Abstract 3254: Promotion of colon cancer invasion and metastasis via activation of Notch-Dab1-Abl-RhoGEF protein Trio

Abstract

Abstract We have recently identified a metastasis suppressor gene for colorectal cancer (CRC); AES/Aes which encodes an endogenous inhibitor of Notch signaling. When Aes is knocked out in the adenomatous epithelium of intestinal polyposis mice, their tumors become malignant, showing marked submucosal invasion and intravasation. Here we show that one of the genes induced by Notch signaling in CRC is DAB1/Dab1. Genetic depletion of Dab1 suppresses cancer invasion and metastasis in the Notch signaling-activated mice. Dab1 is phosphorylated by Abl tyrosine kinase, which activates Abl reciprocally. Consistently, inhibition of Abl suppresses cancer invasion in mice. Furthermore, we show that one of the targets of Abl Tyr-kinase is Rac/Rho-GEF protein Trio, and that phosphorylation at its Tyr residue 2681 (pY2681) causes Rho activation in CRC cells. Its unphosphorylatable mutation Trio(Y2681F) reduces the RhoGEF activity, and inhibits invasion of CRC cells. Importantly, Trio(pY2681) correlates with significantly poorer prognosis of CRC patients after surgery. These results indicate that Trio(pY2681) is one of the downstream effects by Notch signaling activation in CRC, and can be a prognostic marker, helping determine the therapeutic modality of CRC patients. Citation Format: Mark Taketo. Promotion of colon cancer invasion and metastasis via activation of Notch-Dab1-Abl-RhoGEF protein Trio. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3254. doi:10.1158/1538-7445.AM2015-3254