Discovery of inhibitors of the cancer-promoting phosphatase PRL-3 and their evaluation in intestinal organoids

Upregulation of the phosphatase of regenerating liver (PRL)-3 is associated with colorectal cancer as well as metastasis development and progression. PRL-3's overexpression impairs intestinal self-renewal capacity through causing intestinal stem cell death, correlating this cellular mechanism of tumor onset with PRL-3-mediated higher susceptibility to tumor formation upon inflammatory or mutational events. Therefore, PRL-3 inhibitors hold promise as potential therapeutic agents for cancer treatment. Based on the structure of the PRL inhibitor Analog 3, we evaluated here two sets of focused small molecule libraries and screened them in order to identify more potent and selective PRL-3 inhibitors. The best hit, named PRLthiophenib, showed higher inhibition potency in vitro than Analog 3 with improved selectivity for PRL-3 over other protein tyrosine phosphatases (PTPs), but not within the PRL family, which continues to be a challenge. PRLthiophenib presented high cellular stability and no long-term cytotoxicity. Furthermore, it rescued the growth capacity of an inducible PRL-3-expressing three-dimensional intestinal cell culture organoid system derived from a PRL-3 overexpressing mouse line, mimicking the rescue of intestinal self-renewal capacity. The results introduce PRLthiophenib as a complementary inhibitor to published ones and support drug discovery efforts toward therapeutic targeting of this challenging cancer-promoting phosphatase.