Amino acid cysteine induces senescence and decelerates cell growth in melanoma

Dietary functional food proteins have shown anti-cancer properties, however, the mechanism of their action remains obscured. Amino acids are the main components of proteins. Furthermore, deficiency of certain amino acid enhances the development and progression of cancer. Amino acid metabolism is altered in cancer cells. It is possible that amino acid supplement inhibits cancer development. Thus, the aim of the study is to examine the effect of amino acids on melanoma growth in vitro and in vivo. Among amino acids tested, cysteine revealed a potent inhibitory effect on melanoma viability. Cysteine inhibited proliferation, delayed cell cycle, induced cell senescence, and activated p53-p21 pathway in melanoma. Further, cysteine suppressed microphthalmia-associated transcription factor (MiTF) activation. Cysteine decelerated the growing speed of melanoma tumour in melanoma bearing mice. Thus, cysteine supplement may attenuate melanoma development. The induction of senescence via MiTF suppression and subsequent p53-p21 pathway activation may play a role in its inhibitory effect.