Combined inhibitory effects of soy isoflavones and curcumin on the production of prostate-specific antigen.
BACKGROUND
Sustained chronic inflammation in the prostate promotes prostate carcinogenesis. Since an elevated level of prostate-specific antigen (PSA) per se reflects the presence of inflammation in the prostate, intervention to improve the PSA value might potentially have beneficial effects for the prevention of the development of prostate cancer. Isoflavones and curcumin have anti-inflammatory and anti-oxidant properties. We examined the biological effects of soy isoflavones and curcumin on LNCaP cells. After that, we conducted a clinical trial for men who received prostate biopsies, but were not found to have prostate cancer, to evaluate the effects of soy isoflavones and curcumin on serum PSA levels.


METHODS
The expression of androgen receptor and PSA were examined in LNCaP cells before and after treatment of isoflavones and/or curcumin. Eighty-five participants were randomized to take a supplement containing isoflavones and curcumin or placebo daily in a double-blind study. Subjects were subdivided by the cut-off of their baseline PSA value at 10 microg/ml. We evaluated values of PSA before and 6 months after treatment.


RESULTS
The production of PSA were markedly decreased by the combined treatment of isoflavones and curcumin in prostate cancer cell line, LNCaP. The expression of the androgen receptor was also suppressed by the treatment. In clinical trials, PSA levels decreased in the patients group with PSA >or= 10 treated with supplement containing isoflavones and curcumin (P = 0.01).


CONCLUSIONS
Our results indicated that isoflavones and curcumin could modulate serum PSA levels. Curcumin presumably synergizes with isoflavones to suppress PSA production in prostate cells through the anti-androgen effects.
Ide
Hisamitsu
H
Department of Urology, Teikyo University School of Medicine, Itabashi-ku, Tokyo, Japan.
Tokiwa
Shino
S
Sakamaki
Kentaro
K
Nishio
Koujiro
K
Isotani
Shuji
S
Muto
Satoru
S
Hama
Takanori
T
Masuda
Hiroko
H
Horie
Shigeo
S
D000368:Aged; D000369:Aged, 80 and over; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003474:Curcumin / Q000008:administration & dosage / Q000494:pharmacology*; D004311:Double-Blind Method; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D011944:Receptors, Androgen / Q000096:biosynthesis / Q000097:blood
D000894:Anti-Inflammatory Agents, Non-Steroidal; D007529:Isoflavones; D011944:Receptors, Androgen; D017430:Prostate-Specific Antigen; D003474:Curcumin