The expression of MMP-2, MMP-9, TIMP-1, TIMP-2, and the urokinase receptor were examined in fetal and normal prostate tissues, benign prostatic hyperplasia and prostate cancer (n = 117). In situ hybridization with digoxigenin-labeled oligonucleotide probes demonstrated that TIMP-1 and TIMP-2 were expressed at elevated levels in the stroma of Gleason sum 5 tissues, whereas MMP-2 and MMP-9 were expressed at relatively low levels. In higher Gleason sum tissues (GS 8-10), TIMP-1 and TIMP-2 were not expressed, whereas MMP-2 and MMP-9 were intensely expressed. Furthermore, TIMP-1 and TIMP-2 expression was high in organ-confined specimens (OC, n = 43), somewhat lower in specimens with capsular penetration (CP, n = 29), and low or negative in samples with surgical margin/seminal vesicle (M/SV, n = 17) and lymph node (LN, n = 13) involvement. In contrast, MMP-2 and MMP-9 expression was low in the OC tissues; and noticeably higher in CP, M/SV, and LN specimens. Finally, correlation of TIMP and MMP expression with GS and pathological stage versus cure rate further revealed that a high percentage of organ-confined, GS 5 specimens expressing TIMP and little MMP were cured. In comparison, few of the GS 7-10 patients with capsular penetration and expressing MMP and little TIMP were cured. The data suggest that TIMP-1 (and TIMP-2) and MMP-2 (and MMP-9) are independent predictors of outcome.

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Normal prostate epithelial cells are dif®cult to propagate in vitro without experimental immortalization. The goal of this study was to isolate and characterize a propagable epithelial cell line from normal adult rat prostate. Enrichment of proliferation-competent cells was accomplished in vivo by initiating a single cycle of prostatic involution/regeneration. The RPE-F344 cell line was established from an androgen-deprived, involuted prostate four days after the initiation of regeneration by administration of testosterone. The cell line has been cultured in vitro for b 50 passages, forms a uniform monolayer in culture, exhibits contact inhibition at con¯uence, and does not form colonies in soft agar. Immunocytochemical and RT-PCR analyses demonstrated that the RPE-F344 cells express anti-apoptotic genes associated with cell survival, and several growth factor receptors important in prostate development and homeostasis. RPE-F344 cells are p27kip1 negative, telomerase positive, and express high molecular weight cytokeratins speci®c for prostatic basal cells. They also express low levels of androgen receptor (AR) and prostatic acid phosphatase (PAP); features associated with secretory luminal epithelial cells. RPE-F344 cells are maintained in vitro without androgen supplementation, but addition of 15nM dihydrotesterone (DHT) to the culture media results in a signi®cant but transient enhancement of cellular proliferation. Establishment of RPE-F344-like colonies from rat prostate is limited to the ventral and dorsal lobes of the prostate 2 ± 4 days after initiation of regeneration, suggesting that RPE-F344 cells may originate from a stem celllike compartment that is responsible for regenerative repopulation.