trichostatin-a and daidzein

We have previously shown the reactivation of some methylation-silenced genes in cancer cells by (-)-epigallocatechin-3-gallate, the major polyphenol from green tea. To determine whether other polyphenolic compounds have similar activities, we studied the effects of soy isoflavones on DNA methylation.. Enzyme assay was used to determine the inhibitory effect of genistein on DNA methyltransferase activity in nuclear extracts and purified recombinant enzyme. Methylation-specific PCR and quantitative real-time PCR were employed to examine the DNA methylation and gene expression status of retinoic acid receptor beta (RARbeta), p16INK4a, and O6-methylguanine methyltransferase (MGMT) in KYSE 510 esophageal squamous cell carcinoma cells treated with genistein alone or in combination with trichostatin, sulforaphane, or 2'-deoxy-5-aza-cytidine (5-aza-dCyd).. Genistein (2-20 micromol/L) reversed DNA hypermethylation and reactivated RARbeta, p16INK4a, and MGMT in KYSE 510 cells. Genistein also inhibited cell growth at these concentrations. Reversal of DNA hypermethylation and reactivation of RARbeta by genistein were also observed in KYSE 150 cells and prostate cancer LNCaP and PC3 cells. Genistein (20-50 micromol/L) dose-dependently inhibited DNA methyltransferase activity, showing substrate- and methyl donor-dependent inhibition. Biochanin A and daidzein were less effective in inhibiting DNA methyltransferase activity, in reactivating RARbeta, and in inhibiting cancer cell growth. In combination with trichostatin, sulforaphane, or 5-aza-dCyd, genistein enhanced reactivation of these genes and inhibition of cell growth.. These results indicate that genistein and related soy isoflavones reactivate methylation-silenced genes, partially through a direct inhibition of DNA methyltransferase, which may contribute to the chemopreventive activity of dietary isoflavones.

Topics: Anticarcinogenic Agents; Antineoplastic Agents; Azacitidine; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p16; Decitabine; DNA Methylation; Dose-Response Relationship, Drug; Esophageal Neoplasms; Genistein; Glycine max; Humans; Hydroxamic Acids; Isoflavones; Isothiocyanates; O(6)-Methylguanine-DNA Methyltransferase; Receptors, Retinoic Acid; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sulfites; Sulfoxides; Tea; Thiocyanates

In human prostate cancer cells, the availability of the steroid hormone 1,25-dihydroxyvitamin D(3) for antimitotic action is determined through the activity of the two enzymes CYP24 and CYP27B1, viz. 25-hydroxyvitamin D-24-hydroxylase and 25-hydroxyvitamin D-1alpha-hydroxylase. High performance liquid chromatography (HPLC) analysis of [(3)H]25(OH)D(3) metabolism in human prostate cancer DU-145 cells revealed that genistein and other isoflavonoids, such as dihydrogenistein and daidzein, as well as the antiestrogenic compound ICI 182,780, inhibited Vitamin D-metabolizing enzyme activities. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that only in case of genistein this was due to transcriptional inhibition of CYP24 and CYP27B1 gene expressions. In case of CYP27B1, reduction of gene activity involves histone deacetylation because genistein was inactive in the presence of the histone deactylase inhibitor trichostatin A. In contrast, under the same condition, CYP24 gene activity was largely suppressed. In summary, our results suggest that a combined effect of genistein and trichostatin A could increase the responsiveness of human prostate cancer cells to the antiproliferative action of 1,25-dihydroxyvitamin D(3).

Topics: 25-Hydroxyvitamin D3 1-alpha-Hydroxylase; Cell Division; Chromatography, High Pressure Liquid; Cytochrome P-450 Enzyme Inhibitors; Enzyme Inhibitors; Estradiol; Estrogen Antagonists; Estrogens, Non-Steroidal; Fulvestrant; Genistein; Histone Deacetylases; Humans; Hydroxamic Acids; Isoflavones; Male; Phytoestrogens; Plant Preparations; Prostatic Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Steroid Hydroxylases; Time Factors; Transcription, Genetic; Tumor Cells, Cultured; Vitamin D; Vitamin D3 24-Hydroxylase