Mechanism Of Action Of Arsenic Trioxide Induced Apoptosis In Androgen-Refractory Prostate Cancer PC-3 Cell Line

Prostate cancer is the second diagnosed malignancy and the first cause of death in the western country. The incidence of prostate cancer increases in our country, and it has become the second or the third cancer of genitourologic malignancy .But 2/3 of prostate cancer were advanced cancer when they were diagnosed and could only be treated by androgen ablation therapy.Major of prostate cancer relapse to the status of androgen-refractory prostate cancer.Despite the availability of various therapeutic approachs.none has provided a marked therapeutic effectiveness for such patients. Therefore,investigation of novel therapies for androgen-independence prostate cancer is urgently needed.Since arsenic trioxide has been used by Chinese scholars as a single agent for the treatment of acute promyelocytic leukemia with great success,Its mechanism of anti-cancer action especially for solid tumors have been investigated extensively. Now it is found that arsenic trioxide can inhibit cell proliferation at low concentration and induce apoptosis at high ones. Arsenic trioxide-mediated apoptosis is related to the aberrant expression of apoptosis- related gene such as bcl-2 p53 p21 gene. But the mechanism of action of arsenic trioxide differs in different cancer.To investigated the mechanism of action of arsenic trioxide on androgen-refractory prostate cancer, we used androgen-independent prostate cancer cell line PC-3 as model,and investigated its cell proliferation,gene expression status after it was treated by arsenic trioxide.This study includes three parts as follows:Part IEffect of Arsenic Trioxide Mediated Cell Growth Inhibition, Cell Cycle Arrest and Apoptosis in Androgen-Refractory Prostate Cancer PC-3 Cell LineObjective: To investigate the effect of arsenic trioxide mediated cell growth inhibition,cell cycle arrest and apoptosis in androgen-refractory prostate cancer PC-3 cell line.Methods: PC-3 cell was exposed to different concentration of arsenic trioxide with different time. The situation of cell proliferation was determined by MTT method,cell cycle progression was assessed by flow cytometry.cell morphology was investigated by light microscopy and transmission electron microscopy.Results: Arsenic trioxide inhibited PC-3 cell growth through dose- and time- depend manner (P<0.01), Arsenic trioxide mediated PC-3 cell cycle arrest in G! stage. After incubated with arsenic trioxide for 48 hours ,the rate of G1 cell in PC-3 cells is 44.5% 43.2% ,47.4%, 48.3%, 55.9% 65.1% respectively when the concentration of arsenic trioxide is 0 1 2, 3, 6 10mol/L. After PC-3 cell incubated with arsenic trioxide (3mol/L 6mol/L 10mol/L) for 48 hours, the cell apoptotic rate were 11.8%, 12.7%, 29.6% respectively (P<0.001). The apoptotic body was seen in PC-3 cells examined by transmission electron microscopy after it was treated by 3 mol/L arsenic trioxide for 48 hours.Conclusion: Arsenic trioxide mediated PC-3 cell growth inhibition through dose- and time- depend manner. This effect was related to cell cycle arrest in G1 stage. Arsenic trioxide could induce apoptosis in PC-3 cell line.Part II Analysis of Gene Expression Profiles in PC-3 Cell Line Exposed to Arsenic trioxide bycDNA MicroarrayObjective: To investigate gene expression in prostate cancer PC-3 cell line after it was exposed to arsenic trioxide.Methods: PC-3 cell was exposed to 3mol/L of arsenic trioxide for 24 hours.Cell was collected and gene expression was analyzed by cDNA Microarray.Results: according to screening standard, 46 genes expression were found changed in PC-3 cell after it was exposed to 3mol/L of arsenic trioxide for 24 hours. Among which, 19 genes were down-regulated and 27 genes were up-regulated.These genes we found to be differentially expressed cover a broad range of functional activities: (a) protein translation and synthesis; (b):cell signal transduction;(c):DNA binding and transcription;(d):cell metabolism and stress;(e): cell apoptosis.Conclusion: multiple gene expression changed in PC-3 cell after it...