Endogenous hydrogen sulfide inhibition suppresses tumor growth by promoting apoptosis and pyroptosis in esophageal cancer cells

Background: Hydrogen sulfide (H₂S) has been identified as the third gaseous signaling molecule. Endogenous H₂S plays a key role in the progression of various types of cancer. However, the effect of endogenous H₂S on the growth of esophageal cancer (EC) remains unknown. Methods: In this study, three kinds of H₂S-producing enzymes inhibitors, DL-propargylglycine (PAG, inhibitor of cystathionine-γ-lyase), aminooxyacetic acid (AOAA, inhibitor of cystathionine-β-synthase), and L-aspartic acid (L-Asp, inhibitor of 3-mercaptopyruvate sulfurtransferase) were used to determine the role of endogenous H₂S in the growth of EC9706 and K450 human EC cells. Results: The results indicated that the combination (PAG+AOAA+L-Asp) group showed higher inhibitory effects on the viability, proliferation, migration, and invasion of EC cells than PAG, AOAA, and L-Asp group. Inhibition of endogenous H₂S promoted apoptosis via activation of mitogen-activated protein kinase pathway in EC cells. Endogenous H₂S suppression triggered pyroptosis of EC cells by activating reactive oxygen species-mediated nuclear factor-κB signaling pathway. In addition, the combine group showed its more powerful growth-inhibitory effect on the growth of human EC xenograft tumors in nude mice without obvious toxicity. Conclusion: Our results indicate that inhibition of endogenous H₂S production can significantly inhibit human EC cell growth via promotion of apoptosis and pyroptosis. Endogenous H₂S may be a promising therapeutic target in EC cells. Novel inhibitors for H₂S-producing enzymes can be designed and developed for EC treatment.