Effect Of 17-dmag On Proliferation And Apoptosis Of Human Gastric Cancer Cell Sgc-7901 In Vitro

Gastric cancer is the one of the most common tumors in the digestive tract,but the effect of chemotherapy has been unsatisfactory.Chemotherapy has serious side effects,and some cancer cells often are non-sensitive or quickly have a tolerance, therefore it is imperative to looking for effective drug treatment and adjuvant treatment.Heat shock protein 90(HSP90) is a molecular chaperone required for the stability and function of a number of conditionally activated and/or expressed signaling proteins,as well as multiple mutated,chimerical,and/or over-expressed signaling proteins,which promote cancer cell growth and/or survival.HSP90 has been combined with three structural proteins,involved in the activation and maturation process of these proteins.Tumorigenesis are due to an imbalance between tumor suppressor genes and oncogenes,causing cell malignant transformation,tumor cell signal transduction network imbalance,leading to cancer protein over-expression. HSP90 is over-expressed in a variety of tumor tissues,and it interacts with signaling proteins of intracellular signal transduction pathway,to maintain the normal structure and function of these proteins,so it plays an important role in tumor occurrence and development,therefore it has become the most popular target in anti-tumor research .Geldanamycin(GA) is one of the first specific function inhibitors of HSP90,GA and its semi-synthetic derivatives 17-AAG and 17-DMAG,these small molecular compounds competitive binding with the site of HSP90 N-terminal with the ATP,and thus change it's conformation,so it should not combined with client proteins and other small-molecule protein complex formation,so as to inhibition of its molecular chaperone function,eventually leading to degradation of client proteins,and then preventing tumor survival signaling network,resulting in tumor cell cycle arrested, induction of tumor cell apoptosis.AIM:To explore the effect of 17-dimethylaminoethylamino-17-demethoxy-geldanamycin (17-DMAG),a heat shock protein90 inhibitor,on the growth and apoptosis of gastric cancer cell SGC-7901 in vitro.METHODS:Human gastric cancer cell SGC-7901 was cultivated by routine method,then treated with different concentrations of 17-DMAG.Cell proliferation was detected by MTT assay,and cell cycle examined by flow cytometry and PI stain, while apoptosis was evaluated by flow cytometry and Annexin V-FITC binding assay kit.RESULTS:17-DMAG inhibited the proliferation of SGC-7901 cells in time-dependent (F=246.856,P＜0.001) and dose-dependent manners(F=241.313,P＜0.001).The inhibitory rates between different concentrations and different time groups were significant.After treatment with 17-DMAG,SGC-7901 cell cycle was arrested at G₂/M phase.The control group G₂/M phase cells was 9.2%±0.85%,while the experimental groups(2.5μmol / L and 5μmol/L)were respectively 14.5%±0.62% and 14.5%±0.62%.The difference between experimental groups and control groups was significant(F=231.991,P＜0.001).Treatment with 3μmol/L 17-DMAG after 24 h,an increase in the early apoptotic cell fraction in gastric cancer cell SGC-7901 was identified.The early apoptotic cell population characterized by PI-negative and annexin V-positive cells was 4.77%±1.28%in controls,15.89%±3.57%in 3μmol/L 17-DMAG treated cells,The difference between experimental groups and control groups was significant (t=53.42,P＜0.001).There was also an increase in the late apoptotic cell population. Treatment with 3μmol/L 17-DMAG after 48 h,the late apoptotic cell population characterized by PI-positive and annexin V-positive cells was 2.23%±0.94%in controls,22.10%±6.57%in 3μmol/L 17-DMAG treated cells.The difference between experimental groups and control groups was significant(t=45.18,P＜0.001).CONCLUSION:17-DMAG may inhibit proliferation of gastric cancer cell SGC-7901;induce apoptosis and accumulation in G₂/M phase in vitro.It could be a new medicine to the molecule therapy of gastric cancer.