The Antitumor Effect And Mechanism Of Lewis Lung Cancer Treated With Different Dosing Sequence Of Endostar Combined With Cisplatin

Objectives：To investigate the antitumor effect and mechanism that different dosingsequence for the combination of endostar with cisplatin treat subcutaneoustransplanted tumor of lewis lung cancer mice.Method:Build lewis lung cancer model.When in the10th day,the diameter oftumors reached to about6-8mm,36mice were randomized into6groups. Agroup was NS group：mice were given equal volumes of normal sodium for17days. B group was endostar alone group: mice were given20mg.kg-1ofendostar daily by intraperitoneal injection for14days. C group wascis-platinum alone group: mice were given3mg.kg-1of cis-platinum byintraperitoneal injection for3days. D group was endostar followed bycis-platinum group: mice were treated20mg.kg-1of endostar daily for14days first,and then were given3mg.kg-1of cis-platinum by intraperitonealinjection for3days. E group was endostar following cis-platinum group: micewere given3mg.kg-1of cis-platinum by intraperitoneal injection for3daysfirst, and then were treated20mg.kg-1of endostar daily for14days. F groupwas endostar simultaneously with cis-platinum group: mice were treated20mg.kg-1of endostar daily for14days，and were given3mg.kg-1ofcis-platinum by intraperitoneal injection on the forth、fifth、sixth day. Thetumor’s long and short diameters were measured every other day, draw growth curve of the tumor volume. All mice were put to death in23daysafter starting treatment,the tumors were totally stripped. Weight the tumorsand calculate the tumor weight inhibition rate. Tumor tissues of mice wereobtained, investigated by histopathology and used for immunohistochemicalstaining for VEGF.Results:1.Growth curve of the tumor volume, the tumor volume, the tumorweight and the inhibition rate of tumor weight: The tumor volume increasedgradually in all groups during all the period of treatment，the tumor volume ofNS group and endostar alone group is the fastest, the tumor volume ofcis-platinum alone group grows slower than NS group and endostar alonegroup. The growth speed of tumor volume in Group endostar followed bycis-platinum, Group endostar following cis-platinum and Group endostarsimultaneously with cis-platinum were the slowest. At the beginning oftreatment, there were no differences among all combined groups in the growthspeed of the tumor volume. The growth speed of the tumor volume in Groupendostar followed by cis-platinum is much faster than Group endostarfollowing cis-platinum and Group endostar simultaneously with cis-platinumin17day after treatment. The tumor volume in Group NS, Group endostaralone, Group cis-platinum alone, Group endostar followed by cis-platinum,Group endostar following cis-platinum and Group endostar simultaneouslywith cis-platinum respectively were6800.00±1160.64,6000.00±1589.20,4641.33±889.94,4200.00±429.30,2601.00±567.50,2523.08±621.86in23dayafter treatment. The tumor volume of NS group and endostar alone group wasgreater than the other four groups(P<0.05),but there was no statisticallysignificant difference between the two groups（P>0.05）.The tumor volume of cis-platinum alone group and endostar followed by cis-platinum group weregreater than endostar following cis-platinum group and endostarsimultaneously with cis-platinum group （P<0.05）， but no statisticallysignificant difference was found between cis-platinum alone group andendostar followed by cis-platinum group(P>0.05).Compared with Groupendostar following cis-platinum, Group endostar simultaneously withcis-platinum had no statistically significant difference(P>0.05).NS group,endostar alone group, cis-platinum alone group, endostar followed bycis-platinum group, endostar following cis-platinum group and endostarsimultaneously with cis-platinum group, their tumor weight and tumor weightinhibition rate respectively were6.05±1.92；5.03±1.63，16.9%；3.63±0.83，40.0%；3.39±0.78，43.9%；2.25±0.36，62.8%；2.11±0.29，65.1%.The tumorweight of NS group and endostar alone group was greater than the other fourgroups(P<0.05),but there was no statistically significant difference betweenthe two groups. The tumor weight of cis-platinum alone group and endostarfollowed by cis-platinum group were greater than endostar followingcis-platinum group and endostar simultaneously with cis-platinum group(P<0.05).There was no statistically signifiant difference between cis-platinumalone group and endostar followed by cis-platinum group (P>0.05). Nostatistically significant difference in tumor weight was found between Groupendostar following cis-platinum and Group endostar simultaneously withcis-platinum(P>0.05).2.HE staining showed the histopathology of tumor tissue：The tumorcells thrived and closely packed，there was no or point necrosis in NS group;the tumor cells distributed sheet, there were a little necrosis area in endostaralone group. The tumor cells arranged in cords, the volume of tumor cells were small, the tumor tisse showed partial necrosis in cis-platinum alonegroup; the tumor cells distributed in the small bronchus in combined groups,the tumor volume decrease obviously, the combined groups showed a largetumor nerotic area.3. Immunohistochemical staining for VEGF: The VEGF expressed in thecytoplasm of cancerous cells and vacular endothelial cytoplasm, and itscytoplasm was dyed yellow or yellow-brown. NS group, endostar alone group,cis-platinum alone group, endostar followed by cis-platinum group, endostarfollowing cis-platinum group and endostar simultaneously with cis-platinumgroup, their integral of VEGF respectively were：5.162±0.832，2.368±0.553，4.865±0.923，3.653±0.482，2.165±0.356，2.053±0.431.The expression ofVEGF was obvisusly higher in Group NS and Group cis-platinum alonecompared to the other four Groups(P<0.05).But there was no statisticallysignifiant difference between the two groups(P>0.05).The average expressionof VEGF was higher in Group endostar followed by cis-platinum comparedwith Groups endostar alone, endostar following cis-platinum and endostarsimultaneously with cis-platinum (P<0.05). No statistically significantdifference was found among Group endostar alone, Group endostar followingcis-platinum and endostar simultaneously with cis-platinum(P>0.05).Conclusion:1.Different dosing sequence of endostar combined with cisplatin canaffect the inhibition of tumor growth, the tumor suppression effect in Groupendostar simultaneously with cis-platinum and Group endostar followingcis-platinum is better than Group endostar followed by cis-platinum.2.VEGF is vascular endothelial growth factor, and promote tumorangiogenesis. After treated with endostar，the expression of VEGF decreased. While the surviving and repopulating tumor cells induced the expression ofVEGF after treated with cis-platinum.3.The mechanism why the tumor inhibition effect of endostar followingcis-platinum group and endostar simultaneously with cis-platinum group wasbetter than endostar followed by cis-platinum group may be that endostarcould offset cis-platinum induced VEGF up-regulation，tumor angiogenesisreduced，cancer cells are lack of oxygen and nutrients.4.The―normalization‖of the tumor vasculature might not be the primarymechanism for the improved chemotherapeutic effect. The patient was givenchemotherapeutic drugs to reduce tumor loading, and then followed byendostar or simultaneously with endostar to offset cis-platinum inducedVEGF up-regulation,that may be a new mechanism.