The compound 2‐(naphthalene‐2‐thio)‐5,8‐dimethoxy‐1,4‐naphthoquinone induces apoptosis via reactive oxygen species‐regulated mitogen‐activated protein kinase, protein kinase B, and signal transducer and activator of transcription 3 signaling in human gastric cancer cells.

Hit, Lead & Candidate Discovery It is reported that 1,4‐naphthoquinones and their derivatives have potent antitumor activity in various cancers, although their clinical application is limited by observed side effects. To improve the therapeutic efficacy of naphthoquinones in the treatment of cancer and to reduce side effects, we synthesized a novel naphthoquinone derivative, 2‐(naphthalene‐2‐thio)‐5,8‐dimethoxy‐1,4‐naphthoquinone (NTDMNQ). In this study, we explored the effects of NTDMNQ on apoptosis in gastric cancer cells with a focus on reactive oxygen species (ROS) production. Our results demonstrated that NTDMNQ exhibited the cytotoxic effects on gastric cancer cells in a dose‐dependent manner. NTDMNQ significantly induced mitochondrial‐related apoptosis in AGS cells and increased the accumulation of ROS. However, pre‐treatment with N‐acetyl‐L‐cysteine (NAC), an ROS scavenger, inhibited the NTDMNQ‐induced apoptosis. In addition, NTDMNQ increased the phosphorylation of p38 kinase and c‐Jun N‐terminal kinase (JNK) and decreased the phosphorylation of extracellular signal‐regulated kinase (ERK), protein kinase B (Akt), and Signal Transducer and Activator of Transcription 3 (STAT3); these effects were blocked by mitogen‐activated protein kinase (MAPK) inhibitor and NAC. Taken together, the present findings indicate that NTDMNQ‐induced gastric cancer cell apoptosis via ROS‐mediated regulation of the MAPK, Akt, and STAT3 signaling pathways. Therefore, NTDMNQ may be a potential treatment for gastric cancer as well as other tumor types. [ABSTRACT FROM AUTHOR]