The Effect And Mechanism Of Citrus Flavonoids Nobiletin On K562 Cells In Vitro And In Vivo

Objective: To investigate the inhibitory effect of citrus flavonoids nobiletin on K562 cells and discuss its antiangiogenic activity and mechanism.Methods: In vivo, the model of K562 cells xenograft was established in nude mice. The inhibitory rate of nobiletin on tumor was calculated according to the measured tumor weight. Knubbly histopathological change was observed by hematoxylin and eosin(HE) staining. Immunohistochemistry assay was used to determine the effect of nobiletin on VEGF expression and MVD; In vitro, MTT method was used to examin the effect of nobiletin on cell growth in K562 cells. Inducing apoptosis of nobiletin on K562 cells was observed by Acridine orange/ethidium bromide fluorescent double stain (AO/EB). The cell apoptosis was detected by Annexin V-FITC/PI. The expression level of VEGF mRNA was determined by RT-PCR and the VEGF protein level was detected by Western blotting.Results:(1) Compared with control group, NOB could significantly inhibit K562 cells proliferation in vivo and in vitro.(2) In model control group, tumor tissue was rich in angiogenesis and strong growth, and the cell structure was integral. In NOB and CTX groups, tumor tissue had obvious hemorrhage necrotic areas with infiltration of the granulocyte, lysis of the necrosis nucleolus and cell fusion.(3) The results of immunohistochemical technology showed that the expression of VEGF and CD34 in nobiletin groups decreased significantly comparing with the model control group(P<0.01,P<0.05).(4) AO/EB fluorescence and Annexin V-FITC/PI staining showed that: In control group, the apoptotic cells were rare. Compared with the control group, NOB significantly increased the number of apoptosis cell and cell apoptosis rate rose significantly(P<0.01).(5) RT-PCR and Western blotting results showed that NOB could decrease the protein and mRNA expression levels of VEGF. Compared with control group, the effect was significant(P<0.01).Conclution: Nobiletin could significantly inhibit K562 cells proliferation in vivo and in vitro. and remarkably decreased the angiogenesis within tumor tissues by reducing the VEGF expression and inducing apoptosis of K562 Cells.