Characterization of novel NQO1-targeted therapeutic and theranostic compounds for tumor selective chemotherapy

Abstract NAD(P)H-quinone oxidoreductase 1 (NQO1) is a rational target for designing tumor-selective anticancer therapies because the 2-electron reductase is expressed at very low levels in normal tissues but present abundantly (5 to 200-fold) in human cancers due to the inherent oxidative stress and inducibility by NRF2 transcription. NQO1 can catalyze repeated futile redox cycling of quinone to hydroxyquinone forms of certain quinones (e.g., beta-lapachone) consuming NADPH and generating rapid bursts of ROS preferentially in tumor tissues. However, the natural compound quinones have no clinical applications because of their insolubility and induction of hemolytic anemia. Therefore, we designed and synthesized specific NQO1- activated quinones, a spiroisoindolinone called GNQ-9 and a derivative of ES936 (a proven inhibitor of NQO1) that are bioactivated by purified NQO1 and in tumor cell cultures. The catalytic activity was inhibited by dicoumarol and the compounds triggered profound ROS generation and apoptosis in NQO1-proficient but not-deficient tumor cells. Evidence suggested the cell killing is mediated by ROS, ER stress, and abundant release of DAMP molecules indicative of immunogenic cell death in GNQ-9 treated cells. Normal cell counterparts were not affected by the NQO1 activators. Besides the pancreatic cancer MiaPaca2 xenografts, GNQ-9 also eliminated the U87 glioblastoma with great efficacy in intracranial xenograft models, thus verifying its BBB penetrability. A potent inactivation of the MGMT, a redox-sensitive DNA repair protein in GNQ-9 treated cells and a synergistic cell killing by Temozolomide was also noted. Since the tumor-restricted high levels of NQO1 provide excellent opportunities for imaging cancer biopsies and the extent of surgical resection, we have developed a near-infrared probe (NIR-ASM) that specifically detects NQO1 activity in live cells and cancer tissues (Sci. Reports 2019, 9:8577). This turn-on probe remains non-fluorescent until cleavage by NQO1 and the product fluoresces with a peak at 646 nm. In live nude mice bearing both NQO1-proficient A549 and NQO1-deficient MDAMB 231 xenografts on opposite flanks, injections of the NIR-ASM probe resulted in the A549 tumors developing an intense signal within 5 minutes, while the NQO1-negative tumors never developed any. Further, we have developed theranostic probes capable of generating a) intense fluorescence in the NIR range and b) ROS/hydrogen peroxide following catalysis by NQO1 in situ. These probes have demonstrated a simultaneous reduction of NQO1 activity and tumor growth delay in mice with NQO1-rich tumors. Collectively, these efforts represent a new direction for the development of promising NQO1-directed drugs and cancer imaging associated therewith (supported by a Cancer Prevention and Research Institute of Texas [CPRIT] grant RP170207 to KSS). Citation Format: Kalkunte S. Srivenugopal, Surendra R. Punganuru, Viswanath Arutla, AEM Adnan Khan. Characterization of novel NQO1-targeted therapeutic and theranostic compounds for tumor selective chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 457.