Abstract 5452: AXIN2 differentially modulates stem cell subpopulations providing a potential therapeutic opportunity for targeting colorectal cancer stem cells

Abstract

Abstract Constitutively activated WNT-signaling promotes stem cell (SC) overpopulation which drives most colorectal cancer (CRC) development. It is not known, however, how WNT-signaling activity regulates different SC sub-populations. We previously reported that SC population size decreases as AXIN2 is knocked down, and increases when AXIN2 is overexpressed. Changes in cell cycle and apoptotic rate were also observed. Here, we present our recent results on changes between different SC subpopulations (ALDH+ vs. LGR5+) that occur due to AXIN2 modulation. We hypothesize that modulation of AXIN2 promotes differential expansion between different CRC SC subpopulations (ALDH+ and LGR5+). We observed that AXIN2 not only increases LGR5+ SC population size, but also expands the ALDH+ SC population to a greater extent as shown by an increased ALDH+-to-LGR5+ SCs ratio. This indicates that AXIN2, via WNT signaling, regulates SC population size, particularly ALDH+ SCs. Since the ALDH SC marker is also a key component in the retinoic acid (RA) signaling pathway, we surmised that increased AXIN2 would not only lead to elevated ALDH levels, but also upregulate the RA-signaling pathway components in CRC cells. To this end, we conducted NanoString mRNA profiling to study the effects of AXIN2 knockdown and overexpression in HT29 and SW480 CRC cells. The results showed that increased AXIN2 significantly up-regulated several key components of the RA-signaling pathway. Taken together, our results indicate that AXIN2 drives a shift in SC subpopulation sizes favoring the ALDH+ SCs. It also promotes the RA-signaling component expression - a pathway known to regulate SC differentiation. As a potential treatment strategy for CRC, therapeutically inducing high levels of AXIN2 could shift the balance between SC populations towards ALDH+ SCs, which may provide a way to target cancer SCs with retinoids to induce their differentiation. Citation Format: Chi Zhang, Caroline O. Facey, Lynn M. Opdenaker, Bruce M. Boman. AXIN2 differentially modulates stem cell subpopulations providing a potential therapeutic opportunity for targeting colorectal cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5452.