DD3(PCA3)-based molecular urine analysis for the diagnosis of prostate cancer.

BACKGROUND: DD3(PCA3) is the most prostate cancer-specific gene described to date. To assess the clinical utility of DD3(PCA3) a time-resolved fluorescence-based, quantitative RT-PCR analysis for DD3(PCA3) was developed. METHODS: The diagnostic potential of DD3(PCA3) was determined by quantitative measurement of DD3(PCA3) transcripts in non-malignant and malignant prostate specimens. Moreover, DD3(PCA3) transcripts were determined quantitatively in urine sediments obtained after prostatic massage. A cohort of 108 men, admitted for prostate biopsies based on a PSA of >3ng/ml, was studied. RESULTS: Prostate tumors showed a 66-fold up-regulation of DD3(PCA3) (median 158.4.10(5) copies/microg tissue RNA) when compared to benign prostate tissue (median 2.4.10(5) copies/microg tissue RNA). This up-regulation was found in more than 95% of prostate cancer specimens studied. These data revealed that specimens with less than 10% of cancer cells could be accurately discriminated from non-cancer tissues. Hence, detection of a small fraction of prostate cancer cells in a background of normal cells seemed feasible. Therefore, this DD3(PCA3)-based RT-PCR assay was used for the identification of prostate cancer in urine sediments obtained after prostatic massage. From 108 men with a serum PSA value >3ng/ml, 24 men were shown to have prostate cancer upon biopsy. Of these 24 men, 16 were shown to be positive for DD3(PCA3), indicating a sensitivity of the assay of 67%. Furthermore, a negative predictive value of 90% was calculated. CONCLUSION: The quantitative RT-PCR assay for DD3(PCA3) described, bears great promise as a tool for molecular urine analysis. It has great potential in reducing the number of unnecessary biopsies. A multi-center study using this DD3(PCA3) assay can provide the basis for the utility of molecular diagnostics in clinical urological practice.

Intermediate cells in human prostate epithelium are enriched in proliferative inflammatory atrophy.

Within the human prostate epithelium four cell populations can be discriminated based on their expression of keratins (K). Basal cells express high levels of K5 and K14, as well as p63, whereas they have very low levels of androgen receptor, prostate-specific antigen (PSA), K8, and K18. Luminal secretory cells lack p63, K5, and K14 but express high levels of K8, K18, androgen receptor, and PSA. Additionally, cells have been identified with a keratin phenotype intermediate between basal and luminal cells that co-express high levels of K5 and K18 (K5/18) as well as hepatocyte growth factor receptor c-MET. Although intermediate cells have been proposed as precursor cells of prostate cancer, their biology is ill defined. Epithelial cells in proliferative inflammatory atrophy (PIA) appear to be cycling rapidly as indicated by expression of Ki-67, and morphological transitions have been identified between PIA and high-grade prostate intraepithelial neoplasia. Many of the atrophic epithelial luminal cells in PIA are candidates for intermediate cells based in part on weak expression of PSA and androgen receptor, high levels of K8/18, and lack of p63. The objective of this study was to further clarify the phenotype of the proposed intermediate cells in PIA and to quantitatively determine the level in which these intermediate cells preferentially occur in PIA lesions. Intermediate cells were immunohistochemically demonstrated using antibodies to K5, K14, K18, and c-MET. Using radical prostatectomy specimens (n = 15) the area fraction of intermediate cells in normally differentiated prostate epithelium and PIA were quantified by a grid point counting method. Atrophic luminal cells of PIA lesions expressed K5 in 39.2 +/- 7.4% of cells compared to 2.4 +/- 2.3% in normal epithelium (P < 0.00001). By contrast, K14 was only expressed in 3.0 +/- 3.2% of the luminal cells. Previous studies have shown that virtually 100% of these atrophic luminal cells are strongly positive for K8/18. c-MET was present in 44.1 +/- 14.1% of luminal cells in PIA but only in 2.1 +/- 2.8% of luminal cells in normal epithelium (P < 0.00001). To unambiguously determine whether intermediate luminal cells in PIA show increased proliferative activity and decreased p27(kip1) expression, double-staining immunofluorescence of Ki-67 and K5, as well as p27(Kip1) and K5 was performed. Luminal cells in PIA often co-expressed K5 and Ki-67. Although p27(Kip1) was strongly expressed in K5-negative differentiated cells in normal epithelium, p27(Kip1) staining was absent in many of the K5-positive cells in the luminal compartment of PIA. We conclude that cells phenotypically intermediate between basal and secretory cells are enriched in PIA lesions. The finding of a large number of highly proliferating intermediate cells in PIA provides further support that these cells may serve as preferred target cells in prostate carcinogenesis.

Intermediate cells in normal and malignant prostate epithelium express c-MET: implications for prostate cancer invasion.

BACKGROUND: Analysis of keratin (K) expression discriminates luminal (K18) and intermediate (K5/18) cells in prostate carcinoma, while basal (K5/14) cells are absent. Intermediate cells have been proposed as targets of malignant transformation in prostate cancer and precursors of androgen-independent tumor progression. We demonstrate localization of hepatocyte growth factor (HGF) receptor c-MET in intermediate cells in both normal and malignant prostate epithelium. METHODS: Receptor localization was analyzed using triple staining for c-MET, K5, K14, and K18. The percentage of strongly c-MET positive cells was determined in 15 prostate cancer patients undergoing androgen-deprivation and 14 patients without neo-adjuvant treatment. Effects of HGF were investigated on prostate cancer cell line DU145. RESULTS: c-MET expression in non-malignant epithelium was strong in intermediate cells absent in differentiated cells, and heterogeneous in basal cells. In prostate cancer, intermediate cells displayed high c-MET levels coupled with mild expression in differentiated cells. During androgen-deprivation, 7.6% of tumor cells revealed high c-MET expression compared to 1.7% without treatment (P = 0.02). Matrigel penetration of DU145 was 8.2 +/- 1.7 mm(2) after HGF stimulation compared to 3.6 +/- 2.4 mm(2) in controls (P < 0.02). CONCLUSIONS: Intermediate cells in normal and malignant prostate epithelium express high c-MET levels, indicating that they are prone to stromal invasion in prostate carcinoma.