Journal Article

The chemopreventive action of catechins in the TRAMP mouse model of prostate carcinogenesis is accompanied by clusterin over-expression

Andrea Caporali, Pierpaola Davalli, Serenella Astancolle, Domenico D'Arca, Maurizio Brausi, Saverio Bettuzzi and Arnaldo Corti

in Carcinogenesis

Volume 25, issue 11, pages 2217-2224
Published in print November 2004 | ISSN: 0143-3334
Published online November 2004 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgh235
The chemopreventive action of catechins in the TRAMP mouse model of prostate carcinogenesis is accompanied by clusterin over-expression

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Clusterin (CLU) protein is widely distributed in animal tissues and is involved in many different processes, including apoptosis and neoplastic transformation. Green tea catechins (GTC) are known to exert chemopreventive effects in many cancer models, including transgenic adenocarcinoma mouse prostate (TRAMP) mice that spontaneously develop prostate cancer (CaP). We report here that growth of SV40-immortalized human prostate epithelial cells (PNT1A) as well as tumorigenic, poorly differentiated prostate cancer cells (PC-3) was potently inhibited by EGCG, the major green tea catechin, while normal human prostate epithelial cells were not significantly affected. IC50 doses of EGCG for 24 h caused caspase cascade activation and CLU protein accumulation in both cells lines but not in normal cells, in which CLU remained undetectable. While 100% of TRAMP mice developed CaP, only 20% of those receiving 0.3% GTC in drinking water developed the neoplasm. In TRAMP mice, the CLU gene was dramatically down-regulated during onset and progression of CaP. In GTC-treated TRAMP mice in which tumor progression was chemoprevented, CLU mRNA and protein progressively accumulated in the prostate gland. CLU dropped again to undetectable levels in animals in which GTC chemoprevention failed and CaP developed. Up-regulation of histone H3 and down-regulation of growth arrest-specific gene 1 (Gas1) mRNAs in CaP-developing TRAMP mice demonstrated a high proliferation rate in tumors, while the opposite occurred in the glands of GTC chemoprevented animals. Failure of GTC chemoprevention caused induction of both histone H3 and Gas1 and down-regulation of CLU. Immunohistochemistry experiments confirmed CLU down-regulation during CaP onset and progression, and CLU sustained expression in chemoprevented TRAMP mice. A possible role for CLU as a novel tumor-suppressor gene in the prostate is thus suggested.

Keywords: CaP, prostate cancer; CLU, clusterin; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; Gas1, growth arrest-specific gene 1; GTC, green tea catechins; PIN, prostate intra-epithelial neoplasia; TRAMP, transgenic adenocarcinoma mouse prostate

Journal Article.  6068 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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