Melatonin induces apoptosis and inhibits the proliferation of cancer cells via reactive oxygen species-mediated MAPK and mTOR pathways

Reena Kasi, Pei Ling Yeo, Khuen Yen Ng, Rhun Yian Koh, Gnanajothy Ponnudurai, Yee Lian Tiong, Soi Moi Chye

Research output: Contribution to journalArticleResearchpeer-review


Background: Recent human and animal studies have demonstrated the oncostatic properties of N-acetyl-5-methoxytryptamine (melatonin) in different types of cancer. However, in few cancer cell lines including colorectal cancer cell line (HT-29), acute T cell leukemia cell line (JURKAT) and cervical cancer cell line (HeLa), precise oncostatic mechanism induced by melatonin is yet to be described.

Objectives: The aim of this study is to investigate the effects of melatonin in HT-29, JURKAT and HeLa cells and to determine the underlying molecular mechanism.

Methods: Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay while cell cycle, apoptosis and membrane potential were analysed by flow cytometry. Reactive oxygen species (ROS) was detected by 2',7'-dichlorofluorescein diacetate (DCFH-DA) staining. Protein expressions were determined by Western blot.

Results: Our results showed that melatonin suppressed cell proliferation, increased the number of sub G1 hypodiploid cells and cell cycle arrest in HT-29, JURKAT and HeLa cells. Besides, melatonin also induced early and late apoptosis, although there were marked variations in responses between different cell lines (sensitivity; HeLa > HT-29 >JURKAT). Apart from that, staining with DCHF-DA demonstrated ROS production that was induced in a dose-dependent manner in HeLa, HT-29 and JURKAT cells. Moreover, the apoptotic process and oncostatic effect of melatonin were seen to be associated with extracellular-signal-regulated kinase (ERK) and stress-activated protein kinase/c-Jun NH (2)-terminal kinase (SAPK-JNK) signalling cascades in HeLa cells. In HT-29 and JURKAT cells, melatonin induced apoptosis via activation of p38 mitogen-activated protein kinases (p38), ERK and SAPK-JNK signalling pathways. In all three cell lines, the apoptotic event was triggered by the mammalian target of rapamycin (mTOR)-mediated activation of the downstream target rapamycininsensitive companion of mTOR (RICTOR) and/or regulatory-associated protein of mTOR (RAPTOR) proteins.

Conclusion: Our findings confirm that melatonin induces apoptosis through reactive oxygen speciesmediated dysregulated mitogen-activated protein kinase (MAPK) and mTOR signalling pathways in these cancer cell lines.
Original languageEnglish
Pages (from-to)44-56
Number of pages13
JournalClinical Cancer Drugs
Issue number1
Publication statusPublished - May 2020


  • Melatonin
  • apoptosis
  • cancer
  • Reactive oxygen species
  • MAPK
  • mTOR

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