| Objective:To stimulate the embryonic cells of the Musca domestica using lipopolysaccharide(LPS) for production of antibacterial peptide and to extract antibacterial peptide.To research the inhibitory action of the antibacterial peptide on melanoma cells A375 and human myeloid leukemia cells K562.Methods:(1) The logarithmic growth phase's embryonic cells of the Musca domestica were stimulated using no-serum M3 insect medium which contained 20mg/L LPS for sixteen hours.The antibacterial peptide was extracted from supematant fluid.(2) The antibacterial peptide was prepared 40,80,160,320 and 640μg/mL five density groups by PBS.The MTT experiments were made for melanoma cells A375 and human myeloid leukemia cells K562 and used isometric PBS in the control group.The inhibitory action of the antibacterial peptide on two tumor cells was observed.Meanwhile the human umbilical vein vascular endothelial cells were been normal control group.(3) The growth curves of A375 cells and K562 cells in the above five density groups were made by MTT method and two tumour cells of isometric culture medium were been the control groups.(4) The pristine apoptosis ratio and changes of A375 cells and K562 cells in five density groups of antibacterial peptide were detected by apoptosis detection kit.(5) The cell cycle and the cell apoptosis ratio of A375 cells and K562 cells were detected in five density groups of antibacterial peptide by flow cytometry.(6) The effective inhibition ratio of homoharringtonine and the antibacterial peptide on K562 cells and human umbilical vein vascular endothelial cells was detected by flow cytometry.Results:(1) The inhibition zone demonstrated that the antibacterical peptide from the embryonic cells of the Musca domestica had inhibition activity to Escherichia coli.(2) The MTT examination demonstrated that the five density antibacterical peptides had all inhibition activities on A375 cells and K562 cells,compared with the normal control group, the difference had significance(P＜0.05).The five density groups of antibacterical peptides had no inhibition activities on human umbilical vein vascular endothelial cell, compared with the normal control group,the difference had no significance(P＞0.05).(3) Under effects of the different density antibacterical peptides,growth of K562 cells and A375 cells was inhibited obviously,and along with time extension and medicine density increase,cell mortality rate rised.(4) In different density antibacterical peptides the pristine apoptosis ratio of A375 cells and K562 cells had not significant difference(P＞0.05).(5) For A375 cells,five density antibacterical peptides produced all rise of the G2/M,in the highly concentration groups(＞160μg/mL) the G0/G1 reduced and PI advanced obviously.For K562 cells,the influence of different density antibacterical peptides to S phase had the significance differencecompared with the normal control group(P＜0.05).Each density groups produced all rise of the G0/G1 of K562 cells and reduce of the cell multiplication index PI.Compared with the normal control group,the apoptosis ratio of the A375 cells and the K562 cells in various density groups had not significant difference(P＞0.05).(6) The effective killed and wound ratio of the control group,of the homoharringtonine group and of the antibacterial peptide group from the embryonic cells of the Musca domestica on the K562 cells were 27.30%,80.48%and 83.33%,respectively;on human umbilical vein vascular endothelial cells were 44.00%, 84.78%and 36.37%,respectively.Conclusion:(1) The antibacterical peptide from the embryonic cell of the Musca domestica has inhibitional activity to Escherichia coli.(2) The antibacterical peptide from the embryonic cell of the Musca domestica has inhibitory activity on melanoma cells A375 and human myeloid leukemia cells K562,but has not inhibition activity on the human umbilical vein vascular endothelial cell.(3) The inhibitory activity of the antibacterical peptide from the embryonic cells of the Musca domestica on tumour cells enhances with the time-extention and dose-increase.(4) The inhibition mechanism of the antibacterical peptide from the embryonic cells of the Musea domestica on A375 cells and K562 cells maybe arrest normal development of the cell cycle.(5) Compared with the common chemotherapeutics medicine,the merit of the antibacterical peptide from the embryonic cells of the Musca domestica is that it can kill the tumor cells effectively,but no damage the normal person cells.
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