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Diagnostic potential of transcript signatures in minimal prostate tissue specimens. Manfred P. Wirth Department of Urology Technical University of Dresden. [supported by a grant from the DFG]. Objective. main problem: early identification of significant PCa for therapeutic decisions
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Diagnostic potential of transcript signatures in minimal prostate tissue specimens Manfred P. Wirth Department of Urology Technical University of Dresden [supported by a grant from the DFG]
Objective • main problem: early identification of significant PCa for therapeutic decisions • need for new additional PCa-markers to improve diagnostic and prognostic power • quantification of transcript markers as promising tool • expression signatures more reliable than single markers
Material & methods I • establishment of standardized quantitative • PCR-assays (using gene-specific fluorescent probes) • 169 matched pairs of malignant and non-malignant prostate tissue specimens (Tu + Tf) from RPE specimens • evaluation of 4 housekeeping genes as reference • for internal normalization: • different expression between Tu and Tf?
Material & methods II • different expression of 3 reference genes: • GAPDH = glyceraldehyde-3-phosphate dehydrogenase • HPRT = hypoxanthine phosphoribosyltransferase • PBGD = porphobilinogen deaminase • only TATA box binding protein (TBP) suitable (no different expression)
Material & methods III 12 PCa-related genes known from literature were tested * prostate-specific genes, but not highly overexpressed in PCa
Material & methods III • evaluation of single & combined markers • (ROC-analyses) • mathematical models for PCa-specific transcript signatures • goals: -prediction of PCa-presence • - prediction of tumor extension • - prediction of tumor aggressiveness • final aim: bioprofiling of PCa
Evaluation of single markers: overexpression in PCa? n=169 PCA3 (=DD3), AMACR, PSGR, hepsin, TRPM8 & PSMA most promising PCa transcript markers
predicted probability of tumor AUC = 0.89 (95% CI 0.76 ... 1.00) 1- Specificity Optimized 4-gene-model for PCa-prediction: EZH2 + PCA3 + prostein + TRPM8 • classification of relative expression levels of these 4 genes according optimized cut-offs logit-value for each tissue sample (Tu and Tf) • logit-model: p = exp(logit)/[1+exp(logit)] probability (p) of PCa presence in the analyzed tissue samples: median p for Tu 81% median p for Tf 21% ROC-analysis of the 4-gene-combination n=169
Dependence of marker expression on tumor stage: Discrimination between organ-confined disease (OCD) and non- organ-confined disease (NOCD) for therapeutic decision? Tf: n=169 OCD: n=90 NOCD: n=79 • comparison only of Tu-samples of OCD vs. NOCD or • comparison of Tf- vs. Tu-samples of OCD vs. Tu-samples NOCD • mathematical models for OCD-prediction in process
Transfer to artificial biopsies • translation of the techniques to prostate biopsies • additional diagnostic tool on minimal prostate • tissue samples for better PCa-detection • 11 selected PCa-related genes and TBP • first results of application and validation of two • multi-gene-models for PCa prediction
H&E-stained cuttings (PCa-patient: pT2a, pN0, pMx Gleason Score: 7 [3+4]) Tu-prostate tissue sample Tf-prostate tissue sample Artificial needle core biopsies from RPE explants • artificial biopsies: Tf & Tu from one RPE specimen • snap-frozen in planar direction on paper strip in liquid N2 • cryo-cuttings for RNA-isolation & pathological survey
artificial biopsies (cryo conservation): prostate tissue sample between glass plates biopsy on paper strip liquid nitrogen Cryo-cuttings: --for RNA isolation and 6 representaive cryo-slices for histopthaological examination biopsy profile cryo-slices Handling and processing of artificial biopsies
Patient cohort of the pilot study • 11 patients with a primary PCa • age: 51 to 71 years (median 66 years) • serum PSA levels: 1.29 to 24.32 ng/ml (median 6.9 ng/ml) • Histopathological examination: according to the UICC system • 7 patients (64%) with organ-confined disease (OCD; pT2) • 4 patients (36%) with non organ-confined disease (NOCD; pT3/T4) • Tumor grading: 2 patients with low grade (GS 6) • 8 patients with intermediate grade (GS 7) • and 1 patient with high grade (GS 8)
Validation of the multi-gene model on artificial biopsies • „false-positive“: meaning? • verification in future studies with increased sample numbers
Outlook I • translation of the techniques to diagnostic biopsies • improvement of PCa detection • (Are false-positives really false-positives?) • correct prediction of tumor aggressiveness • active surveillance vs. curative treatment • correlation of transcript signatures with outcome? • follow-up needed for prognostic purposes
Outlook II • detection of PCa-specific transcripts in urine samples • non-invasive tumor detection? • PCA3 (DD3) detection in urine samples in • validation (APTIMA PCA3; Gen-probe incorp.) • (PCA3 is a non-coding RNA only at transcript level measurable) • transcript quantification in urine samples as a promising tool
Acknowledgment • Dept. of Urology, Technical University of Dresden: • Laboratory: Axel Meye, Susanne Füssel, Susanne Unversucht, • Andrea Lohse, Silke Tomasetti, Uta Schmidt • Clinic: Michael Fröhner, Stefan Zastrow, Marc-Oliver Grimm • Inst. of Pathology, Technical University of Dresden: • Gustavo Baretton, Michael Haase, Marietta Toma • Inst. of Medical Informatics and Biometry • Rainer Koch