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Cancer cell drug resistance hinders significantly therapeutic modalities in oncology. Dacarbazine is chemotherapeutic agent traditionally used for melanoma treatment although it's effectiveness insufficient. In the present study we performed NGS-based transcriptomic profiling of B16 melanoma tumors after Dacarbazine treatment in vivo. Whole transcriptome sequencing revealed 34 differentially expressed genes most of them associated with drug resistance and apoptosis evading. In accordance to bionformatic analysis, 6 signaling cascades: “D-Amino acid metabolism”, “NF-kappa B signaling pathway”, “Phosphatidylinositol signaling system”, “P53 signaling pathway”, “IL-17 signaling pathway” and “Bile secretion” were enriched by differentially expressed genes. Next we provided a combined treatment by Dacarbazine and miR-204-5p mimic as miR-204-5p was considered previously implicated in cancer drug resistance. This approach lead to an increase of miR-204-5p expression in B16 melanoma cells in vivo that was accompanied by subsequent decrease in the expression of miR-204-5p target genes – BCL2 and SIRT1 in the primary tumors. MiR-204-5p overexpression with Dacarbazine application resulted in increased the weight, and volume of primary tumors and diminished the proportion of β-Galactosidase expression in melanoma B16-bearing mice. Taking together, our study revealed that although miR-204-5p showed antiproliferative capacities in vitro, it's mimic in combination with Dacarbazine is able to potentiate tumor growth triggering probably a switch from senescent to proliferative phenotype of malignant cells.

The treatment of melanoma remains a challenge, despite novel approaches recently becoming available for disseminated tumors. RNA targeting is being intensively studied in various types of disease. The aim of the present study was to explore whether the in vivo use of a microRNA (miR)-204-5p inhibitor affected melanoma progression, and whether its metastasis affects target organ remodeling. CD45RO+, CD3+, CD8+, forkhead box P3+, smooth muscle α-actin+ cells in the lungs of B16 melanoma-bearing mice were evaluated using immunohistochemistry following miR-204-5p inhibitor transfection. Next, CD45RO expression in peripheral blood mononuclear cells (PBMCs), as well as the apoptosis of these cells, were measured by flow cytometry. The results revealed that the number of CD45RO+ cells was decreased in the lungs of B16 melanoma-bearing mice and CD45RO+ PBMCs following the use of an miR-204-5p inhibitor, which was associated with increased levels of PBMC apoptosis. In conclusion, the findings of the present study suggested that targeting miR-204-5p in melanoma metastasis target organs could be used to develop novel approaches for the treatment of disseminated forms of the disease.

Melanoma is highly heterogeneous type of malignant neoplasm that is responsible for the majority of deaths among other types of skin cancer. In the present study, we screened a list of differentially expressed genes in two primary, drug-naïve melanoma cell lines derived from patients with melanoma following treatment of the cells with the chemotherapeutic agent dacarbazine. The aim was to determine the transcriptomic profiles and associated alterations in the cell phenotype. We found the vascular endothelial growth factor A/vascular endothelial growth factor receptor 2, phosphoinositide 3-kinase/protein kinase B and focal adhesion signaling pathways to be top altered after dacarbazine treatment. In addition, we observed the expression levels of genes associated with tumor dissemination, integrin β8 and matrix metalloproteinase-1, to be diminished in both cell lines studied, the results of which were confirmed by reverse transcription-quantitative polymerase chain reaction. By contrast, plexin A2 expression was found to be upregulated in K2303 cells, where reduced migration and invasion were also observed, following dacarbazine treatment. Plexin A2 downregulation was associated with the promotion of migrative and invasive capacities in B0404 melanoma cells. Since plexin A2 is semaphorin co-receptor that is involved in focal adhesion and cell migration regulation, the present study suggested that plexin A2 may be implicated in the dacarbazine-mediated phenotypic shift of melanoma cells. We propose that the signature of cancer cell invasiveness can be revealed by using a combination of transcriptomic and functional approaches, which should be applied in the development of personalized therapeutic strategies for each patient with melanoma.