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 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 5

Targeting ITPKB leads to cisplatin-induced ROS accumulation and rebalanced redox attenuates apoptosis and restores cisplatin-resistant tumor growth.

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Targeting ITPKB leads to cisplatin-induced ROS accumulation and rebalanc...
(A and B) Intracellular ROS levels in cisplatin-resistant cells incubated with 1 μM IP4-PM (A) or with rescue expression of shRNA-resistant ITPKB WT or kinase-dead mutant (DN: D897N) (B) in the presence of cisplatin. (C) Effect of antioxidant NAC on cellular ROS level (top), apoptotic cell death (middle), and cell viability (bottom) of cisplatin-resistant cells with ITPKB knockdown and cisplatin treatment. Cells were treated with 0.5 mM NAC and cisplatin (KB-3-1cisR, 5 μg/ml; A549cisR, 2 μg/ml), and ROS levels and apoptosis/cell viability were measured after 12 and 48 hours, respectively. (D–F) Rescue effect of NAC on tumor growth of xenograft mice bearing ITPKB-knockdown KB-3-1cisR cells. Mice were treated with PBS, cisplatin (5 mg/kg i.p. twice per week), or NAC (10 mg/ml in drinking water) 3 days after xenograft, and tumor size was measured (D). Tumor weight (E) and H2O2 level and ITPKB knockdown efficiency in tumors (F) are shown. Scale bars: 10 mm for D. Error bars represent SEM for D and SD for E (n = 8). Data are mean ± SD from 3 technical replicates of each sample for A–C and F and are representative of 2 (A, B, and F) and 3 (C) independent biological experiments. Statistical analysis was performed by 2-way ANOVA for D and 1-way ANOVA for all other data (*P < 0.05; **P < 0.01; ***P < 0.005; ****P < 0.0001).