Inhibited Melanoma Tumor Growth Research Articles

A programmable targeted protein-degradation platform for versatile applications in mammalian cells and mice

Myriad physiological and pathogenic processes are governed by protein levels and modifications. Controlled protein activity perturbation is essential to studying protein function in cells and animals. Based on Trim-Away technology, we screened for truncation variants of E3 ubiquitinase Trim21 with elevated efficiency (ΔTrim21) and developed multiple ΔTrim21-based targeted protein-degradation systems (ΔTrim-TPD) that can be transfected into host cells. Three ΔTrim-TPD variants are developed to enable chemical and light-triggered programmable activation of TPD in cells and animals. Specifically, we used ΔTrim-TPD for (1) red-light-triggered inhibition of HSV-1 virus proliferation by degrading the packaging protein gD, (2) for chemical-triggered control of the activity of Cas9/dCas9 protein for gene editing, and (3) for blue-light-triggered degradation of two tumor-associated proteins for spatiotemporal inhibition of melanoma tumor growth in mice. Our study demonstrates that multiple ΔTrim21-based controllable TPD systems provide powerful tools for basic biology research and highlight their potential biomedical applications.

RIPK4 downregulation impairs Wnt3A-stimulated invasiveness via Wnt/β-catenin signaling in melanoma cells and tumor growth in vivo.

The role of Wnt signaling in oncogenesis and drug resistance is well known. Receptor-interacting protein kinase (RIPK4) contributing to the increased activity of many signaling pathways, including Wnt/β-catenin, may be an important target for designing new drugs for metastatic melanoma, but its role in melanoma is not fully understood. We tested the effect of genetic manipulation of RIPK4 (CRISPR/Cas9) on xenograft growth. In addition, immunohistochemistry was used to detect active β-catenin, Ki67 and necrosis in xenografts. Wnt signaling pathway activity was examined using Western blot and Top-Flash. The effect of RIPK4 knockout on melanoma cells in vitro stimulated Wnt3A on wound overgrowth, migration and invasion ability was then evaluated. Our study showed that CRISPR/Cas9-mediated RIPK4 knockout (KO) significantly reduced tumor growth in a mouse model of melanoma, particularly of WM266.4 cells. RIPK4 KO tumors exhibited lower percentages of Ki67+ cells as well as reduced necrotic area and decreased levels of active β-catenin. In addition, we observed that RIPK4 knockout impaired Wnt3A-induced activation of LRP6 and β-catenin, as manifested by a decrease in the transcriptional activity of β-catenin in Top-Flash in both tested melanoma cell lines, A375 and WM266.4. Prolonged incubation (48h) with Wnt3A showed reduced level of MMP9, C-myc, and increased SOX10, proteins whose transcription is also dependent on β-catenin activity. Moreover, RIPK4 knockout led to the inhibition of scratch overgrowth, migration and invasion of these cells compared to their controls. RIPK4 knockdown inhibits melanoma tumor growth and Wnt3A stimulated migration and invasion indicating that RIPK4 might be a potential target for melanoma therapy.

Abstract 2784: JW-1-283 inhibits melanoma tumor growth via the stabilization of p53 pathway

Abstract Melanoma is the most lethal skin cancer, with the increasing incidence in the past decade. Despite the significant advancements in immune therapy and targeted therapy, the overall prognosis for metastatic melanoma remains unsatisfactory. TP53 is a tumor suppressor, but its wildtype is inactivated in about 90% of melanoma. Since activated p53 can promote cancer cell apoptosis and thus effectively inhibit tumor growth and tumor metastasis, reactivation of p53 is considered a promising strategy for cancer therapy. Herein, we report a recently developed small molecule compound, JW-1-283, targeting the interactions between MDM2 E3 ubiquitin-protein ligase and p53 protein. In vitro, JW-1-283 showed potent cytotoxicity against A375 melanoma cell line (IC50 2.2±0.3 μM) which has wildtype p53, but its potency is substantially reduced in two other melanoma cell lines with either p53 mutation (M14) or p53 null (RPMI-7951) status. Treatment with JW-1-283 significantly dose-dependently reduced the stemness in A375 melanoma cells, as indicated by low numbers of colony formation, impaired tumor sphere formation abilities, and inhibition of cancer cell migration. Mechanistically, JW-1-283 disrupts the p53-MDM2 interaction, prevents p53 and MDM2 degradation in the existence of cycloheximide, and induces p38 and p53 phosphorylation in the apoptotic pathway. Genetic knockdown of p38 by siRNA further confirmed that the stabilized p53 could be subsequently phosphorylated by p38, leading to induced apoptosis as well as S phase cell cycle arrest. In vivo, when A375 tumors grown in NSG mice were treated with 7.5 mg/kg of JW-1-283 intraperitoneally every other day for a consecutive of 16 days, significant inhibition of tumor growth was observed, along with decreased tumor cell proliferation, tumor angiogenesis, and enhanced tumor cell apoptosis. In summary, this work provides the initial proof-of-concept of developing the JW-1-283 scaffold as a potential strategy for advanced melanoma, which inhibits tumor growth by activating the p53 signaling pathway. Citation Format: Yang Xie, Kelli Hartman, Zhongzhi Wu, Wei Li. JW-1-283 inhibits melanoma tumor growth via the stabilization of p53 pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2784.

Circ_0084043-miR-134-5p axis regulates PCDH9 to suppress melanoma.

The low survival rates, poor responses, and drug resistance of patients with melanoma make it urgent to find new therapeutic targets. This study investigated whether the circ_0084043-miR-134-5p axis regulates the antitumor effect of protocadherin 9 (PCDH9) in melanoma. Ectopic expression or knock down (KD) of PCDH9 with a lentivirus vector, we explored its effects on the proliferation, invasion, and apoptosis of melanoma and verified its regulatory effect on ras-related C3 botulinum toxin substrate 1 (RAC1), proline-rich tyrosine kinase 2 (Pyk2), Cyclin D1, matrix metalloproteinase 2 (MMP2), and MMP9. We further observed the effect of KD circ_0084043 on the malignant behavior of melanoma and studied whether circ_0084043 sponged miR-134-5p and regulated PCDH9. We found that circ_0084043 was overexpressed in melanoma and associated with the malignant phenotype. PCDH9 was poorly expressed in human melanoma tissues, and overexpression of PCDH9 inhibited melanoma progression. Quantitative real-time PCR and Western blotting results showed that overexpression of PCDH9 could downregulate RAC1, MMP2, and MMP9 and upregulate Pyk2 and Cyclin D1. Circ_0084043 KD inhibited invasion and promoted apoptosis in melanoma cells. Circ_0084043 could sponge miR-134-5p and thus indirectly regulate PCDH9. Furthermore, we discovered that inhibiting circ_0084043 had an anti-PD-Ll effect. In vivo, PCDH9 overexpression inhibited melanoma tumor growth, but PCDH9 KD promoted it. In conclusion, PCDH9, which is regulated by the circ 0084043-miR-134-5p axis, can suppress malignant biological behavior in melanoma and influence the expression levels of Pyk2, RAC1, Cyclin D1, MMP2, and MMP9.

147 (PB027) - Combination Therapy with Poly-gamma-glutamic Acid and Anti-PD-1 Results in Synergistic Therapeutic Effects against Cancers

Background: Combinatorial therapeutic strategies based on innate immunity have the potential to enhance the treatment efficacy of cancer therapies. We have been demonstrated that poly-γ-glutamic acid (γ-PGA) has a potent innate immune modulating activities including natural killer cell activation and interferon secretion through Toll-like receptor 4 and may be a useful mean for immunotherapeutic as reported previously. The programmed death protein 1 (PD-1) plays a critical part in downregulating immune responses and limiting immunogenic response in T cells. Here, we report the anti-cancer effects of γ-PGA combined with PD-1 blockade in murine colon adenocarcinoma and murine melanoma. Material and methods: It was performed to evaluate the in vivo combinatorial anti-cancer effects by oral administration of γ-PGA and intraperitoneal injection of anti-PD-1 in C57BL/6N mice transplanted with MC38 cell, a colorectal cancer cell. And the another study was carried out to examine the synergetic therapeutic efficacy by γ-PGA and anti-PD-1 against B16F10 melanoma tumor model in mice. Results: Combination therapy with γ-PGA and anti-PD-1 produced significantly longer tumor growth delay than other treatment and almost completely inhibited melanoma tumor growth, and also the improved longterm survival rate was shown compared to γ-PGA or anti-PD-1 alone. Similar experiment was performed in melanoma tumor and the result shows that co-treatment with γ-PGA and anti-PD-1 significantly prolonged survival rate compared with anti-PD-1 alone in MC38 tumor model and dramatically reduced MC38 tumor growth but had no synergistic effect. The results showed that the survival rate of the combinatorial treatment was superior to anti-PD-1 alone. Conclusions: Based on the resistance mechanism of PD-1 blockade with low response rates in many patients, γ-PGA treatment having an innate immune modulating activity combined with anti-PD-1 can induce stronger anti-tumor immunity and destroy the target cancer cells. In this study, oral administration of γ-PGA with intraperitoneal injection of anti-PD-1 dramatically inhibited tumor growth and enhanced the survival rate in MC38 and B16F10 tumor-bearing mice. The study demonstrates that the tumor microenvironment was controlled by administration of γ-PGA, thus results in exertion of immune checkpoint inhibitor. These data provide a strong preclinical evidence for a novel combinatorial therapeutic strategy that can be assessed in prospective clinical trials. No conflict of interest.

Co-targeting of specific epigenetic regulators in combination with CDC7 potently inhibit melanoma growth

SummaryMelanoma is a highly aggressive skin cancer that frequently metastasizes, but current therapies only benefit some patients. Here, we demonstrate that the serine/threonine kinase cell division cycle 7 (CDC7) is overexpressed in melanoma, and patients with higher expression have shorter survival. Transcription factor ELK1 regulates CDC7 expression, and CDC7 inhibition promotes cell cycle arrest, senescence, and apoptosis, leading to inhibition of melanoma tumor growth and metastasis. Our chemical genetics screen with epigenetic inhibitors revealed stronger melanoma tumor growth inhibition when XL413 is combined with the EZH2 inhibitor GSK343 or BRPF1/2/3 inhibitor OF1. Mechanistically, XL413 with GSK343 or OF1 synergistically altered the expression of tumor-suppressive genes, leading to higher apoptosis than the single agent alone. Collectively, these results identify CDC7 as a driver of melanoma tumor growth and metastasis that can be targeted alone or in combination with EZH2 or BRPF1/2/3 inhibitors.

In Vitro and In Vivo Anticancer and Genotoxicity Profiles of Green Synthesized and Chemically Synthesized Silver Nanoparticles.

Silver nanoparticles were green synthesized (Ag-PTs) employing the crude extract of Padina tetrastromatica, a marine alga, and their anticancer and safety profile were compared with those of chemically synthesized silver nanoparticles (Ag-NPs) by in vitro and in vivo models. Ag-PT exhibited potent cytotoxicity against B16-F10 (IC50 = 3.29), MCF-7 (IC50 = 4.36), HEPG2 (IC50 =3.89), and HeLa (IC50 = 4.97) cancer cell lines, whereas they exhibited lower toxicity on normal CHO-K1 cells (IC50 = 5.16). The potent anticancer activity of Ag-PTs on cancer cells is due to the liberation of ions from the nanoparticles. Increased ion internalization to the cells promotes reactive oxygen species (ROS) production and ultimately leads to cell death. The in vitro anticancer results and in vivo melanoma tumor regression study showed significant inhibition of melanoma tumor growth due to Ag-PT treatment. Ag-PT is involved in the upregulation of the p53 protein and downregulation of Sox-2 along with the Ki-67 protein. The antitumor effects of Ag-PTs may be due to the additional release of ions at a lower pH of the tumor microenvironment than that of the normal tissue. The results of safety investigations of Ag-PT by studying mitotic chromosome aberrations (CAs), micronucleus (MN) induction, and mitotic index (MI) demonstrated Ag-PT to be less genotoxic compared to Ag-NP. The bioefficacy and toxicology outcomes together demonstrated that the green synthesized silver nanoparticles (Ag-PTs) could be explored to develop a biocompatible, therapeutic agent and a vehicle of drug delivery for various biomedical applications.

Nano-hydroxyapatite-evoked immune response synchronized with controllable immune adjuvant release for strengthening melanoma-specific growth inhibition

Concerns about the potential systematic toxicity limit the extensive application of traditional therapeutic drugs for melanoma therapy, nano-hydroxyapatite (nHA) with good biocompatibility and anti-tumor ability could be an alternative choice. In this study, nHA was employed as an anti-tumor biomaterial due to its tumor-specific toxicity. Meanwhile, granulocyte-macrophage colony-stimulating factor (GM-CSF) served as the immune adjuvant to activate the immune response. The delivery platform was fabricated by co-encapsulation of both nHA and GM-CSF into a biocompatible thermosensitive PLGA-PEG-PLGA hydrogel. The results showed that the bio-activities of nHA and GM-CSF could be well-maintained within the hydrogel. Interestingly, the addition of nHA could attenuate the burst release of GM-CSF due to possible protein absorption capacity of nHA, which is beneficial for GM-CSF sustainable release at the tumor site, achieving boosted and prolonged anti-tumor immunity. The in vitro and in vivo data demonstrated that nHA/GM-CSF hydrogel exhibited greater potency to inhibit tumor growth via enhanced CD8+ T-cell response compared with hydrogel and nHA hydrogel groups, contributed by the synergistic effects of nHA and GM-CSF. Overall, the strategy combining nHA and immune adjuvant shows great promise, which largely broadens the choice of combinational therapies for melanoma. Statement of significanceNano-hydroxyapatite (nHA) has been confirmed to specifically inhibit melanoma tumor growth and induce immune response. However, its antitumor efficiency and immunity-evoking capacity are limited. In this study, granulocyte-macrophage colony-stimulating factor (GM-CSF) was introduced to serve as the immune adjuvant. Both of them were encapsulated into a biocompatible thermosensitive PLGA-PEG-PLGA hydrogel. The addition of nHA could attenuate the burst release of GM-CSF due to the interaction with nHA, which is beneficial for GM-CSF sustainable release at tumor site, achieving boosted and prolonged anti-tumor immunity. Anti-tumor immune response could be activated due to the release of tumor-associated antigen and tumor debris induced by the specifically tumor inhibition effect of nHA and GM-CSF. The combination of nHA and GM-CSF could play synergistic inhibiting effect on tumor growth via boosting and prolonging anti-tumor immunity.

Itraconazole-Induced the Activation of Adenosine 5'-Monophosphate (Amp)-Activated Protein Kinase Inhibits Tumor Growth of Melanoma via Inhibiting ERK Signaling.

Itraconazole, an effective broad-spectrum antifungal drug, has been well established for its anticancer activity in cancers including melanoma. However, details concerning its underlying mechanism in melanoma are unclear. This work investigated the function of itraconazole-induced 5'-monophosphate (AMP)-activated protein kinase alpha (AMPKα) in melanoma progression through ERK signaling. The AMPKα level in melanoma tissues and cells was assessed by RT-qPCR and western blot. Survival analysis of patients with melanoma based on the AMPKα expression level was performed according to TCGA database. Melanoma cell proliferation, migration, and invasion were examined using CCK-8, colony formation, wound healing, and Transwell assays. A xenograft tumor model was established to examine the effect of itraconazole on tumor growth in vivo. The AMPKα mRNA and protein levels were reduced in melanoma tissues and cells. A low expression of AMPKα indicated a poor prognosis. Functionally, itraconazole restrained melanoma cell proliferation, migration, and invasion by upregulating AMPKα. Itraconazole activated AMPK signaling and inhibited ERK signaling in melanoma cells. Activation of ERK signaling reversed the effect of itraconazole on cellular process in melanoma. Moreover, itraconazole-induced AMPKα inhibited melanoma tumor growth in vivo by inhibiting ERK signaling. Itraconazole-induced AMPKα inhibits the progression of melanoma by inhibition of ERK signaling.

Synthesis and biological evaluation of selective survivin inhibitors derived from the MX-106 hydroxyquinoline scaffold.

The survivin (BIRC5) expression is very low in normal differentiated adult tissues, but it is one of the most widely upregulated genes in tumor cells. The overexpression of survivin in many cancer types has been positively correlated with resistance to chemotherapy, tumor metastasis, and poor patient survival. Survivin is considered to be a cancer specific biomarker and serves as a potential cancer drug target. In this report, we describe the design and syntheses of a series of novel selective survivin inhibitors based on the hydroxyquinoline scaffold from our previously reported lead compound MX-106. The best compound identified in this study is compound 12b. Invitro, 12b inhibited cancer cell proliferation with an average IC50 value of 1.4μM, using a panel of melanoma, breast, and ovarian cancer cell lines. The metabolic stability of 12b improved over MX-106 by 1.7-fold (88 vs 51min in human microsomes). Western blot analyses demonstrated that treatments with 12b selectively decreased survivin protein levels, but negligibly affected other closely related members in the IAP family proteins, and strongly induced cancer cell apoptosis. Invivo, compound 12b effectively inhibited melanoma tumor growth when tested using a human A375 melanoma xenograft model. Further evaluation using an aggressive, orthotopic ovarian cancer mouse model showed that 12b was highly efficacious in suppressing both primary tumor growth in ovaries and tumor metastasis to multiple peritoneal organs. Collectively, results in this study strongly suggest that the hydroxyquinoline scaffold, represented by 12b and our earlier lead compound MX-106, has abilities to selectively target survivin and is promising for further preclinical development.

Circ_0062270 upregulates EPHA2 to facilitate melanoma progression via sponging miR-331-3p

BackgroundCircular RNA (circRNA) has been confirmed to play a vital role in melanoma progression. ObjectiveThe regulatory function of circ_0062270, a novel circRNA, in melanoma progression is unclear. MethodsRelative expression levels of circ_0062270 and microRNA (miR)-331-3p were determined using qRT-PCR. Cell counting kit 8 assay, EdU staining and flow cytometry were used to measure cell proliferation, cell cycle distribution and apoptosis. The protein levels of proliferation, apoptosis and metastasis-related markers, as well as EPH receptor A2 (EPHA2), were tested using western blot analysis. Besides, cell migration and invasion were evaluated using transwell assay. Meanwhile, the interaction between miR-331-3p and circ_0062270 or EPHA2 was confirmed by dual-luciferase reporter assay or RIP assay. Additionally, tumor xenograft models were constructed to investigate the function of circ_0062270 on melanoma tumor growth in vivo. ResultsThe expression of circ_0062270 was increased in melanoma tissues and cells. Knockdown of circ_0062270 inhibited proliferation, promoted apoptosis, and repressed metastasis in melanoma. Moreover, circ_0062270 could serve as miR-331-3p sponge, and miR-331-3p could target EPHA2. Furthermore, miR-331-3p inhibitor and EPHA2 overexpression reversed the inhibitory effect of circ_0062270 silencing on melanoma progression. In addition, silenced circ_0062270 also could inhibit melanoma tumor growth in vivo. ConclusionCirc_0062270 accelerated the progression of melanoma through regulating the miR-331-3p/EPHA2 axis, suggesting that circ_0062270 might be a novel potential therapeutic target for melanoma.

Synthetic multiepitope neoantigen DNA vaccine for personalized cancer immunotherapy

Neoantigen-based personalized vaccination has emerged as a viable method for tumor immunotherapy. Here we set up a DNA-based neoantigen vaccine platform with comprehensive identification of individual somatic mutations using whole-exome sequencing (WES) and RNA-seq, bioinformatic prediction of neo-epitopes, dendritic cell (DC)-based efficacy prevalidation of vaccine candidates, optimization of the DNA vaccine and its nanocarrier and adjuvant, and preparation of a liposome-encapsulated multiepitope DNA vaccine. The DNA vaccine was efficiently uptaken by DCs and induced effective immune response against mouse melanoma cells, leading to significant inhibition of melanoma tumor growth and reduction of lung metastasis in a mouse model. Numerous intratumoral infiltrated CD8+ T-cells with specific in vitro killing ability towards melanoma cells were identified. Our study offers evidence that a multiepitope neoantigen DNA vaccine in a nanocarrier can be exploited for personalized tumor immunotherapy and as a reliable prevalidation approach for rapid enrichment of effective neoantigens.

The HGR motif is the antiangiogenic determinant of vasoinhibin: implications for a therapeutic orally active oligopeptide

The hormone prolactin acquires antiangiogenic and antivasopermeability properties after undergoing proteolytic cleavage to vasoinhibin, an endogenous prolactin fragment of 123 or more amino acids that inhibits the action of multiple proangiogenic factors. Preclinical and clinical evidence supports the therapeutic potential of vasoinhibin against angiogenesis-related diseases including diabetic retinopathy, peripartum cardiomyopathy, rheumatoid arthritis, and cancer. However, the use of vasoinhibin in the clinic has been limited by difficulties in its production. Here, we removed this barrier to using vasoinhibin as a therapeutic agent by showing that a short linear motif of just three residues (His46-Gly47-Arg48) (HGR) is the functional determinant of vasoinhibin. The HGR motif is conserved throughout evolution, its mutation led to vasoinhibin loss of function, and oligopeptides containing this sequence inhibited angiogenesis and vasopermeability with the same potency as whole vasoinhibin. Furthermore, the oral administration of an optimized cyclic retro-inverse vasoinhibin heptapeptide containing HGR inhibited melanoma tumor growth and vascularization in mice and exhibited equal or higher antiangiogenic potency than other antiangiogenic molecules currently used as anti-cancer drugs in the clinic. Finally, by unveiling the mechanism that obscures the HGR motif in prolactin, we anticipate the development of vasoinhibin-specific antibodies to solve the on-going challenge of measuring endogenous vasoinhibin levels for diagnostic and interventional purposes, the design of vasoinhibin antagonists for managing insufficient angiogenesis, and the identification of putative therapeutic proteins containing HGR.

PH-Triggered Copper-Free Click Reaction-Mediated Micelle Aggregation for Enhanced Tumor Retention and Elevated Immuno-Chemotherapy against Melanoma.

Natural killer (NK) cell-based immunotherapy presents a promising antitumor strategy and holds potential for combination with chemotherapy. However, the suppressed NK cell activity and poor tumor retention of therapeutics hinder the efficacy. To activate NK cell-based immuno-chemotherapy and enhance the tumor retention, we proposed a pH-responsive self-aggregated nanoparticle for the codelivery of chemotherapeutic doxorubicin (DOX) and the transforming growth factor-β (TGF-β)/Smad3 signaling pathway inhibitor SIS3. Polycaprolactone-poly(ethylene glycol) (PCL-PEG2000) micelles modified with dibenzylcyclooctyne (DBCO) or azido (N3) and coated with acid-cleavable PEG5000 were established. This nanoplatform, namely, M-DN@DOX/SIS3, could remain well dispersed in the neutral systemic circulation, while quickly respond to the acidic tumor microenvironment and intracellular lysosomes, triggering copper-free click reaction-mediated aggregation, leading to the increased tumor accumulation and reduced cellular efflux. In addition, the combination of DOX with SIS3 facilitated by the aggregation strategy resulted in potent inhibition of melanoma tumor growth and significantly increased NK cells, NK cell cytokines, and antitumor T cells in the tumor. Taken together, our study offered a new concept of applying copper-free click chemistry to achieve nanoparticle aggregation and enhance tumor retention, as well as a promising new combined tumor treatment approach of chemotherapy and immunotherapy.

Long noncoding RNA LINC01291 promotes the aggressive properties of melanoma by functioning as a competing endogenous RNA for microRNA-625-5p and subsequently increasing IGF-1R expression

Studies have confirmed the relationship between dysregulated long noncoding RNAs and melanoma pathogenesis. However, the regulatory functions of long intergenic non-protein coding RNA 1291 (LINC01291) in melanoma remain unknown. Therefore, we evaluated LINC01291 expression in melanoma and explored its roles in regulating tumor behaviors. Further, the molecular events via which LINC01291 affects melanoma cells were investigated. LINC01291 expression in melanoma cells was analyzed using The Cancer Genome Atlas database and quantitative real-time polymerase chain reaction. Functional assays, including the Cell Counting Kit-8 assay, colony formation assay, flow cytometry, cell migration and invasion assays, and tumor xenograft models, were used to examine LINC01291’s role in melanoma cells. Additionally, bioinformatics analysis, RNA immunoprecipitation, luciferase reporter assay, and western blotting were conducted to determine the tumor-promoting mechanism of LINC01291. LINC01291 was upregulated in melanoma tissues and cell lines. Following LINC01291 knockdown, cell proliferation, colony formation, migration, and invasion were diminished, whereas apoptosis was enhanced and the cell cycle was arrested at G0/G1. In addition, loss of LINC01291 decreased the chemoresistance of melanoma cells to cisplatin. Furthermore, LINC01291 interference inhibited melanoma tumor growth in vivo. Mechanistically, LINC01291 functions as a competing endogenous RNA by sponging microRNA-625-5p (miR-625-5p) in melanoma cells and maintaining insulin-like growth factor 1 receptor (IGF-1R) expression. Rescue experiments revealed that the roles induced by LINC01291 depletion in melanoma cells could be reversed by suppressing miR-625-5p or overexpressing IGF-1R. Our study identified the LINC01291/miR-625-5p/IGF-1R competing endogenous RNA pathway in melanoma cells, which may represent a novel diagnostic biomarker and an effective therapeutic target for melanoma.

Brachytherapy in a Single Dose of 10Gy as an "in situ" Vaccination.

Radiotherapy (RT) is one of the major methods of cancer treatment. RT destroys cancer cells, but also affects the tumor microenvironment (TME). The delicate balance between immunomodulation processes in TME is dependent, among other things, on a specific radiation dose. Despite many studies, the optimal dose has not been clearly determined. Here, we demonstrate that brachytherapy (contact radiotherapy) inhibits melanoma tumor growth in a dose-dependent manner. Doses of 10Gy and 15Gy cause the most effective tumor growth inhibition compared to the control group. Brachytherapy, at a single dose of ≥ 5Gy, resulted in reduced tumor blood vessel density. Only a dose of 10Gy had the greatest impact on changes in the levels of tumor-infiltrating immune cells. It most effectively reduced the accumulation of protumorogenic M2 tumor-associated macrophages and increased the infiltration of cytotoxic CD8+ T lymphocytes. To summarize, more knowledge about the effects of irradiation doses in anticancer therapy is needed. It may help in the optimization of RT treatment. Our results indicate that a single dose of 10Gy leads to the development of a robust immune response. It seems that it is able to convert a tumor microenvironment into an “in situ” vaccine and lead to a significant inhibition of tumor growth.

Silver Prussian Blue Analogue Nanoparticles: Rationally Designed Advanced Nanomedicine for Multifunctional Biomedical Applications.

The development of simple, cost-effective, and advanced multifunctional technology is the need of the hour to combat cancer as well as bacterial infections. There have been reports of silver nanoparticles (AgNPs), silver salts, and Prussian blue (PB) being used for medicinal purposes which are clinically approved. In this context, in the present communication, we incorporated PB and silver salts (silver nitrate) to develop silver PB analogue nanoparticles (SPBANPs), a new nanomedicine formulation as a safer and effective mode of treatment strategy (2-in-1) for both cancer and bacterial infections. Considering all fundamental issues of nanomedicine, along with understanding of the biological impact of PB, we designed a simple, fast, efficient, cheap, and eco-friendly method for the synthesis of [poly(N-vinyl-2-pyrrolidone)]-stabilized silver hexacyanoferrate nanoparticles (silver PB analogue: Ag3[Fe(CN)6] abbreviated as SPBANPs). Various analytical tools were used to analyze and characterize the nanomaterials (SPBANPs). The SPBANPs were highly stable for several weeks in various phosphate buffers with a range of physiological pH conditions (pH = 6-8). The nanoparticles showed biocompatibility in vivo in C57BL6/J mice that encouraged us to screen the nanoparticles for various biomedical applications. The SPBANPs themselves exhibited remarkable inhibition of cancer cell proliferation (B16F10, A549, MCF-7, and SK-OV-3) in vitro. Substantial inhibition of melanoma tumor growth was observed in the C57BL6/J mouse model (aggressive murine melanoma model: B16F10) after intraperitoneal administration of the SPBANPs without any anticancer drug. Additionally, the SPBANPs exhibited excellent antibacterial activity in various Gram-negative (Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa) and Gram-positive (Bacillus subtilis) bacteria. Interestingly, this nanoformulation itself works as a drug delivery vehicle, as well as an anticancer and antibacterial agent. The in vitro and in vivo results together demonstrate that this biocompatible nanoformulation (SPBANPs) without an anticancer drug or antibiotic could be explored to develop as a multifunctional therapeutic agent (2-in-1) for the treatment of cancer and bacterial infections in the near future.

Matrix metalloproteinases-9 as a promising target for anti-cancer vaccine: inhibition of melanoma tumor growth in mice immunized with syngeneic MMP-9 peptides

Matrix metalloproteinases-9 as a promising target for anti-cancer vaccine: inhibition of melanoma tumor growth in mice immunized with syngeneic MMP-9 peptides

Abstract 3276: Damage-associated molecular pattern (DAMP) induction by 15-deoxy, Δ12,14-prostaglandin J2-ethanolamide: Examination of tumor selectivity, dendritic cell activation and oxidative stress in melanoma

Abstract Melanoma is the most lethal form of skin cancer in the United States. Current trends show that melanoma incidence has been increasing for the last 30 years. Chemotherapeutic agents for advanced stage metastatic melanoma have limited efficacy. Although the use of immune-modulating agents such as checkpoint inhibitors has significantly improved therapeutic outcomes, these agents can cause life-threatening autoimmune side effects. Therefore, immunotherapeutic agents that can preferentially eliminate melanoma cells are needed. Agents that induce the release of damage-associated molecular patterns (DAMPs) can stimulate antitumor immunity. DAMPs are produced by damaged or dying cancer cells and include signals such as expression of cell surface calreticulin (ecto-CRT) and the secretion of ATP. DAMPs can recruit and activate immune cells such as dendritic cells which in turn stimulate tumor-specific cytotoxic T cells to kill cancer cells in a process referred to as immunogenic cell death. The elicitation of DAMPs depends on endoplasmic reticulum stress (ER) and oxidative stress. Our group found that our patented agent, 15-deoxy, Δ12,14-prostaglandin J2-ethanolamide (15dPMJ2), inhibits melanoma tumor growth. In addition, 15dPMJ2 induces DAMPs in melanoma cells via an ER stress dependent mechanism. The purpose of this study was to investigate the selectivity of DAMP induction in melanoma by 15dPMJ2, the effect of 15dPMJ2-treated cells on the activation of bone marrow-derived dendritic cells (BMDCs) and the role of oxidative stress in this process. To determine if 15dPMJ2 causes tumor-selective activation of BMDCs, we first examined ecto-CRT and the release of ATP in B16F10 melanoma cells and Melan-A non-tumorigenic melanocytes. Our results showed that 15dPMJ2 significantly increased DAMP expression in tumorigenic compared to non-tumorigenic melanocytes. Importantly, we found that 15dPMJ2-treated B16F10 cells induced maturation of BMDCs as manifested by an increase in the expression of MHCII, CD80 and CD86. However, 15dPMJ2-treated Melan-A cells did not activate BMDCs. In this study, we also tested the role of oxidative stress in 15dPMJ2-induced DAMPs. Our results showed that the antioxidant Trolox significantly decreased 15dPMJ2 induced ecto-CRT and ATP release in B16F10 cells. However, Trolox did not inhibit the activation of BMDCs by 15dPMJ2-treated B16F10 cells. These results suggest that oxidative stress plays an important role in 15dPMJ2-induced DAMPs, but it is not required for the BMDC activation. In conclusion, 15dPMJ2can selectively induce DAMPs in melanoma which results in the activation of BMDCs. Hence, 15dPMJ2 is a potential small molecule immunotherapeutic for melanoma. Citation Format: Ahmed Elhassanny, Rene Escobedo, Daniel Ladin, Rukiyah Van Dross. Damage-associated molecular pattern (DAMP) induction by 15-deoxy, Δ12,14-prostaglandin J2-ethanolamide: Examination of tumor selectivity, dendritic cell activation and oxidative stress in melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3276.

820 m6A mRNA demethylase FTO regulates tumorigenicity and response to anti-PD-1 immunotherapy in melanoma

Analogous to epigenetic regulation of gene expression through the reversible DNA and histone modifications, post-transcriptional N6-methyladenosine (m6A) methylation of adenosine residues in mRNA as well as lncRNA provides an additional layer of regulation that may alter mRNA metabolism and gene expression. Recently, m6A RNA methylation research was revived by the discovery of the fat mass- and obesity-associated protein (FTO) as the first RNA demethylase, implying that m6A RNA methylation is a reversible and dynamic modification and may have critical biological functions. However the role of FTO in melanoma tumorigenicity remains unknown. Here we show that N6-methyladenosine (m6A) mRNA demethylation by FTO promotes melanoma growth and inhibits response to anti-PD-1 blockade therapy and cell killing induced by interferon gamma (IFNg). FTO is up-regulated in human melanoma, suggesting an oncogenic role of FTO in melanoma. FTO knockdown inhibited melanoma cell proliferation, migration, and invasion in vitro, which is reversed by knockdown of the m6A methyltransferases METTL3 and METTL14. FTO knockdown inhibited melanoma tumor growth in vivoin both xenograft and syngeneic melanoma mouse models. FTO is up-regulated by metabolic stress through the autophagy/NF-kB pathway. m6A immunoprecipitation sequencing (m6A-seq) and RNA-seq analyses showed that FTO knockdown increases m6A modifications in the critical melanoma-promoting genes including PDCD1, CXCR4 and SOX10, leading to increased RNA decay through the m6A reader YTHDF2. Our findings demonstrate a key role of FTO as a RNA demethylase in promoting melanoma growth, and suggest that the combination of FTO inhibition with targeted therapy or immunotherapies may improve therapeutic response.