Robust Colonic Epithelial Regeneration and Amelioration of Colitis via FZD-Specific Activation of Wnt Signaling.

BACKGROUND AND AIMS: Current management of inflammatory bowel disease leaves a clear unmet need to treat the severe epithelial damage. Modulation of Wnt signaling might present an opportunity to achieve histological remission and mucosal healing when treating IBD. Exogenous R-spondin, which amplifies Wnt signals by maintaining cell surface expression of Frizzled (Fzd) and low-density lipoprotein receptor-related protein receptors, not only helps repair intestine epithelial damage, but also induces hyperplasia of normal epithelium. Wnt signaling may also be modulated with the recently developed Wnt mimetics, recombinant antibody-based molecules mimicking endogenous Wnts. METHODS: We first compared the epithelial healing effects of RSPO2 and a Wnt mimetic with broad Fzd specificity in an acute dextran sulfate sodium mouse colitis model. Guided by Fzd expression patterns in the colon epithelium, we also examined the effects of Wnt mimetics with subfamily Fzd specificities. RESULTS: In the DSS model, Wnt mimetics repaired damaged colon epithelium and reduced disease activity and inflammation and had no apparent effect on uninjured tissue. We further identified that the FZD5/8 and LRP6 receptor-specific Wnt mimetic, SZN-1326-p, was associated with the robust repair effect. Through a range of approaches including single-cell transcriptome analyses, we demonstrated that SZN-1326-p directly impacted epithelial cells, driving transient expansion of stem and progenitor cells, promoting differentiation of epithelial cells, histologically restoring the damaged epithelium, and secondarily to epithelial repair, reducing inflammation. CONCLUSIONS: It is feasible to design Wnt mimetics such as SZN-1326-p that impact damaged intestine epithelium specifically and restore its physiological functions, an approach that holds promise for treating epithelial damage in inflammatory bowel disease.

Development of Potent, Selective Surrogate WNT Molecules and Their Application in Defining Frizzled Requirements.

WNTs regulate myriad biological processes during embryonic development and are key regulators of stem cell function, tissue homeostasis, and injury repair in adults. The creation of WNT-based therapies has been hampered by challenges in developing soluble, potent, and selective WNT molecules. Soluble WNT surrogates have been reported, but they demonstrate relatively weak WNT signaling activity. Here, we describe a platform for potent, selective WNT surrogate generation. We identify multivalent binding to Frizzleds (FZDs) and low-density lipoprotein receptor-related proteins (LRPs) to be a requirement for maximal WNT/ß-catenin activation. Furthermore, we show that recruitment of two different FZDs together with LRP causes efficient signaling. Surrogate WNT targeting either FZD1,2,7 or FZD5,8 induces expansive growth of intestinal organoids. This flexible WNT surrogate platform yields potent agonists with any desired receptor specificity and will be useful for research and therapeutic applications for tissue regeneration.

Metabolic Enzyme Sulfotransferase 1A1 Is the Trigger for N-Benzyl Indole Carbinol Tumor Growth Suppression.

In an attempt to identify novel therapeutics and mechanisms to differentially kill tumor cells using phenotypic screening, we identified N-benzyl indole carbinols (N-BICs), synthetic analogs of the natural product indole-3-carbinol (I3C). To understand the mode of action for the molecules we employed Cancer Cell Line Encyclopedia viability profiling and correlative informatics analysis to identify and ultimately confirm the phase II metabolic enzyme sulfotransferase 1A1 (SULT1A1) as the essential factor for compound selectivity. Further studies demonstrate that SULT1A1 activates the N-BICs by rendering the compounds strong electrophiles which can alkylate cellular proteins and thereby induce cell death. This study demonstrates that the selectivity profile for N-BICs is through conversion by SULT1A1 from an inactive prodrug to an active species that induces cell death and tumor suppression.