Hybridization-Based Discovery of Novel Quinazoline-2-Indolinone Derivatives as Potent and Selective PI3Kα Inhibitors

Chemistry Medicinal Chemistry Pharmacy Oncology Medicine
molecular hybridization quinazoline 2-indolinone PI3Kα inhibitor non-small cell lung cancer

Research and Development of a Novel PI3Kα Inhibitor: Molecular Hybridization Technology Leads to a Breakthrough in Lung Cancer Treatment

Academic Background

Cancer, particularly non-small cell lung cancer (NSCLC), is the second leading cause of death worldwide. Currently, chemotherapy is the primary treatment method, but due to its lack of targeting, it often comes with severe toxic side effects. Therefore, developing new, highly effective, and low-toxicity anticancer drugs has become an urgent priority. Phosphatidylinositol 3-kinase (PI3K) plays a crucial role in cell growth, proliferation, and survival, and the abnormal activation of its α-subtype (PI3Kα) is closely related to the development of various cancers. Selective inhibition of PI3Kα has become a focal point of recent research. However, only a few PI3Kα inhibitors (such as Alpelisib) have been approved for clinical use, and they are often associated with insufficient selectivity and significant side effects.

Molecular hybridization is a drug design method that combines two or more pharmacophores into a single molecule, simplifying pharmacokinetics, reducing drug interactions, and enhancing the affinity between drugs and their targets. Quinazoline and 2-Indolinone, as two heterocyclic compounds with significant antitumor activity, have shown great potential in anticancer drug development. In recent years, constructing novel PI3Kα inhibitors through molecular hybridization technology has become an important pathway for developing highly effective, low-toxicity anticancer drugs.

Source of the Paper

This paper was co-authored by Changqun Liu, Yuening Cao, Yi Zuo, and others, with the research team affiliated with the State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine; The General Hospital of the Western Theater Command PLA; and The First Affiliated Hospital of Shenzhen University. The paper was published online in the Journal of Advanced Research on March 2, 2024.

Research Process

  1. Molecular Hybridization and Compound Synthesis
    The research team designed and synthesized 26 novel hybrid compounds (QHIDs) by combining quinazoline and 2-indolinone using molecular hybridization technology. The synthesis process included multiple steps, such as nitro reduction, condensation reactions, and alkylation, ultimately yielding the target compounds. The structures of all compounds were confirmed using nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LCMS).

  2. In Vitro Antitumor Activity Evaluation
    The cytotoxicity of the 26 QHIDs was tested in six cancer cell lines with high PI3K expression (B16, MCF-7, HCT116, H22, PC-3, A549) using the MTT assay, and IC50 values were calculated. The results showed that Compound 8 exhibited significant inhibitory effects on the proliferation of various cancer cells, especially A549 cells (IC50 value of 0.64 μM), with activity significantly superior to that of the marketed drug Gefitinib (IC50 value of 49.94 μM).

  3. PI3Kα Kinase Inhibition Activity Detection
    The inhibitory activity of QHIDs against PI3Kα, PI3Kβ, PI3Kγ, and PI3Kδ was detected using the ADP-Glo™ lipid kinase system. The results showed that Compound 8 exhibited the strongest inhibitory activity against PI3Kα (IC50 value of 9.11 nM), and its selectivity for PI3Kα was significantly higher than that for other subtypes (selectivity for PI3Kβ, PI3Kγ, and PI3Kδ was 10.41, 16.99, and 37.53 times, respectively).

  4. Molecular Docking Simulation
    The binding modes of Compound 3 and Compound 8 with PI3Kα were studied using molecular docking technology. The results showed that Compound 8 tightly bound to PI3Kα through multiple interaction sites, particularly the 2-indolinone structure forming hydrogen bonds with key residues of PI3Kα (such as Arg852), which may be an important reason for its high selectivity.

  5. In Vivo Antitumor Experiments
    A non-small cell lung cancer (NSCLC) model was established in mice, and treatments included PBS, Gefitinib, and Compound 8 (15 mg/kg, 30 mg/kg). The results showed that Compound 8 significantly inhibited tumor growth, and no significant toxic side effects were observed during treatment.

Main Results

  1. Compound 8 Exhibits Significant Proliferation Inhibition in Various Cancer Cells: Its IC50 value for A549 cells was 0.64 μM, with activity significantly superior to Gefitinib.
  2. Compound 8 Shows High Selectivity and Strong Inhibition Activity Against PI3Kα: Its IC50 value was 9.11 nM, with selectivity significantly higher than that for other PI3K subtypes.
  3. Compound 8 Induces Apoptosis by Inhibiting the PI3K/AKT/mTOR Signaling Pathway: It significantly reduced the phosphorylation levels of PI3K, AKT, and mTOR and activated the mitochondrial apoptosis pathway.
  4. Compound 8 Exhibits Significant Antitumor Effects In Vivo Without Toxicity: In mouse experiments, Compound 8 significantly inhibited tumor growth, and no significant toxic side effects were observed.

Conclusions and Significance

This study successfully constructed a series of PI3Kα inhibitors with significant antitumor activity and high selectivity through molecular hybridization technology. Among them, Compound 8, as a representative novel quinazoline-2-indolinone hybrid compound, not only exhibits high selectivity and strong inhibition activity against PI3Kα but also significantly inhibits the progression of non-small cell lung cancer. Compound 8 exerts its antitumor effects by inhibiting the PI3K/AKT/mTOR signaling pathway, inducing mitochondrial dysfunction and apoptosis. Additionally, Compound 8 demonstrated significant antitumor effects in vivo without toxicity, laying a solid foundation for future clinical studies.

Research Highlights

  1. Innovative Application of Molecular Hybridization Technology: For the first time, quinazoline and 2-indolinone were combined to construct a series of novel hybrid compounds, providing new ideas for the development of PI3Kα inhibitors.
  2. High Selectivity and Strong Inhibition Activity of Compound 8: Its selectivity for PI3Kα was significantly higher than that for other PI3K subtypes, and its inhibitory activity was superior to that of the marketed drug Alpelisib.
  3. Antitumor Effects Validated in In Vitro and In Vivo Experiments: Compound 8 not only exhibited significant antitumor activity in vitro but also demonstrated tumor growth inhibition without toxicity in mouse experiments.

This study provides a new pathway for the development of PI3Kα inhibitors and offers important theoretical evidence for future clinical research in the treatment of non-small cell lung cancer.