Abstract 2733: KITENIN and ErbB4 contribute to further malignant changes in colorectal cancer through c-Jun/AP-1 activation

Abstract KITENIN (KAI1 C-terminal interacting tetraspanin, Vangl1) is not only a major component of PCP pathway but also a functional protein promoting colorectal cancer (CRC) cell motility and invasiveness. Here, we report the mechanism of which KITENIN leads further malignant changes in CRC progression after loss of tumor suppressor Adenomatous polyposis coli (APC). KITENIN increases the level of AP-1 activity through interaction with Dvl2, which is subsequently being degraded. Decreasing Dvl2 via interaction with KITENIN or via treatment of si-RNA to Dvl2 significantly increases the AP-1 activity through elevating the level of c-jun and c-jun phosphorylation. EGF acts upstream of KITENIN/AP-1 signaling and induces synergic AP-1 activation in the presence of elevated KITENIN, which requires the interaction of KITENIN with ErbB4. The morphological characteristics of adenocarcinoma were observed in intestinal tumor tissues from compound villin-KITENIN transgenic/APCmin/+ mice but not from APCmin/+ mice, both of which express the elevated level of ErbB4. This result demonstrates that further malignant phenotype of intestinal tumor can be induced by elevated KITENIN and ErbB4 via promoting c-Jun/AP-1 activation within an APC loss-associated tumor microenvironment. Our present results suggest the possibility of the addition of anti-KITENIN therapy to the use of EGFR inhibitors in the treatment of CRC patients with APC mutation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2733. doi:10.1158/1538-7445.AM2011-2733