s-allylmercaptocysteine and Leukemia--Erythroblastic--Acute

Growth-inhibitory effects on DS19 mouse erythroleukemia cells were seen in the micromolar concentration range with allicin and S-allylmercaptocysteine and in the millimolar range with allyl butyrate, allyl phenyl sulfone, and S-allyl cysteine. Increased acetylation of histones was induced by incubation of cells with the allyl compounds at concentrations similar to those that resulted in the inhibition of cell proliferation. The induction of histone acetylation by S-allylmercaptocysteine was also observed in Caco-2 human colon cancer cells and T47D human breast cancer cells. In contrast to the effect on histone acetylation, there was a decrease in the incorporation of phosphate into histones when DS19 cells were incubated with 25 microM S-allylmercaptocysteine. Histone deacetylase activity was inhibited by allyl butyrate, but there was little or no effect with the allyl sulfur compounds examined in this study. A similar degree of downregulation of histone deacetylase and histone acetyltransferase was observed when DS19 cells were incubated with S-allylmercaptocysteine or allyl isothiocyanate. The induction of histone acetylation by S-allylmercaptocysteine was not blocked by a proteasome inhibitor. The mechanism by which S-allylmercaptocysteine induces histone acetylation remains to be characterized. It may be related in part to metabolism to allyl mercaptan, which is a more effective inhibitor of histone deacetylase.

Topics: Acetylation; Acetyltransferases; Allyl Compounds; Animals; Antineoplastic Agents; Breast Neoplasms; Colonic Neoplasms; Cysteine; Disulfides; Electrophoresis, Polyacrylamide Gel; Female; Histone Acetyltransferases; Histone Deacetylases; Histones; Humans; Leukemia, Erythroblastic, Acute; Leupeptins; Mice; Saccharomyces cerevisiae Proteins; Sulfinic Acids; Tumor Cells, Cultured

Organosulfur compounds are the biologically active components of allium vegetables. Many health benefits have been ascribed to them, including inhibition of carcinogenesis. Inasmuch as several of these thioallyl compounds are quite unstable and others are rapidly inactivated in the body, we have investigated one of the stable components present in aged garlic extract, S-allylmercaptocysteine (SAMC), in an effort to determine whether it can inhibit proliferation of cancer cells. Proliferation and viability of two erythroleukemia cell lines, HEL and OCIM-1, two hormone-responsive breast and prostate cancer cell lines, MCF-7 and CRL-1740, respectively, and normal human umbilical vein endothelial cells in response to different concentrations of SAMC were studied for up to two weeks. There were variations in sensitivity to this organosulfur compound in the different cell lines examined, but the two hormone-responsive cancer cell lines of breast and prostate clearly were far more susceptible to the growth-inhibitory influence of the thioallyl compound. The antiproliferative effect of SAMC was limited to actively growing cells. Human umbilical vein endothelial cells that had reached confluence escaped the reduction in viability so noticeable in the cancer cell lines tested. Our studies thus give evidence of a direct effect of SAMC on established cancer cells.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Division; Cell Survival; Cysteine; Humans; Leukemia, Erythroblastic, Acute; Male; Prostatic Neoplasms; Tumor Cells, Cultured

The antiproliferative potential of S-allylmercaptocysteine (SAMC), a stable organosulfur compound of aged garlic extract, has been investigated using two erythroleukemia cell lines, HEL and OCIM-1. It induces a dose-dependent inhibition of cell growth with a 50% lethal dose of 0.046 mM for OCIM-1 cells and 0.093 mM for HEL cells. [3H]thymidine incorporation was reduced in cells treated with this thioallyl compound, and analysis of high-molecular-weight DNA showed fragmentation compatible with apoptosis. Flow cytometric analyses of DNA revealed an abnormal cell cycle progression in both types of erythroleukemia cells, with the major portion of the unsynchronized cells in the G2/M phase. Measurement of acid-soluble free sulfhydryl groups showed an initial increase in response to SAMC followed by a progressive dose-dependent decrease with extended incubation of cells. We conclude from these studies that SAMC is an effective antiproliferative agent against erythroleukemia cells that induces cell death by apoptosis.

Topics: Apoptosis; Cell Cycle; Cell Division; Cysteine; DNA; DNA Fragmentation; Dose-Response Relationship, Drug; Flow Cytometry; Garlic; Humans; Leukemia, Erythroblastic, Acute; Plants, Medicinal; Sulfhydryl Compounds; Thymidine; Tritium; Tumor Cells, Cultured