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.