A study on Milk Thistle

[vindiesel]

Silymarin inhibits function of the androgen receptor by reducing nuclear localization of the receptor in the human prostate cancer cell line LNCaP

Wen Zhu, Jin-San Zhang and Charles Y.F. Young,1

Department of Biochemistry and Molecular Biology and Department of Urology, Mayo Graduate School, Mayo Clinic/Foundation, Rochester, MN 55905, USA

A number of reports have shown that the polyphenolic flavonoid silymarin (SM) is an effective anticancer agent. Agents with novel mechanisms of blocking androgen receptor (AR) function may be useful for prostate cancer prevention and therapy. Previous studies showed that silibinin (S, the major active component of SM, could inhibit cell proliferation of a human prostate cancer cell line, LNCaP, by arresting the cell cycle at the G1 phase without causing cell death. This study further delineates the potential molecular mechanism by which SM and SB exhibit antiproliferative effects on androgen-responsive prostate cancer cells by inhibiting function of the AR. We observed that SM and SB inhibited androgen-stimulated cell proliferation as well as androgen-stimulated secretion of both prostate-specific antigen (PSA) and human glandular kallikrein (hK2). Additionally, for the first time, we show that an immunophilin, FKBP51, is androgen regulated and that this up-regulation is suppressed by SM and SB. We further demonstrate that transactivation activity of the AR was diminished by SM and SB using gene transfer of PSA promoter and hK2 androgen-responsive element constructs. However, expression and steroid-binding ability of total AR were not affected by SM in western blotting and ligand-binding assays. Intriguingly, we found that nuclear AR levels are significantly reduced by SM and SB in the presence of androgens using western blotting assay and immunocytochemical staining. This study provides a new insight into how SM and SB negatively modulate androgen action in prostate cancer cells.

[vindiesel]

Pregnenolone

Neurosteroids: biosynthesis, metabolism and function of pregnenolone and dehydroepiandrosterone in the brain.

Pregnenolone (P) and dehydroepiandrosterone (D) accumulate in the brain as unconjugated steroids and their sulfate (S) and fatty acid (L) esters. The microsomal acyl-transferase activity is highest in immature (1-3 weeks old) male rats. The immunocytochemical and biochemical evidence for P biosynthesis by differentiated oligodendrocytes is reviewed. The importance of P synthesis for its brain accumulation is assessed by the intracysternal injection of the inhibitor aminoglutethimide. Primary glial cell cultures convert P to 20-OH-P, PL, progesterone, 5 alpha-pregnane-3,20-dione and 3 alpha-hydroxy-5 alpha-pregnane-20-one (Polone). Astroglial cell cultures also produce these metabolites, whereas neurons from 17-day mouse embryos only form 20-OH-P. P and D are converted to the corresponding 7 alpha-hydroxylated metabolites by a very active P-450 enzyme from rat brain microsomes. Several functions of neurosteroids are documented. P decreases in olfactory bulb of intact male rats exposed to the scent of estrous females. D inhibits the aggressive behavior of castrated male mice towards lactating female intruders. The D analog 3 beta-methyl-androst-5-en-17-one, which cannot be metabolized into sex steroids and is not demonstrably androgenic or estrogenic is at least as efficient as D. Both compounds elicit a marked decrease of PS in rat brain. The Cl- conductance of gamma-aminobutyric (GABAA) receptor is stimulated by GABA agonists, an effect which is enhanced by Polone and antagonized by PS. Thus, P metabolites in brain as well as steroids of extraencephalic sources may be involved physiologically in GABAA receptor function. The neurosteroids accumulated in brain may be precursors of sex steroid hormones and progesterone receptors have been localized in glial cells. P and D do not bind to any known intracellular receptor. A heat stable P binding protein has been found in brain cytosol with distinct ligand specificity. A binding component specific for steroids sulfates, including Polone S, DS and PS, in the order of decreasing affinity is localized in adult rat brain synaptosomal membranes. Its relationship to the GABAA receptor is under current investigation.

[ludakris9]

bump thanks for the info bro.

[vindiesel]

Originally Posted by ludakris9

bump thanks for the info bro.

sis, not bro ct*)

[SHINE]

Originally Posted by missdiesel

Silymarin inhibits function of the androgen receptor by reducing nuclear localization of the receptor in the human prostate cancer cell line LNCaP

Wen Zhu, Jin-San Zhang and Charles Y.F. Young,1

Department of Biochemistry and Molecular Biology and Department of Urology, Mayo Graduate School, Mayo Clinic/Foundation, Rochester, MN 55905, USA

A number of reports have shown that the polyphenolic flavonoid silymarin (SM) is an effective anticancer agent. Agents with novel mechanisms of blocking androgen receptor (AR) function may be useful for prostate cancer prevention and therapy. Previous studies showed that silibinin (S, the major active component of SM, could inhibit cell proliferation of a human prostate cancer cell line, LNCaP, by arresting the cell cycle at the G1 phase without causing cell death. This study further delineates the potential molecular mechanism by which SM and SB exhibit antiproliferative effects on androgen-responsive prostate cancer cells by inhibiting function of the AR. We observed that SM and SB inhibited androgen-stimulated cell proliferation as well as androgen-stimulated secretion of both prostate-specific antigen (PSA) and human glandular kallikrein (hK2). Additionally, for the first time, we show that an immunophilin, FKBP51, is androgen regulated and that this up-regulation is suppressed by SM and SB. We further demonstrate that transactivation activity of the AR was diminished by SM and SB using gene transfer of PSA promoter and hK2 androgen-responsive element constructs. However, expression and steroid-binding ability of total AR were not affected by SM in western blotting and ligand-binding assays. Intriguingly, we found that nuclear AR levels are significantly reduced by SM and SB in the presence of androgens using western blotting assay and immunocytochemical staining. This study provides a new insight into how SM and SB negatively modulate androgen action in prostate cancer cells.

Looks like milk thistle might have then verry positive effects as part of pct to help reduce effects of adnrogens on the prostate (enlargment) and to help restart the hpta do to androgens feed back on the hpta maybe?

although ATD I think has a much stronger anti-androgen effect than SM.

good read, thanks!