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)

A highly sensitive nested reverse transcriptase-PCR assay, with primers derived from the prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSM) cDNA sequences, has been used to detect occult hematogenous micrometastatic prostate cells. In 77 patients with prostate cancer, PSM and PSA primers detected circulating prostate cells in 48 (62.3%) and 7 (9.1%) patients, respectively. In treated stage D disease patients, PSM primers detected cells in 16 of 24 patients (66.7%), while PSA primers detected cells in 6 of 24 (25%). In post-radical prostectomy patients with negative serum PSA values, PSM primers detected metastases in 21 of 31 patients (67.7%), whereas PSA primers detected cells in only 1 of 33 (3.0%), indicating that micrometastatic spread may be a relatively early event in prostate cancer. The analysis of 40 individuals without known prostate cancer provides evidence that this assay is highly specific and suggests that PSM expression may predict the development of cancer in patients without clinically apparent prostate cancer. Using PSM primers, we detected micrometastases in 4 of 40 controls, 2 of whom had known benign prostatic hyperplasia and were later found to have previously undetected prostate cancer. The clinical significance of detection of hematogenous micrometastic prostate cells using PSM primers and potential applications of this molecular assay, as well as the assay for PSA, merit further study.
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PMID:Sensitive nested reverse transcription polymerase chain reaction detection of circulating prostatic tumor cells: comparison of prostate-specific membrane antigen and prostate-specific antigen-based assays. 752 94

N-Acetylaspartylglutamate (NAAG) is the most prevalent peptide neurotransmitter in the mammalian nervous system. NAAG selectively activates the type 3 metabotropic glutamate receptor. It is inactivated by peptidase activity on the extracellular face of the plasma membrane of neurons and glia. The human gene that codes for prostate-specific membrane antigen (PSM) has been shown to produce peptidase activity against NAAG. We cloned the human PSM cDNA and used it to probe a rat hippocampal cDNA library. We identified a cDNA containing a complete coding region that possesses 83% homology with the PSM gene. The predicted 752-amino acid sequence has 85% identity and 91% similarity to the PSM sequence. CHO cells transfected with this cDNA expressed NAAG peptidase activity at a level similar to that obtained from rat brain membranes. The peptidase activity was inhibited by beta-NAAG, quisqualate, and pteroylglutamate but not aspartylglutamate or pteroic acid. In situ hybridization data demonstrated the widespread distribution of the peptidase mRNA in the brain, consistent with the distribution of peptidase activity. The highest levels of hybridization were detected in the hippocampus, dentate gyrus, piriform cortex, choroid plexus of the ventricles, pineal gland, anterior pituitary, and supraoptic nucleus. Three transcripts (estimated at 5, 3.4, and 2.9 kb) were identified in northern blots of rat brain, while in rat kidney the third transcript appeared slightly smaller than 2.9 kb. With use of reverse transcriptase PCR with primers for the 5' end, the central region, and the 3' end of the hippocampal cDNA, the expected amplification products were obtained from rat brain RNA. Spinal cord yielded an amplification product only with primers for the 5' end of the hippocampal cDNA.
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PMID:Molecular cloning of a peptidase against N-acetylaspartylglutamate from a rat hippocampal cDNA library. 937 57

Understaging is commonly associated with therapeutic failure of surgical intervention in apparently localized prostate cancers. Methods that specifically detect prostate cancer cells in the circulation may be able to identify metastatic cancers and thus aid in the selection of the most adequate therapy. The high sensitivity and specificity of the reverse transcriptase-polymerase chain reaction (RT-PCR) encouraged various groups to investigate the mRNA expression of prostate-specific markers in the peripheral blood of patients with prostate cancer. However, probably due to methodological differences, many contradictory results have been obtained with the markers studied so far: prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSM). For this reason, clinical decisions should not be based yet on RT-PCR results. Future research and long-term follow-up on the patients may point out whether RT-PCR assays, following appropriate standardization, will have an additive value in prostate cancer staging and in prediction of tumor progression.
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PMID:Clinical usefulness of RT-PCR detection of hematogenous prostate cancer spread. 944 45

Circulating prostate cells can be detected in cancer patients by using reverse transcriptase-PCR (RT-PCR) assay for prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSM) mRNA. A quality-control study involving a conventional RT-PCR assay was performed and, surprisingly, detected both transcripts in many negative control cell lines and in normal blood samples. The existence of an illegitimate transcription of the PSA and PSM genes was evidenced by sequence analysis of several PSM and PSA-PCR products. Sequencing indeed demonstrated the presence of a PSA or PSM polymorphism in some but not all the cell lines and patient samples, as well as a heterozygous mutation (G to A; Asp to Asn) in the Jurkat cell line. Moreover, the amount of PSA transcript in MCF-7, a PSA-negative breast line, increased after incubation with cycloheximide. Interestingly, the frequency of positivity was as high as 12% in male samples if only tested once, but dropped to 3% upon multiple testing of the same cDNA. This highlights the stochastic effects in RT-PCR results at high sensitivity, hence the importance of repetitive testing in clinical samples. Decreasing the number of cycles avoided the amplification of illegitimate transcripts but also affected the limit of detection, as evidenced with PSA and PSM cDNA containing plasmids, mixing of LNCap with normal blood samples, and the PSA-PSM-negative K562 cell line. The current data raise the need for a multicentric standardization of the RT-PCR methodology used to amplify PSA and PSM transcripts.
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PMID:Expression of prostate-specific antigen and prostate-specific membrane antigen transcripts in blood cells: implications for the detection of hematogenous prostate cells and standardization. 951 Aug 50

Although adenocarcinoma of the prostate is recently becoming one of most common malignancies in Japanese men, it still poses many questions regarding its etiology, pathology, pathogenesis and clinical management. Many reports have been made on oncogene and tumor suppressor gene, however, frequent genetic alterations have not been identified during prostate cancer development. Loss of heterozygosity (LOH) on 8p might be an important event in the early stage of prostatic carcinogenesis, whereas alteration in 17p is now considered a late event. Numerous reports about the androgen receptor (AR) gene have revealed that mutations in the coding region of AR possibly results in an acquired resistance to androgen blockade therapy and anti-androgen withdrawal syndrome. It has been also shown that shorter CAG repeats of AR gene are associated with a higher risk of prostate cancer. Regarding molecular diagnosis, prostate-specific membrane antigen (PSM) appears to be a new molecule with many potentially valuable applications. PSM-reverse transcriptase-polymerase chain reaction (RT-PCR) is probably more sensitive and specific than PSA-RT-PCR to predict micrometastatic disease. Gene therapy based on the above molecular aspect is currently under investigation but not generally used yet.
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PMID:[Molecular biological aspect]. 961 16

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

Human prostate-specific membrane antigen (PSMA), a 100-kDa integral transmembrane glycoprotein, is considered to be a highly specific marker of the prostate gland, and has successfully been used as a marker of circulating prostatic epithelial cells. Extended PSMA homology has been demonstrated with a cDNA found in rat cerebral and renal tissues. In this study, we aimed to evaluate the expression of PSMA mRNA in a variety of human renal cancer tissues (n = 20) and cell lines (n = 12). Using reverse transcriptase-polymerase chain reaction, DNA sequencing, blottings, and specific anti-PSMA labelling with CYT 351 antibody, we identified PSMA mRNA and protein in normal and in neoplastic renal tissue. The sequence of the polymerase-chain-reaction products is identical to that of PSMA cDNA derived from prostate tissue. Immunological staining with the CYT 351 reveals that PSMA is expressed mainly in tubular cells. Since PSMA does not appear to be restricted to prostatic tissue, this novel biomarker may prove useful in the staging of renal cancer and in the search for the hematogenous spread of renal cells.
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PMID:Molecular expression of PSMA mRNA and protein in primary renal tumors. 1007 9

The detection of prostate-specific membrane antigen (PSM) mRNA in the peripheral blood of prostate cancer patients by a nested reverse transcriptase-polymerase chain reaction (RT-PCR) assay is a useful and sensitive method for the identification of small foci of metastatic lesions. In this study, a nested RT-PCR assay was performed using the two different PSM-derived oligonucleotide primer sets reported by Israeli et al. and Loric et al. (termed PSM primers-1 and primers-2, respectively, in this report), and the differences in the specificity and sensitivity of these primer sets for detecting prostate cancer cells in the blood are discussed. The PCR assay using PSM primers-1 showed DNA bands for 4 of 7 cases of metastatic prostate cancer and amplified the untreated genomic DNA, while that using PSM primers-2 showed 6 bands without the amplification of the genomic DNA. In conclusion, PSM primers-2 is superior to PSM primers-1 for the detection of PSM mRNA in the peripheral blood of prostate cancer patients.
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PMID:Prostate-specific membrane antigen-derived primers in a nested reverse transcription polymerase chain reaction for detecting prostatic cancer cells. 1018 95

We will review the evolution, benefits, and limitations of PSMA testing in the past, as well as its current and future value. Prostate cancer has been the most frequently diagnosed cancer and the second leading cause of cancer death in men in the United States. It has a wide spectrum of biological behavior between latent (indolent) and progressive (aggressive). Further identification of prostate-specific membrane antigen (PSMA) as a prognostic proliferation marker may enhance our understanding of the types of prostate cancer. A review of PSMA testing in the past as well as currently was conducted. Studies were reviewed that deal with detection of PSMA in serum and seminal fluid, reverse transcriptase-polymerase chain reaction (RT-PCR), immunoscintigraphy, and immunohistochemical assays. PSMA is expressed primarily in benign and cancerous prostatic epithelial cells. It is up-regulated in hormone resistant states, and in metastatic situations or other clinical situations where there is tumor recurrence or extension. Based on current results, PSMA detected in the serum by western blotting can assist in the identification, staging, and monitoring of metastatic prostate cancer. In addition, PSMA shows a promising role in directed imaging and therapy of recurrent or metastatic disease.
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PMID:Prostate-specific membrane antigen (PSMA): current benefits and future value. 1061 92

Originally, prostate-specific membrane antigen (PSMA) was described in benign and malignant prostate cells. On the basis of recent reports that this antigen also is expressed in normal renal proximal tubular cells and in the neovascular endothelium associated with renal carcinoma, we used a nested reverse transcriptase-polymerase chain reaction assay to evaluate whether PSMA-expressing cells might be present in specimens of peripheral blood obtained from renal cancer patients, benign renal tumor patients, and healthy volunteers. Our reverse transcriptase-polymerase chain reaction PSMA assay had a sensitivity of detecting 1 lymph node prostate cancer (LNCaP) per 10(7) lymphocytes. None of the 20 non-renal cancer controls were positive for PSMA mRNA, whereas 11 of 50 patients (22%) with diagnosed renal cancer were positive. Despite a comparative increase of PSMA positivity with stage, no statistical correlation was found. However, 44% of PSMA-positive patients had tumor size greater than 12 cm, versus only 9% in patients negative for PSMA (P = .03), and 67% of positive PSMA patients were found to have vascular invasion versus only 16% of patients negative for PSMA (P = .006; odds ratio, 10.8). This preliminary study suggests the possibility that PSMA expression in peripheral blood might be a useful biomarker for detecting or monitoring the progression of renal cancer in patients.
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PMID:Detection of prostate-specific membrane antigen expressing cells in blood obtained from renal cancer patients: a potential biomarker of vascular invasion. 1119 72


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