IKKα as a potential novel target for treatment of colorectal cancer.

Abstract

174 Background: Colorectal cancer (CRC) is a heterogeneous disease leading to different survival outcomes for patients with the same stage of disease. The non-canonical NF-κB pathway has been shown to have a key role in tumorigenesis, and the aim of this study was to investigate the role of IKKα, the main catalytic component of this pathway in CRC. Methods: A tissue microarray was retrospectively constructed from a patient cohort (1033) with stage I-III CRC who underwent surgery. IHC was utilised to examine cytoplasmic and punctate IKKα expression and determine any association with clincopathological features and cancer specific survival (CSS). To assess IKKα inhibition, organoids were prepared from wild type (WT) mouse colon, mouse models of CRC (Apc and Apc.KRAS.pT53.TGFbR2 (AKPT)) and patient derived human organoids. These were treated with an IKKα inhibitor, SU1433 and organoid size and cell viability assessed. Results: High cytoplasmic expression of IKKα was associated with increasing T stage (p = 0.012), poor tumour differentiation (p = 0.010), tumour necrosis (p = 0.013) and low proliferation status (p = 0.013) but was not associated with CSS. High punctate IKKα expression associated with tumour differentiation (p = 0.001), necrosis (p = 0.004), proliferation (p = 0.044) and MMR competence (p < 0.001) and was also significantly associated with reduced CSS (HR1.20 95%CI 1.02-1.42, p < 0.001). SU1433 did not significantly impact on WT (C57/B16) organoid viability up to a concentration of 1 uM, however organoid size and cell viability was significantly reduced in a dose dependent manner in organoids from both Apc and AKPT mouse models. A similar reduction was observed in patient derived human organoids. Conclusions: Punctate IKKα expression was associated with poor cancer specific survival in CRC patients, and inhibition with SU1433, impacted on CRC mouse and patient derived human organoid size and cell viability. These results suggest that, following further investigation and confirmation, IKKα may be employed as a novel therapeutic target in CRC.