Melatonin regulates cancer migration and stemness and enhances the anti‐tumour effect of cisplatin

Melatonin, a lipophilic hormone released from the pineal gland, has oncostatic effects on various types of cancers. However, its cancer treatment potential needs to be improved by deciphering its corresponding mechanisms of action and optimising therapeutic strategy. In the present study, melatonin inhibited gastric cancer cell migration and soft agar colony formation. Magnetic‐activated cell sorting was applied to isolate CD133(+) cancer stem cells. Gene expression analysis showed that melatonin lowered the upregulation of LC3‐II expression in CD133(+) cells compared to CD133(−) cells. Several long non‐coding RNAs and many components in the canonical Wnt signalling pathway were altered in melatonin‐treated cells. In addition, knockdown of long non‐coding RNA H19 enhanced the expression of pro‐apoptotic genes, Bax and Bak, induced by melatonin treatment. Combinatorial treatment with melatonin and cisplatin was investigated to improve the applicability of melatonin as an anticancer therapy. Combinatorial treatment increased the apoptosis rate and induced G0/G1 cell cycle arrest. Melatonin can regulate migration and stemness in gastric cancer cells by modifying many signalling pathways. Combinatorial treatment with melatonin and cisplatin has the potential to improve the therapeutic efficacy of both.