Reactive Oxygen Species: Its Pathway And Effects On The Metastasis Of Epithelial Ovarian Tumor

Background：Epithelial ovarian cancer, accounting for75%of all ovarian tumors,and90-95%of ovarian malignancies, is one of the diseases of high lifetime riskand malignance in the female genital system.recently, it’s reported that metastasisand therapy-resistance is the main cause of low5-year survival rate. Almost75%of tumors are confirmed to be aggressive and distantly metastatic(FIGO Stage IIIor IV). Although, searching further mechanisms of EOC’s metastasis and finding outthe way to repress its invasion remain unclear.Large amounts of researchesdemonstrate that hypoxia plays an important role in tumor metastatic spread andaggressivenes. However, the molecular mechanisms from hypoxia to tumor invasion arepoorly understood. It’s also reported that the level of Reactive Oxygen Speciesin tumor cell is correlated to its malignant phenotype. The higher level of ROS underthe hypoxia, the more aggressive the tumor cell is, leading to invasion. And thusROS is involved1-2.Carcinoma invasion is a multistep process, in which epithelialtumor cells lose junctions between adjacent cells, leading to migration and invasion.Such kind of process is called EMT(epithelial mesenchymal transition)2. Generally,with down-regulation of E-cadherin, a hallmark of EMT, the tumor cell will show ainvasive and metastatic phenotype3. Which is the pathway to connect ROS and E-cadmay probably be HIF-1α and LOX4-5.Objective：To investigate the whole molecular pathway referred to before fromhypoxia to metastasis, we raised a suppose. It includes reduced oxygen tensions andup-regulation of ROS, resulting in the increase of HIF and then transcriptionalinduction of LOX and LOXL2. It comes out repression of E-cadherin and the processof epithelial to mesenchymal tranition, leading to enhanced invasion and metastasis.Methods：We divided our research to four parts, and the first two one is celltests with Human epithelial ovarian cancer cell lines, SKOV-3. we controlled ROSlevel by chemicals-Emodin and DTT, constructed SiRNA to calm the expression of HIF-1a,used β-APN to suppress the LOX level. We divided cells into groups which dealedwith the ways mentioned above. We tested intracellular ROS level by DCFH-DAfluorescent colouration and FCM, protein of the possible molecular pathway byWesterning blotting, mRNA by RT-PCR, cellular biological process by wound healing assay and Transwell test. The third one is animal test, which is to analysis thedifference of Tumor formation by the Emodin-injected mice and the PBS-injected mice,and to test E-cadherin by immunohistochemistry. In the fourth part, we collectedClinical specimens and their information with analysis and E-cadherin-test. So thatwe can verify the relation of ROS，E-cadherin，and invasion.Conclusions：We raised a suppose that it include reduced oxygen tensions andup-regulation of ROS, resulting in the increase of HIF and then transcriptionalinduction of LOX. It comes out repression of E-cadherin and the process of epithelialto mesenchymal tranition, leading to enhanced invasion and metastasis...