Dual blocking of PI3K and mTOR signaling by DHW‐221, a novel benzimidazole derivative, exerts antitumor activity in human non‐small cell lung cancer

Abstract

Dear Editor, We previously designed and synthesized a novel benzimidazole compound, DHW-221. 1 Here, we evaluated its anti-NSCLC activity as a PI3K/mTOR dual-target inhibitor and comprehensively described for the first time the mechanism underlying the PI3K/AKT/mTOR signaling pathwaymediated antitumor effects of DHW-221. Our findings indicated that the antitumor activity of DHW-221 was significantly stronger than that of NVP-BEZ235, a dual PI3K/mTOR inhibitor currently undergoing a phase II clinical trial.The PI3K/AKT/mTOR pathway is a key mediator of receptor tyrosine kinase signal transduction. The PI3K family can be divided into three categories. 2 Class I PI3K and mTOR, sharing structural homology in the kinase domain, 3 are considered important targets for malignancy therapy. 4 Thus, the thought of blocking the PI3K/AKT/mTOR pathway by double inhibition of PI3K/mTOR was proposed. 5 Herein, we systematically elucidated the anti-NSCLC effects associated with DHW-221mediated dual PI3K/mTOR inhibition and identified the mechanism underlying this effect both in vitro and in vivo.First, we identified potential targets of DHW-221. Molecular docking indicated that DHW-221 fitted well into the PI3K-ATP binding pocket and formed hydrogen bonds with Gln859 and Arg770. For mTOR, DHW-221 precisely overlapped with it and formed two more hydrogen bonds (Val2240 and Thr2245) than NVP-BEZ235 (Figure 1A). Docking results with PI3Kβ/γ/δ are shown in Figure S1. Subsequent kinase assay suggested that DHW-221 significantly inhibits the kinase activity of the main PI3K isoforms 1 (IC 50 : PI3Kα,0.5 nM; PI3Kβ,1.9 nM; PI3Kγ,1.8 nM; PI3Kδ,0.74 nM), as well as that of mTOR (IC 50 : 3.9 nM) (Table S1). Cellular thermal shift assay was used to further evaluate the binding mode, the thermal stability of DHW-221 combined with PI3K/mTOR was concentration-dependently enhanced (Figure 1B).

DHW-221, a Dual PI3K/mTOR Inhibitor, Overcomes Multidrug Resistance by Targeting P-Glycoprotein (P-gp/ABCB1) and Akt-Mediated FOXO3a Nuclear Translocation in Non-small Cell Lung Cancer

“…Thus, we assessed the effect of DHW-221 on the PI3K/Akt signaling pathway in A549/Taxol and A549 cells by Western blot analysis. Treatment with various concentrations of DHW-221 and GDC-0980 significantly decreased the expression levels of PI3Kp110a and p-Akt in a concentration-dependent manner, while no obvious change was observed in the total Akt level, which suggested that DHW-221 blocked the PI3K/Akt signaling pathway in both A549/Taxol and A549 cells (Figure 5B), agreeing with a previous study (24). FOXO3a, a direct downstream target of Akt, is directly phosphorylated by Akt at the Ser253 site, which allows it to bind to its chaperone protein, 14-3-3, resulting in transfer from the nucleus to the cytoplasm; this process is an important tumorigenic mechanism for evading cancer cell apoptosis (14).…”

“…Previous studies have shown that DHW-221 has a pro-apoptotic effect in NSCLC cells (24). Therefore, we investigated whether DHW-221 triggers apoptosis in A549/Taxol cells.…”

“…Previously, we reported that DHW-221 exerts a remarkable antitumor activity in NSCLC cells (24), but the effect of DHW-221 in MDR NSCLC cells remains unclear. To determine whether A549/Taxol cells are MDR, we compared the cellular morphological changes in A549/Taxol and A549 cells.…”

“…Additionally, studies have shown that inhibition or knockout of PI3K 110a contributes to overcome P-gp-mediated MDR in cancer (22). In a previous study, we designed and synthesized a novel PI3K/mTOR dual inhibitor, 2,4-difluoro-N-(5-(1-(4-(2-hydroxyethoxy)phenyl)-1H-benzo [d]imidazol-6-yl)-2-methoxypyridin-3-yl)benzenesulfonamide (DHW-221), and we demonstrated that it exerts a remarkable antitumor activity in NSCLC cells (23,24). However, the effect of DHW-221 in Taxol-resistant NSCLC cells remains unclear.…”

DHW-208, A Novel Phosphatidylinositol 3-Kinase (PI3K) Inhibitor, Has Anti-Hepatocellular Carcinoma Activity Through Promoting Apoptosis and Inhibiting Angiogenesis

“…In recent years, 4-amino-quinazoline derivatives, which are kinase inhibitors have attracted attention in the field of pharmaceutical chemistry ( 43 , 44 ). These 4-amino-quinazoline derivatives have also been reported to be inhibitors of PI3Kα and PI3Kδ, suggesting that 4-amino-quinazoline derivatives are potential targeted antitumor drugs ( 6 , 22 , 45 ).…”