Enzyme-Catalyzed Activation of Pro-PROTAC for Cell-Selective Protein Degradation

Proteolysis targeting chimera(PROTAC)technology is a chemical protein knockdown approach that degrades protein by hijacking the cellular ubiquitinproteasome system to impede tumor growth.Its therapeutic potential,however,isdifficult to define due to the lack of control over the cell selectivity of PROTACs,in particular,if the therapeutic purpose is to be executedin a specific cell type.Herein,we report the design of a Pro-PROTAC and its catalytic activation of the endogenous overexpressed enzyme in cancer cells for cellselective protein degradation.We demonstrate that the chemical modification of the binding site between PROTAC and E3 ligase with trimethyl-locked quinone efficiently blocks the protein degradation capability of PROTAC.However,NAD(P)H quinone dehydrogenase 1(NQO1),an enzyme overexpressed in cancer cells,could reduce the trimethyl-locked quinone to remove the chemical modification and activate NQO1-PROTAC for cancer cell-selective protein degradation.Further,we show that NQO1-catalyzedβ-Lapachone reduction potentiated cellular oxidative stress to activate aryl boronic acid-caged ROS-PROTAC in living cells for bromodomain-containing protein 4 degradation with enhanced cell selectivity.Collectively,our strategy of designing Pro-PROTAC in response to endogenous species of diseased cells expands the chemical biology toolbox for cell-selective protein degradation and would be of great interest in targeted therapeutics discovery.