Colorectal Tumors Are Effectively Eradicated by Combined Inhibition of β-Catenin, KRAS, and the Oncogenic Transcription Factor ITF2

Colorectal carcinomas (CRC) harbor well-defined genetic abnormalities, including aberrant activation of beta-catenin (beta-cat) and KRAS, but independent targeting of these molecules seems to have limited therapeutic effect. In this study, we report therapeutic effects of combined targeting of different oncogenes in CRC. Inducible short hairpin RNA (shRNA)-mediated silencing of beta-cat, ITF2, or KRAS decreased proliferation by 88%, 72%, and 45%, respectively, with no significant apoptosis in any case. In contrast, combined blockade of beta-cat and ITF2 inhibited proliferation by 99% with massive apoptosis. Similar effects occurred after combined shRNA against beta-cat and KRAS. In vivo, single oncogene blockade inhibited the growth of established tumors by up to 30%, whereas dual beta-cat and ITF2 targeting caused 93% inhibition. Similar tumor growth suppression was achieved by double beta-cat/KRAS shRNA in vivo. Our findings illustrate an effective therapeutic principle in CRC based on a combination targeting strategy that includes the ITF2 oncogene, which represents a novel therapeutic target. Cancer Res; 70(18); 7253-63. (C)2010 AACR.