Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methotrexate (MTX) is a dihydrofolate reductase (DHFR) inhibitor widely used as an anticancer drug in different kinds of human cancers. Here we investigated the anti-tumor mechanism of MTX against non-small cell lung cancer (NSCLC) A549 cells. MTX not only inhibited in vitro cell growth via induction of apoptosis, but also inhibited tumor formation in animal xenograft model. RNase protection assay (RPA) and RT-PCR demonstrated its induction of p53 target genes including DR5, p21, Puma and Noxa. Moreover, MTX promoted p53 phosphorylation at Ser15 and acetylaion at Lys373/382, which increase its stability and expression. The apoptosis and inhibition of cell viability induced by MTX were dependent on p53 and, partially, on p21. In addition, MTX also increased E-cadherin expression through inhibition of histone deacetylase (HDAC) activity and downregulation of polycomb group protein enhancer of zeste homologue 2 (EZH2). Therefore, the anticancer mechanism of MTX acts through initiation of p53-dependent apoptosis and restoration of E-cadherin expression by downregulation of HDAC/EZH2.
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PMID:Methotrexate induces apoptosis through p53/p21-dependent pathway and increases E-cadherin expression through downregulation of HDAC/EZH2. 2111 63

Identification of point mutations has been facilitated by a number of techniques, including transfection assays, oligonucleotide hybridization, electrophoretic migration of heteroduplexes, RNase mismatch analysis, direct sequencing, and DNA-polymerase catalyzed amplification. The large number of available techniques emphasizes the importance of developing rapid and reliable methods to identify molecular changes in genes. To date, we have concentrated on exploiting DNA-polymerase catalyzed amplification methods (1,2) in conjunction with direct manual and automated DNA sequencing to detect point mutations in the dihydrofolate reductase (DHFR) gene of methotrexate-resistant cells.
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PMID:Manual and automated direct sequencing of product generated by the polymerase chain reaction. 2140 Feb 72

This brief review discusses our current understanding of the molecular basis of enzyme catalysis. A historical development is presented, beginning with steady state kinetics and progressing through modern fast reaction methods, nuclear magnetic resonance, and single-molecule fluorescence techniques. Experimental results are summarized for ribonuclease, aspartate aminotransferase, and especially dihydrofolate reductase (DHFR). Multiple intermediates, multiple conformations, and cooperative conformational changes are shown to be an essential part of virtually all enzyme mechanisms. In the case of DHFR, theoretical investigations have provided detailed information about the movement of atoms within the enzyme-substrate complex as the reaction proceeds along the collective reaction coordinate for hydride transfer. A general mechanism is presented for enzyme catalysis that includes multiple intermediates and a complex, multidimensional standard free energy surface. Protein flexibility, diverse protein conformations, and cooperative conformational changes are important features of this model.
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PMID:Flexibility, diversity, and cooperativity: pillars of enzyme catalysis. 2202 78


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