Glutathione S-transferase pi is upregulated in the stromal compartment of hormone independent prostate cancer

BACKGROUND: Glutathione S-transferase (GST) pi is a detoxifying enzyme abundant in normal prostate basal cells but only rarely expressed in prostate cancer cells. The current studies are the first to focus on GST pi in the stromal compartment of prostate tumors. METHODS: We employed immunohistochemical, immunofluorescence, and Western blot analysis to measure GST pi expression and subcellular localization in 21 primary and metastatic tumors from patients with hormone independent prostate cancer, as well as seven lymph node metastases and six prostatectomy specimens. RESULTS: GST pi was detectable in stromal cells in 17 of the 21 hormone independent prostate tumors. GST pi tissue distribution in hormone independent tumors coincided with vimentin staining, suggesting that GST pi is expressed by reactive fibroblasts and/or myofibroblasts. CONCLUSIONS: The current results suggest that prostate cancer cells induce an injury response in the stroma during progression to hormone independence, which results in GST pi expression. Stromal GST pi may contribute to chemoresistence of advanced prostate cancer.