Carcinogenesis Advance Access published online on April 15, 2008
Carcinogenesis, doi:10.1093/carcin/bgn097
Glutathione S-transferase pi mediates proliferation of androgen independent prostate cancer cells.
1 Department of Experimental Pathology and Tumor Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
2 Section for Studies on Metastasis, National Cancer Center Research Institute, Tokyo, Japan
*To whom correspondence should be addressed. Tel: +81 52 853 8156; Fax: +81 52 841 0817; Email: masamoto{at}med.nagoya-cu.ac.jp
Prostate cancers generally acquire an androgen independent growth capacity with progression, resulting in resistance to anti-androgen therapy. Therefore, identification of the genes regulated through this process may be important for understanding of mechanisms of prostate carcinogenesis. We here utilized androgen dependent/independent transplantable tumors, newly established with the "Transgenic Rat Adenocarcinoma in Prostate" (TRAP) model, to analyze their gene expression using microarrays. Among the overexpressed genes in androgen independent prostate cancers compared to the androgen dependent tumors, glutathione S-transferase, pi (GST-pi) was included. In line with this, human prostate cancer cell lines PC3 and DU145 (androgen independent) had higher expression of GST-pi compared to LNCaP (androgen dependent) as determined by semi-quantitative RT-PCR analysis. To investigate roles of GST pi expression in androgen independent human prostate cancers, GST-pi was knocked down by a siRNA, resulting in significant decrease of the proliferation rate in the androgen independent PC3 cell line.
In vivo, administration of GST-pi siRNA/atelocollagen complex decreased GST-pi protein expression, resulting in enhanced numbers of TUNEL positive apoptotic cells. These findings suggest that GST-pi might play important roles in proliferation of androgen independent human prostate cancer cells.
Received December 1, 2007; revised April 2, 2008; accepted April 8, 2008.