Chemopreventive efficacy of inositol hexaphosphate against prostate tumor growth and progression in TRAMP mice.
OBJECTIVE
Herein, for the first time, we evaluated the in vivo chemopreventive efficacy of inositol hexaphosphate (IP6), a major constituent of high-fiber diets, against prostate tumor growth and progression in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model.


METHODS
Beginning at 4 weeks of age, male TRAMP mice were fed 2% (w/v) IP6 in drinking water or only drinking water till 24 weeks of age, and then sacrificed. Prostate tissue was subjected to histopathologic analysis and to immunohistochemical analyses for proliferation and apoptosis.


RESULTS
IP6 feeding did not show any adverse effect on fluid and diet consumption and body weight. There was a significant reduction (40%; P < 0.01) in lower urogenital tract weight in IP6-fed mice. IP6 inhibited prostate cancer progression at prostatic intraepithelial neoplasia stage and strongly reduced the incidence of adenocarcinoma (prostatic intraepithelial neoplasia/adenocarcinoma, 75:25% in the IP6 group versus 39:61% in the control group; P < 0.05). The incidences of well-differentiated and poorly differentiated adenocarcinomas in the IP6-fed group were reduced by 44% and 62%, respectively. Immunohistochemical analysis of prostate tissue showed a 26% decrease (P < 0.05) in proliferation cell nuclear antigen-positive cells and a 3.5-fold increase in apoptotic cells with no effect on Tag expression by IP6.


CONCLUSIONS
These findings are both novel and highly significant in establishing for the first time that oral IP6, without any toxicity, suppresses prostate tumor growth and progression at the neoplastic stage, thereby reducing the incidence of adenocarcinoma through its antiproliferative and proapoptotic effects, and thus indicating that IP6 could have potential chemopreventive effects against human prostate cancer.
Raina
Komal
K
Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver, Denver, Colorado 80262, USA.
Rajamanickam
Subapriya
S
Singh
Rana P
RP
Agarwal
Rajesh
R
D000230:Adenocarcinoma / Q000517:prevention & control*; D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D010833:Phytic Acid / Q000627:therapeutic use*; D011471:Prostatic Neoplasms / Q000517:prevention & control*
D000970:Antineoplastic Agents; D010833:Phytic Acid