Key Word(s): 1. STAT3; 2. Snail; 3. SGC7901;

4. vector constuction; Presenting Author: SHANSHAN SHEN Additional Authors: XIAOPING ZOU Corresponding Author: XIAOPING ZOU Affiliations: Nanjing Drum Tower Hospital Objective: The oxidative stress plays an essential role in carcinogenesis and progression click here of colorectal cancer through many mechanisms, in which NF-κB (nuclear factor kappa B) signaling pathway is particularly involved. ABCG2 (ATP-Binding Cassette Family G2 Transporters) is an ABC (ATP-binding cassette) transporter. Previously, many studies in colorectal caner have focused on its relevance to multidrug resistance, however, other functions of ABCG2 remains largely unexplored. Our previous study for the first time demonstrated that the ABCG2 is capable of protecting HEK293 cells (human embryonic kidney epithelial cells 293) from ROS (Reactive oxygen species)-mediated cell damage and death. In normal circumstances, ABCG2 protect gastrointestinal epithelium cells from toxins and loss of ABCG2 in local intestinal tract might lead to the carcinogenesis of colorectal cancer. Since ABCG2 and oxidative stress is cloesly related to bilogical characteristics of colorectal cancer, we hypothesize that ABCG2 may reduce oxdative stress and inhibit the malignant behaviour of colorectal cancer. NF-κB

signaling pathway may be involved in the Gefitinib effects of ABCG2. Methods: Immunohistochemistry (IHC) was applied to examine the protein expression of ABCG2 and NF-κB in 21 colorectal carcinoma specimens and 21 normal colorectal epithelial specimens from Drum Tower Hospital Affiliated to Medical School of Nanjing University. RT-PCR and Western blot were used to test the ABCG2 expression level in four different colorectal cancer cell lines (LoVo, HT-29, Caco-2, Sw480) and LoVo cells which were confirmed to have no ABCG2 expression were selected to do

the following ABCG2 overexpressing experiments. The construction and cloning of ABCG2-pEGFP-C1 Urease recombinant plasmid were followed the manufacturer’s protocols and the recombinant plasmid was identified by restriction enzyme test and sequencing. The expression of cloned ABCG2 in transfected LoVo cells transient transfected with Lipofectamine 2000 was examined by Western blotting and Immunocytochemistry. The effects of ABCG2 on the ROS production induced by hydrogen peroxide (H2O2) were monitored by ROS assay. The effects of ABCG2 on the viability of H2O2-treated cells were measured using propidium iodide (PI) assay following manufacturer’s instructions. All the data were analyzed with SPSS 16.0 statistical software package. The comparison between two samples was analyzed by Student t-test and multiple samples were compared by one-way ANOVA.