AgNPs Kill Acute Myeloid Leukemic Cells Through Inhibiting The Phosphorylation Of ERK1/2

Objective: To investigate the killing effects of Ag-NPs and Ag ions on acute myeloid leukemia cells, and explore the underlying molecular mechanism.Methods:(1) The silver nanoparticles(Ag-NPs) were synthesized by using Cyclic Differential Pulse Voltammetry, with Silver wires and polyvinylpyrrolidone(PVP) solution as raw materials, and then the particle size and distribution were determined by transmission electron microscopy(TEM) and laser particle size distribution analyzer;(2) Cell viability after exposure to Ag-NPs were determined by MTT assay;(3) NRASG12 V over-expressing leukemia cell lines were established using retroviruses;(5) Cell apoptosis were determined by Annexin V/PI assay;(6) Expression of p-ERK1/2 protein was detected by Western blotting.Results:(1) The Ag-NPs particulates synthesized without PVP could be observed a obvious agglomerate phenomenon, while the Ag-NPs particulates synthesized with 1 mg/m L and 5 mg/m L PVP solution added are well distributed and no clustering is observed. The higher concentration of PVP leads to a smaller Radius of hydration kinetics of Ag NPs;(2) The Ag-NPs prepared with 5 mg/m L PVP shows the strongest killing effect on leukemic cells, and the killing effect is cell type-specific and independent of PVP;(3) Ag ions show more toxic on leukemia cells than Ag-NPs under the same concentration;(4) More obvious phagocytosis of Ag-NPs are observed in leukemia cells compared with Ag ions;(5) Ag-NPs reduce the phosphorylation levels of ERK1/2 in leukemic cell lines, and induce cell death. Combination of Ag-NPs and U0126 can enhance the killing effect;(6) overexpression of NrasG12 V or h GM-CSF treatment can increase the intracellular p-ERK1/2 levels, promote cell proliferation, and reduce the sensitivity of leukemic cells to Ag-NPs. Ag-NPs affect the survival of leukemia cells through affecting p-ERK1/2 levels.Conclusions: The PVP concentration used during the preparation affects physicochemical properties and killing effect of Ag-NPs on leukemia cells. Leukemia cells show stronger phagocytic ability on Ag-NPs than Ag ions. Ag ions show more toxic on leukemia cells than Ag-NPs under the same concentration; Increasing the p-ERK1/2 levels in leukemia cells can stimulate cell proliferation, while reducing the p-ERK1/2 levels can lead to cell death. Ag-NPs kill leukemia cells by reducing p-ERK1/2 levels of leukemia cells. In turn, the leukemic cells with higher p-ERK1/2 levels by overexpression of NRAS G12 V or treated with GM-CSF are more resistant to Ag-NPs. Combination of Ag-NPs and U0126 can enhance the killing effect of Ag-NPs. Therefore, assessing intracellular p-ERK1/2 levels may be necessary before the use of Ag-NPs in inhibiting tumor cells. In this study, we have also provided a potential threapeutic strategy of using Ag NPs to assist in tackling MEK-p ERK associated treatment refractoriness.