct naïve T cell encounters its cognate antigen presented by an antigen presenting cell, then the T cell can activate and proliferate. Here, mathematical modeling is used to explore the possibility that immune activation in lymph nodes is a rate-limiting step in anti-cancer immunity and can affect response rates to immune checkpoint therapy. The model provides a mechanistic framework for optimizing cancer immunotherapy and developing testable solutions to unleash anti-tumor immune responses for more patients with cancer. The results show that antigen production rate and trafficking of naïve T cells into the lymph nodes are key parameters and that treatments designed to enhance tumor antigen production can improve immune checkpoint therapies. The model underscores the potential of radiation therapy in augmenting tumor immunogenicity and neoantigen production for improved ICB therapy, while emphasizing the need for careful consideration in cases where antigen levels are already sufficient to avoid compromising the immune response.

Tumor cell cytoplasmic metallothionein expression associates with differential tumor immunogenicity and prognostic outcome in high-grade serous ovarian carcinoma.

The underlying mechanism of high T-cell presence as a favorable prognostic factor in high-grade serous ovarian carcinoma (HGSOC) is not yet understood. In addition to immune cells, various cofactors are essential for immune processes. One of those are metallothioneins (MTs), metal-binding proteins comprising various isoforms. MTs play a role in tumor development and drug resistance. Moreover, MTs influence inflammatory processes by regulating zinc homeostasis. In particular, T-cell function and polarization are particularly susceptible to changes in zinc status. The aim of the present study was to investigate a possible role of MT-mediated immune response and its association with prognostic outcome in ovarian cancer. A retrospective study was conducted on a clinically well-characterized cohort of 24 patients with HGSOC treated at the University Hospital of Essen. Gene expression patterns for anti-cancer immunogenicity-related targets were performed using the NanoString nCounter platform for digital gene expression analysis with the appurtenant PanCancer Immune Profiling panel, consisting of 770 targets and 30 reference genes. Tumor-associated immunohistochemical MT protein expression was evaluated using a semi-quantitative four-tier Immunohistochemistry (IHC) scoring. MT immunoexpression was detected in 43% (10/23) of all HGSOC samples. MT immunoexpression levels showed a significant association to survival, leading to prolonged progression-free and overall survival in positively stained tumors. Furthermore, T-cell receptor signaling gene signature showed a strong activation in MT-positive tumors. Activated downstream signaling cascades resulting in elevated interferon-gamma expression with a shift in the balance between T helper cells (TH1 and TH2) could be observed in the MT-positive subgroup. In addition, a higher expression pattern of perforin and several granzymes could be detected, overall suggestive of acute, targeted anti-cancer immune response in MT-positive samples. This is the first study combining broad, digital mRNA screening of anti-tumor immune response-associated genes and their relation to MT-I/II in ovarian cancer. MT overexpression is associated with molecular characteristics of an anti-cancer immune response and is a strong prognostic marker in ovarian HGSOC. The observed immune cell activation associated with tumor MT expression comprises but is not limited to T cells and natural killer cells.

Biomimetic inducer enabled dual ferroptosis of tumor and M2-type macrophages for enhanced tumor immunotherapy

Tumor-associated macrophages (TAMs) are abundant in the tumor microenvironment which promotes the formation of the immunosuppressive tumor microenvironment (ITME) through multiple mechanisms, severely counteracting the therapeutic efficacy of immunotherapy. In this study, a novel biomimetic ferroptosis inducer (D@FMN-M) capable of ITME regulation for enhanced cancer ferroptosis immunotherapy is reported. Upon tumor accumulation of D@FMN-M, the intratumoral mild acidity triggers the biodegradation of Fe-enriched nanocarriers and the concurrent co-releases of dihydroartemisinin (DHA) and Fe3+. The released Fe3+ is reduced to Fe2+ by consuming intratumoral glutathione (GSH), which promotes abundant free radical generation via triggering Fenton and Fe2+-DHA reactions, thus inducing ferroptosis of both cancer cells and M2-type TAMs. Resultantly, the anticancer immune response is strongly activated by the massive tumor-associated antigens released by ferroptositic cancer cells. Also importantly, the ferroptosis-sensitive M2-type TAMs will be either damaged or gradually domesticated to ferroptosis-resistant M1 TAMs under the ferroptosis stress, favoring the normalization of ITME and finally amplifying cancer ferroptosis immunotherapeutic efficacy. This work provides a novel strategy for ferroptosis immunotherapy of solid tumors featuring TAMs infiltration and immunosuppression by inducing dual ferroptosis of tumor cells and M2-type TAMs.

Engineered Microcystis aerugiosa Hydrogel as an Anti‐Tumor Therapeutic by Augmenting Tumor Immunogenicity and Immune Responses

AbstractCancer immunotherapy holds great promise but is generally limited by insufficient induction of anticancer immune responses. In this work, Microcystis aerugiosa (MA) is observed to act as an immune stimulator, which activates the cGAS‐STING and IRF‐signaling pathways of dendritic cells (DCs), induces immunostimulatory factors production, eventually resulting in the death of tumor cells by promoting cytotoxic CD8+ T cells infiltration. To further enhance the tumor immunogenicity, MA is engineered with polydopamine (PDA) and assembled in injectable Pluronic F127 hydrogels (denoted as MA@PDA‐F127). The introduction of PDA endows the MA@PDA‐F127 with photothermal therapy capability, which enhances the immunogenicity by in situ exposing damage‐associated molecular patterns and tumor antigens from dying tumor cells. Importantly, the surface‐rich reaction sites in thermosensitive MA@PDA‐F127 hydrogels capture antigens, facilitating long retention of antigens exposure and enhancing DCs maturation for advanced anti‐tumor immune response. Accordingly, in situ administration of MA@PDA‐F127 hydrogels in a single dose achieves efficient eradication of both primary and distant tumors in an orthotopic tumor metastasis model. Furthermore, this hydrogel can sensitize immune checkpoint inhibitor therapy and enhance T cell infiltration in a murine tumor model. Collectively, MA@PDA‐F127 hydrogel offers an effective anti‐tumor therapeutic by augmenting tumor immunogenicity and activating a systematic immune response.

Determinants for Antitumor and Protumor Effects of Programmed Cell Death.

Cytotoxic anticancer therapies activate programmed cell death in the context of underlying stress and inflammatory signaling to elicit the emission of danger signals, cytokines, and chemokines. In a concerted manner, these immunomodulatory secretomes stimulate antigen presentation and T cell-mediated anticancer immune responses. In some instances, cell death-associated secretomes attract immunosuppressive cells to promote tumor progression. As it stands, cancer cell death-induced changes in the tumor microenvironment that contribute to antitumor or protumor effects remain largely unknown. This is complicated to examine because cell death is often subverted by tumors to circumvent natural, and therapy-induced, immunosurveillance. Here, we provide insights into important but understudied aspects of assessing the contribution of cell death to tumor elimination or cancer progression, including the role of tumor-associated genetics, epigenetics, and oncogenic factors in subverting immunogenic cell death. This perspective will also provide insights on how future studies may address the complex antitumor and protumor immunologic effects of cell death, while accounting for variations in tumor genetics and underlying microenvironment.

Antitumor Immunity Mediated by Photodynamic Therapy Using Injectable Chitosan Hydrogels for Intratumoral and Sustained Drug Delivery.

Photodynamic therapy (PDT) is an anticancer therapy with proven efficacy; however, its application is often limited by prolonged skin photosensitivity and solubility issues associated with the phototherapeutic agents. Injectable hydrogels which can effectively provide intratumoral delivery of photosensitizers with sustained release are attracting increased interest for photodynamic cancer therapies. However, most of the hydrogels for PDT applications are based on systems with high complexity, and often, preclinical validation is not provided. Herein, we provide a simple and reliable pH-sensitive hydrogel formulation that presents appropriate rheological properties for intratumoral injection. For this, Temoporfin (m-THPC), which is one of the most potent clinical photosensitizers, was chemically modified to introduce functional groups that act as cross-linkers in the formation of chitosan-based hydrogels. The introduction of -COOH groups resulted in a water-soluble derivative, named PS2, that was the most promising candidate. Although PS2 was not internalized by the target cells, its extracellular activation caused effective damage to the cancer cells, which was likely mediated by lipid peroxidation. The injection of the hydrogel containing PS2 in the tumors was monitored by high-frequency ultrasounds and in vivo fluorescence imaging which confirmed the sustained release of PS2 for at least 72 h. Following local administration, light exposure was conducted one (single irradiation protocol) or three (multiple irradiation protocols) times. The latter delivered the best therapeutic outcomes, which included complete tumor regression and systemic anticancer immune responses. Immunological memory was induced as ∼75% of the mice cured with our strategy rejected a second rechallenge with live cancer cells. Additionally, the failure of PDT to treat immunocompromised mice bearing tumors reinforces the relevance of the host immune system. Finally, our strategy promotes anticancer immune responses that lead to the abscopal protection against distant metastases.

Tumor-Infiltrating CD103+ Tissue-Resident Memory T Cells and CD103-CD8+ T Cells in HNSCC Are Linked to Outcome in Primary but not Metastatic Disease.

High numbers of tumor-infiltrating lymphocytes (TIL) are linked to better survival in patients with cancer. Tissue-resident memory T cells (TRM; CD8+CD103+) are recognized as a key player of anticancer immune response. To assess TRM cells in primary, metastatic, and recurrent head and neck squamous cell carcinoma (HNSCC), we developed a tissue microarray (TMA) and used multiplex IHC (MxIHC). Samples from primary tumors of 379 HNSCC cases treated at Southampton Hospitals between 2000 and 2016 were collected and analyzed. Of these, 105 cases had lymph node metastases and 82 recurrences. A TMA was generated with triplicate cores for each sample. MxIHC with a stain-and-strip approach was performed using CD8, CD103, and TIM3. Scanned slides were analyzed (digital image analysis) and quality checked (QC). After QC, 194 primary tumors, 76 lymph node metastases, and 65 recurrences were evaluable. Alcohol consumption was statistically significantly correlated with a reduction of TRM cells in primary tumors (nondrinker vs. heavy drinker: P = 0.0036). The known survival benefit of TRM cell infiltration in primary tumors was not found for lymph node metastasis. In recurrences, a high TRM cell number led to a favorable outcome after 12 months. The checkpoint molecule TIM3, was expressed significantly higher on TRM and non-TRM cells in the lymph node compared with primary tumors (P < 0.0001), which was also seen in recurrences (P = 0.0134 and P = 0.0007, respectively). We confirm the prognostic impact of TIL in primary tumors and in recurrences. TRM cell density in lymph node metastases was not linked to outcome. The role of TIM3, as a therapeutic target remains to be defined.

Clinical trial links oncolytic immunoactivation to survival in glioblastoma

Immunotherapy failures can result from the highly suppressive tumour microenvironment that characterizes aggressive forms of cancer such as recurrent glioblastoma (rGBM)1,2. Here we report the results of a first-in-human phase I trial in 41 patients with rGBM who were injected with CAN-3110—an oncolytic herpes virus (oHSV)3. In contrast to other clinical oHSVs, CAN-3110 retains the viral neurovirulence ICP34.5 gene transcribed by a nestin promoter; nestin is overexpressed in GBM and other invasive tumours, but not in the adult brain or healthy differentiated tissue4. These modifications confer CAN-3110 with preferential tumour replication. No dose-limiting toxicities were encountered. Positive HSV1 serology was significantly associated with both improved survival and clearance of CAN-3110 from injected tumours. Survival after treatment, particularly in individuals seropositive for HSV1, was significantly associated with (1) changes in tumour/PBMC T cell counts and clonal diversity, (2) peripheral expansion/contraction of specific T cell clonotypes; and (3) tumour transcriptomic signatures of immune activation. These results provide human validation that intralesional oHSV treatment enhances anticancer immune responses even in immunosuppressive tumour microenvironments, particularly in individuals with cognate serology to the injected virus. This provides a biological rationale for use of this oncolytic modality in cancers that are otherwise unresponsive to immunotherapy (ClinicalTrials.gov: NCT03152318).

Age-induced changes in anti-tumor immunity alter the tumor immune infiltrate and impact response to immuno-oncology treatments.

Immuno-oncology (IO) research relies heavily on murine syngeneic tumor models. However, whilst the average age for a cancer diagnosis is 60 years or older, for practical purposes the majority of preclinical studies are conducted in young mice, despite the fact that ageing has been shown to have a significant impact on the immune response. Using aged (60-72 weeks old) mice bearing CT26 tumors, we investigated the impact of ageing on tumor growth as well as the immune composition of the tumor and peripheral lymphoid organs. We found many differences in the immune cell composition of both the tumor and tumor-draining lymph node between aged and young mice, such as a reduction in the naïve T cell population and a decreased intratumoral CD8/Treg ratio in aged animals. We hypothesized that these differences may contribute to impaired anti-cancer immune responses in aged mice and therefore assessed the anti-tumor efficacy of different IO therapies in aged mice, including both co-stimulation (using an anti-OX40 antibody) and immune checkpoint blockade (using anti-PD-L1 and anti-CTLA-4 antibodies). Whilst aged mice retained the capacity to generate anti-tumor immune responses, these were significantly attenuated when compared to the responses observed in young mice. These differences highlight the importance of age-related immunological changes in assessing and refining the translational insights gained from preclinical mouse models.

The BCL2 inhibitor venetoclax mediates anticancer effects through dendritic cell activation.

BCL2 is an apoptosis-inhibitory oncoprotein that also possesses apoptosis-unrelated activities. Pharmacological BCL2 inhibitors have been developed with the scope of driving BCL2-dependent cancer cells into apoptosis, and one BCL2 antagonist, venetoclax, has been clinically approved for the treatment of specific leukemias and lymphomas. Nonetheless, it appears that venetoclax, as well as genetic BCL2 inhibition, can mediate anticancer effects through an indirect action. Such an indirect effect relies on the enhancement of the immunostimulatory function of dendritic cells, hence increasing tumor immunosurveillance. Mechanistically, BCL2 inhibition involves improved antigen presentation by conventional type-1 dendritic cells (cDC1s) due to the activation of an interferon response, leading to a T cell-mediated anticancer immune response that can be further enhanced by PD-1 blockade. These findings support the emerging hypothesis that successful antineoplastic drugs generally mediate their effects indirectly, through the immune system, rather via merely cell-autonomous effects on malignant cells.

Emerging Immune Checkpoint Molecules on Cancer Cells: CD24 and CD200.

Cancer immunotherapy strategies are based on the utilization of immune checkpoint inhibitors to instigate an antitumor immune response. The efficacy of immune checkpoint blockade, directed at adaptive immune checkpoints, has been demonstrated in select cancer types. However, only a limited subset of patients has exhibited definitive outcomes characterized by a sustained response after discontinuation of therapy. Recent investigations have highlighted the significance of immune checkpoint molecules that are overexpressed in cancer cells and inhibit myeloid lineage immune cells within a tumor microenvironment. These checkpoints are identified as potential targets for anticancer immune responses. Notably, the immune checkpoint molecules CD24 and CD200 have garnered attention owing to their involvement in tumor immune evasion. CD24 and CD200 are overexpressed across diverse cancer types and serve as signaling checkpoints by engaging their respective receptors, Siglec-10 and CD200 receptor, which are expressed on tumor-associated myeloid cells. In this review, we summarized and discussed the latest advancements and insights into CD24 and CD200 as emergent immune checkpoint moieties, further delving into their therapeutic potentials for cancer treatment.

THU493 The Role Of Liver Receptor Homolog1 (LRH-1) In Regulating Breast Cancer Progression By Modulating The Immune Response

Abstract Disclosure: Y. Wang: None. N. Krawczynska: None. S. Bendre: None. H. Vidana Gamage: None. A. Nelczyk: None. A. Das Gupta: None. E.R. Nelson: None. Breast cancer is the most common type of cancer and the second leading cause of death among American women. While immunotherapy holds much promise, the current FDA-approved immunotherapies are effective for only a subset of patients lacking expression of estrogen receptor, progesterone receptor and HER2, but positive for PD-L1. Thus, there is strong impetus to develop novel ways to engage the immune system. We have demonstrated that cholesterol metabolism and homeostasis within myeloid cells can either promote or suppress anti-cancer immunity. One of the regulators of cholesterol homeostasis is Liver Receptor Homolog 1 (LRH-1/NR5A2). We have found that elevated LRH-1 expression in breast tumors is associated with an increased survival. LRH-1 is highly expressed in myeloid cells, particularly neutrophils, a major immune population of the tumor microenvironment. Therefore, we hypothesized that LRH-1 plays modulatory roles in myeloid cells, that subsequently impacts breast cancer progression. Specifically, we evaluated the impact of LRH-1 on myeloid cell biology, including NETosis and phagocytosis. Treatment of neutrophils with an agonist of LRH-1, DLPC, resulted in decreased NETosis, a function of neutrophils previously implicated in recurrence and metastasis. Treatment with an antagonist resulted in increased NETosis. Both the agonist and antagonist exhibited dose-depended effects, strongly suggesting that LRH-1 regulates the process of NETosis. Macrophage phagocytosis is an important initial step towards antigen presentation and activation of T cells. Bone marrow derived macrophages treated with the LRH-1 antagonist exhibited decreased phagocytosis activity, in a dose dependent manner. Treatment with the agonist (DLPC) did not alter phagocytosis, but this may be because basal phagocytosis was already very high. Collectively, our data indicate that LRH-1 plays important roles in the regulation of myeloid cell function, including NETosis in neutrophils and phagocytosis in macrophages. Overall, these findings suggest that LRH-1 activity would be beneficial for an anti-cancer immune response, and therefore position LRH-1 as a therapeutic target. Our ongoing studies will assess the role of LRH-1 in other myeloid cell-related functions including efferocytosis, T-cell expansion and differentiation. Presentation: Thursday, June 15, 2023

Dual mechanism of Let-7i in tumor progression.

Let-7i regulates tumors primarily by binding to the 3' untranslated region (3' UTR) of mRNA, which indirectly regulates post-transcriptional gene expression. Let-7i also has an epigenetic function via modulating DNA methylation to directly regulate gene expression. Let-7i performs a dual role by inducing both the promotion and inhibition of various malignancies, depending on its target. The mechanism of Let-7i action involves cancer cell proliferation, migration, invasion, apoptosis, epithelial-mesenchymal transition, EV transmission, angiogenesis, autophagy, and drug resistance sensitization. Let-7i is closely related to cancer, and hence, is a potential biomarker for the diagnosis and prognosis of various cancers. Therapeutically, it can be used to promote an anti-cancer immune response by modifying exosomes, thus exerting a tumor-suppressive effect.

Nanoassembly of doxorubicin-conjugated polyphosphoester and siRNA simultaneously elicited macrophage- and T cell- mediated anticancer immune response for cancer therapy

Efficiently reawakening immune cells, including T cells and macrophages, to eliminate tumor cells is a promising strategy for cancer treatment, but remains a huge challenge nowadays. Herein, a nanoassembly formed by doxorubicin (DOX)-conjugated polyphosphoester (PP-(hDOX)) and CD47-targeting siRNA (siCD47) via electrostatic and π-π stacking interactions, termed as PP-(hDOX&siCD47), was developed to reawaken the T cell and macrophage-mediated anticancer activity. The PP-(hDOX&siCD47) could efficiently blockade antiphagocytic signal by downregulation of CD47 expression to reactive macrophage-mediated anticancer immunotherapy. Moreover, the conjugated DOX of PP-(hDOX&siCD47) can perform the chemotherapy towards tumor cells and also elicit the T cell-mediated anticancer immune response via immunogenic cell death (ICD) effect. Therefore, the PP-(hDOX&siCD47) treatment could significantly increase M1-like macrophages proportion and tumor infiltration of CD8+ T cells, while the proportions of regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC) were considerably reduced in tumor tissue, eventually achieving significantly tumor growth inhibition. Overall, this study provides a simple siRNA and DOX codelivery approach to simultaneously elicit the macrophage- and T cell-mediated anticancer immune response for cancer therapy.

Dysregulation of DNAM-1-Mediated NK Cell Anti-Cancer Responses in the Tumor Microenvironment.

NK cells play a pivotal role in anti-cancer immune responses, thanks to the expression of a wide array of inhibitory and activating receptors that regulate their cytotoxicity against transformed cells while preserving healthy cells from lysis. However, NK cells exhibit severe dysfunction in the tumor microenvironment, mainly due to the reduction of activating receptors and the induction or increased expression of inhibitory checkpoint receptors. An activating receptor that plays a central role in tumor recognition is the DNAM-1 receptor. It recognizes PVR and Nectin2 adhesion molecules, which are frequently overexpressed on the surface of cancerous cells. These ligands are also able to trigger inhibitory signals via immune checkpoint receptors that are upregulated in the tumor microenvironment and can counteract DNAM-1 activation. Among them, TIGIT has recently gained significant attention, since its targeting results in improved anti-tumor immune responses. This review aims to summarize how the recognition of PVR and Nectin2 by paired co-stimulatory/inhibitory receptors regulates NK cell-mediated clearance of transformed cells. Therapeutic approaches with the potential to reverse DNAM-1 dysfunction in the tumor microenvironment will be also discussed.

Intermittent fasting induced ketogenesis inhibits mouse epithelial ovarian cancer by promoting antitumor T cell response

In various cancer models, dietary interventions have been shown to inhibit tumor growth, improve anticancer drug efficacy, and enhance immunity, but no such evidence exists for epithelial ovarian cancer (EOC), the most lethal gynecologic cancer. The anticancer immune responses induced by 16-h intermittent fasting (IF) were studied in mice with EOC. IF consistently reduced metabolic growth factors and cytokines that stimulate tumor growth, creating a tumor-hostile environment. Immune profiling showed that IF dramatically alters anti-cancer immunity by increasing CD4+ and CD8+ cells, Th1 and cytotoxic responses, and metabolic fitness. β-hydroxy butyrate (BHB), a bioactive metabolite produced by IF, partially imitates its anticancer effects by inducing CD8+ effector function. In a direct comparison, IF outperformed exogenous BHB treatment in survival and anti-tumor immune response, probably due to increased ketogenesis. Thus, IF and one of its metabolic mediators BHB suppress EOC growth and sustain a potent anti-tumor Tcell response.