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  • 1
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Competitive RT-PCR ; LDL-Rezeptor ; HMG-CoA-Reduktase ; Key words LDL receptor ; HMG-CoA reductase ; Competitive RT-PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The present study exemplifies the method of quantitative reverse transcriptase – polymerase chain reaction (cRT-PCR) by quantifying, in bovine tissues, the specific mRNAs for the two key proteins which regulate cellular cholesterol metabolism, the low density lipoprotein (LDL) -receptor and the 3-hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) reductase. Our data reveal a broad range of expression for both mRNAs. The LDL-receptor mRNA expression was highest in the adrenal gland (6.7 × 104 molecules/ug cellular RNA) followed by the corpus luteum of the ovary, intermediate in the liver (8.6 × 102 molecules/ug cellular RNA) and not detectable in the large intestine. Expression of the HMG-CoA reductase almost paralleled LDL-receptor values. It was found to be highest in the ovary (6.1 × 106 molecules/ug cellular RNA) followed by the adrenal gland, intermediate in the liver (3.1 × 105 molecules/ug cellular RNA) and lowest in the large intestine (9.9 × 104 molecules/ug cellular RNA). These data are consistent with other reports concerning the quantitative analysis of the expression of both proteins as determined by other experimental approaches. Thus cRT-PCR is a valuable tool for the quantitative analysis of the LDL-receptor and the HMG-CoA reductase.
    Notes: Zusammenfassung In der vorliegenden Arbeit wird eine Methode zur exakten Quantifizierung spezischer RNA, die kompetitive und damit quantitative Reverse-Transkriptase-Polymerase-Kettenreaktion (cRT-PCR) exemplarisch beschrieben. Im Vergleich mit konventionellen Verfahren hat diese Methode den Vorteil, daß bereits geringe Mengen an Untersuchungsmaterial zur Analyse ausreichen. Die spezifischen mRNAs für 2 Schlüsselproteine des zellulären Cholesterinstoffwechsels, den Low-density-Lipoprotein(LDL)-Rezeptor und die 3-hydroxy-3-methylglutaryl-Coenzym A(HMG-CoA)-Reduktase wurde in verschiedenen bovinen Geweben gemessen. Dabei zeigte sich eine besonders hohe Expression beider mRNAs in den steroidhormonproduzierenden Geweben, i. e. Corpus luteum des Ovars und der Nebenniere, eine mittlere Expression in der Leber und eine niedrige bzw. nicht meßbare Expression im Dickdarm. Die hier am Beispiel des LDL-Rezeptors und der HMG-CoA-Reduktase exemplarisch vorgestellte Methode der quantitativen RT-PCR läßt sich nicht nur in der Routinediagnostik, sondern auch auf eine Vielzahl von wissenschaftlichen Fragestellungen auf dem Gebiet der Stoffwechsel-, Entzündungs- und Tumorpathologie anwenden.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 121 (1995), S. 343-349 
    ISSN: 1432-1335
    Keywords: HMG-CoA reductase ; LDL receptor ; Tumour cells ; Drug resistance ; Polymerase chain reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Competitive inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase are currently used to treat patients with hypercholesterolaemia. These inhibitors affect not only cholesterol biosynthesis, but also the production of non-steroidal mevalonate derivatives, that are involved in a number of growth-regulatory processes. As a consequence, their potential use as anticancer drugs has been suggested. In order to examine long-term effects of this potential therapeutic approach, we cultivated the gastric carcinoma cell line, EPG85-257, and the breast tumour cell line, MDA-MB231, in the presence of increasing concentrations of the HMG-CoA reductase inhibitor, pravastatin. For both cell lines, this procedure led to the selection of resistant variants able to proliferate in more than 1000 μM inhibitor. By competitive reverse transcriptase/polymerase chain reaction assay (cRT-PCR), the expression of the mRNA for two key proteins of cellular cholesterol metabolism, HMG-CoA reductase and lowdensity lipoprotein (LDL) receptor, were analysed in sensitive and resistant cells. Despite similar growth rates, MDA-MB231 cells expressed approximately four times more HMG-CoA reductase mRNA than EPG85-257 cells and over 30 times more LDL receptor mRNA. Both mRNA species were coordinately regulated in the parental and in the pravastatin-resistant variant cells. Expression was highly stimulated (3- to 4-fold for the HMG-CoA reductase and 2- to 3-fold for the LDL receptor) in the resistant variants when cultured in lipoprotein-deficient medium in the presence of 1000 μM pravastatin. Immunocytological analysis of the expression of the HMG-CoA reductase and LDL receptor protein were in accordance with the data on specific mRNA expression obtained by cRT-PCR. Southern blot analysis revealed a 1.5-fold amplification of the HMG-CoA reductase gene in resistant MDA-MB231 cells, but not in the resistant EPG85-257 variant. Our data provide evidence for resistance mechanisms to pravastatin that are independent of the amplification of the HMG-CoA reductase gene. By analogy to the cell-culture models employed in this study, it is conceivable that similar mechanisms might occur in human tumour cells in vivo during longterm treatment with HMG-CoA reductase inhibitors. This might limit their application as chemotherapeutic anticancer agents.
    Type of Medium: Electronic Resource
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