During embryonic development melanoblasts the precursors of melanocytes emerge from a

During embryonic development melanoblasts the precursors of melanocytes emerge from a subpopulation of the neural crest stem cells and migrate to colonize skin. the presence of neural and cancer stem cell biomarkers as well as death receptors DR5 and FAS in both adherent and spheroid cultures of melanoma cells; iii) anti-apoptotic effects of the endogenous production of cytokines and iv) the ability of melanoma cells to perform neural trans-differentiation. We demonstrated that programed necrosis or necroptosis could be induced in two metastatic melanoma lines FEMX and OM431 while the mitochondrial pathway of apoptosis was prevalent in a vast majority of melanoma lines. All melanoma lines used in the current study expressed substantial levels of pluripotency markers SOX2 and NANOG. There was a trend for increasing expression of Nestin an early neuroprogenitor marker during melanoma progression. Most of the melanoma lines including WM35 FEMX and A375 can grow as a 7-Methyluric Acid spheroid culture in serum-free media with supplements. It was possible to induce neural trans-differentiation of 1205Lu and OM431 melanoma cells in serum-free media supplemented with insulin. This was confirmed by the expression of neuronal markers Doublecortin and β3-Tubulin by significant growth of neurites and by the negative regulation of this process by a dominant-negative Rac1N17. These results suggest a relative plasticity of differentiated melanoma cells and a possibility for their neural trans-differentiation without the necessity for preliminary dedifferentiation. Introduction Significant STEP progress has been made during the last 15 years in new molecule targeted therapies for treatment of advanced cancers including melanomas. There are several dominant genetic alterations during melanoma carcinogenesis: i) and gene mutations [1-3] which were found in nearly 50%-60% and 20% of melanomas respectively; ii) deletion of the locus which encoded two tumor suppressor proteins p16INK4a and p14ARF was found in up to 50% of melanomas [4]; iii) deletion or mutation of PTEN an endogenous inhibitor of PI3K-AKT was found in 20% of melanomas [5]; iv) finally mutations of were found in 19% of melanomas [6]. Small molecule inhibitors such as vemurafenib suppress permanently active mutated BRAF that results in the arrest of proliferation and the subsequent death of melanoma cells and during individual treatment [1 7 A complementary approach to improve the survival of individuals with metastatic melanoma is based on the usage of immune-stimulating monoclonal antibodies which suppress endogenous inhibitors of the immune response: ipilimumab that blocks CTLA-4 7-Methyluric Acid [8] and nivolumab that blocks PD-1 receptor [9]. Regrettably tumor relapse regularly follows within several months in individuals treated with specific molecule inhibitors or after immunostimulation [10 11 Resistance of melanoma to therapy is definitely in general a result of Darwinian selection among the strongly heterogeneous human population of malignancy clones with dramatic genomic instability [12] which is 7-Methyluric Acid definitely accompanied by genetic epigenetic or microenvironmentally controlled suppression of proapoptotic signaling pathways in these clones in concert with overactivation of the prosurvival and proliferative pathways [13]. Standard examples of the selective pressure for malignancy cell survival are overactivation of CRAF after stable inhibition of BRAF [14] and overactivation of STAT3 in the case of use of MEK-ERK inhibitors in melanoma cells [15 16 Such compensatory mechanisms for reestablishing activity of essential signaling proteins and enzymes in malignancy cells after treatment could be based on metabolic rules crosstalk in the cell signaling networks or finally on gene mutations. Comprehensive 7-Methyluric Acid analysis of a landscape of driver mutations in melanoma indeed revealed several novel mutations including RAC1 P29S (4%-9% of patient’s melanomas) that confers resistance to pharmacological inhibition of BRAF [6 17 Additionally 7-Methyluric Acid a role for activation of Notch1 signaling in promoting resistance to MAPK inhibitors in BRAF V600K mutated cells was highlighted [18]. Hence a suppression of tumor cell proliferation/survival through combined inhibition of special signaling pathways [19] as well as reestablishing of effective induction of cell death in resistant metastatic melanoma cells look like a 7-Methyluric Acid predominant restorative goal..