Biomedical subjects

Mark Schrader

Publications and source records attributed to Mark Schrader.

30 records · Page 2Linked to original sources

PubMed2005

Expression levels of the EZH2 polycomb transcriptional repressor correlate with aggressiveness and invasive potential of bladder carcinomas.

The polycomb group protein enhancer of zeste 2 (EZH2) is a transcriptional repressor involved in the control of cellular proliferation and oncogenesis. The aim of the present study was to quantify EZH2 expression in bladder carcinomas and to correlate the data with clinicopathological findings. EZH2 mRNA expression was measured by real-time reverse transcription-polymerase chain reaction in tumor tissue specimens obtained from 37 patients with urothelial carcinomas of the bladder and in four bladder cancer cell lines. EZH2 levels were normalized to expression of the housekeeping porphobilinogen deaminase gene. EZH2 transcripts were commonly detected in tumor tissue. Transcript levels correlated significantly with the invasiveness of bladder tumors (p = 0.029) with elevated EZH2 mRNA expression measured in invasive bladder carcinomas (median value, 38.92) compared with non-invasive tumors (15.51). In addition, levels of expression were significantly higher in high-grade (G3) than in low-grade (G1/2) lesions (p < 0.001). EZH2 mRNA levels in bladder carcinoma cell lines were within the range of high-grade invasive bladder cancers. In conclusion, expression levels of EZH2 are elevated in aggressive and invasive urothelial carcinomas, suggesting that deregulated EZH2 expression may be involved in the progression of bladder tumors.

Aged↗

PubMed2004

The inhibitor of apoptosis (IAP) survivin is expressed in human testicular germ cell tumors and normal testes.

Deregulated apoptosis of germ cells may contribute to malignant transformation as well as male infertility. We analyzed expression of the inhibitor of apoptosis survivin by polymerase chain reaction (PCR) in testicular germ cell tumors (TGCTs, n=28), normal testes (n=19) and testes with defective spermatogenesis (n=22). In a subset of samples (n=35), survivin transcript levels were quantified using real-time PCR. While survivin mRNA was expressed at high levels in undifferentiated TGCTs and normal testes, it was lost in mature teratomas and germ cell aplasia. Survivin expression in both normal and transformed germ cells is in contrast to its sharp differential expression in other tissues. Survivin expression correlates with the differentiation state of TGCTs and may be relevant for their tumorigenesis and malignant potential.

Cell Transformation, Neoplastic↗

PubMed2004

Expression of the apoptosis inhibitor survivin in testicular tissue of infertile patients.

Summary Apoptosis is a common phenomenon during spermatogenesis, and its dysregulation has been associated with male infertility. Survivin is an inhibitor of apoptosis protein that regulates apoptosis at cell division and is overexpressed in common human cancers. We investigated whether survivin mRNA expression is detectable in testicular biopsies from patients with infertility of varying aetiology. The aim of this study was to examine the testicular survivin expression in azoospermic men with normal spermatogenesis and in those with specific spermatogenic disorders. Survivin mRNA expression was detected by reverse transcriptase-polymerase chain reaction in histologically classified testicular biopsy specimens from 30 azoospermic men. Survivin was found to be expressed in normal spermatogenesis (n = 10), in post-meiotic spermatogenic arrest (n = 6), and in specimens showing a mixed picture of pre-meiotic maturation arrest with sparse islands of post-meiotic arrest (n = 2). In contrast, a lack of survivin expression was seen in specimens without haploid germ cells (pre-meiotic maturation arrest, n = 2) and in those with Sertoli-cell-only syndrome (SCOS, n = 10). These data indicate for the first time that survivin is expressed in human testis. Moreover, its expression seems to correlate with the stage of maturation arrest in patients presenting with spermatogenic disorders. Survivin mRNA expression was not found in SCOS specimens, possibly indicating germ-cell-specific expression in human testicular tissue. Thus, survivin is a potential molecular marker of spermatogenesis, whose expression is altered in specific spermatogenic disorders.

Apoptosis↗

PubMed2003

Real-time quantitative reverse transcriptase-polymerase chain reaction for luteinizing hormone-releasing hormone receptor gene mRNA expression in human prostate cancer.

OBJECTIVES: To determine quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) detection of luteinizing hormone-releasing hormone (LHRH) receptor mRNA expressing prostate cancer (CaP) and benign prostatic hyperplasia (BPH) tissue by sequence-specific detection with hybridization probes using the LightCycler. Various in vitro studies have indicated that LHRH agonists and antagonists may have a direct inhibitory effect on CaP mediated by specific LHRH receptors. The incidence of LHRH receptor mRNA expression was demonstrated in 50% to 100% of clinical CaP and BPH tissue by current RT-PCR methods. However, qualitative RT-PCR can only demonstrate the existence of a gene; an exact quantification of LHRH-receptor mRNA expression has not yet been done. METHODS: Quantitative real-time RT-PCR for LHRH receptor mRNA was performed using the LightCycler system and the RNA Amplification Kit hybridization probes in 35 patients with CaP and 38 patients with BPH. RESULTS: Thirty-one (88.6%) of the 35 patients with CaP and 36 (94.7%) of the 38 patients with BPH had positive RT-PCR for LHRH receptor mRNA. The number of positive amplifications per 1 microg total RNA was not significantly lower in CaP at 695,428 +/- 350,860 than in BPH at 1,617,654 +/- 787,874. Patients with CaP evidenced a significant negative correlation between the amplification rate for LHRH receptor mRNA and Gleason score (r = -0.476; P = 0.004). CONCLUSIONS: In the past, the potential mechanisms acting on LHRH receptors in CaP have been identified as possible antitumor strategies for this type of cancer. Our study is the first to show that CaP does not have a higher expression of LHRH receptor mRNA expression than BPH when using quantitative sequence-specific oligonucleotide hybridization probes that only detect certain PCR products.

Adenocarcinoma↗

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

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↗

PubMed2002

Quantification of cyclin A1 and glyceraldehyde-3-phosphate dehydrogenase expression in testicular biopsies of infertile patients by fluorescence real-time RT-PCR.

The objective of this study was to establish a classification of meiotic disorders by detection of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and cyclin A1 mRNA in patients presenting with non-obstructive azoospermia. GAPDH and cyclin A1 expression levels were detected in 37 histologically classified testicular tissue specimens by one-line RT-PCR. Levels of cyclin A1 expression (NCyclinA1) were high in tissue specimens with full spermatogenesis [3.519 +/- 3.141 (mean +/- SD)] but only minimal in those without haploid germ cells. A lack of cyclin A1 expression was seen in most sertoli-cell-only syndrome (SCOS) specimens. The criteria for an ideal internal standard were only partially met by GAPDH, as we detected decreased expression in tissue samples with maturation arrest [(268.2 +/- 106.2 relative gene expression (mean +/- SD)] and SCOS (201.7 +/- 95.2) compared to those with normal histological findings (325.1 +/- 129.3). It was concluded that the level of cyclin A1 mRNA expression predicts meiotic disorders during spermatogenesis. GAPDH is not an ideal internal standard for specific gene expression in testicular tissue specimens.

Adult↗

PubMed2002

Cyclin A1 and gametogenesis in fertile and infertile patients: a potential new molecular diagnostic marker.

BACKGROUND: The study aim was to evaluate cyclin A1 mRNA expression levels as a potential molecular diagnostic parameter in the work-up of testicular tissue from fertile versus infertile patients. METHODS: Cyclin A1 expression was quantified in 55 cryopreserved testicular tissue specimens by fluorescence real-time RT-PCR. A conventional histological work-up was performed concomitantly in all tissue specimens with additional semi-thin sectioning in all cases of non-obstructive azoospermia (n = 12), maturation arrest (n = 17) and Sertoli cell-only syndrome (SCOS; n = 9). RESULTS: The mean (+/- SD) normalized cyclin A1 expression (N(CyclinA1)) was 3.82 +/- 2.23 relative gene expression (RGE) in tissue specimens with normal spermatogenesis, and 0.625 +/- 0.221 RGE in those with maturation arrest at the level of early spermatids. Only minimal N(CyclinA1) was detected in tissue specimens with spermatogonia only or maturation arrest at the level of primary spermatocytes (0.005 +/- 0.008). Cyclin A1 expression was absent in the majority of SCOS specimens (0.002 +/- 0.002). CONCLUSIONS: These investigations suggested that cyclin A1 expression is altered in cases of spermatogenic disorders. Moreover, the level of cyclin A1 mRNA expression correlates with gametogenic disorders and seems well suited for a molecular-diagnostic classification supplementing the histopathological evaluation of spermatogenic disorders.

Biomarkers↗

PubMed2002

Testicular sperm extraction in azoospermic patients with gonadal germ cell tumors prior to chemotherapy--a new therapy option.

BACKGROUND: In view of the high cure rates in patients with testicular germ cell tumors (TGCT), increasing clinical importance is attached to protection of fertility. Long-term infertility due to cytostatic therapy may be expected in more than 50% of the patients at a cumulative dose of cisplatin > 0.6 g/m2. The standard procedure for fertility protection in cancer patients includes cryopreservation of ejaculated spermatozoa. Considering that some patients have tumor-induced azoospermia, we examined the usefulness of testicular sperm extraction before therapy. METHOD: A survey of the literature served as a basis for investigating biological and clinical aspects of the impact of chemotherapy on male fertility. A study of our patient population also enabled us to explore the option of extracting sperm from the contralateral healthy testis prior to treatment in 14 azoospermic patients with testicular germ cell tumors. RESULTS: We were able to successfully recover haploid germ cells in 6/14 testicular biopsies from azoospermic patients with testicular germ cell cancer prior to treatment. Maturation arrest was found in 3/14 cases and Sertoli-cell-only syndrome in the rest. None of the patients had secondary healing or a treatment delay because of the testicular biopsy. CONCLUSION: Since the post-therapeutic fertility status is difficult to predict in cancer patients, we think that TESE should be regarded as a general option prior to cancer treatment and offered to azoospermic cancer patients. New guidelines should be established in this connection.

Antineoplastic Agents↗

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↗