Murine Tumor Cells Research Articles

Noncanonical TRAIL Signaling Promotes Myeloid-Derived Suppressor Cell Abundance and Tumor Growth in Cholangiocarcinoma

Proapoptotic tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) signaling as a cause of cancer cell death is a well-established mechanism. However, TRAIL-receptor (TRAIL-R) agonists have had very limited anticancer activity in human beings, challenging the concept of TRAIL as a potent anticancer agent. Herein, we aimed to define mechanisms by which TRAIL+ cancer cells can leverage noncanonical TRAIL signaling in myeloid-derived suppressor cells (MDSCs) promoting their abundance in murine cholangiocarcinoma (CCA). Multiple immunocompetent syngeneic, orthotopic models of CCA were used. Single-cell RNA sequencing and cellular indexing of transcriptomes and epitopes by sequencing of CD45+ cells in murine tumors from the different CCA models was conducted. In multiple immunocompetent murine models of CCA, implantation of TRAIL+ murine cancer cells into Trail-r-/- mice resulted in a significant reduction in tumor volumes compared with wild-type mice. Tumor-bearing Trail-r-/- mice had a significant decrease in the abundance of MDSCs owing to attenuation of MDSC proliferation. Noncanonical TRAIL signaling with consequent nuclear factor-κB activation in MDSCs facilitated enhanced MDSC proliferation. Single-cell RNA sequencing and cellular indexing of transcriptomes and epitopes by sequencing of immune cells from murine tumors showed enrichment of a nuclear factor-κB activation signature in MDSCs. Moreover, MDSCs were resistant to TRAIL-mediated apoptosis owing to enhanced expression of cellular FLICE inhibitory protein, an inhibitor of proapoptotic TRAIL signaling. Accordingly, cellular FLICE inhibitory protein knockdown sensitized murine MDSCs to TRAIL-mediated apoptosis. Finally, cancer cell-restricted deletion of Trail significantly reduced MDSC abundance and murine tumor burden. Our findings highlight the therapeutic potential of targeting TRAIL+ cancer cells for treatment of a poorly immunogenic cancer.

EVALUATION OF THE CYTOTOXICITY AND GENOTOXICOLOGICAL SAFETY PROFILE OF BIOACTIVE SILVER(I) COMPLEXES WITH AMINOADAMANTANE LIGANDS

Silver(I) complexes of amantadine (atdH), memantine (mtnH) and rimantadine (rtdH), named Ag-atd, Ag-mtn and Ag-rtd, respectively, were recently synthesized and described in the literature as promising antibacterial agents. In the present study, the cytotoxicity of such complexes was evaluated against cultures of primary epidermal keratinocytes (HaCaT) and murine melanoma tumor cells (B16-F10), and mutagenicity was studied by the Ames test to investigate their abilities to induce gene mutations. The Ames test was performed using Salmonella Typhimurium strains (TA98, TA100, TA102 and TA97a) capable of detecting frameshift and base pair substitution gene mutations, in experiments with and without metabolic activation (microsomal fraction S9). This study revealed significant cytotoxic activity against tumor cells and selectivity of Ag-atd and Ag-rtd complexes when compared to non-tumor human keratinocyte cells. Moreover, the Ag(I) complexes did not induce a significant growth in the number of revertant colonies when comparing with the negative control, both in the experiments without and with metabolic activation, indicating absence of mutagenic activity. The results are encouraging and collaborate in the genotoxicological investigations necessary for understanding the interaction and ability of the silver complexes to induce mutations and contribute to ensure their uses as future antibacterial or antitumor agents.

Assessment of myeloid-derived suppressor cell differentiation ex vivo.

Myeloid-derived suppressor cells (MDSCs) are major promoters of progression and metastasis in cancer. MDSCs inhibit the anti-tumor immune response through multiple mechanisms. The main MDSC functions in cancer are related to the inactivation of T cells and the establishment of an immunosuppressive tumor microenvironment (TME) through the production of pro-inflammatory cytokines, among other mechanisms. MDSCs are phenotypically similar to conventional myeloid cells, so their identification is challenging. Moreover, they infiltrate the tumors in limited numbers, and their purification from within the tumors is technically difficult and makes their study a challenge. Therefore, several ex vivo differentiation methods have been established. Our differentiation method leads to MDSCs that closely model tumor-infiltrating counterparts. In this protocol, MDSCs are differentiated from bone marrow precursors by incubation in differentiation medium produced by murine tumor cell lines engineered to constitutively express granulocyte-monocyte colony stimulating factor (GM-CSF). These ex vivo-generated MDSC subsets show high fidelity compared to their natural tumor-infiltrated counterparts. Moreover, the high yields of purification from these ex vivo differentiated MDSC enable their use for validation of new treatments in high-throughput assays. In this chapter we describe the engineering of a stable cell line overexpressing GM-CSF, followed by production and collection of conditioned media supporting MDSC differentiation. Finally, we detail the isolation procedure of bone marrow cells and the specific MDSC differentiation protocol.

Study of the cytotoxic activity of alcoholic and aqueous extracts of Iraqi aromatic rice bran on B16 cell line

The test was conducted on a sample consisting of mixing three samples of Iraqi Aromatic rice (Amber) bran obtained from the private mills in Najaf Governorate. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method was used to study the cytotoxic effect of alcoholic and aqueous extract of Iraqi Aromatic rice bran on B16 cell line, it is a murine tumor cell line used as a model to study human melanoma. The results showed that all concentrations of alcoholic extract (5, 10, 20, 40, and 80) % caused a significant inhibition on the B16 cell line. The inhibition rate reached to (13.00, 27.00, 47.33, 71.67 and 86.67) % respectively, after 48 hours while the cell viability was (87.00, 73.00, 52.67, 28.33and 13.33) % with a statistically significant difference at P≤. 0.05 compared to the control. The results showed that the aqueous extract had less inhibition effectiveness (for the same concentrations) after 48 hours, (10.00, 19.33, 27.00, 46.67 and 66.33) % and the cell viability rate was (90.00, 80.67, 73.00, 53.33 and 33.67) % respectively. The study shows that both alcoholic and aqueous extract prepared from Iraqi Aromatic rice bran had a toxic and anti-proliferative effect on B16 cell line, and this effect increases with increasing concentration. Treatment of these cells with the two extracts caused shrinkage, a decrease in numbers, and a clear morphological change in this type of cells.

Ex vivo photothermal treatment-induced immunogenic cell death for anticancer vaccine development

Photothermal therapy is an anti-cancer strategy that induce cell death by converting light energy into heat energy. During photothermal therapy, cancer cells were treated with photothermal agents, such as indocyanine green, and irradiated with a laser. Heat stress in cancer cells results in cellular death and inflammatory responses. In the present study, we demonstrated how ex vivo photothermal (PT)-treated cells underwent immunogenic cell death. PT treatment caused significant expression of heat shock protein (HSP) 27, HSP70, and HSP90 in murine tumor cells. To evaluate the immunogenicity of heat-stressed cells, lysate from PT-treated tumor cells or water-based heated cells was pulsed to syngeneic bone-marrow-derived dendritic cells (DCs) to generate a DC-based vaccine. Administration with PT-treated tumor lysates-pulsed DC vaccine resulted in significant inhibition of tumor growth in BALB/c and C57BL/6 syngeneic tumor-bearing mice. The immunogenicity of PT-treated cancer cells was reduced in the presence of HSP inhibitors, J2, VER-155008 or 17-AAG. Our study elucidates how PT techniques have distinct mechanisms from water-based heating and might be a potentially robust and efficient solution to developing an anti-cancer vaccine.

Extracellular vesicles and co-isolated endogenous retroviruses from murine cancer cells differentially affect dendriticcells.

Cells secrete extracellular vesicles (EVs) and non-vesicular extracellular (nano)particles (NVEPs or ENPs) that may play a role in intercellular communication. Tumor-derived EVs have been proposed to induce immune priming of antigen presenting cells or to be immuno-suppressive agents. We suspect that such disparate functions are due to variable compositions in EV subtypes and ENPs. We aimed to characterize the array of secreted EVs and ENPs of murine tumor cell lines. Unexpectedly, we identified virus-like particles (VLPs) from endogenous murine leukemia virus in preparations of EVs produced by many tumor cells. We established a protocol to separate small EVs from VLPs and ENPs. We compared their protein composition and analyzed their functional interaction with target dendritic cells. ENPs were poorly captured and did not affect dendritic cells. Small EVs specifically induced dendritic cell death. A mixed large/dense EV/VLP preparation was most efficient to induce dendritic cell maturation and antigen presentation. Our results call for systematic re-evaluation of the respective proportions and functions of non-viral EVs and VLPs produced by murine tumors and their contribution to tumor progression.

Abstract B005: Molecular, metabolic and functional CD4 T cell paralysis in lymph node impedes tumor control

Abstract Introduction: CD4 T cells are important in anti-tumor immunity, yet the regulation of CD4 tumor-specific T (TTS) cells during cancer development is still unclear. So far, studies have primarily focused on studying bulk CD4 tumor-infiltrating lymphocytes (TILs) with unknown antigen specificities, or transferring in vitro activated CD4 T cells as adoptive cell therapy (ACT), which fail to directly address how naïve CD4 TTS cells are activated and then differentiate in vivo in response to tumor progression. Therefore, studies addressing these questions will be critical to understand the state of anti-tumor CD4 T cells available for restorative therapies. Methods: To address these key questions, we developed two murine tumor cell lines, PyMG (an orthotopic breast tumor) and MC38GP (an adenocarcinoma tumor) expressing the LCMV glycoprotein 1-100 sequence (LCMV-GP1-100). The sequence contains an MHCII-epitope GP61-80 and an MHCI-epitope GP33-43, that can be recognized by TCR transgenic CD4 T cells (SMARTAs) and CD8 T cells (P14s), enabling direct in vivo identification of CD4 TTS cells. Results: We demonstrate that following tumor initiation, CD4 TTS cells are initially primed in the tumor draining lymph node (dLN), but rapidly frozen into a “paralyzed” state. The paralyzed state freezes CD4 TTS cell clonal expansion, impairs differentiation, limits IFNγ production, and redirects metabolic circuits, which together impede tumor control. Transcriptional programming of CD4 TTS cell paralysis is unique to the tumor setting and distinct from well-defined effector and exhaustion programming. In comparison, CD8 TTS cells do not manifest the proliferation defect. Paralysis is actively maintained throughout cancer progression by a functional interplay of regulatory T cells (Tregs) and CTLA4. Depleting Tregs induces robust proliferation of CD4 TTS cells, yet concurrently pushes the proliferated cells to become highly suppressive tumor-specific induced Tregs (iTregs). The differentiation of iTregs is dependent on the CTLA4 expression on CD4 TTS cells. Alleviating suppressive signals from both Tregs and CTLA4 is required to restore CD4 TTS cells proliferation, reduce iTreg differentiation and promote T helper cell differentiation. Overcoming CD4 TTS cell paralysis established long-term tumor control, demonstrating a novel immune evasion mechanism that specifically cripples CD4 TTS cells to favor tumor progression. Conclusion: Our study demonstrates that during early stages of cancer, the CD4 TTS cell development is quickly paralyzed at multiple levels of functional development. Overcoming their paralysis established long-term tumor control, demonstrating a novel immune evasion mechanism that specifically cripples CD4 TTS cells to favor tumor progression. Citation Format: Mengdi Guo, Diala Abd-Rabbo, Bruna Bertol, Madeleine Carew, David G Brooks. Molecular, metabolic and functional CD4 T cell paralysis in lymph node impedes tumor control [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B005.

Alpha-Pinene As a Novel Therapeutic Agent for T-Cell Tumors

T-cell acute leukemia and lymphoma have poor prognoses, necessitating the development of novel therapeutic agents. In this study, we investigated the antitumor activity of α-pinene, a monoterpene compound, against T-cell tumors. We evaluated the effects of α-pinene on cell growth inhibition in vitro using the murine T-cell tumor cell line EL-4 and the human-derived T-cell tumor cell line Molt-4. In addition, we assessed the effects of limonene, another monoterpene with reported tumor-suppressive effects, as a comparative agent. Both α-pinene and limonene demonstrated concentration- and time-dependent inhibition of cell growth in both the EL-4 and Molt-4 cell lines (Figure 1). Moreover, α-pinene exhibited greater potency than limonene in inhibiting the growth of various hematologic malignancies. Importantly, α-pinene and limonene had minimal effects on the growth of normal murine spleen T cells. Further investigation of the mechanisms of action of α-pinene revealed its ability to induce apoptosis and cell cycle arrest in EL-4 and Molt-4 cells. Transcriptomic profiling of α-pinene-treated EL-4 cells using RNA-seq identified differentially expressed genes associated with cellular damage and mitochondrial dysfunction. Increased intracellular ROS levels and mitochondrial impairment were observed in the T-cell tumors treated with α-pinene. The activation of intrinsic apoptotic pathways involving EGR1, p53, BCL-2, and BAX was found to contribute to α-pinene-induced apoptosis in T-cell tumors. Moreover, α-pinene inhibited the NF-κB signaling pathway, resulting in the reduced nuclear translocation of NF-κB p65 and decreased total intracellular NF-κB p65 levels in EL-4 cells. Additionally, we discovered that α-pinene induced ferroptosis, a newly identified programmed cell death process, in EL-4 cells through lipid peroxidation and iron accumulation. Activation of the system x c−/GSH/GPX4 axis and upregulation of iron transporters, such as Slc39a8 and TfR1, were observed in α-pinene-induced ferroptosis. Treatment with the ferroptosis inhibitor Fer-1 partially reversed the tumor-inhibiting effect of α-pinene in EL-4 cells. Finally, we administrated α-pinene to mice subcutaneously injected with luciferase-expressing EL-4 to evaluate the efficacy of α-pinene in vivo. The tumor growth was significantly inhibited by α-pinene treatment (vehicle: 1055 ± 101 mm 3; α-pinene: 701 ± 82 mm 3, p < 0.01, Figure 2) without adverse effects on body weight or behavior. Immunohistochemistry analyses revealed a significant increase of CD8 + T-cells (vehicle: 8.1 ± 2.7 cells / field of view; α-pinene: 43.1 ± 12.2 cells / field of view , p < 0.05) and NK1.1 + cells (vehicle: 5.1 ± 1.0 cells / field of view ; α-pinene: 41.1 ± 9.8 cells / field of view , p < 0.01) in the tumors, suggesting that α-pinene may have an indirect antitumor effect by recruiting immune cells into tumors. Overall, our findings demonstrate the antitumor activity of α-pinene against T-cell tumors through the induction of apoptosis, cell cycle arrest, and ferroptosis. α-Pinene shows promise as a potential therapeutic agent for T-cell tumors and warrants further investigation for its clinical application.

Combination of verteporfin-photodynamic therapy with 5-aza-2'-deoxycytidine enhances the anti-tumour immune response in triple negative breast cancer.

Triple negative breast cancer (TNBC) is a subtype of breast cancer characterised by its high tumourigenic, invasive, and immunosuppressive nature. Photodynamic therapy (PDT) is a focal therapy that uses light to activate a photosensitizing agent and induce a cytotoxic effect. 5-aza-2'-deoxycytidine (5-ADC) is a clinically approved immunomodulatory chemotherapy agent. The mechanism of the combination therapy using PDT and 5-ADC in evoking an anti-tumour response is not fully understood. The present study examined whether a single dose of 5-ADC enhances the cytotoxic and anti-tumour immune effect of low dose PDT with verteporfin as the photosensitiser in a TNBC orthotopic syngeneic murine model, using the triple negative murine mammary tumour cell line 4T1. Histopathology analysis, digital pathology and immunohistochemistry of treated tumours and distant sites were assessed. Flow cytometry of splenic and breast tissue was used to identify T cell populations. Bioinformatics were used to identify tumour immune microenvironments related to TNBC patients. Functional experiments showed that PDT was most effective when used in combination with 5-ADC to optimize its efficacy. 5-ADC/PDT combination therapy elicited a synergistic effect in vitro and was significantly more cytotoxic than monotherapies on 4T1 tumour cells. For tumour therapy, all types of treatments demonstrated histopathologically defined margins of necrosis, increased T cell expression in the spleen with absence of metastases or distant tissue destruction. Flow cytometry and digital pathology results showed significant increases in CD8 expressing cells with all treatments, whereas only the 5-ADC/PDT combination therapy showed increase in CD4 expression. Bioinformatics analysis of in silico publicly available TNBC data identified BCL3 and BCL2 as well as the following anti-tumour immune response biomarkers as significantly altered in TNBC compared to other breast cancer subtypes: GZMA, PRF1, CXCL1, CCL2, CCL4, and CCL5. Interestingly, molecular biomarker assays showed increase in anti-tumour response genes after treatment. The results showed concomitant increase in BCL3, with decrease in BCL2 expression in TNBC treatment. In addition, the treatments showed decrease in PRF1, CCL2, CCL4, and CCL5 genes with 5-ADC and 5-ADC/PDT treatment in both spleen and breast tissue, with the latter showing the most decrease. To our knowledge, this is the first study that shows which of the innate and adaptive immune biomarkers are activated during PDT related treatment of the TNBC 4T1 mouse models. The results also indicate that some of the immune response biomarkers can be used to monitor the effectiveness of PDT treatment in TNBC murine model warranting further investigation in human subjects.

Antitumor activity of bengamide ii in a panel of human and murine tumor cell lines: In vitro and in vivo determination of effectiveness against lung cancer

Lung cancer is the most commonly diagnosed cancer and the one that causes the most deaths worldwide, so there is a need for therapies that improve survival rates. Products derived from marine organisms are a source of novel and potent antitumor compounds, but they present the great obstacle of their obtaining from the natural environment and the problems associated with the synthesis and biological effects of chemical analogues. In this work, a Bengamide analogue (Bengamide II) was chemically synthesized and in vitro and in vivo studies were performed to determine its antitumor activity and mechanisms of action. It was shown to have potent antiproliferative activity in lung cancer lines in 2D and 3D models. In addition, Bengamide II-treated cells showed G2/M and G0/G1 cell cycle arrest, together with a decrease in the proliferation marker Ki67. As for the mechanism of action, the treatment was associated with increased LC3-II expression and production of acidic vesicles signaling autophagy. In addition, Bengamide II treatment was associated with caspase-3 activation and DNA fragmentation related to apoptosis. Furthermore, a reduction of VEGFA expression, related to angiogenesis, was also observed. In vivo studies showed that Bengamide II markedly reduced tumor volume and metastases increasing survival. Additionally, it revealed no systemic toxicity in in vivo models at the therapeutic doses used, which is essential for its future clinical use. Taken together, the chemically synthesized bengamide analogue Bengamide II, is a promising drug for lung cancer treatment showing relevant antitumor activity and significant safety.

Antitumor activity of cordycepin in murine malignant tumor cell line: An in vitro and in silico study

Cordycepin, also known as 3′-deoxyadenosine, is a substance similar to adenosine found in the entomopathogenic fungus Cordyceps militaris. This fungus is recognized for its remarkable therapeutic properties. This study seeks to investigate the antitumor activity of cordycepin in Dalton's lymphoma (DL) malignant cancer cell line using cytotoxicity and apoptosis as key parameters. Molecular docking (MD) and molecular dynamic simulation (MDS) were used to further validate the wet lab findings. Cytotoxicity study revealed that cordycepin induced significant cytotoxicity (P ≤ 0.05) in the DL cell line after 24 h of treatment. The efficacy of cordycepin as an apoptotic agent was substantiated by the highly promising results obtained through the apoptotic assay, utilizing the acridine orange/ethidium bromide (AO/EB) dual staining method. Cordycepin interacted with the active sites of antiapoptotic target proteins (BCL-XL, SURVIVIN, BCL-2, BCL-B, HSP90, and IAP1), as demonstrated by MD study that corroborated the findings of cytotoxicity and apoptotic assays. The comparative examination of docking outcomes indicated that cordycepin exhibits higher affinity for HSP90 in comparison to other targets. Molecular dynamics simulation for 120 ns further validated the findings of MD as cordycepin remained bound with HSP90 throughout the entire simulation time (120 ns) with favourable binding energy.

A biodegradable drug‐controlled delivery system based on mesoporous manganese dioxide and poly(dopamine)

AbstractMesoporous manganese dioxide (mMnO2) was first synthesized for the loading of methotrexate (MTX), and then dopamine was in situ polymerized on the surface of the MTX‐loaded mMnO2 (mMnO2‐MTX) in an alkaline solution to encapsulate the drug in the mesopores of mMnO2. Both low pH and glutathione (GSH) can result in the degradation of mMnO2 and poly(dopamine) (PDA), and thus the delivery of MTX from the mMnO2‐MTX‐PDA can be triggered by low pH and GSH. Near‐infrared (NIR) light‐responsive delivery of MTX can be achieved owing to the outstanding photothermal conversion capability of PDA; on the other hand, the mMnO2‐MTX‐PDA can be utilized for photothermal therapy under the irradiation of NIR light due to the elevated temperature. The results of cytotoxicity test demonstrate that the pH, GSH, and NIR light tri‐responsive drug‐controlled delivery system has excellent biocompatibility, while exhibits pronounced growth inhibition against murine breast tumor cell line 4T1.

Intratumoral administration of unconjugated Accum™ impairs the growth of pre-established solid lymphoma tumors.

The Accum™ technology was initially designed to enhance the bioaccumulation of a given molecule in target cells. It does so by triggering endosomal membrane damages allowing endocytosed products to enter the cytosol, escaping the harsh environmental cues of the endosomal lumen. In an attempt to minimize manufacturing hurdles associated with Accum™ conjugation, we tested whether free Accum™ admixed with antigens could lead to outcomes similar to those obtained with conjugated products. Surprisingly, unconjugated Accum™ was found to promote cell death in vitro, an observation further confirmed on various murine tumor cell lines (EL4, CT-26, B16, and 4 T1). At the molecular level, unconjugated Accum™ triggers the production of reactive oxygen species and elicits immunogenic cell death while retaining its innate ability to cause endosomal damages. When administered as a monotherapy to animals with pre-established EL4 T-cell lymphoma, Accum™ controlled tumor growth in a dose-dependent manner, and its therapeutic effect relies on CD4 and CD8 T cells. Although unconjugated Accum™ synergizes with various immune checkpoint inhibitors (anti-CTLA4, anti-PD-1, or anti-CD47) at controlling tumor growth, its therapeutic potency could not be further enhanced when combined with all three tested immune checkpoint inhibitors at once due to its dependency on a specific dosing regimen. In sum, we report in this study an unprecedented new function for unconjugated Accum™ as a novel anticancer molecule. These results could pave the path for a new line of investigation aimed at exploring the pro-killing properties of additional Accum™ variants as a mean to develop second-generation anticancer therapeutics.

Tumors recycle glucocorticoids to drive Treg-mediated immunosuppression.

Suppression of antitumor immunity is a prominent feature of the tumor microenvironment. In this issue of the JCI, Taves, Otsuka, and authors show that glucocorticoids (GCs), which are potent immunosuppressive hormones mainly produced by the adrenals, can be reconverted from their inactive form to active metabolites via the 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) enzyme expressed by murine tumor cell lines. In the tumor microenvironment, GCs acted on CD4+ regulatory T cells to enhance their immunosuppressive function and promote tumor growth. The findings suggest that targeting GC recycling as a strategy for modulating tumor immunosuppression has the potential to improve therapeutic efficacy of immune checkpoint blockade.

Mast Cells Retard Tumor Growth in Ovarian Cancer: Insights from a Mouse Model.

Ovarian cancer has the highest mortality rate among female reproductive tract malignancies. A complex network, including the interaction between tumor and immune cells, regulates the tumor microenvironment, survival, and growth. The role of mast cells (MCs) in ovarian tumor pathophysiology is poorly understood. We aimed to understand the effect of MCs on tumor cell migration and growth using in vitro and in vivo approaches. Wound healing assays using human tumor cell lines (SK-OV-3, OVCAR-3) and human MCs (HMC-1) were conducted. Murine ID8 tumor cells were injected into C57BL6/J wildtype (WT) and MC-deficient C57BL/6-KitW-sh/W-sh (KitW-sh) mice. Reconstitution of KitW-sh was performed by the transfer of WT bone marrow-derived MCs (BMMCs). Tumor development was recorded by high-frequency ultrasonography. In vitro, we observed a diminished migration of human ovarian tumor cells upon direct or indirect MC contact. In vivo, application of ID8 cells into KitW-sh mice resulted in significantly increased tumor growth compared to C57BL6/J mice. Injection of BMMCs into KitW-sh mice reconstituted MCs and restored tumor growth. Our data show that MCs have a suppressive effect on ovarian tumor growth and may serve as a new therapeutic target.

Targeting FOXP3 Tumor-Intrinsic Effects Using Adenoviral Vectors in Experimental Breast Cancer.

The regulatory T cell master transcription factor, Forkhead box P3 (Foxp3), has been detected in cancer cells; however, its role in breast tumor pathogenesis remains controversial. Here we assessed Foxp3 tumor intrinsic effects in experimental breast cancer using a Foxp3 binder peptide (P60) that impairs Foxp3 nuclear translocation. Cisplatin upregulated Foxp3 expression in HER2+ and triple-negative breast cancer (TNBC) cells. Foxp3 inhibition with P60 enhanced chemosensitivity and reduced cell survival and migration in human and murine breast tumor cells. We also developed an adenoviral vector encoding P60 (Ad.P60) that efficiently transduced breast tumor cells, reduced cell viability and migration, and improved the cytotoxic response to cisplatin. Conditioned medium from transduced breast tumor cells contained lower levels of IL-10 and improved the activation of splenic lymphocytes. Intratumoral administration of Ad.P60 in breast-tumor-bearing mice significantly reduced tumor infiltration of Tregs, delayed tumor growth, and inhibited the development of spontaneous lung metastases. Our results suggest that Foxp3 exerts protumoral intrinsic effects in breast cancer cells and that gene-therapy-mediated blockade of Foxp3 could constitute a therapeutic strategy to improve the response of these tumors to standard treatment.

Phosphorylated nuclear DICER1 promotes open chromatin state and lineage plasticity of AT2 tumor cells in lung adenocarcinomas.

KRAS/ERK pathway phosphorylates DICER1, causing its nuclear translocation, and phosphomimetic Dicer1 contributes to tumorigenesis in mice. Mechanisms through which phospho-DICER1 regulates tumor progression remain undefined. While DICER1 canonically regulates microRNAs (miRNA) and epithelial-to-mesenchymal transition (EMT), we found that phosphorylated nuclear DICER1 (phospho-nuclear DICER1) promotes late-stage tumor progression in mice with oncogenic Kras, independent of miRNAs and EMT. Instead, we observe that the murine AT2 tumor cells exhibit altered chromatin compaction, and cells from disorganized advanced tumors, but not localized tumors, express gastric genes. Collectively, this results in subpopulations of tumor cells transitioning from a restricted alveolar to a broader endodermal lineage state. In human LUADs, we observed expression of phospho-nuclear DICER1 in advanced tumors together with the expression of gastric genes. We define a multimeric chromatin-DICER1 complex composed of the Mediator complex subunit 12, CBX1, MACROH2A.1, and transcriptional regulators supporting the model that phospho-nuclear DICER1 leads to lineage reprogramming of AT2 tumor cells to mediate lung cancer progression.

Tumor aerobic glycolysis confers immune evasion through modulating sensitivity to T cell-mediated bystander killing via TNF-α

Metabolic reprogramming toward glycolysis is a hallmark of cancer malignancy. The molecular mechanisms by which the tumor glycolysis pathway promotes immune evasion remain to be elucidated. Here, by performinggenome-wide CRISPR screens in murine tumor cells co-cultured with cytotoxic Tcells (CTLs), we identified that deficiency of two important glycolysis enzymes, Glut1 (glucose transporter 1) and Gpi1 (glucose-6-phosphate isomerase 1), resulted in enhanced killing of tumor cells by CTLs. Mechanistically, Glut1 inactivation causes metabolic rewiring toward oxidative phosphorylation, which generates an excessive amount of reactive oxygen species (ROS). Accumulated ROS potentiate tumor cell death mediated by tumor necrosis factor alpha (TNF-α) in a caspase-8- and Fadd-dependent manner. Genetic and pharmacological inactivation of Glut1 sensitizes tumors to anti-tumor immunity and synergizes with anti-PD-1 therapy through the TNF-α pathway. The mechanistic interplay between tumor-intrinsic glycolysis and TNF-α-induced killing provides new therapeutic strategies to enhance anti-tumor immunity.

ADAM12 expression is upregulated in cancer cells upon radiation and constitutes a prognostic factor in rectal cancer patients following radiotherapy.

Radiotherapy is one of the most common cancer treatments, yet, some patients require high doses to respond. Therefore, the development of new strategies leans toward personalizing therapy to avoid unnecessary burden on cancer patients. This approach prevents the administration of ineffective treatments or uses combination strategies to increase the sensitivity of cancer cells. ADAM12 has been shown to be upregulated in many cancers and correlate with poor survival and chemoresistance, thus making it a potential candidate responsible for radioresistance. Here, we show that ADAM12 expression is upregulated in response to irradiation in both mouse and human cancer cells in vitro, as well as in tumor tissues from rectal cancer patients. Interestingly, the expression of ADAM12 following radiotherapy correlates with the initial disease stage and predicts the response of rectal cancer patients to the treatment. While we found no cell-autonomous effects of ADAM12 on the response of colon cancer cells to irradiation in vitro, depletion of ADAM12 expression markedly reduced the tumor growth of irradiated cancer cells when subcutaneously transplanted in syngeneic mice. Interestingly, loss of cancer cell-derived ADAM12 expression increased the number of CD31+FAP- cells in murine tumors. Moreover, conditioned medium from ADAM12-/- colon cancer cells led to increased tube formation when added to endothelial cell cultures. Thus, it is tempting to speculate that altered tumor vascularity may be implicated in the observed effect of ADAM12 on response to radiotherapy in rectal cancer. We conclude that ADAM12 represents a promising prognostic factor for stratification of rectal cancer patients receiving radiotherapy and suggest that targeting ADAM12 in combination with radiotherapy could potentially improve the treatment response.

Combination therapy with hydrogen peroxide and irradiation promotes an abscopal effect in mouse models.

Hydrogen peroxide (H2 O2 ) induces oxidative stress and cytotoxicity, and can be used for treating cancers in combination with radiotherapy. A product comprising H2 O2 and sodium hyaluronate has been developed as a radiosensitizer. However, the effects of H2 O2 on antitumor immunity remain unclear. To investigate the effects of H2 O2 , especially the abscopal effect when combined with radiotherapy (RT), we implanted murine tumor cells simultaneously in two locations in mouse models: the hind limb and back. H2 O2 mixed with sodium hyaluronate was injected intratumorally, followed by irradiation only at the hind limb lesion. No treatment was administered to the back lesion. The H2 O2 /RT combination significantly reduced tumor growth at the noninjected/nonirradiated site in the back lesion, whereas H2 O2 or RT individually did not reduce tumor growth. Flow cytometric analyses of the tumor-draining lymph nodes in the injected/irradiated areas showed that the number of dendritic cells increased significantly with maturation in the H2 O2 /RT combination group. In addition, analyses of tumor-infiltrating lymphocytes showed that the number of CD8+ (cluster of differentiation 8) T cells and the frequency of IFN-γ+ (interferon gamma) CD8+ T cells were higher in the noninjected/nonirradiated tumors in the H2 O2 /RT group compared to those in the other groups. PD-1 (programmed death receptor 1)blockade further increased the antitumor effect against noninjected/nonirradiated tumors in the H2 O2 /RT group. Intratumoral injection of H2 O2 combined with RT therefore induces an abscopal effect by activating antitumor immunity, which can be further enhanced by PD-1 blockade. These findings promote the development of H2 O2 /RT therapy combined with cancer immunotherapies, even for advanced cancers.