Cold atmospheric plasma (CAP) is an intensively-studied approach for the treatment of malignant neoplasms. Various active oxygen and nitrogen compounds are believed to be the main cytotoxic effectors on biotargets; however, the comprehensive mechanism of CAP interaction with living cells and tissues remains elusive. In this study, we experimentally determined the optimal discharge regime (or semi-selective regime) for the direct CAP jet treatment of cancer cells, under which lung adenocarcinoma A549, A427 and NCI-H23 cells demonstrated substantial suppression of viability, coupled with a weak viability decrease of healthy lung fibroblasts Wi-38 and MRC-5. The death of CAP-exposed cancer and healthy cells under semi-selective conditions was caspase-dependent. We showed that there was an accumulation of lysosomes in the treated cells. The increased activity of lysosomal protease Cathepsin D, the transcriptional upregulation of autophagy-related MAPLC3B gene in cancer cells and the changes in autophagy-related proteins may have indicated the activation of autophagy. The addition of the autophagy inhibitor chloroquine (CQ) after the CAP jet treatment increased the death of A549 cancer cells in a synergistic manner and showed a low effect on the viability of CAP-treated Wi-38 cells. Downregulation of Drp1 mitochondrial protein and upregulation of PINK1 protein in CAP + CQ treated cells indicated that CQ increased the CAP-dependent destabilization of mitochondria. We concluded that CAP weakly activated pro-survival autophagy in irradiated cells, and CQ promoted CAP-dependent cell death due to the destabilization of autophagosomes formation and mitochondria homeostasis. To summarize, the combination of CAP treatment with CQ could be useful for the development of cold plasma-based antitumor approaches for clinical application.

Relevance. Uveal melanoma (UM) is a subtype of melanoma that represents the majority of adult ocular cancers. The rare frequency of the disease does not allow to conduct large-scale clinical trials of new agents and approaches, which limits progress in its treatment. Half of patients with UM develop metastatic forms of the disease, which generally have unfavorable prognosis. Therefore, personal cell cultures derived from tumor material of patients are relevant for determining molecular and genetic features of tumor melanocytes and for testing new antitumor drugs. Purpose. To evaluate the aggressiveness of choroidal melanoma by molecular and genetic characterization of melanocytes isolated from the tumor. Material and methods. The study was performed using personal cultures of human UM cells. Karyotyping of cells was performed by GTG staining analysis of the metaphase plates, mutational burden was assessed by NGS sequencing, protein products were evaluated by western blotting. Results. In this work, three personal cultures of human UM cells, uMel1, uMel3 and uMel5, cultured for at least 22 passages, were obtained from tumor material of patients diagnosed with UM for the analysis of molecular and genetic characteristics. Since the development of the metastatic form of UM correlates with chromosomal alterations in tumor melanocytes, karyotyping was performed, which showed that in all cultures, most cells had a near-diploid phenotype. Only in uMel1 and uMel3 cells were chromosomal rearrangements specific for UM – in chromosomes 3, 6, and 8. In uMel5 cells, a deletion was found in the region of the long arm of chromosome 11. In addition, the patient with uMel5 tumor had a history of skin melanoma, for which the typical somatic mutation profile differs from that of UM. Somatic mutations in hotspots of ALK, BRAF, EGFR, HER2, IL17RA, KRAS, METand NRASgenes were analyzed by NGS-sequencing method. No mutations were detected at the tested loci in cells from all cultures tested. Analysis of tumor suppressor BAP1 (BRCA-associated protein) showed its low level in uMel3 and uMel5 cell cultures, which may indicate a high risk of metastasis. Conclusion. The obtained personalized cultures of UM cells are models that allow in vitroand in vivoinvestigation of UM with different molecular and genetic signatures. Key words: uveal melanoma, personalized cell cultures, karyotype, BAP1, BRAF, NGS-sequencing

The epidermal growth factor receptor (EGFR) is an oncogenic tyrosine kinase that is involved in tumor initiation and progression, making EGFR inhibitors and monoclonal antibodies to this receptor essential for anti-tumor therapy. We have previously shown that EGFR transgene expression in the human breast adenocarcinoma cell line MCF7 (MCF7-EGFR) stimulates the 3D spheroid-like growth. The primary focus of our present work was to investigate whether EGFR inhibition could affect the assembly of spheroids or lead to the destruction of pre-existing spheroids. We compared the effects of anti-EGFR siRNA, the anti-EGFR monoclonal antibody cetuximab, and the tyrosine kinase inhibitor AG1478 on dissociated and spheroid MCF7-EGFR cells. MCF7-EGFR cells were found to have a 2.5-fold higher sensitivity towards the cytotoxic effects of cetuximab and AG1478 compared with the parental MCF7 cell line. The suppression of EGFR mRNA with siRNA was found to reduce the sphere formation, whereas treating the pre-existing spheroids had no such effect. Treatment of dissociated spheroids with cetuximab and AG1478 was also found to inhibit the MCF7-EGFR sphere formation. We suggest that EGFR expression is important, at least, during the spheroid formation stage. The transition of a MCF7wt adherent cell culture to MCF7-EGFR spheroids was accompanied by a considerable increase in N-cadherin adhesion proteins. The level of N-cadherin decreased when MCF7-EGFR cells were treated with siRNA and cetuximab. Thus, we have demonstrated that N-cadherin is involved in the EGFR-dependent formation of MCF7-EGFR spheroids. Accordingly, MCF7-EGFR spheroids can be considered a suitable model for studying aggressive hormone-positive breast tumors.

Uveal melanoma (UM) is the most prevalent primary intraocular tumor in adults. Transcription factor ZEB1 is one of the potential master regulators of melanocytes plasticity, because it is recognized as a “driver” of epithelial-to-mesenchymal transitions (EMTs) in carcinomas. We studied the correlation of tumor invasiveness with ZEB1 status and vascular endothelial growth factor/its receptor (VEGF-A/VEGFR2) in UM cells, and also with melanocyte’s differentiation rate. Eight UM cell cultures were characterized by melanosomes content using an ETM. ZEB1, VEGF-A and VEGFR2 levels in UM cells were detected by RT-PCR, Western blot, ELISA and flow cytometry. Effects of siRNA-dependent ZEB1 knockdown on UM cell proliferation and their sensitivity to the VEGF-A inhibitor Eylea (aflibercept) were tested by MTT and in a real-time proliferation assay. UMs with an invasive growth type can maintain a high degree of melanocyte differentiation. All ZEB1^low cells were obtained from spindle cell tumors. The sensitivity of UM cells to Eylea inversely correlated with the level of the VEGFR2 receptor. ZEB1 knockdown completely blocked VEGF-A production while anti-VEGF treatment stimulated ZEB1 increase. In UM cell cultures, ZEB1 is a positive regulator of VEGF-A expression. In addition, there is probably a ZEB1 feedback loop that is sensitive to a drop in VEGF-A concentration. The data obtained allow us to consider ZEB1 silencing as an auxiliary link for a combined strategy of killing UM cells.