Mouse Melanoma Cells Research Articles

Tumor Vaccine Exploiting Membranes with Influenza Virus-Induced Immunogenic Cell Death to Decorate Polylactic Coglycolic Acid Nanoparticles.

Immunogenic cell death (ICD) of tumor cells, which is characterized by releasing immunostimulatory "find me" and "eat me" signals, expressing proinflammatory cytokines and providing personalized and broad-spectrum tumor antigens draws increasing attention in developing a tumor vaccine. In this study, we aimed to investigate whether the influenza virus (IAV) is efficient enough to induce ICD in tumor cells and an extra modification of IAV components such as hemeagglutinin (HA) will be helpful for the ICD-induced cells to elicit robust antitumor effects; in addition, to evaluate whether the membrane-engineering polylactic coglycolic acid nanoparticles (PLGA NPs) simulating ICD immune stimulation mechanisms hold the potential to be a promising vaccine candidate, a mouse melanoma cell line (B16-F10 cell) was infected with IAV rescued by the reverse genetic system, and the prepared cells and membrane-modified PLGA NPs were used separately to immunize the melanoma-bearing mice. IAV-infected tumor cells exhibit dying status, releasing high mobility group box-1 (HMGB1) and adenosine triphosphate (ATP), and exposing calreticulin (CRT), IAV hemeagglutinin (HA), and tumor antigens like tyrosinase-related protein 2 (TRP2). IAV-induced ICD cells enhance biomass-derived carbon (BMDCs) migration, antigen uptake, cross-presentation, and maturation in vitro. Furthermore, immunization with IAV-induced ICD cells effectively suppressed tumor growth in melanoma-bearing mice. The isolated cell membrane inherited the immunological characteristics from the ICD cells and elicited robust antitumor immune responses through decorating PLGA NPs loading with a tumor-specific helper T-cell peptide and supplemented with ATP in a hydrogel system. This study indicated a promising strategy for developing cell-based and personalized tumor vaccines through fully taking advantage of the immune stimulation mechanisms of ICD occurrence in tumor cells, IAV modification, and nanoscale delivery.

Palmitoyl copper peptide and acetyl tyrosine complex enhances melanin production in both A375 and B16 cell lines

Copper peptide, a low molecular weight peptide composed of glycyl-L-histidyl-L-lysine-copper, possesses anti-aging, anti-inflammatory, and wound healing properties. In this study, we investigated the effects of a combination agent CP-AcT, composed of palmitoyl copper peptide (pal-GHK-Cu) and acetyl tyrosine (N-Acetyl-L-tyrosine), on melanin production in the human malignant melanoma cell line A375 and the mouse melanoma cell line B16. Firstly, the cytotoxicity of CP-AcT at various concentrations (0-8 μg/mL) on HaCat, HFF, A375, and B16 cells was evaluated. Subsequently, the effects of the CP-AcT on tyrosinase activity both extracellular and intracellularly, as well as on melanin production in two melanoma cell lines, were evaluated under conditions that did not compromise cell viability. Additionally, quantitative gene plex (QGP) combined with branched DNA (bDNA) technology was used to analyze the effects of CP-AcT on the expression of melanin-related genes in A375 cells, with a focus on five specific genes. Finally, the effects of the CP-AcT on the expression of three proteins involved in the biosynthesis pathway of melanin: tyrosinase (TYR), dopachrome tautomerase (DCT), and endothelin 3 (EDN3) were analyzed. The results indicate that the complex CP-AcT effectively promotes melanin production in both types of melanoma cells.

Deficiency of myeloid discoidin domain receptor 2 aggravates melanoma lung and bone metastasis.

Melanoma, one of the most prevalent cancers worldwide, frequently metastasizes to the lung and bones. Tumor-associated macrophages play essential roles in melanoma metastasis but the underlying mechanism remains obscure. We previously demonstrated that specific knockout of Ddr2, a receptor tyrosine kinase, exacerbates systemic inflammation via modulating macrophage repolarization. To investigate whether myeloid Ddr2 regulates melanoma growth and metastasis, we injected B16BL6 melanoma cells into Ddr2LysM (cKO) mice via subcutaneous neck, tail vein, and left ventricle, respectively. We found that the growth of melanoma cells in cKO mice was significantly retarded, as demonstrated by the subcutaneous transplantation tumor model. Unexpectedly, the melanoma metastasis to the lung or bone was significantly stimulated in cKO mice, indicating the complicated role of Ddr2 in macrophages in melanoma development. Furthermore, Ddr2 in macrophages regulated the migration of B16BL6 cells in the co-culture system. Bioinformatics analysis showed that Ddr2 expression correlates with improved prognostic outcomes in melanoma, and high expression of Ddr2 is protective in melanoma metastasis. Our results enrich the current knowledge of Ddr2 in tumor biology and indicate that more consideration should be taken when applying Ddr2 inhibition as a melanoma treatment strategy.

Valorization of Hom Thong Banana Peel (Musa sp., AAA Group) as an Anti-Melanogenic Agent Through Inhibition of Pigmentary Genes and Molecular Docking Study.

Prolonged and unprotected exposure to the environment explicitly influences the development of hyperpigmented lesions. The enzyme tyrosinase (TYR) is a key target for regulating melanin synthesis. Several bioactive compounds derived from plant extracts have been found to possess potent anti-melanogenesis properties against TYR. In particular, the potential of banana peels from various varieties has garnered interest due to their application in skin hyperpigmentation treatment. A molecular docking study demonstrated interactions between rosmarinic acid, which is predominantly found in all Hom Thong peel extracts, and the active site of TYR (PDB ID: 2Y9X) at residues HIS263, VAL283, SER282, and MET280, with the lowest binding energy of -5.05 kcal/mol, showing the strongest interaction. Additionally, Hom Thong banana peels are rich in phenolic compounds that could inhibit melanin content and tyrosinase activity in both human and mouse melanoma cells. These effects may be attributed to the suppression of gene expression related to melanogenesis, including the regulator gene MITF and pigmentary genes TYR, TRP-1, and DCT, indicating effects comparable to those of the standard treatment groups with arbutin and kojic acid. Our findings indicated the potential of Hom Thong peel extracts as anti-melanogenic agents.

Medicinal potential of adventitious root cultures of Hypericum perforatum: study on antioxidant stress and anti-melanogenic properties.

Adventitious root (AR) culture is an effective method for the production of Hypericum perforatum raw materials. However, the ARs are seldom utilized in practical applications. Therefore, this study investigated the effects of H. perforatum ARs on antioxidative stress and anti-melanogenesis, aiming for future applications in the development of related products. In the antioxidative stress experiment, tert-butyl hydroperoxide-stimulated HepG2 cells were pre-treated with 12.5-50 μg mL-1 of AR ethanolic extract (HpE), which significantly increased (P < 0.05) cell viability and reduced reactive oxygen species levels. In alcohol-stimulated mice, pre-treatment with HpE (2.5-10 mg kg-1) enhanced the activities of superoxide dismutase, catalase, glutathione, ethanol dehydrogenase, and acetaldehyde dehydrogenase, while reducing the levels of alanine aminotransferase, aspartate aminotransferase, and triglycerides. In the anti-melanogenesis experiment, α-melanocyte-stimulating hormone-stimulated B16-F10 mouse melanoma cells were pre-treated with 25-100 μg mL-1 of HpE, resulting in increased tyrosinase activity and melanin content, along with a decrease in the expression levels of microphthalmia-associated transcription factor, tyrosinase-related proteins, and tyrosinase. HpE efficiently protects HepG2 cells from oxidative stress and safeguards the liver in mice by mitigating oxidative damage. Additionally, HpE inhibits melanin synthesis in B16-F10 cells by suppressing tyrosinase activity. These findings suggest that H. perforatum ARs hold potential for use in the development of healthy foods, cosmetics, and pharmaceutical products aimed at antioxidative stress and anti-melanogenesis. © 2024 Society of Chemical Industry.

A Lucknolide Derivative Induces Mitochondrial ROS-Mediated G2/M Arrest and Apoptotic Cell Death in B16F10 Mouse Melanoma Cells.

Melanoma is an aggressive skin cancer with a high risk of cancer-related deaths, and inducing apoptosis in melanoma cells is a promising therapeutic strategy. This study investigates the anti-tumor potential of a novel lucknolide derivative LA-UC as a therapeutic candidate for melanoma. Lucknolide A (LA), a tricyclic ketal-lactone metabolite isolated from marine-derived Streptomyces sp., was chemically modified by introducing a 10-undecenoyl group to synthesize LA-UC. LA-UC preferentially inhibited the proliferation of melanoma cells, including B16F10, while exerting minimal effects on normal melanocytes or other tumor cell types, indicating the selective action of LA-UC against melanoma cells. LA-UC decreased G2/M checkpoint proteins, including cyclin B1 and Cdc2, while activating caspase-3 and caspase-9, resulting in G2/M cell cycle arrest and inducing apoptotic cell death in B16F10 cells. The addition of a pan-caspase inhibitor confirmed the caspase-dependent mechanism of LA-UC-induced cell death. Additionally, LA-UC elevated mitochondrial ROS levels, leading to mitochondrial membrane disruption, upregulation of pro-apoptotic proteins, and DNA damage in melanoma cells. The ROS scavenger N-acetylcysteine reduced LA-UC-induced mitochondrial ROS accumulation, mitochondrial membrane disruption, DNA damage, and apoptosis. Collectively, these findings suggest that LA-UC induces G2/M cell cycle arrest and caspase-dependent apoptosis in B16F10 cells through excessive mitochondrial ROS generation, membrane impairment, and DNA damage, highlighting its potential as a promising therapeutic candidate for melanoma treatment.

Single-Cell Analysis of Immune Synapse Formation Associated with Melanoma-T Cell Contact

Extracellular vesicles (EVs) derived from an anaplastic mouse melanoma cell line made by Nanog overexpression of F10 (Nanog +F10 cells) suppressed the metastasis of Nanog +F10 cells. We suspected the involvement of immune cell system and focused on the cytotoxic activity of T cells. T cells are reported to form immune synapses when they come into contact with cancer cells and promote the introduction of cell-killing factors into cancer cells from the sites near immune synapses. However, the dynamic process of formation and loss of immune synapses is still unclear. Especially it is thought to differ depending on the type and the stage of cancer. Therefore, we believe that it is important to analyze the dynamic behavior of immune synapses in order to elucidate their possible role in the metastasis suppression mechanism of Nanog +F10-EVs. In this study, a cytotoxic T cell line (CTLL-2) was used as a T cell model. The purpose of this study was to perform microscopic fluorescence analysis of immune synapses that are expected to be generated when CTLL-2 cells are loaded with Nanog +F10-EVs and then co-cultured with Nanog +F10 cells. We focused on PKCθ, one of the proteins constituting immunological synapses. First, Nanog +F10-EVs were extracted from Nanog +F10 cells by ultracentrifugation. The Nanog +F10-EVs or PBS was added to CTLL-2 cells and cultured overnight. Then, Nanog +F10 cells were co-cultured with the previously treated CTLL-2 cells on poly-L-lysine-coated glass slides. Cells were then fixed in 4% PFA/PBS, permeabilized with 0.1% Triton X-100, and blocked with 3% BSA/PBS. Immunostaining was then performed with drops of PE-labeled PKCθ antibody and Alexa Fluor® 647-labeled Nanog antibody prepared in 1.5% BSA/PBS to a concentration of 10 µg/mL. Observations were made using a confocal microscope LSM510 to observe the contact between CTLL-2 cells and Nanog +F10 cells. The results showed that PKCθ was localized at the plasma membrane in Nanog +F10 cells as expected, but its expression was weak in CTLL-2 cells. When multiple cells formed clusters, the localization was even more pronounced along the cell-cell contact surfaces, with areas of elevated PKCθ expression found on the Nanog +F10 cell side at sites where CTLL-2 cells were likely in contact. On the other hand, in the case of Nanog +F10-EVs loaded CTLL-2 cells, the observed fluorescence intensity suggests that the expression of PKCθ in CTLL-2 cells increased. Furthermore, the expression of PKCθ tended to increase when CTLL-2 cells and Nanog +F10 cells were co-cultured for longer periods of time. It was found that the cytotoxic activity of CTLL-2 cells may be related to this increased expression of PKCθ.

Abstract C044: Single cell RNA-sequencing coupled with lineage tracing identifies novel clonal populations associated with immunotherapy resistance

Abstract Although immune checkpoint inhibitors (ICIs) have revolutionized melanoma treatment, many individuals either show no response or eventually develop acquired resistance. This variability could be linked to differences in the tumor immune microenvironment, pre-existing drug-resistant cells or treatment induced changes in melanoma cell states. Using single cell RNA sequencing (scRNA-seq) coupled with heritable barcodes, this study aims to lineage trace changes in melanoma transcriptional cell states and map changes in the tumor immune microenvironment to uncover if preexisting and/or therapy-induced melanoma transcriptional cell states lead to resistance to ICIs. In this study, we used YUMMER1.7 mouse melanoma cells which were transduced with barcodes under conditions that allow delivery of a single unique barcode to each cell, this served as a cell lineage tag. Each barcode is heritable and stably transcribed into RNA molecules so that individual barcoded cells can be matched with a gene expression profile from scRNA-seq outputs. The barcoded cells were subcutaneously injected into C57BL/6 mice, and once tumors were established, mice were treated with 3 cycles of anti-PD-1 and anti-CTLA-4 therapy. Lineage tracing and scRNA-seq analyses were performed on tumors harvested prior to treatment, early on treatment (Day 6), during minimal residual disease (Day 13) and upon relapse. Early on treatment (Day 6)- two tumour groups were harvested, those that responded well and others that only partially responded. Our results showed that during the early on treatment phase (Day 6) tumors that responded well and those that only partially responded displayed distinct barcodes. Additionally, prevalent barcoded cells identified at the minimal residual disease phase were also dominant upon relapse. Analysis of the transcriptional states is underway to determine if ICI therapy induces transcriptional heterogeneity in sensitive and tolerant cells and if a particular or several transcriptional states lead to relapse. This study will potentially identify predictive response biomarkers and vulnerabilities of ICI naïve and resistant cells that could be targeted to improve outcomes for melanoma patients. We will also identify neoadjuvant approaches, to remove the inherent heterogeneity within the tumor cell population, facilitating a more uniform sensitivity to ICIs. Citation Format: Reem Saleh, Riyaben Patel, Dane Vassiliadis, Fayrouz Hammal, Benjamin Blyth, Xin Du, Katie Fennell, Mark A. Dawson, Grant A. McArthur, Karen Sheppard. Single cell RNA-sequencing coupled with lineage tracing identifies novel clonal populations associated with immunotherapy resistance [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C044.

Notch1 blockade by a novel, selective anti-Notch1 neutralizing antibody improves immunotherapy efficacy in melanoma by promoting an inflamed TME

BackgroundImmune checkpoint inhibitors (ICI) have dramatically improved the life expectancy of patients with metastatic melanoma. However, about half of the patient population still present resistance to these treatments. We have previously shown Notch1 contributes to a non-inflamed TME in melanoma that reduces the response to ICI. Here, we addressed the therapeutic effects of a novel anti-Notch1 neutralizing antibody we produced, alone and in combination with immune checkpoint inhibition in melanoma models.MethodsAnti-Notch1 was designed to interfere with ligand binding. Mice were immunized with a peptide encompassing EGF-like repeats 11–15 of human Notch1, the minimal required region that allows ligand binding and Notch1 activation. Positive clones were expanded and tested for neutralizing capabilities. Anti-Notch1-NIC was used to determine whether anti-Notch1 was able to reduce Notch1 cleavage; while anti-SNAP23 and BCAT2 were used as downstream Notch1 and Notch2 targets, respectively. K457 human melanoma cells and the YUMM2.1 and 1.7 syngeneic mouse melanoma cells were used. Cell death after anti-Notch1 treatment was determined by trypan blue staining and compared to the effects of the gamma-secretase inhibitor DBZ. 10 mg/kg anti-Notch1 was used for in vivo tumor growth of YUMM2.1 and 1.7 cells. Tumors were measured and processed for flow cytometry using antibodies against major immune cell populations.ResultsAnti-Notch1 selectively inhibited Notch1 but not Notch2; caused significant melanoma cell death in vitro but did not affect normal melanocytes. In vivo, it delayed tumor growth without evident signs of gastro-intestinal toxicities; and importantly promoted an inflamed TME by increasing the cytotoxic CD8+ T cells while reducing the tolerogenic Tregs and MDSCs, resulting in enhanced efficacy of anti-PD-1.ConclusionsAnti-Notch1 safely exerts anti-melanoma effects and improves immune checkpoint inhibitor efficacy. Thus, anti-Notch1 could represent a novel addition to the immunotherapy repertoire for melanoma.

Unraveling the Role of JMJD1B in Genome Stability and the Malignancy of Melanomas.

Genome instability relies on preserving the chromatin structure, with any histone imbalances threating DNA integrity. Histone synthesis occurs in the cytoplasm, followed by a maturation process before their nuclear translocation. This maturation involves protein folding and the establishment of post-translational modifications. Disruptions in this pathway hinder chromatin assembly and contribute to genome instability. JMJD1B, a histone demethylase, not only regulates gene expression but also ensures a proper supply of histones H3 and H4 for the chromatin assembly. Reduced JMJD1B levels lead to the cytoplasmic accumulation of histones, causing defects in the chromatin assembly and resulting in DNA damage. To investigate the role of JMJD1B in regulating genome stability and the malignancy of melanoma tumors, we used a JMJD1B/KDM3B knockout in B16F10 mouse melanoma cells to perform tumorigenic and genome instability assays. Additionally, we analyzed the transcriptomic data of human cutaneous melanoma tumors. Our results show the enhanced tumorigenic properties of JMJD1B knockout melanoma cells both in vitro and in vivo. The γH2AX staining, Micrococcal Nuclease sensitivity, and comet assays demonstrated increased DNA damage and genome instability. The JMJD1B expression in human melanoma tumors correlates with a lower mutational burden and fewer oncogenic driver mutations. Our findings highlight JMJD1B's role in maintaining genome integrity by ensuring a proper histone supply to the nucleus, expanding its function beyond gene expression regulation. JMJD1B emerges as a crucial player in preserving genome stability and the development of melanoma, with a potential role as a safeguard against oncogenic mutations.

IRF2 loss is associated with reduced MHC I pathway transcripts in subsets of most human cancers and causes resistance to checkpoint immunotherapy in human and mouse melanomas

BackgroundIn order for cancers to progress, they must evade elimination by CD8 T cells or other immune mechanisms. CD8 T cells recognize and kill tumor cells that display immunogenic tumor peptides bound to MHC I molecules. One of the ways that cancers can escape such killing is by reducing expression of MHC I molecules, and loss of MHC I is frequently observed in tumors. There are multiple different mechanisms that can underly the loss of MHC I complexes on tumor and it is currently unclear whether there are particular mechanisms that occur frequently and, if so, in what types of cancers. Also of importance to know is whether the loss of MHC I is reversible and how such loss and/or its restoration would impact responses to immunotherapy. Here, we investigate these issues for loss of IRF1 and IRF2, which are transcription factors that drive expression of MHC I pathway genes and some killing mechanisms.MethodsBioinformatics analyses of IRF2 and IRF2-dependent gene transcripts were performed for all human cancers in the TCGA RNAseq database. IRF2 protein-DNA-binding was analyzed in ChIPseq databases. CRISRPcas9 was used to knock out IRF1 and IRF2 genes in human and mouse melanoma cells and the resulting phenotypes were analyzed in vitro and in vivo.ResultsTranscriptomic analysis revealed that IRF2 expression was reduced in a substantial subset of cases in almost all types of human cancers. When this occurred there was a corresponding reduction in the expression of IRF2-regulated genes that were needed for CD8 T cell recognition. To test cause and effect for these IRF2 correlations and the consequences of IRF2 loss, we gene-edited IRF2 in a patient-derived melanoma and a mouse melanoma. The IRF2 gene-edited melanomas had reduced expression of transcripts for genes in the MHC I pathway and decreased levels of MHC I complexes on the cell surface. Levels of Caspase 7, an IRF2 target gene involved in CD8 T cell killing of tumors, were also reduced. This loss of IRF2 caused both human and mouse melanomas to become resistant to immunotherapy with a checkpoint inhibitor. Importantly, these effects were reversible. Stimulation of the IRF2-deficient melanomas with interferon induced the expression of a functionally homologous transcription factor, IRF1, which then restored the MHC I pathway and responsiveness to CPI.ConclusionsOur study shows that a subset of cases within most types of cancers downregulates IRF2 and that this can allow cancers to escape immune control. This can cause resistance to checkpoint blockade immunotherapy and is reversible with currently available biologics.

A new isocoumarin from sponge endophytic fungus Aspergillus ochraceopetaliformis with cytotoxic activity

A new isocoumarin, 8-hydroxy-3-methyliscoumarin-6-yl acetate (1), was isolated together with five known compounds from sponge endophytic fungus Aspergillus ochraceopetaliformis. The structure of the new compound was established based on 1D and 2D NMR spectral analysis. Compounds 1–6 were evaluated for their cytotoxic activities and antimicrobial activities. Compounds 1 and 6 display cytotoxic activities against mouse melanoma cells B16 with IC50 values 72.5 ± 2.6 and 1.0 ± 0.5 µM, respectively. Compounds 4 and 5 displayed faint antimicrobial activities of Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus.

Circular RNA-encoded oncogenic PIAS1 variant blocks immunogenic ferroptosis by modulating the balance between SUMOylation and phosphorylation of STAT1

BackgroundThe clinical response rate to immune checkpoint blockade (ICB) therapy in melanoma remains low, despite its widespread use. Circular non-coding RNAs (circRNAs) are known to play a crucial role in cancer progression and may be a key factor limiting the effectiveness of ICB treatment.MethodsThe circRNAs that were downregulated after coadministration compared with single administration of PD-1 inhibitor administration were identified through RNA-seq and Ribo-seq, and thus the circPIAS1 (mmu_circ_0015773 in mouse, has_circ_0008378 in human) with high protein coding potential was revealed. Fluorescence in situ hybridization (FISH) assays were conducted to determine the localization of circPIAS1 in human and mouse melanoma cells, as well as its presence in tumor and adjacent tissues of patients. Validation through dual-luciferase reporter assay and LC–MS/MS confirmed the ability of circPIAS1 to encode a novel 108 amino acid polypeptide (circPIAS1-108aa). Specific antisense oligonucleotides (ASOs) targeting the junction site of circPIAS1 were developed to reduce its intracellular levels. Proliferation changes in melanoma cells were assessed using CCK8, EdU, and colony formation assays. The impact of circPIAS1-108aa on the ferroptosis process of melanoma cells was studied through GSH, MDA, and C11-BODIPY staining assays. Western Blot, Immunoprecipitation (IP), and Immunoprecipitation-Mass Spectrometry (IP-MS) techniques were employed to investigate the impact of circPIAS1-108aa on the P-STAT1/SLC7A11/GPX4 signaling pathway, as well as its influence on the balance between STAT1 SUMOylation and phosphorylation. Additionally, a melanoma subcutaneous transplanted tumor mouse model was utilized to examine the combined effect of reducing circPIAS1 levels alongside PD-1 inhibitor.ResultsCompared with the group treated with PD-1 inhibitor alone, circPIAS1 was significantly down-regulated in the coadministration group and demonstrated higher protein coding potential. CircPIAS1, primarily localized in the nucleus, was notably upregulated in tumor tissues compared to adjacent tissues, where it plays a crucial role in promoting cancer cell proliferation. This circRNA can encode a unique polypeptide consisting of 108 amino acids, through which it exerts its cancer-promoting function and impedes the effectiveness of ICB therapy. Mechanistically, circPIAS1-108aa hinders STAT1 phosphorylation by recruiting SUMO E3 ligase Ranbp2 to enhance STAT1 SUMOylation, thereby reactivating the transduction of the SLC7A11/GPX4 signaling pathway and restricting the immunogenic ferroptosis induced by IFNγ. Furthermore, the combination of ASO-circPIAS1 with PD-1 inhibitor effectively inhibits melanoma growth and significantly enhances the efficacy of immune drugs in vivo.ConclusionsOur study uncovers a novel mechanism regarding immune evasion in melanoma driven by a unique 108aa peptide encoded by circPIAS1 in melanoma that dramatically hinders immunogenic ferroptosis triggered by ICB therapy via modulating the balance between SUMOylation and phosphorylation of STAT1. This work reveals circPIAS1-108aa as a critical factor limiting the immunotherapeutic effects in melanoma and propose a promising strategy for improving ICB treatment outcomes.

Cancer Cell-Selective Inhibition of Migration by Styrenic Catiomer Emulsions.

Cancer metastasis remains the most formidable cause of mortality and morbidity in cancer patients. Developing an effective and economical method toward cancer antimetastatic strategy demands immediate attention in anticancer therapy. Herein, we followed a cost-effective greener method for preparing a small family of amphiphilic catiomers with varied styrene content (45, 63, and 83%), which revealed the unique potential of promoting normal cell migration while retarding cancer metastasis. The styrenic polymers formed micellar self-assembly in aqueous phase and exhibited a cationic charge. Polymers were quite nontoxic up to 200 μg/mL concentration toward human embryonic kidney cell HEK293 as well as human, triple negative breast cancer cell MDAMB-231, mouse melanoma cell B16F10, and human oral squamous carcinoma cell FaDu. Confocal imaging and fluorescence activated cell sorting (FACS) showed effective incorporation of polymers within cells. Interestingly, the polymer-treated HEK293 cells underwent prominent wound healing in scratch assay. However, the as-synthesized polymer-treated cancer cells resisted migration as analyzed from the scratch assay. A mechanistic study using immunoblotting assay established upregulation of migratory proteins vimentin and TGF-β and downregulation of E-cadherin in normal HEK293 cells. Remarkably, this trend was completely reversed in cancer cell MDAMB-231. This study describes the extraordinary potential of styrenic catiomers as wound healers for normal cells while inhibiting cancer metastasis.

Scar/WAVE drives actin protrusions independently of its VCA domain using proline-rich domains

Cell migration requires the constant modification of cellular shape by reorganization of the actin cytoskeleton. Fine-tuning of this process is critical to ensure new actin filaments are formed only at specific times and in defined regions of the cell. The Scar/WAVE complex is the main catalyst of pseudopod and lamellipodium formation during cell migration. It is a pentameric complex highly conserved through eukaryotic evolution and composed of Scar/WAVE, Abi, Nap1/NCKAP1, Pir121/CYFIP, and HSPC300/Brk1. Its function is usually attributed to activation of the Arp2/3 complex through Scar/WAVE's VCA domain, while other parts of the complex are expected to mediate spatial-temporal regulation and have no direct role in actin polymerization. Here, we show in both B16-F1 mouse melanoma and Dictyostelium discoideum cells that Scar/WAVE without its VCA domain still induces the formation of morphologically normal, actin-rich protrusions, extending at comparable speeds despite a drastic reduction of Arp2/3 recruitment. However, the proline-rich regions in Scar/WAVE and Abi subunits are essential, though either is sufficient for the generation of actin protrusions in B16-F1 cells. We further demonstrate that N-WASP can compensate for the absence of Scar/WAVE's VCA domain and induce lamellipodia formation, but it still requires an intact WAVE complex, even if without its VCA domain. We conclude that the Scar/WAVE complex does more than directly activating Arp2/3, with proline-rich domains playing a central role in promoting actin protrusions. This implies a broader function for the Scar/WAVE complex, concentrating and simultaneously activating many actin-regulating proteins as a lamellipodium-producing core.

Experimental Study on Biomimetic Curcumin-Mediated Sonodynamic Therapy of Melanoma

To study the role of curcumin-mediated sonodynamic therapy in the treatment of malignant melanoma, and to provide a new strategy for the treatment of malignant melanoma. The ultrasonic sound and vibration method was applied to coat curcumin with mouse melanoma cell membrane, thereby forming biomimetic curcumin. The morphology of biomimetic curcumin was observed by transmission electron microscope. Flow cytometry was used to analyze the effect of biomimetic curcumin in terms of in vitro targeting, apoptosis, and intracellular reactive oxygen species (ROS) production. The in vivo experiment was divided into control group, US group, turmeric group, imitation turmeric group, and imitation turmeric+US group, with 3 mice in each group. The in vivo safety of biomimetic curcumin was evaluated by HE staining. In addition, HE, CD31, Ki67, and TUNEL stainings were performed to evaluate the in vivo anti-melanoma therapeutic effect of ultrasound combined with biomimetic curcumin. The biomimetic curcumin had a generally uniform morphology and possessed a core-shell structure. Flow cytometry analysis performed with FlowJo showed that the biomimetic curcumin could be effectively taken up by melanoma cells. The apoptosis rate was (10.30±0.61)% in the control group, (10.41±3.13)% in the ultrasound group, (24.97±1.38)% in the curcumin group, (31.39±3.84)% in the biomimetic curcumin group, and (40.89±0.79)% in the biomimetic curcumin and ultrasound combination group. The apoptosis rate in the biomimetic curcumin and ultrasound combination group was higher than those in the other groups (P<0.05). The results of ROS flow cytometry showed that, compared with the control group, the ultrasound group demonstrated almost no increase in the fluorescence intensity, while the other groups showed an increase in the fluorescence intensity to varying degrees. There was no significant difference in the fluorescence intensity between the biomimetic curcumin group ([1.10±0.38]%) and the curcumin group ([0.73±0.26]%) (P>0.05). The fluorescence intensity of the biomimetic curcumin and ultrasound combination group ([3.35±0.04]%) was higher than those of the other groups (P<0.05). HE staining showed no obvious abnormalities in the morphology of heart, liver, spleen, lung, and kidney tissues in any of the treatment groups. HE staining showed the most significant changes in cell morphology in the biomimetic curcumin and ultrasound combination group, followed by the biomimetic curcumin group and the curcumin group. No obvious abnormalities in tumor cell morphology were observed in the ultrasound group. According to the respective results of CD31 staining, Ki67 staining, and TUNEL staining, the biomimetic curcumin and ultrasound combination group had the largest brown area, the highest number of red fluorescence, and the highest number of green fluorescence, followed by the biomimetic curcumin group and the curcumin group. The biomimetic curcumin displays uniform morphology, a core-shell structure, and good targeting properties. When it is used in combination with ultrasound, biomimetic curcumin demonstrates a good anti-tumor therapeutic effect both in vivo and in vitro.

IRF2 loss is associated with reduced MHC I pathway transcripts in subsets of most human cancers and causes resistance to checkpoint immunotherapy in human and mouse melanomas.

In order for cancers to progress, they must evade elimination by CD8 T cells or other immune mechanisms. CD8 T cells recognize and kill tumor cells that display immunogenic tumor peptides bound to MHC I molecules. One of the ways that cancers can escape such killing is by reducing expression of MHC I molecules, and loss of MHC I is frequently observed in tumors. There are multiple different mechanisms that can underly the loss of MHC I complexes on tumor and it is currently unclear whether there are particular mechanisms that occur frequently and, if so, in what types of cancers. Also of importance to know is whether the loss of MHC I is reversible and how such loss and/or its restoration would impact responses to immunotherapy. Here, we investigate these issues for loss of IRF1 and IRF2, which are transcription factors that drive expression of MHC I pathway genes and some killing mechanisms. Bioinformatics analyses of IRF2 and IRF2-dependent gene transcripts were performed for all human cancers in the TCGA RNAseq database. IRF2 protein-DNA-binding was analyzed in ChIPseq databases. CRISRPcas9 was used to knock out IRF1 and IRF2 genes in human and mouse melanoma cells and the resulting phenotypes were analyzed in vitro and in vivo. Transcriptomic analysis revealed that IRF2 expression was reduced in a substantial subset of cases in almost all types of human cancers. When this occurred there was a corresponding reduction in the expression of IRF2-regulated genes that were needed for CD8 T cell recognition. To test cause and effect for these IRF2 correlations and the consequences of IRF2 loss, we gene-edited IRF2 in a patient-derived melanoma and a mouse melanoma. The IRF2 gene-edited melanomas had reduced expression of transcripts for genes in the MHC I pathway and decreased levels of MHC I complexes on the cell surface. Levels of Caspase 7, an IRF2 target gene involved in CD8 T cell killing of tumors, were also reduced. This loss of IRF2 caused both human and mouse melanomas to become resistant to immunotherapy with a checkpoint inhibitor. Importantly, these effects were reversible. Stimulation of the IRF2-deficient melanomas with interferon induced the expression of a functionally homologous transcription factor, IRF1, which then restored the MHC I pathway and responsiveness to CPI. Our study shows that a subset of cases within most types of cancers downregulates IRF2 and that this can allow cancers to escape immune control. This can cause resistance to checkpoint blockade immunotherapy and is reversible with currently available biologics.

Regulation of cholesterol biosynthesis by CTCF and H3K27 methylation is critical for cell migration

CTCF is a key factor in three-dimensional chromatin folding and transcriptional control that was found to affect cancer cell migration by a mechanism that is still poorly understood. To identify this mechanism, we used mouse melanoma cells with a partial loss of function (pLoF) of CTCF. We found that CTCF pLoF inhibits cell migration rate while leading to an increase in the expression of multiple enzymes in the cholesterol biosynthesis pathway along with an elevation in the cellular cholesterol level. In agreement with the cholesterol change we detected altered membrane dynamics in CTCF pLoF cells as measured by reduced formation of migrasomes, extracellular vesicles formed at the rear side of migrating cells. Inhibition of cholesterol synthesis in CTCF pLoF cells restored the cellular migration rate and migrasome formation, suggesting that CTCF supports cell migration by suppressing cholesterol synthesis. Detailed analysis of the promoter of Hmgcs1, an early enzyme in the cholesterol synthesis pathway, revealed that CTCF prevents formation of a loop between that promoter and another promoter 200 kb away. CTCF also supports PRC2 recruitment to the promoter and deposition of H3K27me3. H3K27me3 at the promoter of Hmgcs1 prevents SREBP2 binding and activation of transcription. By this mechanism, CTCF fine-tunes cholesterol levels to support cell migration. Notably, genome wide association studies suggest a link between CTCF and cholesterol-associated diseases, thus CTCF emerges as a new regulator of cholesterol biosynthesis.

Editorial Expression of Concern: A sphingolipid rich lipid fraction isolated from attenuated Leishmania donovani promastigote induces apoptosis in mouse and human melanoma cells in vitro

Editorial Expression of Concern: A sphingolipid rich lipid fraction isolated from attenuated Leishmania donovani promastigote induces apoptosis in mouse and human melanoma cells in vitro

Tumor-derived GLI1 promotes remodeling of the immune tumor microenvironment in melanoma

BackgroundMelanoma progression is based on a close interaction between cancer cells and immune cells in the tumor microenvironment (TME). Thus, a better understanding of the mechanisms controlling TME dynamics and composition will help improve the management of this dismal disease. Work from our and other groups has reported the requirement of an active Hedgehog-GLI (HH-GLI) signaling for melanoma growth and stemness. However, the role of the downstream GLI1 transcription factor in melanoma TME remains largely unexplored.MethodsThe immune-modulatory activity of GLI1 was evaluated in a syngeneic B16F10 melanoma mouse model assessing immune populations by flow cytometry. Murine polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) were differentiated from bone marrow cells and their immunosuppressive ability was assessed by inhibition of T cells. Conditioned media (CM) from GLI1-overexpressing mouse melanoma cells was used to culture PMN-MDSCs, and the effects of CM were evaluated by Transwell invasion assay and T cell inhibition. Cytokine array analysis, qPCR and chromatin immunoprecipitation were performed to explore the regulation of CX3CL1 expression by GLI1. Human monocyte-derived dendritic cells (moDCs) were cultured in CM from GLI1-silenced patient-derived melanoma cells to assess their activation and recruitment. Blocking antibodies anti-CX3CL1, anti-CCL7 and anti-CXCL8 were used for in vitro functional assays.ResultsMelanoma cell-intrinsic activation of GLI1 promotes changes in the infiltration of immune cells, leading to accumulation of immunosuppressive PMN-MDSCs and regulatory T cells, and to decreased infiltration of dendric cells (DCs), CD8 + and CD4 + T cells in the TME. In addition, we show that ectopic expression of GLI1 in melanoma cells enables PMN-MDSC expansion and recruitment, and increases their ability to inhibit T cells. The chemokine CX3CL1, a direct transcriptional target of GLI1, contributes to PMN-MDSC expansion and recruitment. Finally, silencing of GLI1 in patient-derived melanoma cells promotes the activation of human monocyte-derived dendritic cells (moDCs), increasing cytoskeleton remodeling and invasion ability. This phenotype is partially prevented by blocking the chemokine CCL7, but not CXCL8.ConclusionOur findings highlight the relevance of tumor-derived GLI1 in promoting an immune-suppressive TME, which allows melanoma cells to evade the immune system, and pave the way for the design of new combination treatments targeting GLI1.