IRE-1-Targeting Caged Prodrug with Endoplasmic Reticulum Stress-Inducing and XBP-1S-Inhibiting Activities for Cancer Therapy

• Published in: Molecular pharmaceutics 2022-04, Vol.19 (4), p.1059-1067
• Main Authors: Shao, Andong, Xu, Qin, Kang, Chang Won, Cain, Christopher F., Lee, Avery C., Tang, Chih-Hang Anthony, Del Valle, Juan R., Hu, Chih-Chi Andrew
• Format: Article
• Language: English
• Subjects: Apoptosis; Endoplasmic Reticulum Stress; Humans; Neoplasms - drug therapy; Prodrugs - pharmacology
• ISSN: 1543-8384; 1543-8392
• DOI: 10.1021/acs.molpharmaceut.1c00639

Activation of the IRE-1/XBP-1s pathway supports tumor progression. Here, we report a novel prodrug, TC-D-F07, in which a thiol-reactive dinitrobenzenesulfonyl (Dns) cage was installed onto the C8 hydroxyl of the covalent IRE-1 inhibitor D-F07. The electron-withdrawing Dns group in TC-D-F07 stabilizes the neighboring 1,3-dioxane acetal, allowing for stimulus-mediated control of its inhibitory activity. TC-D-F07 exhibits high sensitivity to intracellular thiols. Because tumor cells exhibit higher concentrations of glutathione and cysteine, treatment with TC-D-F07 results in more sustained levels of D-F07 in transformed versus normal cells. In addition, we show that a dinitrophenyl cysteine adduct resulting from cleavage of the Dns group induces endoplasmic reticulum (ER) stress, causing tumor cells to increase the expression of XBP-1s. The accumulated levels of D-F07 and its gradual decomposition into the active IRE-1 inhibitor eventually deprive tumor cells of XBP-1s, leading to more severe apoptosis than those treated with its uncaged analogue.