Hydrogen sulfide generation from l-cysteine in the human glioblastoma-astrocytoma U-87 MG and neuroblastoma SHSY5Y cell lines

Hydrogen sulfide (H2S) is endogenously synthesized from l-cysteine in reactions catalyzed by cystathionine beta-synthase (CBS, EC 4.2.1.22) and gamma-cystathionase (CSE, EC 4.4.1.1). The role of 3-mercaptopyruvate sulfurtransferase (MPST, EC 2.8.1.2) in H2S generation is also considered; it could be important for tissues with low CTH activity, e.g. cells of the nervous system. The expression and activity of CBS, CTH, and MPST were detected in the human glioblastoma-astrocytoma (U-87 MG) and neuroblastoma (SHSY5Y) cell lines. In both cell lines, the expression and activity of MPST were the highest among the investigated enzymes, suggesting its possible role in the generation of H2S. The RP-HPLC method was used to determine the concentration of cystathionine and alpha-ketobutyrate, products of the CBS- and CTH-catalyzed reactions. The difference in cystathionine levels between cell homogenates treated with totally CTH-inhibiting concentrations of dl-propargylglycine and without the inhibitor was used to evaluate the activity of CBS. The higher expression and activity of CBS, CTH and MPST in the neuroblastoma cells were associated with more intensive generation of H2S in the presence of 2 mM cysteine. A threefold higher level of sulfane sulfur, a potential source of hydrogen sulfide, was detected in the astrocytoma cells in comparison to the neuroblastoma cells

Effect of S-Allyl -L-Cysteine on MCF-7 cell Line 3-mercaptopyruvate sulfurtransferase/sulfane sulfur system, viability and apoptosis

The S-Allyl-L-cysteine (SAC) component of aged garlic extract (AGE) is proven to have anticancer, antihepatotoxic, neuroprotective and neurotrophic properties. -Cystathionase (CTH), cystathionine -synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (MPST) are involved in H2S/sulfane sulfur endogenous formation from L-cysteine. The aim of the study was to determine the e ect of SAC on MCF-7 cells survival and apoptosis, which is a widely known approach to reduce the number of cancer cells. An additional goal of this paper was to investigate the e ect of SAC on the activity and expression of enzymes involved in H2S production. The experiments were carried out in the human breast adenocarcinoma cell line MCF-7. Changes in the cell viability were determined by MTT assay. Cell survival was determined by flow cytometry (FC). Changes in enzymes expression were analyzed using Western blot. After 24 h and 48 h incubation with 2245 M SAC, induction of late apoptosis was observed. A decrease in cell viability was observed with increasing SAC concentration and incubation time. SAC had no significant cytotoxic e ect on the MCF-7 cells upon all analyzed concentrations. CTH, MPST and CBS expression were confirmed in non-treated MCF-7 cells. Significant decrease in MPST activity at 2245 M SAC after 24 h and 48 h incubation vs. 1000 M SAC was associated with decrease in sulfane sulfur levels. The presented results show promising SAC e ects regarding the deterioration of the MCF-7 cells’ condition in reducing their viability through the downregulation of MPST expression and sulfate sulfur level reduction

S-Allyl-L-Cysteine Affects Cell Proliferation and Expression of H₂S-Synthetizing Enzymes in MCF-7 and MDA-MB-231 Adenocarcinoma Cell Lines

S-allyl-L-cysteine (SAC) is a sulfur compound present in fresh garlic. The reference literature describes its anticancer, antioxidant and neuroprotective effects. Breast cancer is infamously known as one of the most commonly diagnosed malignancies among women worldwide. Its morbidity and mortality make it reasonable to complete and expand knowledge on this cancer’s characteristics. Hydrogen sulfide (H2S) and its naturally occurring donors are well-known investigation subjects for diverse therapeutic purposes. This study was conducted to investigate the SAC antiproliferative potential and effect on three enzymes involved in H2S metabolism: 3-mercaptopyruvate sulfurtransferase (MPST), cystathionine γ-lyase (CTH), and cystathionine β-synthase (CBS). We chose the in vitro cellular model of human breast adenocarcinomas: MCF-7 and MDA-MB-231. The expression of enzymes after 2, 4, 6, 8, and 24 h incubation with 2.24 mM, 3.37 mM, and 4.50 mM SAC concentrations was examined. The number of living cells was determined by the MTS assay. Changes in cellular plasma membrane integrity were measured by the LDH test. Expression changes at the protein level were analyzed using Western blot. A significant decrease in viable cells was registered for MCF-7 cells after all incubation times upon 4.50 mM SAC exposure, and after 6 and 24 h only in MDA-MB-231 upon 4.50 mM SAC. In both cell lines, the MPST gene expression significantly increased after the 24 h incubation with 4.50 mM SAC. S-allyl-L-cysteine had opposite effects on changes in CTH and CBS expression in both cell lines. In our research model, we confirmed the antiproliferative potential of SAC and concluded that our studies provided current information about the increase in MPST gene expression mediated by S-allyl-L-cysteine in the adenocarcinoma in vitro cellular model for the MCF-7 and MDA-MB-231 cell lines. Further investigation of this in vitro model can bring useful information regarding sulfur enzyme metabolism of breast adenocarcinoma and regulating its activity and expression (gene silencing) in anticancer therapy