Influence of CXCR4/SDF-1 axis on E-cadherin/β-catenin complex expression in HT29 colon cancer cells

AIM:To study the influence of CXCR4/stromal cellderived factor-1(SDF-1) axis on E-cadherin/β-catenin complex expression in HT29 colon cancer cells and its underlying mechanisms.METHODS:Effect of SDF-1 on E-cadherin/β-catenin expression was detected by immunocytochemistry.E-cadherin and β-catenin mRNA expression levels were measured by reverse transcriptase-polymerase chain reaction.SDF-1-induced phosphorylation of phosphatidylinositol 3-kinase(PI3K)/AKT and β-catenin was detected by Western blotting.RESULTS:The E-cadherin and β-catenin mRNA expression levels in HT29 cells were lower 48 h after incubated with SDF-1 at the concentrations of 20 and 40 ng/mL(P < 0.05).SDF-1-induced significant phosphorylation of PI3K/AKT and β-catenin.AMD3100 and LY294002 inhibited the phosphorylation of PI3K/AKT and β-catenin.CONCLUSION:SDF-1 down-regulates the E-cadherin/β-catenin complex expression in HT29 cells by decreasing mRNA synthesis and increasing β-catenin phosphorylation.

Effects of Different Substrates on Microstructures and Mechanical Properties of a Bulk Nanocrystalline Structure Pure Iron Prepared by Aluminothermic Reaction Casting

A simple method was developed to produce the nanocrystalline pure iron by aluminothermic reaction cast- ing. The mierostructure of the iron was investigated by optical microseope （OM）, transmission electron microscope （TEM）, electron probe micro-analyzer （EPMA）, scanning electron microscope （SEM） and X-ray diffraction （XRD）. The mechanical performances of nanoerystalline pure iron were tested. It is found that the pure iron consists of nanoerystalline ferrite. For different substrates of eopper and glass, the average grain size of the ferrite was 38 and 35 nm, respectively, which is larger on copper substrate than that on glass. The hardness, compressive strength, tensile strength, and total elongation are 167 and 137 HB, 400 and 500 MPa, 243 and 185 MPa, 16% and 10% on copper substrate and glass suhstrate, respectively. The hardness, tensile strength and total elongation are all larger on copper substrate than those on glass substrate, while the eompressive strength is lower. The large supercooling in the product solidification provides the condition for high nucleation rate and thus leads to nano-grained austenite and final nano-grained ferrite transformed from those small austenite grains.