The inhibitory mechanisms of β-lapachone on cisplatin-induced damages in fibroblast

• Main Authors: Yu-Ting Lo, 羅于庭
• Other Authors: Hsiu-Ni Kung
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/qvd6gn

碩士 === 國立臺灣大學 === 解剖學暨細胞生物學研究所 === 103 === DNA-damaging agents can be used as chemotherapeutic drugs,which have a long history in clinical use. Cisplatin (CDDP) is categorized as the most popular and the first line chemotherapeutic drug. It has a platinum core with two chloride leaving groups and two amine non-leaving groups. When cisplatin enters cells, the aquation of the leaving groups allows the platinum core to bind to DNA bases. Thus, adducts are formed on the DNA. These structures block the progression of the replication fork and causing cell cycle abnormality. In addition, studies have shown that cisplatin may also form DNA adduct on mitochondria DNA. These structures interfere with the production of the proteins involved in the electron transport chain, therefore, causing mitochondria dysfunction and ROS production. Based on the fact, cisplatin has a promising potential on treating solid tumors. However, the damaging effects not only affect the targeted cancer cells, but also the non-targeted normal tissues. It is important for clinic to discover the solution to this problem. Previous studies have shown that β-lapachone (β-lap) is effective in proliferation of many types of cells in vitro and promoting wound healing in vivo. The effect of β-lap in cells is tightly relied on the activity of NAD(P)H:quinone dehydrogenase 1 (NQO1), which is shown to involve in the maintenance of chromosomal integrity through p53 stabilization. Moreover, recent studies have reported that β-lap pretreatment ameliorates cisplatin-induced acute kidney injury and hearing impairment. Those evidences imply that it is possible for non-cancer cells to be protected by β-lap, while treating with cisplatin, with blocking the DNA damaging effect of cisplatin on nuclear DNA and mitochondria DNA. In addition to the above-mentioned mechanism, recent studies have shown that despite the protecting role of autophagy in the occurrences of cisplatin-resistance, it may play a pro-death role under certain conditions. In this study, NIH3T3 fibroblast was used as a cell model to investigate the inhibitory mechanisms of β-lap on the damages caused by cisplatin and to explore the role of autophagy. We found that β-lap was effective in rescuing the cisplatin-induced cell death, NAD+/NADH ratio decline and protecting cells from cisplatin-induced DNA damage. Besides, the pretreatment of β-lapachone protected cells from cisplatin-mediated mitochondrial dysfunction. We also discovered a phenomenon that the levels of autophagy markers, LC3BII and MDC fluorescences, were increased by cisplatin treatment, and the increase can be blocked by β-lap. Therefore, autophagy may also play a role in the protecting mechanisms of β-lap. According to the above results, β-lap may be a potential chemoprotective agent in the treatment of cancer.