Novel chloroquine derivative suppresses melanoma cell growth by DNA damage through increasing ROS levels.

Melanoma is a fatal cancer with a significant feature of resistance to traditional chemotherapeutic drugs and radiotherapy. A mutation in the kinase BRAF is observed in more than 66% of metastatic melanoma cases. Therefore, there is an urgent need to develop new BRAF-mutant melanoma inhibitors. High-dose chloroquine has been reported to have antitumour effects, but it often induces dose-limiting toxicity. In this study, a series of chloroquine derivatives were synthesized, and lj-2-66 had the best activity and was selected for further investigation. Furthermore, the anti-BRAF-mutant melanoma effect and mechanism of this compound were explored. CCK-8 and colony formation assays indicated that lj-2-66 significantly inhibited the proliferation of BRAF-mutant melanoma cells. Flow cytometry revealed that lj-2-66 induced G2/M arrest in melanoma cells and promoted apoptosis. Furthermore, lj-2-66 increased the level of ROS in melanoma cells and induced DNA damage. Interestingly, lj-2-66 also played a similar role in BRAF inhibitor-resistant melanoma cells. In summary, we found a novel chloroquine derivative, lj-2-66, that increased the level of ROS in melanoma cells and induced DNA damage, thus leading to G2/M arrest and apoptosis. These findings indicated that lj-2-66 may become a potential therapeutic drug for melanoma harbouring BRAF mutations.