Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report a quantitative analytical methodology for prostate-specific antigen (PSA) mRNA, which is based on the coamplification of the target with a recombinant RNA internal standard (IS) using reverse transcriptase-polymerase chain reaction. PSA mRNA and the RNA IS contain the same primer recognition sites and generate amplification products that have identical sizes but differ in a 24-bp sequence located in the center of the molecule. Amplified sequences are labeled with biotin using a biotinylated upstream primer. The products are captured on streptavidin-coated microtiter wells and hybridized to specific probes labeled with the hapten digoxigenin. The hybrids are determined using alkaline phosphatase-labeled anti-digoxigenin antibody and time-resolved fluorometry. The ratio of the fluorescence values obtained for the PSA mRNA and the RNA IS is a linear function of the amount of PSA mRNA present in the sample. Samples containing total RNA from PSA-expressing cells (LNCaP cells) in addition to 1 microg of RNA from healthy cells give fluorescence ratios related linearly to the number of cells in the range of 4 to 3000 cells.
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PMID:Quantification of prostate-specific antigen mRNA by coamplification with a recombinant RNA internal standard and microtiter well-based hybridization. 962 39

Our objective was to determine the effect of neoadjuvant hormonal therapy on the presence of circulating prostate cells in patients undergoing radical prostatectomy for prostate cancer. A total of 60 patients at high risk for extraprostatic disease were analyzed for the presence of circulating prostate cells using reverse transcriptase PCR (RTPCR) amplification of the prostate-specific antigen mRNA. Twenty-nine patients underwent radical prostatectomy for a clinical T2b-c tumor or a stage T1c-T2a tumor and a serum prostate-specific antigen level > or =10ng/ml (radical prostatectomy alone), and 31 similarly staged patients received neoadjuvant hormonal therapy before radical prostatectomy (neoadjuvant). Bone marrow samples were used for RTPCR analysis. Twenty-four percent and 58% of the radical-prostatectomy-alone patients and neoadjuvant patients had organ-confined disease, respectively (P = 0.007). In the radical-prostatectomy-alone group, 77% and 14% of patients with extraprostatic and organ-confined disease were RTPCR positive, respectively (P = 0.03). However, in the neoadjuvant group, 46% and 28% of patients with extraprostatic and organ-confined disease were RTPCR positive, respectively (P = 0.29). For patients that were RTPCR positive, 45 % of the neoadjuvant patients had organ-confined disease compared with 6% in the radical-prostatectomy-alone patients (P = 0.018). These data suggest that a subset of the neoadjuvant patients are converted to organ confined disease without eliminating the prostate cells in the bone marrow. Our data suggest that hormonal therapy before radical prostatectomy decreases the occurrence of extraprostatic disease but, to a lesser degree, the incidence of circulating prostate cells. This may partially explain why hormonal therapy before radical prostatectomy has not improved disease-free survival.
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PMID:Effect of neoadjuvant androgen deprivation on circulating prostate cells in the bone marrow of men undergoing radical prostatectomy. 974 28

Although prostate-specific antigen (PSA), or human kallikrein 3, is the most valuable tool available for the diagnosis and management of prostate cancer, as currently used it is insufficiently sensitive and specific for early detection or staging of the malignancy. Many new concepts have been introduced in order to optimize the clinical use of PSA measurements, but each one has its own drawbacks. The molecular forms of PSA, especially the free PSA, seem to be useful for the detection of prostate cancer in men with PSA concentrations falling in the 4-10 microg/l range. New molecular techniques, such as reverse transcriptase polymerase chain reaction for the detection of minimal amounts of PSA messenger RNA and prostate-specific membrane antigen, offer new promise for the prognosis and possibly staging of prostate cancer. On the other hand, human kallikrein 2, a serine protease closely related to PSA that is also expressed predominantly in the prostate, may be a new adjuvant marker for prostate cancer. As for its biological functions, PSA can no longer be regarded as a specific prostate molecule associated mainly with semen liquefaction when it has a possible role as a prognostic indicator in female breast cancer. The biological role of PSA in normal tissues and tumors may be much more complex than previously thought and requires further investigation.
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PMID:Prostate-specific antigen and new related markers for prostate cancer. 980 90

CD44 forms a group of transmembranous glycoproteins formed by alternative splicing of a single mRNA. The expression of v6 exon-containing variants correlates with metastasis and poor prognosis in a number of malignancies. The distribution and prognostic value of CD44s, CD44v5, and CD44v6 were studied immunohistochemically in the radical prostatectomy specimens of 97 patients with prostate cancer and in 12 lymph node metastases. The mean follow-up period was 84 months. The percentage of CD44-immunoreactive cells was scored semiquantitatively. CD44 mRNA expression was studied in nine prostate cancer and eight benign prostatic hyperplasia (BPH) samples by reverse transcriptase-PCR. Benign prostatic glands almost always expressed CD44s, CD44v6, and, at a lower intensity, CD44v5. CD44 scores decreased from low- to high-grade prostatic intraepithelial neoplasia. CD44s, CD44v5, and CD44v6 were expressed in 86, 23, and 69% of the adenocarcinomas, respectively. Gleason sum score (GSS) and pT stage were correlated inversely with CD44s and CD44v6 scores. CD44 was not found in the lymph node metastatic tumor cells. At the mRNA level, 89% of the tumors and all BPH samples expressed CD44s. CD44v6-v10 mRNA was present in 44 and 75% of the tumors and BPH samples, respectively. Loss of CD44s and CD44v6 predicted an adverse prognosis at univariate analysis. The independent prognosticators identified by multivariate analysis were: GSS, pT stage, and CD44s for clinical progression; GSS and CD44s for prostate-specific antigen progression; and GSS for tumor-specific survival. Loss of CD44s expression in prostate adenocarcinoma predicts a poor prognosis, independent of stage and grade.
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PMID:The prognostic value of CD44 isoforms in prostate cancer patients treated by radical prostatectomy. 981 53

Several reverse transcriptase polymerase chain reaction (RT-PCR) assays have been described for the detection of circulating tumour cells in blood and bone marrow. Target mRNA sequences for this purpose are the cytokeratins (CK) 19 and 20, the carcinoembryonic antigen (CEA), and the prostate-specific antigen messages. In this study, we investigated biological factors influencing the specificity of the CK19 and CEA RT-PCR assays. Bone marrow, granulocyte colony-stimulating factor (G-CSF)-mobilized blood stem cells and peripheral blood samples obtained from healthy volunteers (n = 15; CEA n = 7), from patients with epithelial (n = 29) and haematological (n = 23) cancer and from patients with chronic inflammatory diseases (n = 16) were examined. Neither CEA nor cytokeratin 19 messages could be amplified from bone marrow samples from healthy subjects and from patients with haematological malignancies. In contrast, specimens from patients with inflammatory diseases scored positive up to 60%. To investigate the influence of inflammation on target mRNA expression, haemopoietic cells were cultured with and without cytokine stimulation in vitro. CK19 messages could be easily detected in cultured marrow cells without further stimulation, CEA messages only after gamma-interferon (gamma-INF) stimulation. In contrast, G-CSF-mobilized peripheral blood stem cells were positive for CK19 messages only after stem cell factor (SCF) or interleukin stimulation. We conclude that transcription of so-called tissue-specific genes is inductible in haemopoietic tissues under certain conditions. These factors have to be considered in future applications of RT-PCR for the detection of minimal residual disease.
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PMID:Specificity of reverse transcriptase polymerase chain reaction assays designed for the detection of circulating cancer cells is influenced by cytokines in vivo and in vitro. 982 Jan 79

Objectives: We investigated modulation of cell growth and prostate-specific antigen (PSA) gene expression in prostatic cancer cells by the luteinizing hormone-releasing hormone analog (LH-RHa), leuprorelin acetate, alone or combined with other agents. Methods: The effect of the analog on proliferation of both androgen-sensitive and -insensitive prostate cancer cells, maintained in different culture conditions, was evaluated by cell counts at various intervals of time. Basal expression of PSA gene and its variations were determined by a reverse transcriptase-polymerase chain reaction assay. Results: LH-RHa is ineffective in regulating cell growth, when used alone in both hormone-sensitive and -insensitive cell lines. Nevertheless, it counteracts the stimulatory action of androgens on proliferation of LNCaP cells, which respond to low concentrations of dihydrotestosterone. Moreover, LH-RHa has an inhibitory effect on the mitogenic action of epidermal growth factor (EGF) in androgen-unresponsive PC-3 cells. The analog reduces PSA gene expression in both hormone-sensitive and -insensitive cells. Interestingly, it counteracts the gene expression induced by androgens in LNCaP cells and by EGF in PC-3 cells. Conclusions: These data show that LH-RHa may behave like a negative growth factor, which directly regulates cell growth and PSA gene expression. Moreover, our findings support the idea that growth factors may interfere with the androgen signalling pathway.
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PMID:Effect of Leuprorelin Acetate on Cell Growth and Prostate-Specific Antigen Gene Expression in Human Prostatic Cancer Cells. 985 46

The reverse transcriptase-polymerase chain reaction (RT-PCR) assay is an extremely sensitive technique for the detection of circulating cells expressing prostate-specific antigen (PSA) in prostate cancer patients. This article reviews the literature on the use of this technique as a preoperative parameter to predict both extraprostatic disease and PSA recurrence after radical prostatectomy. Despite the relative consensus regarding the increase in RT-PCR-positivity with tumor stage (i.e., clinically localized vs metastatic prostate cancer), the use of RT-PCR as a clinical staging modality is controversial. To date, more than 16 institutions have evaluated the RT-PCR test in prostate cancer. Of these institutions, only two have reported the utility of RT-PCR as a staging modality and three have reported the utility of the test in predicting PSA recurrence. Before further conclusions are drawn regarding the clinical utility of RT-PCR in prostate cancer patients and its routine use is advocated, a larger patient population needs to be studied and followed for longer periods.
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PMID:Molecular staging of prostate cancer: dream or reality? 1007 69

We compared the efficacy of 4 methods for isolating circulating tumor cells: immunocapture with Ber-EP4-coated magnetic beads, density gradient separation, ammonium chloride, and distilled water-mediated erythrocyte lysis. Human blood from healthy volunteers was mixed with serial dilutions of prostate (LNCaP) and liver (HepG2) derived tumor cells. Isolation of circulating tumor cells was followed by reverse transcriptase-polymerase chain reaction with primers specific for prostate-specific antigen and alpha-fetoprotein. Ber-EP4 antigen expression was evaluated by immunohistochemistry in 27 hepatocellular carcinomas and 34 prostate adenocarcinomas. Peripheral blood samples from 12 patients with hepatocellular carcinoma and 10 with prostate adenocarcinoma also were tested. Density gradient separation and Ber-EP4 immunocapture were the most sensitive techniques for isolating circulating tumor cells in in vitro tests. Isolation by density gradient separation was significantly more sensitive than Ber-EP4 immunocapture when applied to peripheral blood samples of patients with cancer, a result consistent with the variable expression of Ber-EP4 antigen that we found by immunohistochemistry in prostate adenocarcinomas and hepatocellular carcinomas.
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PMID:Efficiency of Ber-EP4 antibody for isolating circulating epithelial tumor cells before RT-PCR detection. 1043 96

To determine the potential risk of hematogenous dissemination of prostate cancer cells during radical prostatectomy (RP), we investigated the pre- and intraoperative circulating prostate-specific antigen (PSA) mRNA in patients with clinically localized prostate cancer, with special reference to neoadjuvant hormonal therapy (NHT). Using a nested reverse transcriptase (RT) polymerase reaction (PCR) assay, PSA mRNA in the peripheral blood was evaluated pre- and postoperatively in a total of 23 patients, 10 of whom received NHT with antiandrogens. The RT-PCR assay employed detected one LNCaP cell in 10(7) mononuclear blood cells, and showed no positive signal in the blood samples from all 15 healthy controls. Pre- and intraoperative circulating PSA mRNA was positive in 11 (48%) and 18 patients (78%), respectively. All 11 patients with positive preoperative PSA mRNA continued to be positive during RP, and seven (58%) of 12 patients with negative preoperative PSA mRNA had a positive conversion. Although the patients' ages, preoperative serum PSA values and clinical or pathological stages were not associated with the pre- and intraoperative PSA mRNA results, the NHT group showed a significantly lower incidence of preoperative PSA mRNA positivity (2/10) than the group receiving RP alone (9/13) (20% vs 69%, P = 0.036). NHT, however, showed no suppressive effect on either intraoperative positivity or positive conversion of circulating PSA mRNA. The present study suggests that a substantial number of patients receiving RP are at risk of hematogenous dissemination, and NHT with antiandrogens has a minimal or no suppressive effect on the circulating PSA mRNA during surgical manipulation of the prostate. Because the clinical significance of circulating cancer cells remains to be determined, long-term follow-up in association with the circulating cancer cells assessed by the RT-PCR is essential in order to establish the role of molecular staging as well as NHT.
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PMID:Circulating prostate-specific antigen mRNA during radical prostatectomy in patients with localized prostate cancer: with special reference to neoadjuvant hormonal therapy. 1046 Sep 2

The purpose of this article is to review the available means to investigate whether an elevated serum prostate-specific antigen (PSA) after radical prostatectomy may be explained by the presence of residual benign tissue. To answer this question, one may consider the following features: the kinetics of recurrent/ persistent PSA, the incidence of rising PSA in the presence of capsular incisions exposing benign glands only, the level of urinary PSA and the ratio of free/total PSA in the urine, the results of anastomotic biopsy samples, and the detection of circulating prostate cells by PSA reverse transcriptase-polymerase chain reaction (RT-PCR) after surgery. Capsular incisions exposing benign tissue are not associated with a significant risk of biochemical failure. In case of an organ-confined cancer with negative surgical margins but a rising postoperative PSA, the systematic reevaluation of the initial pathological slides constantly shows capsular effraction or focal positive margins that have been overlooked at the first evaluation. Even when anastomotic biopsies document only benign tissue, the study of PSA doubling time is usually characteristic of the coexistence of residual tumoral cells. However, in a few cases, the persistent negative results of the detection of circulating prostate cells by PSA, RT-PCR in patients with organ-confined cancer and negative margins but elevated postoperative PSA might be explained by the presence of residual benign prostatic hyperplasia tissue. Most of the data in the literature are in favor of the responsibility of persistent/recurrent cancer in the recurring PSA rather than that of benign prostatic hyperplasia/normal residual tissue. Therefore, a persistent/recurrent detectable level of PSA is the serum after radical prostatectomy characterizes biochemical failure.
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PMID:The significance of recurrent PSA after radical prostatectomy: benign versus malignant sources. 1046 14


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