B16F10 Melanoma Cell Line Research Articles

DDDR-07. FUNCTIONAL GENOMICSIN VIVO USING CRISPR/CAS9 IDENTIFIES POTENTIAL METABOLIC VULNERABILITIES WITHIN MELANOMA BRAIN METASTASIS

Abstract BACKGROUND Inhibition of the oxidative phosphorylation (OxPhos) pathway in mice suppressed the growth of melanoma brain metastasis but not extracranial or primary skin melanoma. This indicates that melanoma brain metastasis may have targetable metabolic vulnerabilities. Human clinical trials, however showed toxicities following OxPhos pathway inhibition. This suggests that more selective metabolic targets are needed to minimize off target effects. METHODS We designed a focused CRISPR guide RNA (gRNA) lentiviral knockout library targeting 106 metabolism genes significantly enriched in human melanoma brain metastasis (n=88) relative to extracranial (n=50) or primary skin melanoma (n=52). We infected mouse B16F10 melanoma cell lines with the CRISPR library and implanted 1X106 cells subcutaneously or intracerebrally into male (n=3) and female (n=3) C57/Bl6 mice. DNA from cell lines and tumor samples were sent for next generation sequencing. Candidate metabolism genes that may drive growth of melanoma lesion within the brain were identified based on loss of gRNA copies in brain relative to skin. RESULTS The CRISPR/Cas9 in vivo screen identified metabolic genes whose knockout resulted in loss of gRNA clones within established B16F10 melanoma brain lesions relative to skin lesions. These putative metabolism targets included specific components in the oxidative phosphorylation pathway, choline metabolism, and ubiquitin cascade activation. CONCLUSION Using a focused CRISPR/Cas9 in vivo screen, we uncovered potential metabolic targets within established mouse melanoma brain lesions. vWe are currently performing the in vivo screen in melanoma mouse models with spontaneous brain metastasis. Top 3 hits across all models will be validated individually prior to a compound screen for inhibitors.

Anticancer activity of Lannea coromandelica on B16F10 melanoma cell line: an in vitro and molecular docking approach

BackgroundPhytochemical screening was conducted on various bark extracts of Lannea coromandelica to assess their anticancer property against the B16F10 melanoma cell line. The phytoconstituents that were previously identified were utilized in molecular docking studies against the human tyrosinase related protein 1 (TYRP1) as a target receptor in order to provide more evidence for anticancer property. MethodsBark powder was extracted by maceration method using distilled water and soxhlet extraction using ethanol. The preliminary phytochemical evaluation and determination of total phenolic and flavonoid content of both extracts were conducted using biochemical assays. The present study investigated the possible anticancer effects of ethanol and aqueous extracts on the B16F10 melanoma cell line using the MTT assay and DAPI labelling techniques. The present study employed molecular docking techniques to assess the binding interactions between phytoconstituents and the TYRP1 protein, utilizing AutoDock Vina module of PyRx 0.8 software. ResultsThe phytochemical analysis found flavonoids, steroids, terpenoids, tannins, phenolic compounds, saponins, anthraquinones, cardiac glycosides, and proteins. Ethanolic extract shown preferential cytotoxicity to B16F0 melanoma cell line in-vitro (IC50= 9.69 ± 0.68 μg/ml), while aqueous extract exhibited IC50 = 75.49 ± 5.95 μg/ml. DAPI staining showed that treated cells had altered nucleus morphology, including apoptotic bodies. According to molecular docking investigations, Quercetin has the highest binding affinity (-9.6 Kcal/mol), followed by Catechin and Myricadiol. ConclusionThe current investigation has determined that Lannea coromandelica exhibits cytotoxic characteristic, as evidenced by the utilization of computer aided drug design models and in-vitro experimentation.

The Cervical and Meningeal Lymphatic Network as a Pathway for Retrograde Nanoparticle Transport to the Brain.

The meningeal lymphatic vessels have been described as a pathway that transports cerebrospinal fluid and interstitial fluid in a unidirectional manner towards the deep cervical lymph nodes. However, these vessels exhibit anatomical and molecular characteristics typical of initial lymphatic vessels, with the absence of surrounding smooth muscle and few or absent valves. Given its structure, this network could theoretically allow for bidirectional motion. Nevertheless, it has not been assessed as a potential route for nanoparticles to travel from peripheral tissues to the brain. We employed superparamagnetic iron oxide nanoparticles (SPIONs), exosomes loaded with SPIONs, gold nanorods, and Chinese ink nanoparticles. SPIONs were prepared via chemical coprecipitation, while exosomes were isolated from the B16F10 melanoma cell line through the Exo-Spin column protocol and loaded with SPIONs through electroporation. Gold nanorods were functionalized with polyethylene glycol. We utilized C57BL/6 mice for post-mortem and in vivo procedures. To evaluate the retrograde directional flow, we injected each nanoparticle solution in the deep cervical lymph node. The head and neck were fixed for magnetic resonance imaging and histological analysis. Here we show that extracellular vesicles derived from the B16F10 melanoma cell line, along with superparamagnetic iron oxide nanoparticles, gold nanorods, and Chinese ink nanoparticles can reach the meningeal lymphatic vessels and the brain of C57BL/6 mice after administration within the deep cervical lymph nodes post-mortem and in vivo, exclusively through lymphatic structures. The functional anatomy of dural lymphatics has been found to be conserved between mice and humans, suggesting that our findings may have significant implications for advancing targeted drug delivery systems using nanoparticles. Understanding the retrograde transport of nanoparticles through the meningeal lymphatic network could lead to novel therapeutic approaches in nanomedicine, offering new insights into fluid dynamics in both physiological and neuropathological contexts. Further research into this pathway may unlock new strategies for treating neurological diseases or enhancing drug delivery to the brain.

Novel embelin-loaded transniosomes for topical delivery: comprehensive exploration of in vitro, ex vivo and dermatokinetic assessment for anti-cancer activity.

This study systematically designed and optimised a transniosomal formulation containing embelin for skin cancer management. The transniosomes were developed using a rotary evaporation method and then optimised using a Box-Behnken design. The optimized embelin-loaded transniosomes (Opt-EMB-TNs) exhibited a vesicle size of 149.01 nm, polydispersity index of 0.184, a zeta potential of -21.14 mV, an entrapment efficiency of 75.6 ± 0.65%, drug loading of 3.36 ± 0.03% and drug release of 80.88 ± 2.55%. The antioxidant potential of Opt-EMB-TNs was found to be 88.54% when compared to standard ascorbic acid. Dermatokinetic studies showed a greater drug deposition in targeted skin areas with Opt-EMB-TN gel compared to the embelin conventional gel (EMB-CF gel). In addition, the penetration depth study of the skin sample revealed that the transniosomal gel containing rhodamine B dye exhibited higher penetration than that of the rhodamine B dye containing hydroalcoholic solution. The efficacy of Opt-EMB-TNs for skin cancer was confirmed by cytotoxicity assay against the B16F10 melanoma cell line. The study concluded that the Opt-EMB-TN gel formulation is a promising and effective topical treatment for skin cancer, demonstrating significant potential for further development and clinical application. © 2024 Society of Chemical Industry.

Auto-defense of skin and melanin regulation through glutathione reductase modulation: a new insight

Background: The present study is to understand the Siddha cosmetic preparation - Eve fresh skinbrite cream/herbal extracts used in the cream in down-regulating the melanogenesis process and upregulating glutathione activity to offer skin lightening benefit. Methods: The effect of certain herbal extracts or the combination in reducing tyrosinase activity and associated melanin formation was evaluated in B16F10 melanoma cells and also up regulating glutathione reductase activity leading to the conversion of a reduced form of glutathione (GSH) from GSSG. Results: The extract of Berberis aristata exhibited even activity in inhibiting both tyrosinase and melanin in B16F10 melanoma cell lines. The extract combination also showed a greater effect on increasing GR activity. Conclusions: The herbal ingredients individually and as a combination exhibited strong effects in reducing tyrosinase activity and also upregulating GR activity and thereby reducing skin pigmentation.

Synergistic Effects of Melatonin on Radiosensitization in Carbon-ion Radiotherapy.

Despite the established antitumor effectiveness and synergistic interactions of melatonin with photon irradiation, its role in carbon-ion radiotherapy remains uncertain. This study aimed to elucidate the mechanisms and potential clinical advantages of combining exogenous melatonin therapy with carbon-ion radiotherapy. The investigation assessed the impact of combining exogenous melatonin with photon or carbon-ion irradiation on cell-cycle modulation and DNA-repair capability using the melanoma cell line B16F10. RNA sequencing and bioinformatics analysis were conducted to explore mechanisms and evaluate potential clinical benefits, with validation performed on the osteosarcoma cell line LM8. Pre-treatment with melatonin reduced the survival fraction of B16F10 and LM8 cells upon exposure to photon and carbon-ion radiation. Mechanistically, melatonin was found to inhibit G2/M arrest, preserve DNA damage, and suppress key genes involved in DNA double-strand break repair after 8 Gy carbon-ion radiation. Furthermore, RNA sequencing and bioinformatics analysis revealed favorable changes in genes associated with survival and metastasis, highlighting potential clinical significance. LM8 cells treated with melatonin exhibited increased radiosensitivity and suppression of DNA-repair proteins. The combination of exogenous melatonin not only heightened radiosensitivity and modulated hallmark tumor gene sets in vitro but also markedly suppressed the efficiency of DNA double-strand break-repair pathway, thus enhancing the cytotoxicity of carbon-ion radiotherapy.

Developing Supramolecular Metallogel Derived from Pd2L4 Cage Molecule for Delivering an Anti-Cancer Drug to Melanoma Cell B16-F10.

Supramolecular gels are an important class of materials that are promising for its wide range of applications including drug delivery. While supramolecular gels are intrinsically porous because of the 3D nano-matrix (gel matrix) that is being formed due to supramolecular self-assembly process involving the gelator molecules during gelation, additional nanopores can be introduced to the overall gel if the gelator molecule itself holds molecular cavity such as metal-organic-cage (MOC) molecules. A MOC having the molecular formula [(Pd2L24).4NO3].3H2O.2DMF.MeOH (Pd-cage) (L2=5-Azido-N,N'-di-pyridin-3-yl-isophthalamide) was successfully synthesized and characterized by FT-IR, 1H NMR, ESI-MS and single crystal X-ray diffraction. Stimuli-reversible supramolecular metallogel PdG could easily be formed from Pd-cage in DMSO/water mixture. The molecular cage of Pd-cage was demonstrated to be available for loading an anti-cancer drug namely doxorubicin (DOX). Subsequently, DOX was also loaded within PdG and delivered to melanoma cell line B16-F10 displaying significant anti-cancer activity as revealed by both MTT and scratch assay. Rheoreversibility of PdG and its ability to load and deliver DOX to cancer cells clearly raised hope for developing this metallogel further as topical anticancer gel.

Development and evaluation of berberine-loaded bigel for the treatment of hyperpigmentation on B16F10 melanoma cell line.

Aim: The aim of this study was to optimize, develop, characterize and evaluate a topical nanobigel (BG) formulation containing Berberine (BRB) that exhibits anti-melanogenic properties.Materials & methods: The Berberine-loaded bigel (BRB@BG) formulation was prepared by homogenously mixing the optimized hydrogel and oleogel. BRB@BG was characterized in vitro and cytotoxicity study was conducted to evaluate its effects on murine skin melanoma B16F10 cell lines.Results: The optimized BRB@BG exhibited uniform texture with nanometric size, desirable spreadability and extrudability, suitable for topical applications. Cytotoxicity studies revealed that BRB@BG had a lower IC50 value (4.84μg/ml) on B16F10 cell lines compared with drug alone.Conclusion: In conclusion, the developed BRB@BG formulation showed good potential as safe and effective topical treatment for hyperpigmentation.

A Metal-Free Cycloaddition of α-Diazoacetates with Amino Acid-Derived NHPI Esters for the Facile Synthesis of 1,2,4-Triazoles.

1,2,4-Triazoles are privileged scaffolds for many pharmaceuticals, and methods for structurally diverse compound libraries are of current interest. Here we report an efficient coupling of α-diazoacetates with amino acid-derived alkyl N-hydroxy phthalimide esters, under metal-free conditions involving 1,8-diazabicyclo(5.4.0)undec-7-ene as the base, with which highly functionalized 1,2,4-triazoles can be obtained in excellent yields with remarkable functional group tolerance. Preliminary studies revealed that 1,2,4-triazole 3a exhibits potent inhibition of tyrosinase activities in melanoma B16F10 cell lines, demonstrating promising skin-whitening properties.

Bioactive pH-sensitive nanoemulsion in melanoma cell lines

Melanoma is an aggressive form of skin cancer with elevated propensity to metastasize. One of the major critical issues in the treatment of oncological patients is represented by the development of toxicity and resistance to the available therapies. Great progress has been made in the field of nanotechnologies to limit the unwanted effects of anti-cancer treatments. We explored the potential of creating oil-in-water nanoemulsions composed of oleic acid, as a bioactive carrier for lipophilic drug delivery. This bioactive nanoemulsion was loaded with Curcumin, a natural fluorescent lipophilic compound, used as a model drug to evaluate nanoemulsion capability to: i) encapsulate the lipophilic moiety; ii) interact with the specific cells, and iii) improve the efficacy of the loaded model drug compared to the free one. Therefore, we evaluated the physical–chemical features of Curcumin-loaded nanoemulsions, confirming their pH sensibility and their stability over time. Moreover, the nanoemulsions were able to preserve the loaded Curcumin by degradation/destabilization phenomena. Finally, we verified some of the biological functions of Curcumin delivered by nanoemulsions in the B16F10 melanoma cell line. We obtained evidence of the biological action of Curcumin, suggesting oleic-based nanoemulsions as an efficient nanocarrier for lipophilic drug delivery.

The novel prognostic marker SPOCK2 regulates tumour progression in melanoma.

Secreted protein acidic and cysteine rich/osteonectin, cwcv and kazal-like domain proteoglycan 2 (SPOCK2) is a protein that regulates cell differentiation and growth. Recent studies have reported that SPOCK2 plays important roles in the progression of various human cancers; however, the role of SPOCK2 in melanoma remains unknown. Therefore, this study investigated the roles of SPOCK2 and the related mechanisms in melanoma progression. To evaluate the clinical significance of SPOCK2 expression in patients with melanoma, we analysed the association between SPOCK2 expression and its prognostic value for patients with melanoma using systematic multiomic analysis. Subsequently, to investigate the roles of Spock2 in melanoma progression invitro and invivo, we knocked down Spock2 in the B16F10 melanoma cell line. High SPOCK2 levels were positively associated with good prognosis and long survival rate of patients with melanoma. Spock2 knockdown promoted melanoma cell proliferation by inducing the cell cycle and inhibiting apoptosis. Moreover, Spock2 downregulation significantly increased cell migration and invasion by upregulating MMP2 and MT1-MMP. The increased cell proliferation and migration were inhibited by MAPK inhibitor, and ERK phosphorylation was considerably enhanced in Spock2 knockdown cells. Therefore, Spock2 could function as a tumour suppressor gene to regulate melanoma progression by regulating the MAPK/ERK signalling pathway. Additionally, Spock2 knockdown cell injection induced considerable tumour growth and lung metastasis in C57BL6 mice compared to that in the control group. Our findings suggest that SPOCK2 plays crucial roles in malignant progression of melanoma and functions as a novel therapeutic target of melanoma.

Effect of a novel siRNA delivery system, siRNA ternary complex, on melanoma lung metastasis

In this study, we determined effects of an anionic siRNA delivery vector, siRNA ternary complex, which is constructed with biodegradable dendrigraft poly-L-lysine (DGL) and γ-polyglutamic acid (γ-PGA) on the melanoma cells and melanoma lung metastasis. The siRNA ternary complex showed high cellular uptake and silencing effect in melanoma cell line B16-F10/Luc cells. After intravenous administration of the siRNA ternary complex, high silencing effect was also observed in the lung of B16-F10/Luc melanoma metastasis model mice. Therefore, we applied vascular endothelial growth factor (VEGF)-siRNA on the siRNA ternary complex and determined the effect on the melanoma lung metastasis. The siRNA ternary complex containing VEGF-siRNA reduced VEGF protein levels significantly in in vitro and in vivo, and the complex successfully inhibited melanoma lung metastasis. This biodegradable and effective siRNA delivery vector, siRNA ternary complex, could be available for clinical trials.

Copper-Catalyzed Synthesis of Difluoromethylated/C-4- and C-5-Functionalized Polycyclic Coumarin Derivatives.

A facile and novel synthetic method for the synthesis of functionalized polycyclic coumarins at the C-4 and C-5 positions is proposed for the first time, which employs copper-catalyzed addition reactions of undiscovered alkenes with difluoromethyl radicals to construct polycyclic coumarins. This strategy is characterized by high regioselectivity, easy availability of raw materials, and simple operation. Additionally, such undiscovered coumarin alkenes can be reacted with a variety of difluoromethyl precursors to obtain a wide range of valuable C-4 and C-5 position functionalized/difluoromethylated polycyclic coumarins. More importantly, some of the products showed significant inhibition of proliferation in vitro against melanoma B16-F10 and lung cancer A549 cell lines with optimal IC50 values of 8.57 and 16.04 μM, respectively.

GPR168 functions as a tumor suppressor in mouse melanoma by restraining Akt signaling pathway.

Malignant melanoma (MM) is a malignant tumor associated with high mortality rates and propensity for metastasis. Despite advancement in treatment, the incidence of MM continue to rise globally. GPR168, also known as MrgprF, is a MAS related GPR family member. The low expression of GPR168 has also been reported in many malignant tumors including MM. In the study, the statistical analysis from The Cancer Genome Atlas (TCGA) revealed a significant down regulation of GPR168 in melanoma compared to normal melanocytes, underscoring its importance in MM. The aim of the present study is to investigate the affect of GPR168 overexpression and elucidate its molecular mechanisms in MM cells. In addition, we used mouse melanoma B16-F10 cell line and xenograph tumor model to explore the function of GPR168 in melanoma. Our findings demonstrate that GPR168 overexpression could inhibit B16-F10 cell proliferation, migration, and xenografts tumor growth. Further, mechanistic studies revealed that GPR168 affected B16-F10 progress through Akt signal pathway with the decreased expression of p-Akt, p-GSK-3β, β-catenin, Myc, CyclinD1 and CDK4. In order to validate these findings, a rescue experiment was formulated employing GPR168 polyclonal antibody (Anti-GPR168 pAbs) to block GPR168 functionality. The addition of Anti-GPR168 pAbs into the culture medium restored both cell proliferation and migration. In conclusion, the overexpression of GPR168 in mouse melanoma B16-F10 cells suppressed proliferation and migration through the Akt signaling pathway. These findings collectively propose GPR168 as a promising novel tumor suppressor in MM, suggesting its potential as a therapeutic target in future interventions.

Identification and characterization of a new potent inhibitor targeting CtBP1/BARS in melanoma cells

BackgroundThe C-terminal-binding protein 1/brefeldin A ADP-ribosylation substrate (CtBP1/BARS) acts both as an oncogenic transcriptional co-repressor and as a fission inducing protein required for membrane trafficking and Golgi complex partitioning during mitosis, hence for mitotic entry. CtBP1/BARS overexpression, in multiple cancers, has pro-tumorigenic functions regulating gene networks associated with “cancer hallmarks” and malignant behavior including: increased cell survival, proliferation, migration/invasion, epithelial-mesenchymal transition (EMT).Structurally, CtBP1/BARS belongs to the hydroxyacid-dehydrogenase family and possesses a NAD(H)-binding Rossmann fold, which, depending on ligands bound, controls the oligomerization of CtBP1/BARS and, in turn, its cellular functions.Here, we proposed to target the CtBP1/BARS Rossmann fold with small molecules as selective inhibitors of mitotic entry and pro-tumoral transcriptional activities.MethodsStructured-based screening of drug databases at different development stages was applied to discover novel ligands targeting the Rossmann fold. Among these identified ligands, N-(3,4-dichlorophenyl)-4-{[(4-nitrophenyl)carbamoyl]amino}benzenesulfonamide, called Comp.11, was selected for further analysis. Fluorescence spectroscopy, isothermal calorimetry, computational modelling and site-directed mutagenesis were employed to define the binding of Comp.11 to the Rossmann fold. Effects of Comp.11 on the oligomerization state, protein partners binding and pro-tumoral activities were evaluated by size-exclusion chromatography, pull-down, membrane transport and mitotic entry assays, Flow cytometry, quantitative real-time PCR, motility/invasion, and colony assays in A375MM and B16F10 melanoma cell lines. Effects of Comp.11 on tumor growth in vivo were analyzed in mouse tumor model.ResultsWe identify Comp.11 as a new, potent and selective inhibitor of CtBP1/BARS (but not CtBP2). Comp.11 directly binds to the CtBP1/BARS Rossmann fold affecting the oligomerization state of the protein (unlike other known CtBPs inhibitors), which, in turn, hinders interactions with relevant partners, resulting in the inhibition of both CtBP1/BARS cellular functions: i) membrane fission, with block of mitotic entry and cellular secretion; and ii) transcriptional pro-tumoral effects with significantly hampered proliferation, EMT, migration/invasion, and colony-forming capabilities. The combination of these effects impairs melanoma tumor growth in mouse models. ConclusionsThis study identifies a potent and selective inhibitor of CtBP1/BARS active in cellular and melanoma animal models revealing new opportunities to study the role of CtBP1/BARS in tumor biology and to develop novel melanoma treatments.

Abstract 6745: Crafting hyaluronic acid-based nanoparticles for enhanced LN targeting as a potent priming tool in immunotherapy

Abstract Background: Cholesterol-conjugated hyaluronic acid, synthesized by grafting cholesterol moieties onto hyaluronic acid, spontaneously formed nano-sized hydrogel of approximately 30-100nm in water. This hyaluronic acid derivative (HA nanogel) has demonstrated the ability to encapsulate various modalities, including low- and medium-sized molecules, peptides, and proteins. Previous reports have highlighted its efficacy in solubilizing poorly water-soluble drugs and serving as a sustained-release matrix. In this study, we explore the potential of HA nanogels encapsulating antigen peptides with adjuvant as a cancer vaccine and a priming tool for combinational immunotherapy. Method: We prepared HA nanogels as a novel peptide carrier for cancer vaccines and attempted to encapsulate various peptides, including neoantigen (mERK2) peptides expressed in immune checkpoint inhibitor (ICI) therapy-resistant fibrosarcoma cell line CMS5a, gp-100 peptides expressed in metastatic melanoma cell line B16F10, and MAGEA4. Our experiments covered APC uptake, antigen-specific CTL induction, and anti-tumor studies to demonstrate the utility of HA nanogels in these applications. Results: HA nanogel efficiently formed stable complexes with mERK2, gp-100 and MAGEA4 long peptides, each with diameters of 30-100nm. The facile and simple vaccine formulation processes with HA nanogel achieved high drug content and high encapsulation efficiency of 90% or higher. Fluorescently labeled mERK2 long peptide encapsulated in HA nanogel vaccines were subcutaneously administered to BALB/c mice, and uptake analysis of mERK2 long peptides in draining lymph nodes (dLN) was performed using flow cytometry. In comparison to the group receiving mERK2 long peptide without nanogel encapsulation, the HA nanogel group exhibited higher uptake by macrophages and dendritic cells in the dLN. Administering HA nanogel vaccines containing mERK2 long peptides with CpG oligoDNA resulted in higher antigen-specific CD8+ T cells compared to the group receiving mERK2 long peptides without encapsulation. Strong anti-tumor effects were demonstrated in mice models with subcutaneously transplanted CMS5a and B16F10 cell lines. The enhanced efficacy through co-administration with ICI was also confirmed. Conclusion: HA nanogel vaccines efficiently deliver antigen peptides to macrophages and dendritic cells, inducing antigen-specific CTL responses, thereby demonstrating anti-tumor effects against cold tumors such as CMS5a and B16F10. HA nanogels have the potential not only as carriers for cancer vaccines but also as priming tools for combinational immunotherapy. Citation Format: Takashi Nakai, Fumiyasu Momose, Kohei Yabuuchi, Makiko Yamane, Tae Hayashi, Linan Wang, Yoshiyuki Nakagawa, Shogo Aso, Toru Katsumata, Tsuyoshi Shimoboji, Yoshihiro Miyahara. Crafting hyaluronic acid-based nanoparticles for enhanced LN targeting as a potent priming tool in immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6745.

Abstract 3914: IGSF8 is a novel innate immune checkpoint and cancer immunotherapy target

Abstract Background: Loss of MHC-I antigen presentation is often associated with T-cell excluded tumors, and represents a common mechanism of both primary and acquired resistance to immune checkpoint blockade (ICB) treatment. MHC-I normally acts as a marker of “self” and cells that lack MHC-I are recognized and killed by innate immunity. In this study, we investigated the mechanism of innate immune evasion in tumors with MHC-I antigen presentation defects. Methods: Integrating functional genomics, big data, and artificial intelligence, we discovered that IGSF8 expressed on cancer cells is an evolutionarily conserved innate immune checkpoint. IGSF8 is normally expressed in neuronal tissues and is not essential in vitro or in vivo. However, knockout of IGSF8 in B16-F10 melanoma cell line decreased tumor growth in vivo. For clinical relevance of IGSF8 in tumor immunity, we analyzed genomics, transcriptomics, and clinical data from The Cancer Genome Atlas (TCGA). We developed an antibody (GV20-0251) against IGSF8 and tested its function to induce immune cell killing of cancer cells in vitro and inhibit tumor growth in vivo. Results: IGSF8 has receptors on both natural killer (NK) cells and dendritic cells (DC) to strongly suppress NK cytotoxicity and antigen presentation. In the TCGA tumor profiles, IGSF8 has highest mRNA expression in melanoma and is significantly overexpressed in many cancer types. IGSF8 also shows frequent copy number amplifications. In addition, IGSF8 expression is associated with low antigen presentation, low immune infiltration, and worse overall survival in patients with low MHC class I expression. Immunohistochemistry staining of various cancers showed that IGSF8 expression was primarily observed in malignant cells with low MHC-I. We developed a cross-species reactive antibody against IGSF8 (GV20-0251) which blocks IGSF8 interaction with NK and DC. Flow cytometry of the tumor infiltrating CD45+ cells revealed that IGSF8 inhibition significantly increased NK and dendritic cell infiltration. GV20-0251 enhances NK killing of cancer cells in vitro and increases antigen presentation, NK-mediated cytotoxicity, and T cell signaling in vivo. In multiple syngeneic tumor models (B16-F10, CT26, LLC, 4T1 and EMT6), anti-IGSF8 shows single-agent efficacy and is synergistic with anti-PD1 in controlling tumor growth. Conclusions: IGSF8 is a novel innate immune checkpoint and cancer immunotherapy target. A phase 1 study is ongoing to explore the IGSF8 inhibitor GV20-0251 in patients with advanced or metastatic solid tumors (NCT05669430). Citation Format: X. Shirley Liu, Yulong Li, Xiangyang Wu, Hailing Liu, Huizhu Liu, Caibin Sheng, Qingyang Ding, Yixuan Tang, Chao Liu, Bin Xie, Xi Xiao, Quan Yu, Rongbin Zheng, Xihao Hu, Tengfei Xiao. IGSF8 is a novel innate immune checkpoint and cancer immunotherapy target [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3914.

Nuclear Localization of Yes-Associated Protein Is Associated With Tumor Progression in Cutaneous Melanoma

Yes-associated protein (YAP), an effector molecule of the Hippo signaling pathway, is expressed at high levels in cutaneous melanoma. However, the role of YAP in melanoma progression according to cellular localization is poorly understood. Tissues from 140 patients with invasive melanoma were evaluated by immunohistochemistry. Flow cytometry, western blotting, viability assays, wound healing assays, verteporfin treatment, and xenograft assays were conducted using melanoma cell lines B16F1 and B16F10 subjected to YapS127A transfection and siYap knockdown. Nuclear YAP localization was identified in 63 tumors (45.0%) and was more frequent than cytoplasmic YAP in acral lentiginous and nodular subtypes (P = .007). Compared with cytoplasmic YAP melanomas, melanomas with nuclear YAP had higher mitotic activity (P = .016), deeper invasion (P < .001), and more frequently metastasized to lymph nodes (P < .001) and distant organs (P < .001). Patients with nuclear YAP melanomas had poorer disease-free survival (P < .001) and overall survival (P < .001). Nuclear YAP was an independent risk factor for distant metastasis (hazard ratio: 3.206; 95% CI, 1.032-9.961; P = .044). Proliferative ability was decreased in siYapB16F1 (P < .001) and siYapB16F10 (P = .001) cells and increased in YapS127AB16F1 (P = .003) and YapS127AB16F10 (P = .002) cells. Cell cycle analysis demonstrated relative G1 retention in siYapB16F1 (P < .001) and siYapB16F10 (P < .001) cells and S retention in YapS127AB16F1 cells (P = .008). Wound healing assays showed that Yap knockdown inhibited cell invasion (siYapB16F1, P = .001; siYapB16F10, P < .001), whereas nuclear YAP promoted it (YapS127AB16F, P < .001; YapS127AB16F1, P = .017). Verteporfin, a direct YAP inhibitor, reduced cellular proliferation in B16F1 (P = .003) and B16F10 (P < .001) cells. Proliferative effects of nuclear YAP were confirmed in xenograft mice (P < .001). In conclusion, nuclear YAP in human melanomas showed subtype specificity and correlated with proliferative activity and proinvasiveness. It is expected that YAP becomes a useful prognostic marker, and its inhibition may be a potential therapy for melanoma patients.

Tyrosinase regulates the motility of human melanoma cell line A375 through its hydroxylase enzymatic activity

Melanoma, originating from melanocytes, is a highly aggressive tumor. Tyrosinase is involved in melanin production in melanocytes, and its overexpression is noted in malignant melanomas. However, the role of tyrosinase in melanomas remains unclear. Therefore, this study aimed to evaluate the potential functions of tyrosinase in the human melanoma cell line A375. The expression level of tyrosinase in A375 cells was undetectable. However, markedly increased expression level was observed in the mouse melanoma cell line B16F10 and the human melanoma cell line WM266-4. Subsequently, we investigated the effect of ectopic tyrosinase expression on A375 cell motility using wound-healing assay. The overexpression of tyrosinase resulted in enhanced cell migration in both stable and transient tyrosinase expression cells. The levels of filamentous actin were decreased in tyrosinase-expressing A375 cells, suggesting that tyrosinase regulates cell motility by modulating actin polymerization. Histidine residues in tyrosinase are important for its enzymatic activity for synthesizing melanin. Substitution of these histidine residues to alanine residues mitigated the promotion of tyrosinase-induced A375 cell metastasis. Furthermore, melanin treatment enhanced A375 cell metastasis and phosphorylation of Cofilin. Thus, our findings suggest that tyrosinase increases the migration of A375 cells by regulating actin polymerization through its enzymatic activity.

Low-dose imiquimod induces melanogenesis in melanoma cells through an ROS-mediated pathway

BackgroundMelanogenesis is the process of melanin maturation which not only protects skin from UV radiation but also plays an important role in antigenicity of melanomas. Imiquimod (IMQ) is a toll-like receptor 7 (TLR7) agonist that exhibits antiviral and anticancer activity. ObjectiveTo explore whether IMQ could induce melanogenesis in melanoma cells. MethodsThe mouse melanoma cell line B16F10, the mouse immortalized melanocyte Melan-A, and human melanoma cell lines MNT-1, C32 and A375 were utilized in this study. The pigmented level was observed by the centrifuged cell pellet. The intracellular and extracellular melanin levels were examined in the absorbance in NaOH-extracted cell lysate and cell-cultured medium, respectively. The expression of melanogenesis related proteins was examined by immunoblotting. The intracellular cyclic AMP amount was evaluated by the cAMP Glo assay kit. The activity of phosphodiesterase 4B (PDE4B) was investigated by CREB reporter assay with overexpressed PDE4B or not. ResultsWe demonstrated that a low dose of IMQ could trigger melanogenesis in B16F10 cells. IMQ induced microphthalmia-associated transcription factor (MITF) nuclear translocation, upregulated the expression of melanogenesis-related proteins, increased tyrosinase (TYR) activity, and led to pigmentation in B16F10 cells. Next, we found that IMQ-induced melanogenesis was activated by excessive intracellular cAMP accumulation, which was regulated through IMQ-mediated PDE4B inhibition. Finally, IMQ-induced ROS production was found to be involved in melanogenesis by its control of PDE4B activity. ConclusionsLow dose of IMQ could activate melanogenesis through the ROS/PDE4B/PKA pathway in melanoma cells.