Anti-proliferative potential of sodium thiosulfate against HT 29 human colon cancer cells with augmented effect in the presence of mitochondrial electron transport chain inhibitors

ABSTRACT

Objective: To compare the anti-proliferative effect of sodium thiosulfate on human colorectal cancer cells (HT-29) and normal small intestine cells (IEC6). Methods: Cells (HT-29 and IEC6) were treated with different concentrations of sodium thiosulfate ranging from 0.5 mM to 80 mM for 24 h. Cell viability was measured via crystal violet and MTT assays. HT-29 cells were further treated in the presence and absence of mitochondrial electron transport chain (ETC) inhibitors, KATP channel opener and closer and H2S inhibitors for 24 h followed by sodium thiosulfate in order to study their respective roles in the anti-proliferative activity of sodium thiosulfate. Results: The IC50 values of sodium thiosulfate on HT-29 cells were 40.93 mM and 42.45 mM by crystal violet and MTT assay whereas, in the case of IEC6 cells, the values were 45.17 mM and 47.22 mM. The inhibition of endogenous H2S enzymes and KATP channel induced no change in the anti-proliferative capacity of sodium thiosulfate. However, the anti-proliferative activity of sodium thiosulfate was enhanced in the presence of mitochondrial ETC inhibitors. Conclusions: HT-29 cell growth is effectively attenuated by sodium thiosulfate and the anti-proliferative activity of sodium thiosulfate is enhanced in the presence of mitochondrial ETC inhibitors.