The Effect Of NHE1on Leukemia Angiogenesis And MSC Differentiation

Background:NHE1is a ubiquitously expressed member of the Na+/H+exchanger family that catalyzes the extrusion of intracellular proton ions in exchange for extracellular sodium ions, thereby regulating intracellular pH (pHi). It has long been demonstrated that elevations in pHi are directly correlated with the tumor pathologic processes such as activities of many growth factors and oncogenes, DNA synthesis, cell transformation and proliferation, the metastatic process, and multiple drug resistance. However, the relationship between NHE1and leukemia angiogenesis is not definitely confirmed.In this study, we explore the effect of NHE1inhibition on leukemia angiogenesis, and study the mechanism that mediates it.Aim:To explore the effect of Cariporide on K562cells induced angiogenesis.Methods:The selective NHE1inhibitor Cariporide was used to treat K562cells; MTT was used to detect the cytotoxicity of Cariporide; K562cells intracellular pH (pHi) was analyzed by confocal laser scanning microscope; VEGF expression of K562cells condition medium was evaluated by enzyme linked immunosorbent assay and western blotting; MTT was used to measure the effect of K562cells condition medium on human umbilical vein endothelial cells (HUVECs) proliferation; transwell was used to detect the effect of K562cells condition medium on HUVECs migration; matrigel was used to explore HUVECs in vitro tube formation; xenograft tumor and histology was used to detect tumor growth and the angiogenesis in vivo;.Result:K562cells were incubated with different concentrations of Cariporide, Cariporide could affect K562growth at a concentration higher than40μM. Cariporide has little affect on K562at a small concentration, so we choose a concentration of10μM at the latter experiment; Cultivation of cells with Cariporide resulted in a decrease in pHi value; VEGF expression and secretion was decreased upon Cariporide treatment; The proliferation of HUVECs induced by the CM from Cariporide treated K562cells was decreased compared with CM from control, when the recombinant human VEGF was added into the Cariporide treated CM to a concentration amounts to that of untreated CM, the proliferation of HUVECs was partially restored; CM from Cariporide treated K562cells caused dramatic decrease of HUVEC migration, compared with the CM from control, when the recombinant human VEGF was added into the Cariporide treated CM to a concentration amounts to that of untreated CM, the migration of HUVECs was partially restored; The number of branch points of HUVECs was significantly decreased in Cariporide treated CM compared with control CM, when recombinant human VEGF was added to the Cariporide treated CM to a concentration amounts to untreated, the branch points increased but still less than the untreated; The average of blood vessels observed in the tumors derived from Cariporide group were markedly lower than in control group and the size of tumors formed by Cariporide treated group was significantly smaller than that of control group.Conclusion:Selective inhibition of NHE1by Cariporide could result in a decrease in pHi value, decrease the expression and secretion of VEGF, affect tumor angiogenesis through decreased induction of endothelial cells so as to inhibit tumor growth. NHE1could be a potential therapeutic target for treating leukemia. Background:Na+/H+exchanger1(NHE1) is a ubiquitously expressed member of the Na+/H+exchanger family that catalyzes the extrusion of intracellular proton ions in exchange for extracellular sodium ions, thereby regulating intracellular pH (pHi). High intracellular pH is required for cell proliferation and differentiation. Our precious study has proven that the intracellular pH of MSC is higher than normal differentiated cells, just similar to tumor cells. Targeted inhibition of NHE1could induce differentiation of K562leukemia cells. So, we presume that whether inhibition of NHE1could induce differentiation of MSC cells.Aim:To explore that whether inhibition of NHE1could induce differentiation of MSC cells.Methods:MSC were obtained from human umbilical cord and the surface phenotype, functional characterizations was identified. Selective NHE1inhibitor Cariporide was used to treat MSC cells, the differentiation of MSC cells was compared. The possible siganaling pathway involved was explored.Results:The osteogenic differentiation of MSC cells was up-regulated upon cariporide treatment while the adipogenic differentiation was slightly affected. β-catenin expression was up-regulated upon Cariporide treatment.Conclusion:Cariporide treatment could up-regulate MSC cells osteogenic differentiation through up-regulation of β-catenin, but has little effect on adipogenic differentiation.