Forging a link between oncogenic signaling and immunosuppression in melanoma

Options of Therapeutics and Novel Delivery Systems of Drugs for the Treatment of Melanoma

Melanoma is one of the most severe cancerous diseases. The cells employ multiple signaling pathways, such as ERK, HGF/c-MET, WNT, and COX-2 to cause the cell proliferation, survival, and metastasis. Treatment of melanoma, including surgery, chemotherapy, immunotherapy, radiation, and targeted therapy, is based on 4 major or 11 substages of the disease. Fourteen drugs, including dacarbazine, interferon α-2b, interleukin-12, ipilimumab, peginterferon α-2b, vemurafenib, trametinib, talimogene laherparepvec, cobimetinib, pembrolizumab, dabrafenib, binimetinib, encorafenib, and nivolumab, have been approved by the FDA for the treatment of melanoma. All of them are in conventional dosage forms of injection solutions, suspensions, oral tablets, or capsules. Major drawbacks of the treatment are side effects of the drugs and patients' incompliance to them. These are consequences of high doses and long-term treatments for the diseases. Currently more than 350 NCI-registered clinical trials are being carried out to treat advanced and/or metastatic melanoma using novel treatment methods, such as immune cell therapy, cancer vaccines, and new therapeutic targets. In addition, novel delivery systems using biomaterials of the approved drugs have been developed attempting to increase the drug delivery, targeting, stability, bioavailability, thus potentially reducing the toxicity and increasing the treatment effectiveness. Nanoparticles and liposomes have been emerging as advanced delivery systems which can improve drug stability and systemic circulation time. In this review, the most recent findings in the options for treatment and development of novel drug delivery systems for the treatment of melanoma are comprehensively discussed.

A glioneuronal tumor with CLIP2-MET fusion

We report a case of glioneuronal tumor (GNT) with a discovery of novel gene fusion of CLIP2-MET resulting from aberrant chromosome 7 abnormalities. We executed an elaborate genomic study on this case including whole-exome sequencing and RNA sequencing. Genomic analysis of the tumor revealed aberrations in chromosomes 1 and 7 and a CLIP2-MET fusion. Further analysis of the upregulated genes revealed substantial connections with MAPK pathway activation. We concluded that the chromosome 7 abnormalities prompted CLIP2-MET gene fusion which successively leads to MAPK pathway activation. We deliberated that MAPK pathway activation is one of the driver pathways responsible for the oncogenesis of GNT.

COX-2 as a potential biomarker and therapeutic target in melanoma

With a constantly increasing incidence, cutaneous melanoma has raised the need for a better understanding of its complex microenvironment that may further guide therapeutic options. Melanoma is a model tumor in immuno-oncology. Inflammation represents an important hallmark of cancer capable of inducing and sustaining tumor development. The inflammatory process also orchestrates the adaptative immunosuppression of tumor cells that helps them to evade immune destruction. Besides its role in proliferation, angiogenesis, and apoptosis, cyclooxygenase-2 (COX-2) is a well-known promoter of immune suppression in melanoma. COX-2 inhibitors are closely involved in this condition. This review attempts to answer two controversial questions: is COX-2 a valuable prognostic factor? Among all COX-2 inhibitors, is celecoxib a suitable adjuvant in melanoma therapy?

Expression Profiling of a Human Thyroid Cell Line Stably Expressing the BRAFV600E Mutation

BACKGROUND/AIM

The BRAF^V600E mutation acts as an initiator of cancer development in papillary thyroid carcinoma (PTC). Gene expression changes caused by the BRAF^V600E mutation may have an important role in thyroid cancer development.

MATERIALS AND METHODS

To study genomic alterations caused by the BRAF^V600E mutation, we made human thyroid cell lines that harbor the wild-type BRAF gene (Nthy/WT) and the V600E mutant-type BRAF gene (Nthy/V600E).

RESULTS

Flow cytometry and western blotting showed stable transfection of the BRAF gene. In functional experiments, Nthy/V600E showed increased anchorage-independent growth and invasion through Matrigel, compared to Nthy/WT. Microarray analysis revealed that 2,441 genes were up-regulated in Nthy/V600E compared to Nthy/WT. Gene ontology analysis showed that the up-regulated genes were associated with cell adhesion, migration, and the ERK and MAPK cascade, and pathway analysis showed enrichment in cancer-related pathways.

CONCLUSION

Our Nthy/WT and Nthy/V600E cell line pair could be a suitable model to study the molecular characteristics of BRAF^V600E PTC.

Overcoming melanoma resistance to vemurafenib by targeting CCL2-induced miR-34a, miR-100 and miR-125b

In melanoma, the adaptative cell response to BRAF inhibitors includes altered patterns of cytokine production contributing to tumor progression and drug resistance. Among the factors produced by PLX4032-resistant melanoma cell lines, CCL2 was higher compared to the sensitive parental cell lines and increased upon drug treatment. CCL2 acted as an autocrine growth factor for melanoma cells, stimulating the proliferation and resistance to apoptosis. In patients, CCL2 is detected in melanoma cells in tumors and in plasma at levels that correlate with tumor burden and lactate dehydrogenase. Vemurafenib treatment increased the CCL2 levels in plasma, whereas the long-term clinical response was associated with low CCL2 levels.Increased CCL2 production was associated with miRNA deregulation in the resistant cells. miR-34a, miR-100 and miR-125b showed high expression in both resistant cells and in tumor biopsies that were obtained from treated patients, and they were involved in the control of cell proliferation and apoptosis. Inhibition of CCL2 and of the selected miRNAs restored both the cell apoptosis and the drug efficacy in resistant melanoma cells. Therefore, CCL2 and miRNAs are potential prognostic factors and attractive targets for counteracting treatment resistance in metastatic melanoma.

BRAFV600E Co-opts a Conserved MHC Class I Internalization Pathway to Diminish Antigen Presentation and CD8+ T-cell Recognition of Melanoma

Oncogene activation in tumor cells induces broad and complex cellular changes that contribute significantly to disease initiation and progression. In melanoma, oncogenic BRAF(V600E) has been shown to drive the transcription of a specific gene signature that can promote multiple mechanisms of immune suppression within the tumor microenvironment. We show here that BRAF(V600E) also induces rapid internalization of MHC class I (MHC-I) from the melanoma cell surface and its intracellular sequestration within endolysosomal compartments. Importantly, MAPK inhibitor treatment quickly restored MHC-I surface expression in tumor cells, thereby enhancing melanoma antigen-specific T-cell recognition and effector function. MAPK pathway-driven relocalization of HLA-A*0201 required a highly conserved cytoplasmic serine phosphorylation site previously implicated in rapid MHC-I internalization and recycling by activated immune cells. Collectively, these data suggest that oncogenic activation of BRAF allows tumor cells to co-opt an evolutionarily conserved MHC-I trafficking pathway as a strategy to facilitate immune evasion. This link between MAPK pathway activation and the MHC-I cytoplasmic tail has direct implications for immunologic recognition of tumor cells and provides further evidence to support testing therapeutic strategies combining MAPK pathway inhibition with immunotherapies in the clinical setting.