Association Of BH3-only Proteins With Etoposide-Induced Apoptosis Of Gastric Adenocarcinoma Cells

Background: There has been little progress in the medical treatment of late-stage gastric adenocarcinoma because of the absence of effective systemic therapies. This is believed to be primarily due to resistance of gastric adenocarcinoma to chemotherapy-induced apoptosis. Many different classes of chemotherapeutic drugs induce apoptosis by damaging DNA, leading to activation of the transcription factor p53, which in turn mediates apoptosis primarily by up-regulation of pro-apoptotic proteins such as Puma and Noxa. One of the DNA damaging agents that is commonly used in clinic is the topoismerase-II inhibitor Etoposide. However, the wide variation in sensitivity to Etoposide precludes its use in treatment of gastric adenocarcinoma.Objective: To better understand the mechanisms by which Etoposide induces apoptosis of gastric adenocarcinoma cells, and in particular, to examine the role of the BH3-only proteins of the Bcl-2 family, Noxa, Puma, and Bim in determining sensitivity of gastric adenocarcinoma cells to apoptosis induced by Etoposide. To find new therapy target and theary foundment for clinic treatment.Method: SGC-7901 and BGC-823 gastric adenocarcinoma cells were treated with Etoposide at varying doses for different time periods. The levels of apoptosis were quantitated using Annexin V staing in flowcytometry. The role of caspases in Etoposide induced apoptosis was studied using the pancaspase inhibitor, z-VAD-fmk. The expression of Noxa, Puma, Bim, and p53 at mRNA and protein levels before and after treatment with Etoposide were measured by semi-quantitative RT-PCR and Western blot analysis, respectively.Results: Etoposide induced apoptosis of gastric adenocarcinoma cells in a dose- and...