| BACKGROUND&OBJECTIVE:Gastric cancer is a common malignancy, the incidence of which ranks first in China. Although there are many traditional treatments as surgery, radiotherapy, chemotherapy and immunotherapy, which extend the life of patients with gastric cancer to some extent, still need to improve the cure rate for gastric cancer patients further. Lutein is a natural oxygenated carotenoids,and primarily existences in the diet of vegetables, fruits and so on.medical experiments show that lutein, which is a natural plant of high performance anti-oxidants and plays an important role in the prevention of macular degeneration, cardiovascular disease, cataracts, and the tumor development. But its properties of antioxidant has been used in further treatment of the tumor rarely reported. This study seeks to elucidate the growth inhibiting effect of lutein on SGC-7901cells and its relevent mechanism, and further explore the molecular mechanism.METHODS:Inhibition effect and apoptosis mechanisms on SGC-7901cells of lutein:The growth curve of SGC-7901cells was established for8days with SRB method. Human gastric cancer cell line SGC-7901was treated with various dose of lutein,and cell proliferation was tested by SRB assay.The morphological change of SGC-7901cells after treating by lutein was observed in inverted microscope. Cellular growth inhibition and apoptosis was detected by Hoechst33342/PI assay. The levels of Reactive oxygen species (ROS) within the cells were analyzed by ROS-sensitive fluorometric probe DCFH-DA assay. The change of total glutathione was determined using the color reaction assay:The reaction of GSH and DTNB generated yellow TNB and GSSG. Expression of SOD-2mRNA,IKB alpha mRNA and the nf-kappaB P65mRNA was measured by RT-PCR assay. Western-blot tests the expression of IKB alpha, the nf-kappa B P65and Bcl-Xl in cells.RESULTS:Tests in SRB assay showed that, the inhibition of lutein on SGC-7901cells was dose and time dependent, The inhibition rate was8.57%±2.43%、25.07%±2.90%and32.33%±1.81%after treated with lutein by40mg·L-1in24h、 48h and72h,respectively; While, the inhibition rate was increased to34.72%±4.06%、64.55%±2.48%and83.29%±0.10%after treated with lutein by160mg·L-1in24h、48h and72h,respectively. Fluorescence microscope and hoechst33342/PI assay suggested that lutein can induce SGC-7901cells apoptosis in a dose-dependent manner. Uv spectrophotometer detection shows the activity of intracellular ROS reduction,compared with the DMSO control group according to the change ROS with lutein concentration increases; The change of total glutathione was determined by the color reaction assay which shows that the content of intracellular GSH increase,compared with the DMSO control group according to the change ROS with lutein concentration increases; RT-PCR method show that the express of SOD-2mRNA and IKB alpha rises with lutein concentration increases compared with the DMSO control group, while down-regulate the express of nf-kappaBP65mRNA along with the increase of drug concentration express cut, both a dose dependent. Western blot analysis observed that lutein significantly increased the express of IKB alpha and decreased the activation of nf-kappa BP65and Bcl-X1in lutein exposed SGC-7901cellsCONCLUSION:The molecular mechanism of growth inhibition and apoptosis-inducing effect of lutein on gastric carcinoma cell line SGC-7901,maybe through reducing the activity of ROS in cells, appropriate to increase the intracellular glutathione content, to improve the expression of SOD-2mRNA. At the same time, lutein, inhibit the activation of NF-κB signal transduction pathway, respectively, reduced the expression of NF-κBP65and increase the expression of IKB,-alpha in gene and protein levels. And ultimately lutein cause a significant reduction of anti-apoptotic protein in expression of bcl-X1which dependent on NF-κB signaling pathway. As a result, lutein induced SGC-7901apoptosis and intracellular ROS content as well as NF-κB signal transduction pathway is closely linked. |
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