P-252 YI New Targets of Interest: Inhibition of PAK-1 Improves Inflammation in a Mouse Model of Colitis

RalGAPa2 KO mice received a single intraperitoneal injection of the carcinogen azoxymethane (AOM) (12.5 mg/kg), followed by 3 rounds of 2.0% dextran sulfate sodium (DSS)-induced colitis. We compared the histology between both mice with AOM/DSS-induced colorectal cancer. (2) We transfected RalGAPa2 siRNA into Colon26 cells to examine the involvement of Ral in migratory capacity and invasion capacity of colonic cancer cells by using wound healing assay and cell invasion assay. (3) Furthermore, we performed microarray analysis with epithelial cells isolated from colonic tissues of both mice to identify genes associated with cancer cell invasion, and performed RT-PCR to compare the expression of the identified genes between tumors of WT mice and of RalGAPa2 KO mice. Results: (1) Despite no significant differences in the number and size of tumors between WT mice and RalGAPa2 KO mice, RalGAPa2 KO mice showed a tendency to higher number and larger size of tumors. (2) Significant differences in the percentage of SM invasive tumors were observed between RalGAPa2 KO mice and WT mice (45.5% versus 8.3%, P 1⁄4 0.04). (3) The migratory capacity and invasion capacity of Colon26 cells transfected with RalGAPa2 siRNA was significantly increased compared to those with control siRNA. (4) Microarray analysis demonstrated that at least 2-fold and significant up-regulation genes in RalGAPa2 KO mice versus WT mice were MMP-9 and MMP-13. (5) Quantitative analysis of gene expression showed that significant up-regulation of MMP-9 and MMP-13 gene in RalGAPa2 KO mice was observed in compared with WT mice. Conclusions: This study firstly demonstrated that sustained Ral activation was strongly involved in the invasive capacity of CAC with up-regulation of MMP-9 and MMP-13.