Inositol-triphosphate 3-kinase B confers cisplatin resistance by regulating NOX4-dependent redox balance
Chaoyun Pan, … , Sagar Lonial, Sumin Kang
Chaoyun Pan, … , Sagar Lonial, Sumin Kang
Published June 3, 2019; First published May 13, 2019
Citation Information: J Clin Invest. 2019;129(6):2431-2445. https://doi.org/10.1172/JCI124550.
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Research Article Cell biology Metabolism

Inositol-triphosphate 3-kinase B confers cisplatin resistance by regulating NOX4-dependent redox balance

Abstract

How altered metabolism contributes to chemotherapy resistance in cancer cells remains unclear. Through a metabolism-related kinome RNAi screen, we identified inositol-trisphosphate 3-kinase B (ITPKB) as a critical enzyme that contributes to cisplatin-resistant tumor growth. We demonstrated that inositol 1,3,4,5-tetrakisphosphate (IP4), the product of ITPKB, plays a critical role in redox homeostasis upon cisplatin exposure by reducing cisplatin-induced ROS through inhibition of a ROS-generating enzyme, NADPH oxidase 4 (NOX4), which promotes cisplatin-resistant tumor growth. Mechanistically, we identified that IP4 competes with the NOX4 cofactor NADPH for binding and consequently inhibits NOX4. Targeting ITPKB with shRNA or its small-molecule inhibitor resulted in attenuation of NOX4 activity, imbalanced redox status, and sensitized cancer cells to cisplatin treatment in patient-derived xenografts. Our findings provide insight into the crosstalk between kinase-mediated metabolic regulation and platinum-based chemotherapy resistance in human cancers. Our study also suggests a distinctive signaling function of IP4 that regulates NOX4. Furthermore, pharmaceutical inhibition of ITPKB displayed synergistic attenuation of tumor growth with cisplatin, suggesting ITPKB as a promising synthetic lethal target for cancer therapeutic intervention to overcome cisplatin resistance.

Authors

Chaoyun Pan, Lingtao Jin, Xu Wang, Yuancheng Li, Jaemoo Chun, Austin C. Boese, Dan Li, Hee-Bum Kang, Guojing Zhang, Lu Zhou, Georgia Z. Chen, Nabil F. Saba, Dong M. Shin, Kelly R. Magliocca, Taofeek K. Owonikoko, Hui Mao, Sagar Lonial, Sumin Kang

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Figure 6

ITPKB contributes to cisplatin resistance by dampening NOX4 activity in cancer cells.

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ITPKB contributes to cisplatin resistance by dampening NOX4 activity in ...
(A) Effect of ITPKB knockdown on the activity of ROS-regulating enzymes in KB-3-1cisR and A549cisR cells. Cells with or without ITPKB knockdown were treated with cisplatin (KB-3-1cisR, 5 μg/ml; A549cisR, 2 μg/ml), and activities of redox regulatory enzymes were measured after 12 hours. (B) Effect of NOX1/4 inhibitor GKT137831 on ROS level, NOX activity, and cell viability in ITPKB-knockdown cells in the presence of cisplatin. Cells were treated with GKT137831 (10 μM) and cisplatin as in A. (C) Effect of NOX4 knockdown on ROS level, NOX activity, and cell viability in ITPKB-knockdown cells in the presence of cisplatin. (D and E) Bcl-xL expression (D) and Bax localization (E) change upon GKT137831 treatment in ITPKB-knockdown cells. c, cytosol; m, mitochondria. (F–H) The rescue effect of NOX inhibitor on the tumor growth of ITPKB-knockdown KB-3-1cisR xenograft mice treated with cisplatin. Mice were treated with vehicle control, cisplatin (5 mg/kg), and GKT137831 (30 mg/kg) by i.p. injection twice a week from 3 days after xenograft. Tumor size (F), tumor weight (G), H2O2 level (H, top), NOX activity (H, middle), and ITPKB expression in tumors (H, bottom) are shown. Scale bars: 10 mm for F. Error bars represent SEM for F and SD for G (n = 7). Data are mean ± SD from 3 technical replicates of each sample and are representative of 2 independent biological experiments for A–E and H. Statistical analysis was performed by 2-way ANOVA for F and 1-way ANOVA for all other data (*P < 0.05; **P < 0.01; ***P < 0.005; ****P < 0.0001).