Inhibition of endogenous hydrogen sulfide production suppresses the growth of nasopharyngeal carcinoma cells.

Hydrogen sulfide (H 2 S) has been widely recognized as one of gasotransmitters. Endogenous H 2 S plays a crucial role in the progression of cancer. However, the effect of endogenous H 2 S on the development of nasopharyngeal carcinoma (NPC) is still unknown. In this study, aminooxyacetic acid (AOAA, an inhibitor of cystathionine-β-synthase), dl-propargylglycine (PAG, an inhibitor of cystathionine-γ-lyase), and l-aspartic acid (l-Asp, an inhibitor of 3-mercaptopyruvate sulfurtransferase) were adopted to detect the role of endogenous H 2 S in NPC growth. The results indicated that the combine (PAG + AOAA + l-Asp) group had higher inhibitory effect on the growth of NPC cells than the PAG, AOAA, and l-Asp groups. There were similar trends in the levels of apoptosis and reactive oxygen species (ROS). In addition, the combine group exhibited lower levels of phospho (p)-extracellular signal-regulated protein kinase but higher expressions of p-p38 and p-c-Jun N-terminal kinase than those in the AOAA, PAG, and l-Asp groups. Furthermore, the combine group exerted more potent inhibitory effect on NPC xenograft tumor growth without obvious toxicity. In summary, suppression of endogenous H 2 S generation could dramatically inhibit NPC growth via the ROS/mitogen-activated protein kinase pathway. Endogenous H 2 S may be a novel therapeutic target in human NPC cells. Effective inhibitors for H 2 S-producing enzymes could be designed and developed for NPC treatment.