Biomedical subjects

Hans Krause

Publications and source records attributed to Hans Krause.

25 records · Page 2Linked to original sources

PubMed2003

Methylation-specific PCR for DNA-based detection of occult tumor cells in lymph nodes of prostate cancer patients.

OBJECTIVES: To assess the feasibility of methylation-specific PCR (MSP) for the detection of promoter hypermethylation of the detoxifying glutathione-S-transferase P1 gene (GSTP1) to detect occult prostate cancer cells in lymph nodes (LNs). METHODS: Paraffin-embedded pelvic LNs from 20 patients with pT2pN0M0R0 prostate cancer who developed PSA relapse were assessed by MSP. In 18 of the patients, samples of the primary tumor were obtained for MSP. In 19 patients, bone marrow (BM) aspirates were analyzed preoperatively for disseminated tumor cells by immunocytochemistry (mAb A45-B/B3). In 16 patients, biopsies of the anastomotic region were performed following PSA relapse. As a negative control GSTP1 methylation status was also assessed in LNs from 9 patients for whom an autopsy was performed for non-cancer-related causes. RESULTS: All primary tumors displayed GSTP1 hypermethylation (HM). Preoperative BM assessment showed disseminated tumor cells in 8/20 cases (40%). In 4 patients, biopsies of the vesico-urethral anastomosis showed local tumor recurrence. The LNs in the cancer patients showed GSTP1 HM in 18/20 cases (90%) versus 1/9 patients (11.1%) in the non-cancer cohort (p<0.0001). CONCLUSION: GSTP1 HM appears to be well suited for molecular staging of prostate cancer and accurately detects disseminated tumor cells in LNs, which was seen in 90% of the patients with PSA relapse. However, the limited number of patients and the finding of benign and malignant prostatic tissue at the vesico-urethral anastomosis as a putative local source of PSA recurrence does not allow us to draw conclusions on the prognostic significance of our findings, yet.

Aged↗

PubMed2003

Quantitative real-time rt-PCR for detection of circulating prostate-specific antigen mRNA using sequence-specific oligonucleotide hybridization probes in prostate cancer patients.

OBJECTIVE: A great number of studies have failed thus far to demonstrate that the presence of PSA-expressing tumor cells in the blood of prostate cancer (PC) patients is a highly sensitive prognostic marker, particularly after radical prostatectomy (RPX). These studies have only relied on qualitative or semiquantitative detection techniques, however. We report our initial experience in testing real-time RT-PCR for the detection of PSA mRNA using a quantitative online PCR system, the LightCycler(TM), and sequence-specific oligonucleotide hybridization probes. METHODS: Blood samples were obtained before and after surgery from 129 patients undergoing RPX for localized PC and from 19 patients undergoing transurethral resection of the prostate for benign prostatic hyperplasia (BPH). Quantitative RT-PCR for the detection PSA mRNA was performed using the LightCycler system with RNA Amplification Kit Hybridization Probes and sequence-specific oligonucleotide hybridization probes. RESULTS: PSA mRNA was detected by the LightCycler in 28 patients (39%) with pT2 tumors, in 22 patients (38%) with >pT2 tumors, but in only 3 patients (16%) with BPH. The mean values of the LNCaP cell equivalents were higher in >pT2 patients than in pT2 patients (37 x 10(3) and 104 x 10(3)) or BPH patients (7.1 x 10(3) and 4.8 x 10(3)) both preoperatively (333 x 10(3)/ml blood) and postoperatively (545 x 10(3)). CONCLUSION: Real-time RT-PCR with the LightCycler appears to be a promising method for the preoperative detection of circulating LNCaP tumor cells in PC as reflected by PSA mRNA. Considering the low detection rates in BPH patients, the method may also be suitable for patient monitoring after RPX and could thus play an important role in deciding on early radiotherapy or even hormone ablation therapy. Additional long-term follow-up will have to show whether patients with high expression of PSA mRNA actually have an increased risk or recurrence and whether the method is suitable as well to detect progression.

Aged↗

PubMed2002

The differentiation status of primary gonadal germ cell tumors correlates inversely with telomerase activity and the expression level of the gene encoding the catalytic subunit of telomerase.

BACKGROUND: The activity of the ribonucleoprotein enzyme telomerase is detectable in germ, stem and tumor cells. One major component of telomerase is human telomerase reverse transcriptase (hTERT), which encodes the catalytic subunit of telomerase. Here we investigate the correlation of telomerase activity and hTERT gene expression and the differentiation status of primary testicular germ cell tumors (TGCT). METHODS: Telomerase activity (TA) was detected by a quantitative telomerase PCR ELISA, and hTERT mRNA expression was quantified by online RT-PCR in 42 primary testicular germ cell tumors. The control group consisted of benign testicular biopsies from infertile patients. RESULTS: High levels of telomerase activity and hTERT expression were detected in all examined undifferentiated TGCTs and in the benign testicular tissue specimens with germ cell content. In contrast, differentiated teratomas and testicular control tissue without germ cells (Sertoli-cell-only syndrome) showed no telomerase activity and only minimal hTERT expression. CONCLUSIONS: These findings demonstrate an inverse relationship between the level of telomerase activity and hTERT mRNA expression and the differentiation state of germ cell tumors. Quantification of telomerase activity and hTERT mRNA expression enables a new molecular-diagnostic subclassification of germ cell tumors that describes their proliferation potential and differentiation status.

Catalytic Domain↗

PubMed2002

Methylation-specific PCR for detection of neoplastic DNA in biopsy washings.

Epigenetic DNA alterations such as promoter hypermethylation of glutathione S-transferase P1 (GSTP1) in prostatic adenocarcinoma frequently constitute tumour biomarkers. Neoplastic transformation was identified in washings of prostate biopsies by GSTP1 promoter hypermethylation, using methylation-specific PCR (MSP). Twenty-six patients undergoing sextant transrectal prostate biopsies for clinically suspected prostate cancer were enrolled. All ten patients diagnosed with adenocarcinoma (100%) and four of six patients with prostatic intraepithelial neoplasia (67%), but none of ten patients with benign hyperplasia (0%), exhibited GSTP1 promoter hypermethylation in at least one out of six biopsy washings. Since this approach is transferable to various cancer entities, a sensitive and specific DNA-based analysis of biopsy material seems generally feasible without impeding routine histopathological examination.

Adenocarcinoma↗

PubMed2002

Receptor gene messenger RNA expression in metastatic lesions of prostate cancer.

PURPOSE: There are hardly any options for treating hormone refractory prostate cancer. Some groups have already suggested antitumor therapy of prostate cancer using agonists, antagonists or other concepts acting on luteinizing hormone-releasing hormone (LH-RH) receptor. Few studies have been published to date on the detection of LH-RH receptors in human prostate cancer tissue. However, at this point it is completely unclear in this context whether metastasizing prostate cancer lesions, which may be major potential targets of a type of therapy, have any LH-RH receptors. In this study we examined tumor samples of lymph nodes from patients with prostate cancer obtained during radical prostatectomy and laparoscopic lymphadenectomy for the expression of LH-RH receptor messenger (m)RNA. MATERIALS AND METHODS: Multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) was done to detect the expression of the mRNA of LH-RH receptor, prostate specific antigen and beta-actin in pelvic lymph nodes from 100 patients with prostate cancer. RESULTS: In 27 patients at least 1 histopathological metastasis (19) and/or positive RT-PCR for prostate specific antigen (22) was identified. In 7 of these patients (25.9%) RT-PCR revealed LH-RH mRNA expression. CONCLUSIONS: To our knowledge our study shows for the first time a rather low incidence of LH-RH receptor mRNA in primary pelvic lymph node metastases. However, since other studies show that an increased incidence of LH-RH receptors is typical of the hormone refractory stage of the disease, further studies in this specific patient population may help explain the clinical importance of LH-RH receptors in the development of new therapeutic approaches to advanced prostate cancer.

Actins↗

PubMedDate not supplied

Molecular staging of pelvic surgical margins after radical prostatectomy: comparison of RT-PCR for prostate-specific antigen and telomerase activity.

The further course of prostate cancer (PC) after radical prostatectomy (RPX) is decisively influenced by the local tumor stage. Although it is now possible to assess the risk of local recurrence from the histopathology, precise predictions cannot be made. A more accurate evaluation would be desirable, mainly for early planning of adjuvant therapy. We assessed the detection of telomerase activity using the Telomeric Repeat Amplification Protocol in surgical margins compared to RT-PCR-supported prostate-specific antigen (PSA) mRNA detection and conventional histopathological examination. We examined 95 patients with local PC during RPX and 16 patients with muscle-invasive transitional bladder cancer who underwent radical cystectomy. After RPX or RCX biopsies were obtained from 4 or 3 defined areas of the prostatic fossa and processed by TRAP assay for telomerase activity and by RT-PCR for PSA using a standard protocol. Five of 48 patients (10.4%) with organ-confined prostate cancer (pT2) and 7 of 47 patients (14.9%) with locally advanced PC (>pT2) had positive detection of telomerase activity in at least one positive specimen. In contrast to RT-PCR for PSA mRNA and histological findings for organ-confined and locally advanced disease, detection of telomerase activity yielded no statistically significant correlation to clinical parameters. Only PC-patients with positive histopathological margins had a positive correlation between detection of telomerase activity and high Gleason scores (r=0.65, p=0.022). Based on the results obtained and the current state of knowledge, measurement of telomerase activity must be considered less sensitive than RT-PCR for PSA mRNA in surgical margins, although tumor specificity should theoretically be higher. It is not even sure at the present time whether a combination of both methods offers any recognizable advantage over PSA mRNA detection alone. The value of the results obtained in this study will have to be assessed in a further follow-up to determine whether patients with positive molecular detection have an increased risk of local recurrence.

Aged↗

PubMedDate not supplied

Quantification of human telomerase reverse transcriptase mRNA in testicular germ cell tumors by quantitative fluorescence real-time RT-PCR.

Telomerase is a ribonucleoprotein enzyme which is endogenously expressed in germ, stem and tumor cells, but absent in benign somatic cells. The two major telomerase components are human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT). It has been shown that hTERT is rate-limiting for telomerase activity and that it plays a central role in human carcinogenesis. Here, we investigated the potential of hTERT and hTR gene expression as diagnostic markers in testicular germ cell tumors (TGCT). hTERT mRNA and hTR expression were quantified in 55 testicular germ cell tumors comprising 36 primary and 19 germ cell tumors from retroperitonal sides by fluorescence real-time RT-PCR using the LightCycler technology. Porphobilinogen deaminase (PBGD) was used as housekeeping gene and to enable relative quantification. For comparison to TGCTs, 38 benign testicular biopsies from patients with fertility disorders were assayed. hTERT expression was detected in all examined undifferentiated TGCTs and in the benign testicular tissue specimens with germ cell content (N(hTERT) 38-127). In contrast, mature teratomas from primary and post-chemotherapy masses, which are characterized by well-differentiated tissue components showed a nearly complete downregulation of hTERT expression (N(hTERT) 2-4, p<0.001). hTR levels however, were high in all tumors and independently of the presence of germ cells also in the benign tissue control group. hTERT mRNA is expressed in all undifferentiated TGCTs but repressed in mature teratomas. This suggests an inverse correlation between the differentiation status of germ cell tumors and hTERT expression. Thus, detection of hTERT expression in tumors histopathologically classified as mature teratomas enables a molecular-diagnostic confirmation and might aid decision making for treatment of patients presenting with this tumor subtype.

Age Factors↗