Hydrogen Sulfide as a Novel Regulatory Factor in Liver Health and Disease

Figure 2

A proposed mechanism of the effect of H₂S on the growth and death of cancer. (a) A normal distribution curve is employed to explain the effect of H₂S on the development of cancer. Endogenous H₂S or relatively low levels of exogenous H₂S could promote cancer cell growth, while knockdown/knockout of the expression of H₂S-generating enzyme or exposure of relatively high concentrations of H₂S could induce cancer cell death. (b, A1) Downregulation of endogenous H₂S induces cancer cell death. (c, A2) A certain concentration of H₂S induces growth arrest in cancer cells. (d, A3) Normal level of H₂S in cancer cells promotes cancer cell growth. (e, A4) Treatment with relatively low levels of exogenous H₂S could exert optimal effects on the growth of cancer cells. (f-h, A5-A7) Along with the increase in the levels of exogenous H₂S, the growth of cancer cells is gradually decreased. It is worth noting that the procession of cancer cells is theoretically the same between A1 and A7, A2 and A6, and A3 and A5.