Focal adhesion alterations in G0-positive melanoma cells.

BACKGROUND: Melanoma is a highly heterogeneous malignant tumor that exhibits various forms of drug resistance. Recently, reversal transition of cancer cells to the G0 phase of the cell cycle under the influence of therapeutic drugs has been identified as an event associated with tumor dissemination. In the present study, we investigated the ability of chemotherapeutic agent dacarbazine to induce a transition of melanoma cells to the G0 phase as a mechanism of chemoresistance. METHODS: We used the flow cytometry to analyze cell distribution within cell cycle phases after dacarbazine treatment as well as to identifyG0 -positive cells population. Transcriptome profiling was provided to determine genes associated with dacarbazine resistance. We evaluated the activity of ß-galactosidase in cells treated with dacarbazine by substrate hydrolysis. Cell adhesion strength was measured by centrifugal assay application with subsequent staining of adhesive cells with Ki-67 monoclonal antibodies. Ability of melanoma cells to metabolize dacarbazine was determined by expressional analysis of CYP1A1, CYP1A2, CYP2E1 followed by CYP1A1 protein level evaluation by the ELISA method. RESULTS: The present study determined that dacarbazine treatment of melanoma cells could induce an increase in the percentage of cells in G0 phase without alterations of ß-galactosidase positive cells which corresponded to the fraction of the senescent cells. Transcriptomic profiling of cells under dacarbazine induction of G0 -positive cells percentage revealed that 'VEGFA-VEGFR2 signaling pathway' and 'Cell cycle' signaling were mostly enriched by dysregulated genes. 'Focal adhesion' signaling was also found to be triggered by dacarbazine. In melanoma cells treated with dacarbazine, an increase in G0 -positive cells among adherent cells was found. CONCLUSIONS: Dacarbazine induces the alteration in a percentage of melanoma cells residing in G0 phase of a cell cycle. The altered adhesive phenotype of cancer cells under transition in the G0 phase may refer to a specific intercellular communication pattern of quiescent/senescent cancer cells.

miR-204-5p in vivo inhibition cause diminished CD45RO cells rate in lungs of melanoma B16-bearing mice.

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.

Transcriptomic Profiling Revealed Plexin A2 Downregulation With Migration and Invasion Alteration in Dacarbazine-Treated Primary Melanoma Cells.

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 ß8 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.

Low-energy states, ground states, and variable frustrations of the finite-size dipolar Cairo lattices.

To investigate the influence of geometric frustration on the properties of low-energy configurations of systems of ferromagnetic nanoislands located on the edges of the Cairo lattice, the model of interacting Ising-like magnetic dipoles is used. By the method of complete enumeration, the densities of states of the Cairo pentagonal lattices of a finite number of Ising-like point dipoles are calculated. The calculated ground and low-energy states for systems with a small number of dipoles can be used to solve the problem of searching for the ground states in a system with a relatively large number of dipoles. It is shown that the ground-state energy of the Cairo pentagonal lattices exhibits nonmonotonic behavior on one of the lattice parameters. The lattice parameters can be used to control the degree of geometric frustration. For the studied lattices of a finite number of Ising dipoles on the Cairo lattice in the ground-state configurations, a number of closed pentagons is observed, which are different from the obtained maximum closed pentagons. The magnetic order in the ground-state configurations obeys the ice rule and the quasi-ice rules.