Effect of Hydrogen Sulfide‐Releasing Compounds on Proliferation of Human Colon Cancer HT29 Cells

Abstract

Both natural and synthetic compounds that release hydrogen sulfide (H2S) such as diallyl trisulfide and naproxen‐H2S hybrids growth and proliferation of human colon HT29 cells (Lai et al. J. Cell. Mol. Med 19: 474, 2014; Kodela et al. Drug Des. Dev. Ther. 9:4873, 2015). Aims of the present study were: (a) to investigate the pharmacological action of L‐cysteine (substrate for the biosynthesis of H2S) and NaHS (H2S‐releasing compound) on proliferation of HT29 cells at different time‐points, and (b) to study the role of enzymes (cystathionine β‐synthase, CBS and cystathionine γ‐lyase, CSE) and K+‐ATP channels on the response elicited by H2S‐producing compounds in HT29 cells. The colon adenoma HT29 cells were treated with different concentrations of L‐cysteine (1 μM – 1 mM) and NaHS (1 μM – 1 mM) for 24 and 48 hours, in the absence and presence of inhibitors of CBS and CSE, amino‐oxyacetic acid (AOA, 1 mM), an inhibitor of K+‐ATP channels, glibenclamide (GLB, 10 μM). After incubation, the anti‐proliferative response on cells caused by various agents was determined by MTT Assay. At equimolar concentrations (10 μM and 1 mM), both L‐cysteine and NaHS caused concentration‐dependent inhibitions of cell proliferation after incubation for 24 h, but increased cell growth at these same concentrations after 48 h of incubation. For instance, at 10 μM, both L‐cysteine and NaHS increased cell proliferation by 37% and 51% after 48 h of incubation. Pretreatment of cells with AOA (1 mM) had no significant (P>0.05) effect on the inhibitory response caused by L‐cysteine and NaHS after 24 h incubation. Interestingly, AOA blocked and even reversed the increase in proliferation caused by L‐cysteine (10 μM and 1 mM) and NaHS (10 μM and 1 mM) after 48 h incubation. After 24 h, both L‐cysteine and NaHS caused additional inhibitory effects on cell proliferation in HT 29 cells pretreated with GLB (10 μM). GLB blocked and even reversed the increase in proliferation caused by L‐cysteine and NaHS in HT29 cells after 48 h incubation. We conclude that H2S‐releasing compounds can elicit a time‐dependent inhibitory or excitatory action on the proliferation of HT29 cells. The inhibitory/excitatory effects caused by these compounds depends, at least in part, on endogenous biosynthesis of new gas and the activity of K+‐ATP channels in HT29 cells. Support or Funding Information This research is supported by Tittle III under the Award Number P031B090216;Title III, Part B, Historically Black Graduate Institutions (HBGI) (CFDA No. 84.031B).