Recent advances in the role of endogenous hydrogen sulphide in cancer cells.

Hydrogen sulphide (H 2 S) is a gaseous neurotransmitter that can be self-synthesized by living organisms. With the deepening of research, the pathophysiological mechanisms of endogenous H 2 S in cancer have been increasingly elucidated: (1) promote angiogenesis, (2) stimulate cell bioenergetics, (3) promote migration and proliferation thereby invasion, (4) inhibit apoptosis and (5) activate abnormal cell cycle. However, the increasing H 2 S levels via exogenous sources show the opposite trend. This phenomenon can be explained by the bell-shaped pharmacological model of H 2 S, that is, the production of endogenous (low concentration) H 2 S promotes tumour growth while the exogenous (high concentration) H 2 S inhibits tumour growth. Here, we review the impact of endogenous H 2 S synthesis and metabolism on tumour progression, summarize the mechanism of action of H 2 S in tumour growth, and discuss the possibility of H 2 S as a potential target for tumour treatment.