Drug Combinations as the New Standard for Melanoma Treatment

Prognostic and immune-related value of complement C1Q (C1QA, C1QB, and C1QC) in skin cutaneous melanoma

Background: Skin cutaneous melanoma (SKCM) is a common malignancy that is associated with increased morbidity and mortality. Complement C1Q is composed of C1QA, C1QB, and C1QC and is involved in the occurrence and development of many malignant tumours. However, the effect of C1QA, C1QB, and C1QC expression on tumour immunity and prognosis of cutaneous melanoma remains unclear.

Methods: First, we analysed C1QA, C1QB, and C1QC expression levels and prognostic values using Gene Expression Profiling Interactive Analysis (GEPIA) and Tumour Immune Estimation Resource (TIMER) analysis, and further validation was performed using RT-qPCR, The Human Protein Atlas, The Cancer Genome Atlas (TCGA) dataset, and Gene Expression Omnibus dataset. We then performed univariate/multivariate Cox proportional hazard model, clinicopathological correlation, and receiver operating characteristic curve analysis using TCGA dataset and established a nomogram model. Differentially expressed genes associated with C1QA, C1QB, and C1QC in SKCM were identified and analysed using LinkedOmics, TIMER, the Search Tool for the Retrieval of Interacting Genes database, and Metascape and Cytoscape software platforms. We used TIMER, GEPIA, and single-sample gene set enrichment analysis (ssGSEA) to analyse the relationship between the three genes and the level of immune cell infiltration, biomarkers, and checkpoint expression in SKCM. Finally, GSEA was utilized to study the functional pathways of C1QA, C1QB, and C1QC enrichment in SKCM.

Results: The overexpression of C1QA, C1QB, and C1QC provided significant value in the diagnosis of SKCM and has been associated with better overall survival (OS). Multivariate Cox regression analysis indicated that C1QA, C1QB, and C1QC are independent prognostic biomarkers for patients with SKCM. Immune cell infiltration, biomarkers, and checkpoints were positively correlated with the expression of C1QA, C1QB, and C1QC. Furthermore, the results of functional and pathway enrichment analysis showed that immune-related and apoptotic pathways were significantly enriched in the high-expression group of C1QA, C1QB, and C1QC.

Conclusion: We found that C1QA, C1QB, and C1QC can be used as biomarkers for the diagnosis and prognosis of SKCM patients. The upregulated expression levels of these three complement components benefit patients from OS and may increase the effect of immunotherapy. This result may be due to the dual effects of anti-tumour immunity and apoptosis.

Changes in the Transcriptome and Chromatin Landscape in BRAFi-Resistant Melanoma Cells

Metastatic and drug-resistant melanoma are leading causes of skin cancer-associated death. Mitogen-associated protein kinase (MAPK) pathway inhibitors and immunotherapies have provided substantial benefits to patients with melanoma. However, long-term therapeutic efficacy has been limited due to emergence of treatment resistance. Despite the identification of several molecular mechanisms underlying the development of resistant phenotypes, significant progress has still not been made toward the effective treatment of drug-resistant melanoma. Therefore, the identification of new targets and mechanisms driving drug resistance in melanoma represents an unmet medical need. In this study, we performed unbiased RNA-sequencing (RNA-seq) and assay for transposase-accessible chromatin with sequencing (ATAC-seq) to identify new targets and mechanisms that drive resistance to MAPK pathway inhibitors targeting BRAF and MAPK kinase (MEK) in BRAF-mutant melanoma cells. An integrative analysis of ATAC-seq combined with RNA-seq showed that global changes in chromatin accessibility affected the mRNA expression levels of several known and novel genes, which consequently modulated multiple oncogenic signaling pathways to promote resistance to MAPK pathway inhibitors in melanoma cells. Many of these genes were also associated with prognosis predictions in melanoma patients. This study resulted in the identification of new genes and signaling pathways that might be targeted to treat MEK or BRAF inhibitors resistant melanoma patients. The present study applied new and advanced approaches to identify unique changes in chromatin accessibility regions that modulate gene expression associated with pathways to promote the development of resistance to MAPK pathway inhibitors.

Getting under the skin: The role of CDK4/6 in melanomas

Melanoma is the deadliest type of cancer that affects the largest organ of our body, the skin. In recent years, there is an increase in the incidence and aggressiveness of melanomas. The number of treatment options has grown considerably in the past few years, leading to significant improvements in both overall and progression-free survival. One of the attractive candidates in this wave of treatment options is a cell cycle controller: cyclin-dependent kinases (CDK) 4/6 inhibitors. CDK4/6, a class of serine/threonine kinases expressed in most cell types, controls the first gap phase (G1 to S) of the cell cycle, indicating its vital importance in both normal cellular processes as well as tumorigenesis. Up to 90% of melanoma patients have genomic mutations affecting various parts of CDK4/6 pathway. Noticeably, with the help of next-generation sequencing technology, mutations with high frequency in the CDK4 pathway were also identified in relatively rare subtypes of melanoma including acral melanoma and mucosal melanoma. Therefore, CDK4/6 inhibitors have emerged as powerful and promising anticancer therapies, especially in combination treatment with immunotherapies or other targeted therapies. In this review, we will provide an overview of current scientific knowledge regarding the oncogenic properties of CDK4/6 in melanomas, we mainly discuss the latest genomic and preclinical findings of CDK4 signaling in melanoma, the progress of CDK4 inhibition as combined with other therapies for overcoming resistance and summarize recent advances from clinical trials as well as ongoing studies which gives us a better scope into the effectiveness of CDK4/6 therapy in treating malignant melanomas.

Juniperus communis Suppresses Melanoma Tumorigenesis by Inhibiting Tumor Growth and Inducing Apoptosis

Melanoma, which has a high metastatic capacity and death rate, is a common skin cancer in Western countries. The purpose of this study was to address whether Juniperus communis (JCo) extract is effective in the suppression of melanoma and to elucidate the anticancer mechanisms involved in vitro and in vivo. The antitumor capacities of JCo extract on tumor suppression and toxicity were evaluated and the results demonstrated that the tumor burden was reduced via mediation of cell cycle, reduction of autocrine signaling, and induction of apoptosis. Moreover, JCo extract significantly prolonged the survival rate of the test subjects with only low pathological and physiological toxicity. Additionally, JCo extract also reduced cancer stem cell-related angiogenic and metastatic proteins in the process of tumor elimination. Based on these results, this study suggests that JCo extract suppresses tumor growth and induces apoptosis, and JCo extract may be useful for the prevention of melanoma tumorigenesis.

The BET-bromodomain inhibitor JQ1 mitigates vemurafenib drug resistance in melanoma

Inhibition of BRAF improves therapeutic efficacy of BRAF-mutant melanoma. However, drug resistance to BRAF inhibitor is inevitable, and the drug resistance mechanisms still remain to be elucidated. Here, BRAF mutant cells A375 and SK-MEL-28 were chosen and treated with BRAF inhibitor vemurafenib, and the results showed that the ERK signaling pathway was blocked in these cells. Then, vemurafenib-resistant cells were constructed, and we found that drug resistance-related gene P-gp was overexpressed in the two cell lines. In addition, the histone acetylation was significantly increased on the P-gp promoter region, which suggested that the epigenetic modification participated in the P-gp overexpression. Furthermore, JQ1, a bromodomain inhibitor, was added to the vemurafenib-resistant cells and sensitizes the vemurafenib-induced melanoma cell apoptosis. In C57BL/6 mice intravenously injected with vemurafenib-resistant melanoma cells, cotreatment of vemurafenib and JQ1 also severely suppressed melanoma lung metastasis. Taken together, our findings may have important implications for the combined use of vemurafenib and JQ1 in the therapy for melanoma treatment.

Synergy from gene expression and network mining (SynGeNet) method predicts synergistic drug combinations for diverse melanoma genomic subtypes

Systems biology perspectives are crucial for understanding the pathophysiology of complex diseases, and therefore hold great promise for the discovery of novel treatment strategies. Drug combinations have been shown to improve durability and reduce resistance to available first-line therapies in a variety of cancers; however, traditional drug discovery approaches are prohibitively cost and labor-intensive to evaluate large-scale matrices of potential drug combinations. Computational methods are needed to efficiently model complex interactions of drug target pathways and identify mechanisms underlying drug combination synergy. In this study, we employ a computational approach, SynGeNet (Synergy from Gene expression and Network mining), which integrates transcriptomics-based connectivity mapping and network centrality analysis to analyze disease networks and predict drug combinations. As an exemplar of a disease in which combination therapies demonstrate efficacy in genomic-specific contexts, we investigate malignant melanoma. We employed SynGeNet to generate drug combination predictions for each of the four major genomic subtypes of melanoma (BRAF, NRAS, NF1, and triple wild type) using publicly available gene expression and mutation data. We validated synergistic drug combinations predicted by our method across all genomic subtypes using results from a high-throughput drug screening study across. Finally, we prospectively validated the drug combination for BRAF-mutant melanoma that was top ranked by our approach, vemurafenib (BRAF inhibitor) + tretinoin (retinoic acid receptor agonist), using both in vitro and in vivo models of BRAF-mutant melanoma and RNA-sequencing analysis of drug-treated melanoma cells to validate the predicted mechanisms. Our approach is applicable to a wide range of disease domains, and, importantly, can model disease-relevant protein subnetworks in precision medicine contexts.

Optimized dendritic cell vaccination induces potent CD8 T cell responses and anti-tumor effects in transgenic mouse melanoma models

Despite melanoma immunogenicity and remarkable therapeutic effects of negative immune checkpoint inhibitors, a significant fraction of patients does not respond to current treatments. This could be due to limitations in tumor immunogenicity and profound immunosuppression in the melanoma microenvironment. Moreover, insufficient tumor antigen processing and presentation by dendritic cells (DC) may hamper the development of tumor-specific T cells. Using two genetically engineered mouse melanoma models (RET and BRAF^V600E transgenic mice), in which checkpoint inhibitor therapy alone is not efficacious, we performed proof-of-concept studies with an improved, multivalent DC vaccination strategy based on our recently developed genetic mRNA cancer vaccines. The in vivo expression of multiple chimeric MHC class I receptors allows a simultaneous presentation of several melanoma-associated shared antigens tyrosinase related protein (TRP)-1, tyrosinase, human glycoprotein 100 and TRP-2. The DC vaccine induced a significantly improved survival in both transgenic mouse models. Vaccinated melanoma-bearing mice displayed an increased CD8 T cell reactivity indicated by a higher IFN-γ production and an upregulation of activation marker expression along with an attenuated immunosuppressive pattern of myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg). The combination of DC vaccination with ultra-low doses of paclitaxel or anti-PD-1 antibodies resulted in further prolongation of mouse survival associated with a stronger reduction of MDSC and Treg immunosuppressive phenotype. Our data suggest that an improved multivalent DC vaccine based on shared tumor antigens induces potent anti-tumor effects and could be combined with checkpoint inhibitors or targeting immunosuppressive cells to further improve their therapeutic efficiency.

N6-isopentenyladenosine dual targeting of AMPK and Rab7 prenylation inhibits melanoma growth through the impairment of autophagic flux

Targeting the autophagic process is considered a promising therapeutic strategy in cancer since a great number of tumors, including melanoma, show high basal levels of protective autophagy that contributes to tumor progression and chemoresistance. Here, exploiting both in vitro and in vivo approaches, we identified N6-isopentenyladenosine (iPA), an end product of the mevalonate pathway, as a novel autophagy inhibitor with an interesting anti-melanoma activity. iPA, after being phosphorylated by adenosine kinase into 5'-iPA-monophosphate, induces autophagosome accumulation through AMPK activation, measured by increased fluorescent GFP-LC3 puncta and enhanced conversion into the lipidated autophagosome-associated LC3-II. However, at a later stage iPA blocks the autophagic flux monitored by p62 accumulation, Luciferase reporter-based assay for LC3 turnover in living cells and fluorescence of a tandem RFP-GFP-LC3 construct. Impaired autophagic flux is due to the block of autophagosome-lysosome fusion through the defective localization and function of Rab7, whose prenylation is inhibited by iPA, resulting in a net inhibition of autophagy completion that finally leads to melanoma apoptotic cell death. AMPK silencing prevents apoptosis upon iPA treatment, whereas basal autophagosome turnover is still inhibited due to unprenylated Rab7. These results strongly support the advantage of targeting autophagy for therapeutic gain in melanoma and provide the preclinical rational to further investigate the antitumor action of iPA, able to coordinately induce autophagosome accumulation and inhibit the autophagic flux, independently targeting AMPK and Rab7 prenylation. This property may be particularly useful for the selective killing of tumors, like melanoma, that frequently develop chemotherapy resistance due to protective autophagy activation.

Role of poly(ε-caprolactone) lipid-core nanocapsules on melanoma-neutrophil crosstalk

Metastatic melanoma is an aggressive cancer with increasing incidence and limited therapies in advanced stages. Systemic neutrophilia or abundant neutrophils in the tumor contribute toward its worst prognosis, and the interplay of cancer and the immune system has been shown in tumor development and metastasis. We recently showed the in vivo efficacy of poly(ε-caprolactone) lipid-core nanocapsule (LNC) or LNC loaded with acetyleugenol (AcE-LNC) to treat B16F10-induced melanoma in mice. In this study, we investigated whether LNC or AcE-LNC toxicity could involve modifications on crosstalk of melanoma cells and neutrophils. Therefore, melanoma cells (B16F10) were pretreated with vehicle, LNC, AcE or AcE-LNC for 24 h, washed and, further, cocultured for 18 h with peritoneal neutrophils obtained from C57Bl/6 mice. Melanoma cells were able to internalize the LNC or AcE-LNC after 2 h of incubation. LNC or AcE-LNC pretreatments did not cause melanoma cells death, but led melanoma cells to be more susceptible to death in serum deprivation or hypoxia or in the presence of neutrophils. Interestingly, the production of reactive oxygen species (ROS), which causes cell death, was increased by neutrophils in the presence of LNC- and AcE-LNC-pretreated melanoma cells. LNC or AcE-LNC treatments reduced the concentration of transforming growth factor-β (TGF-β) in the supernatant of melanoma cells, a known factor secreted by cancer cells to induce pro-tumoral actions of neutrophils in the tumor microenvironment. In addition, we found reduced levels of pro-tumoral chemical mediators VEGF, arginase-1, interleukin-10 (IL-10) and matrix metalloproteinase-9 (MMP-9) in the supernatant of LNC or AcE-LNC-pretreated melanoma cells and cocultured with neutrophils. Overall, our data show that the uptake of LNC or AcE-LNC by melanoma cells affects intracellular mechanisms leading to more susceptibility to death and also signals higher neutrophil antitumoral activity.

Combination therapy of PKCζ and COX-2 inhibitors synergistically suppress melanoma metastasis

Background

Metastatic malignant melanoma is one of the most aggressive malignancies and its treatment remains challenging. Recent studies demonstrate that the melanoma metastasis has correlations with the heightened activations of protein kinase C ζ (PKCζ) and cyclooxygenase-2 (COX-2) signaling pathways. Targeted inhibitions for PKCζ and COX-2 have been considered as the promising strategies for the treatment of melanoma metastasis. Thus, the PKCζ inhibitor J-4 and COX-2 inhibitor Celecoxib were combined to treat melanoma metastasis in this study.

Methods

The Transwell assay, Wound-healing assay and Adhesion assay were used to evaluate the inhibition of combined therapy of J-4 and Celecoxib on melanoma cells invasion, migration and adhesion in vitro, respectively. The impaired actin polymerization was observed by confocal microscope and inactivated signal pathways about PKCζ and COX-2 were confirmed by the Western blotting assay. The B16-F10/C57BL mouse melanoma model was used to test the inhibition of combined therapy of J-4 and Celecoxib on melanoma metastasis in vivo.

Results

The in vitro results showed that the combination of J-4 and Celecoxib exerted synergistic inhibitory effects on the migration, invasion and adhesion of melanoma B16-F10 and A375 cells with combination index less than 1. The actin polymerization and phosphorylation of Cofilin required in cell migration were severely impaired, which is due to the inactivation of PKCζ related signal pathways and the decrease of COX-2. The combined inhibition of PKCζ and COX-2 induced Mesenchymal-Epithelial Transition (MET) in melanoma cells with the expression of E-Cadherin increasing and Vimentin decreasing. The secretion of MMP-2/MMP-9 also significantly decreased after the combination treatment. In C57BL/6 mice intravenously injected with B16-F10 cells (5 × 10⁴ cells/mouse), co-treatment of J-4 and Celecoxib also severely suppressed melanoma lung metastasis. The body weight monitoring and HE staining results indicated the low toxicity of the combination therapy.

Conclusions

This study demonstrates that the combination therapy of PKCζ and COX-2 inhibitors can significantly inhibit melanoma metastasis in vitro and in vivo, which will be an efficient strategy for treatment of melanoma metastasis in clinics.

Acetylsalicylic acid inhibits the growth of melanoma tumors via SOX2-dependent-PAF-R-independent signaling pathway

Acquired resistance to standard therapies remains a serious challenge, requiring novel therapeutic approaches that incorporate potential factors involved in tumor resistance. As cancers including melanoma express inflammatory cyclooxygenases generating prostaglandins implicated in tumor growth, we investigated mechanism of anti-inflammatory drug, acetylsalicylic acid (ASA) which has been shown to inhibit various tumor types, however, its effects against highly aggressive melanoma model are unclear. Given our reports that an activation of platelet-activating factor-receptor (PAF-R) augments the growth and impede efficacies of therapeutic agents in experimental melanoma, we also sought to determine if PAF-R mediates anti-melanoma activity of ASA. The current studies using stably PAF-R-positive (B16-PAFR) and negative (B16-MSCV) murine melanoma cells and PAF-R-expressing and deficient mice, demonstrate that ASA inhibits the in-vitro and in-vivo growth of highly aggressive B16F10 melanoma via bypassing tumoral or stromal PAF-R signaling. Similar ASA-induced effects in-vitro were seen in human melanoma and nasopharyngeal carcinoma cells positive or negative in PAF-R. Mechanistically, the ASA-induced decrease in cell survival and increase in apoptosis were significantly blocked by prostaglandin F2 alpha (PGF2α) agonists. Importantly, PCR array and qRT-PCR analysis of B16-tumors revealed significant downregulation of sry-related high-mobility-box-2 (SOX2) oncogene by ASA treatment. Interestingly, modulation of SOX2 expression by PGF2α agonists and upregulation by fibroblast growth factor 1 (FGF-1) rescued melanoma cells from ASA-induced decreased survival and increased apoptosis. Moreover, PGF2α-receptor antagonist, AL8810 mimics ASA-induced decreased melanoma cells survival which was significantly blocked by PGF2α and FGF-1. These findings indicate that ASA inhibits the growth of aggressive melanoma via SOX2-dependent-PAF-R-indepedent pathway.