The Research On Inhibition Effect Of PTD4-Apoptin Protein Against The Various-differentiated Gastric Carcinoma Cells

Objective: To confirm the anticancer effect of PTD4-Apoptin on gastric cancer, westudied with three human gastric cancer cell strains of various differentiation grades,containing poorly-differentiated cells MKN45, low-differentiated cells SGC7901, andwell-differentiated cells MKN28. Meanwhile, we contrasted drug sensitivity between thesegastric cancer cell strains, furthermore found out whether autophagy, which had beendemonstrated to be a considerable factor in drug resistance, would also played a role in therelatively low anticancer effect of PTD4-Apoptin in SGC7901and MKN28cells.Methods: In vitro study, these gastric cancer cell strains, as well as human umbilicalveins endothelial cell strains HUVEC which was used as a contrast, were treated in differentways and tested by MTT for growth inhibition rate, Annexin-V-FITC/PI for apoptotic rate. Invivo study, MKN45cells was injected to the subcutaneous of nude mice to constructtransplantation gastric tumor. The mice were treated with PTD4-Apoptin every day. Thetumor volume was observed for4weeks, by which the tumor growth curve was performed.After4weeks, the mice were executed, the weight of tumors was measured. To mark out theautophagosome, GFP-LC3was transfected within liposome into gastric cancer cells, bywhich its location was observed under fluorescence microscope.Result: After treated with PTD4-Apoptin under certain concentration range, the growthinhibition rate of poorly-differentiated cells MKN45was the highest, in littleconcentration-dependente manner, as to low-differentiated cells SGC7901, the growthinhibition rate was average, in concentration-dependenct manner, and the growth inhibitionrate of well-differentiated cells MKN28was the lowest, in concentration-dependent manner.In vivo study on MKN45cells, there was statistically significant difference between the micetreated with PTD4-Apoptin protein and the negative control groups both on tumor growth curve and tumor weight. Under the fluorescence microscope, green fluorescence in thegastric cancer cell lines transfected with GFP-LC3showed that after treated withPTD4-Apoptin protein, GFP-LC3assembled to be spotty distribution and the amount ofautophagosome increased in SGC7901cells, while no significant difference from thenegative control was found in MKN45cells.Conclusion: The PTD4-Apoptin fusion protein has the anticancer effect that suppressesthe growth of the three various-differentiated human gastric cancer cell strains. It caneffectively supress poorly-differentiated cells MKN45, but is far less effective tolow-differentiated cells SGC7901and well-differentiated MKN28. To some extent,SGC7901cells resistes the anticancer effect of PTD4-Apoptin at low concentration, bycertain pathway in which we consider autophagosome as an important factor.