1. Study On The As2O3-induced Apoptosis In MCF-7 Breast Cancer Cell 2. Effects Of Antrodia camphorata On Thapsigargin-induced Endoplasmic Reticulum Stress In Huh-7

• Main Authors: Sung-Yu Yu, 尤崧宇
• Other Authors: Huei-sheng Huang
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/83188900221747190748

碩士 === 國立成功大學 === 醫學檢驗生物技術學系 === 95 === Part 1.Arsenic trioxide (As2O3) has been used in clinical trial of acute promyelocytic leukemia (APL) patients worldwide and its mechanisms are examined in both in vitro and in vivo studies. Freshly isolated cells from myeloma, leukemia and lymphoma, or cell lines from bladder, stomach, esophagus, neuroblastoma, prostate and ovary, all undergo apoptosis in vitro following treatment with As2O3. However, the mechanism of As2O3-induced cell death has not yet been clarified completely. To examine the effects of As2O3 in breast cancer cell, we firstly measured the cell death index of MCF-7 cells in response to As2O3. MTT assay showed that treatment with As2O3 for 72 hr induced growth inhibition, with IC50 value about 3 μM. It also induced apoptosis in MCF-7 cells upon As2O3 treatment by flow cytometry with propidium iodide staining. Cyclin dependent kinase inhibitor p21WAF1/CIP1 (p21) was well known to play an important role in cancer cell growth inhibition. However, recent reports showed that phosphorylated Akt can phosporylate p21 and lead to cytoplasmic localization of p21, which plays an important role in protecting cells against apoptosis. By using subcellular fractionation with Western blots, we also found that phosphorylated Akt was down-regulated, and then p21 was translocated from cytosol to nucleus upon As2O3 treatment for 4 hr. When the cells treated with the Akt inhibitor LY294002, the down-regulation of phosphorylated Akt also enhanced p21 translocation to nucleus and induced apoptosis by confocal microscopy and flow cytometry analysis. We conclude that As2O3 induced MCF-7 apoptosis via inhibition of Akt phosphorylation, which prevented accumulation of p21 in cytoplasm and lost its role in anti-apoptosis.Part 2.Antrodia camphorata (A. camphorata) is well-known in Taiwan as a traditional Chinese medicine. It has been used as a remedy for drug intoxication, diarrhea, abdominal pain, hypertension, and itchy skin. A. camphorata extract protects hepatic injury in vivo, by antioxidative and free radical scavenging activities. The endoplasmic reticulum (ER) stress is induced by accumulation of unfolded protein response leading to disrupt ER functions. Thapsigargin (TG), an ER stress inducer, causes ER Ca2+ release and increases mitochondrial ROS production. In this study, we tried to evaluate antioxidative effects of A. camphorata during TG-induced ER stress. The results showed that A. camphorata reduced TG or H2O2-induced ROS generation in Huh-7 cells, which indicate that A. camphorata has antioxidative effects to TG-induced ER stress. In addition, down-regulation of TG-induced GRP78 expression by A. camphorata suggests that the antioxidative effects could further improve the ER stress. Finally, TG-induced apoptosis in Huh-7 cells prevented by A. camphorata was also found. In conclusion, the antioxidative and anti-apoptotic effects of A. camphorata should be further exploited to be a promising preventive agent in ER stress-induced diseases.