Abstract 288: Revisiting small molecules that influence the nuclear translocation of thioredoxin-1, prohibitin, and galectin-3 for cancer chemotherapy

Abstract

Abstract Phenyl-3-(2-chloroethyl)ureas (CEU) are alkylating agents exhibiting potent antiproliferative properties both in vitro and in vivo. CEUs' cytoxicity is not influenced by hypoxia or other clinically relevant mechanisms of chemoresistance, such as alteration of topoisomerase II activity and increased P-glycoprotein over-expression, DNA repair, intracellular gluthatione-S-transferase activity. A first subset of CEU exemplified by the prototypical molecules 4-tert-butyl-CEU (tBCEU) and 4-iodo-CEU (ICEU) have been shown to alkylate the colchicine-binding site on βII-tubulin. In parallel, these molecules disrupted the cytoskeleton and arrested the cell cycle in G2/M leading to anoikis. So far we have conducted several structure-activity relationship and molecular pharmacology studies in an attempt to refine the specificity of CEU for β-tubulin and the colchicine-binding site. Unexpectedly, a prototypical molecule designated as 1-(2-chloroethyl)-3-(4-cyclohexylphenyl)urea (cHCEU) emerged as arresting the cell cycle in G0/G1 phase instead of G2/M. Experiments using [14C-urea]-cHCEU showed its binding to thioredoxin isoform-1 (Trx-1) and prohibitin (PHB), but not β-tubulin. Complementary immunocytofluorometry experiments clearly showed the abrogation of the nuclear translocation of Trx-1 from the cytosol. We report herein that in addition to Trx-1 and PHB, cHCEU also alkylates galectin-1 and -3 isoforms. The cellular localization of thioredoxin-1, prohibitin, and galectin-3 (Gal-3) is changed following cHCEU treatment. In addition, the expression of Trx-1, PHB, and Gal-3 seems unaffected by CEU and its analogues. Interestingly, these proteins are all known to play an important role in the cell cycle regulation through various mechanisms. The mechanism(s) underlying the effect of cHCEU on protein translocation is unknow and might be relevant to design new potent anticancer drugs that will target specific and lethal biological pathways essential to tumor growth. Citation Format: Jessica S. Fortin, Thomas E. Wineland, Kelsey E. Duggan, René C.-Gaudreault. Revisiting small molecules that influence the nuclear translocation of thioredoxin-1, prohibitin, and galectin-3 for cancer chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 288.