Study On The Anti-gastric Cancer Activity Of Alboflavomycins Compounds

BackgroundGastric cancer is a leading cause of malignant death worldwide,and early diagnosis of gastric cancer is difficult because most patients are asymptomatic in the early stage,so,most ot the gastric cancer patient was in the middle or late stage when they were diagnosed with stomach cancer.Moreover,drug-resistance is the main reason for the chemotherapy for garstric cancer;therefore,developing effective anticancer reagents and exploring the molecular mechanisms of chemotherapeutics are fundamental for gastric cancer prevention and treatment.Alboflavomycins are serials of antimicrobial and antitumor cyclehexapeptides,which were isolated from Streptomyces alboflavus 313（including NW-G01and 742）.As the alboflavamycines and some anti-cancer drugs（such as mitomycin and daunorubicin and so on）derive from the similar streptomyces,it is possible for these alboflavamycines to exhit their anti-cancer acitivity in different tumors,then we determined the ancti-cancer activity of alboflavamycines in this paper.PurposeTo identify the effect of alboflavamycines on the proliferation and death of garstric cancer cells,and the involved mechanism.Moreover,the in vivo anti-cancer activity of alboflavamycines would also be identified by using the tumor-bearing mice.Therefore,the result of our paper facilitate the application of alboflavamycine in the clinical treatment of garstric cancer,and provide the feedback for the design and synthesis of alboflavamycines.MethodsThe microscopy and crystal violet staning methods were used to screen the efficient concentration range of alboflavamycine in killing tumors.MTT assay was used to determine the effect of alboflavamycines on the proliferation of different tumor cells,and the involved mechanism was explored by determining the ratio of S phase cell and colony formation.Flow cytometry was used to determine cell death and mitochondrial membrane poteintial.Western blot was used to detect protein expression,phophorlation,and cleavage.Tumor-bearing mouse model was established by injuected gastric cancer cells subcutaneously into the right flanks of mice,and tumor size was measured by using vernier calber.Intragatric administration of alboflavamycines was adaped evey day for four weeks,and the mice were sacrificed,and the tumors were removed and weighed for statistical analysis.TUNEL method was used to determine the apoptosis in the tumo tissues.ELISA was used to measure the level of AST,ALT and creminine in mice blood and HE staining method was used to determine the pathological change in liver and kidney tissues.ResultsBy uing microscopy and crystal violet staning,we screened the contration range for alboflavamycines,and found that 15μmol·L^-1 NW-G01 could kill tumor cells significantly,whereas 723 and NW-G01-Br were lesser sensitive,whose effective concentration in killing tumor cells arranged at 60μmol·L^-1.However,tumor cells were more sensitive to 1511 and1433,the two dimer of NW-G01 and 723,respectively,and they killed tumor cells at the concentration ranging from 0.5μmol·L^-1 to 2μmol·L^-1.In addition,all the alboflabamycines could induce cell death in a dose-dependent manner,and the cell death could be inhibited by Z-VAD-FMK,the pan-caspase inhibitor.In addition,NW-G01 and 1511 decreased the mitonchondrial membrane potential,promoted the cytoplasmic tranlocation of Cytochrome C,and induced the cleavage of caspase 9,caspase 3 and its substrate PARP.In addition to the protective role of ectopic expression of Bcl-2 and Bcl-x,the two anti-apoptotic proteins locating in the mitochondrial memebrane,so alboflavamycines induced apoptosis through acitivating mitochondrial apoptosis pathway.We also examined the anti-cancer activity in the tumor-bearing mouse model,and the results demonstrated that NW-G01 and 1511 could inhibit tumor growth in a dose-dependent manner,and the anti-cancer effect of 1511 was better than that of NW-G01.Moreover,the results goted by ELISA and HE staining methods demonstrated that1511 admistration did not induce toxicity in mice.However,significant toxicity of liver and kidney was measured by ELISA and HE staining methods was examined in miced administrated with NW-G01.Therefore,1511 is more safe than NW-G01 for the chemotherapy of gastric cancer cells in tumor-bearing mice.ConclusionsThe alboflavamycines inhibit garstric tumor cell proliferation,induce mitochondria apoptosis in gastric cancer cells,and suppress gastric tumor growth in gartric tumor-bearing mice.Moreover,the anti-cancer activiety and safety increased significantly in the alboflavamycines dimer than in the alboflavamycines monomer.Therefore,our results would promote the application of alboflavamycines in the clinical treatment of gasrtric cancer,and provide feedback for the design of alboflavamycines.