The discovery of novel targeted agents for non-small cell lung cancer (NSCLC) remains an important research landscape due to the limited efficacy, side effects and drug resistance of current treatment options. Among many repurposed drugs, disulphiram (DSF) has shown the potential to target tumours. However, its unpleasant neurotoxicity greatly limits its use. A DSF derivative, S-(N,N-diethyldithiocarbamoyl)-N-acetyl-l-cysteine (DS-NAC), was synthesised against NSCLC. The therapeutic effects, mechanism and toxicities of DS-NAC were evaluated in A549 and H460 cells and the mouse model of in situ lung cancer. The in vitro results exhibited that DS-NAC had potent anti-proliferation, apoptotic, anti-metastasis and epithelial-mesenchymal transition (EMT) inhibition effects. In the orthotopic lung cancer mouse model, therapeutic effects of DS-NAC were better than those of DSF and were similar to docetaxel (DTX). Also, results from western blot and immunohistochemistry showed that DS-NAC in combination with copper exerted therapeutic effects via regulating NF-κB signalling pathway and ROS-related proteins such as HIF-1α, Nrf2 and PKC-δ rather than regulating ROS level directly. Moreover, the safety evaluation study showed that DS-NAC had low haematologic and hepatic toxicities in comparison with DTX as well as low neurological toxicity compared with DSF. DS-NAC could be a promising anti-lung cancer agent with a favourable safety profile.

The exploration of novel anti-lung cancer small-molecule drugs is important for drug resistance and adverse effects of chemotherapeutic drugs in current clinics. Disulfiram (DSF), as an antidote, has been proven to have excellent antitumor effects in combination with copper (Cu). However, the risk for potential neurotoxicity and hepatotoxicity in clinical use, as well as its poor water solubility, limits its use. In this study, we identified a DSF derivative, S-(N,N-diethyldithiocarbamoyl)-N-acetyl-L-cysteine, which could greatly increase the water solubility by converting it to a calcium salt (DS-NAC). The anti-lung cancer pharmacodynamic studies in vitro of DS-NAC were evaluated and a mouse model of lung cancer in situ was established to explore the therapeutic effects of DS-NAC compared with DSF and oxaliplatin (OXA). The results demonstrated that DS-NAC combined with Cu had superior cytotoxicity to DSF and OXA in the CCK8 assay against lung cancer cells, and exhibited potent anti-metastatic, epithelial-mesenchymal transition inhibition. In addition, DS-NAC showed better antitumor effects than DSF and comparable effects to OXA in lung cancer in situ model. In terms of the antitumor mechanism, we discovered that DS-NAC in combination with Cu exerted a greater inhibitory effect on the Notch pathway than DSF, which may account for its excellent antitumor effects. Finally, we verified the safety of DS-NAC in vivo, showing lower hepatotoxicity and neurotoxicity compared with DSF and OXA. DS-NAC is a promising anti-lung cancer drug with a favorable safety profile.