Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The antitumor agent cis-diamminedichloroplatinum(II) (cis-DDP) reacts covalently with DNA and disrupts its secondary structure. Damaged DNA, but not native DNA, is readily digested by S1 nuclease, an endonuclease specific for single stranded polynucleotides. We have measured S1 nuclease digestion of platinated DNA by the release of platinum-DNA adducts and compared it with digestion of unplatinated DNA. The rate of hydrolysis of damaged substrate from platinum-DNA complexes was less than the overall rate of digestion of nucleotides. Similar results were observed for platinum-DNA complexes in native, denatured or renatured conformations. The hydrolysis of denatured platinum-DNA complexes, rb = 0.075 platinum per nucleotide, obeyed Michaelis-Menten kinetics. Taking into account the level of DNA damage, Vm, for the release of platinated adducts was 0.6 times smaller than for digestion of unplatinated DNA. Km values and competition experiments indicated that the enzyme bound equally well to platinated and unplatinated substrates. Similar results were obtained for denatured DNA complexes with trans-DDP while [PtCl(diethylenetriamine)]Cl had no influence on nuclease digestion. These results suggest that bifunctional platinum-DNA lesions have contradictory effects on the hydrolysis of double stranded DNA by S1 nuclease. On one hand they create nuclease sensitive substrate by disrupting DNA secondary structure. On the other, they inhibit digestion of the damaged strand by increasing the activation energy for hydrolysis.
 ...
PMID:Kinetic studies of the hydrolysis of platinum-DNA complexes by nuclease S1. 231 Nov 30

Apoptosis is characterized by typical morphological changes and most frequently fragmentation of DNA into oligonucleosome-size fragments. In order to investigate whether an alteration in the mechanisms involved in the process of apoptosis could contribute to cellular resistance, induction of apoptosis was studied in a cisplatin-resistant cell line (L1210/DDP) derived from a L1210 murine leukemia cell line (L1210/0). Treatments of the parental L1210/0 cell line with two DNA damaging agents (cisplatin and 5-azacytidine) or a protein kinase C inhibitor (staurosporine) led to biochemical events characteristic of apoptosis (as determined by the cell morphology and the oligonucleosomal DNA fragmentation). In contrast, the cisplatin-resistant L1210/DDP subline, which was cross-resistant to 5-azacytidine, did not exhibit any DNA fragmentation or morphological changes typical of apoptosis when exposed to toxic concentrations of either cisplatin or 5-azacytidine. The failure of these cells to undergo apoptosis upon cisplatin or 5-azacytidine exposure has been correlated with the lack of a nuclear endonuclease activity present in wild-type cell nuclei. However, staurosporine, which exerted the same toxicity on both cell lines, induced the internucleosomal DNA fragmentation and morphological features of apoptosis in both of them. This indicates that a functional pathway for apoptosis is preserved in the resistant cells. The induction of this pathway can be correlated with the presence of a cytoplasmic endonuclease activity whose specificity seems different from that operating in L1210/0 cells in terms of cation and pH dependence. Therefore, in these cell lines, different endonucleases are possibly involved in apoptosis. In response to treatment with drugs having different targets, the apoptotic cell death may operate through different signaling pathways, one of them being possibly defective in the L1210/DDP-resistant cells.
 ...
PMID:Cisplatin resistance in a murine leukemia cell line is associated with a defective apoptotic process. 753 90

The interactions of the Escherichia coli endonuclease UvrAB proteins with the DNA mono- and diadducts of both the cis-racemic exo-[N-2-amino-N-2-methylamino-2,2,1-bicycloheptane]dichloroplatin um(II) (complex 1) and cisplatin (cis-diamminedichloroplatinum(II) (cis-DDP)), have been studied. Complex 1 reacts faster with DNA than cis-DDP and gives monoadducts with a longer lifetime (8 h 20 min chelation t 1/2 compared with 2 h 40 min for cis-DDP). Using pSP65 plasmid [3H]DNA, the filter binding assay was associated with the analysis of the nucleoprotein complexes to characterize the UvrAB recognition of the platinum adducts and to demonstrate the occurrence of platinum-mediated DNA-protein cross-linking. First, it is shown that the UvrAB proteins recognize the complex 1 mono- and diadducts with a higher affinity than those of cis-DDP. Fifteen times more cis-DDP adducts per plasmid are required than complex 1 adducts, to lead to similar UvrAB binding. However, the UvrAB proteins recognize monoadducts and diadducts of each complex with a similar affinity. Second, it is shown that UvrB is the protein involved in the nucleo-protein complexes formed from mono- and diadducts of complex 1 and cis-DDP. This protein is also partly cross-linked to DNA with a similar efficiency by monoadducts derived from complex 1 and cis-DDP. However, as UvrB has a greater affinity for the DNA adducts of complex 1 than for those of cis-DDP, more UvrB-platinum-DNA cross-links are formed with complex 1 than with cis-DDP. This study, using a bacterial repair system as a model, points to a possible strategy for making new cytotoxic platinum complexes for mammalian cells.
 ...
PMID:Binding of the Escherichia coli UvrAB proteins to the DNA mono- and diadducts of cis-[N-2-amino-N-2-methylamino-2,2,1-bicycloheptane]dichloroplatinum(II ) and cisplatin. Analysis of the factors controlling recognition and proof of monoadduct-mediated UvrB-DNA cross-linking. 767 59

It has been recently reported that a number of anticancer drugs, including cisplatin, may exert their toxicity by inducing apoptosis. In order to investigate whether an alteration in the mechanisms involved in the process of apoptosis could contribute to cellular resistance, induction of apoptosis was studied in a cisplatin-resistant cell line (L1210/DDP) derived from a L1210 murine leukemia cell line (L1210/0). We first established that the mutant cell line resisted 5-azacytidine, a drug to which it was never exposed and which is known to have a very different mechanism of action from that of cisplatin. We then showed that these cells did not exhibit any DNA fragmentation or morphological changes typical of apoptosis, when exposed to toxic concentrations of either cisplatin or 5-azacytidine. The failure of these cells to undergo typical apoptosis upon cisplatin or 5-azacytidine exposure was correlated with the lack of a nuclear endonuclease activity present in wild type cell nuclei. However, staurosporine, a potent protein kinase C inhibitor, which exerted the same toxicity on both cell lines, induced the internucleosomal DNA fragmentation and morphological features of apoptosis in both of them. This indicates that a functional pathway for apoptosis is preserved in the resistant cells. The induction of this pathway can be correlated with the presence of a cytoplamic endonuclease activity whose specificity seems different from that operating in L1210/0 cells. In conclusion, our data indicate that the mechanisms which control activation of apoptosis in L1210/0 cells differ from those which operate in L1210/DDP cells. One of the differences concerns the nature and the subcellular localization of the endonuclease activity possibly involved in the internucleosomal DNA cleavage.
 ...
PMID:[Cisplatin resistance in a murine leukemia cell line associated with defect of apoptosis]. 868 89

To determine the affinity towards DNA sequences of novel antitumor drugs in comparison with their parental compounds may lead to the design of new analogous drugs with improved antitumor activity. Thus, the affinities of Pt-berenil towards different DNA sites relative to cis-DDP and berenil drugs were analysed using DNase I footprinting and restriction endonuclease analysis. The data show that the Pt-berenil drug inhibits the cutting activity of Hind III enzyme to the same extent as the berenil ligand. In contrast, inhibition by Pt-berenil of the cutting activity of Bam HI enzyme is significantly lower than that of cis-DDP. These results indicate that although the cis-Pt(II) centres of Pt-berenil maintain certain affinity toward G + C regions, which are the main binding sequences of cis-DDP, however, the berenil ligand seems to direct the Pt-berenil molecule towards A + T regions, which are the binding sequences preferred by berenil. In fact, 1H- and 195Pt-NMR spectra of Pt-berenil:nucleoside complexes show that Pt-berenil not only covalently binds to N7 of guanosine but also to N1/N7 of adenosine.
 ...
PMID:The berenil ligand directs the DNA binding of the cytotoxic drug Pt-berenil. 939 76

Recent studies have shown that caspases, which are cystein proteases, elevate endonuclease activity and induce apoptosis. Caspase-1, an interleukin-1beta converting enzyme, has been reported to be related with anti-cancer drug induced apoptosis as well as with caspase-3. To elucidate the caspase-1 activity, which might be a predictor for the effect of chemotherapy, we examined the changes of caspase-1 activity induced after exposure to cisplatin (CDDP) in six gastric cancer cell lines. A high correlation between the 50% inhibitory concentration (IC50) and caspase-1 activity ratio was shown (r=0.83, p=0.041) (caspase-1 activity ratio: the caspase-1 activity of cells at 4 h after CDDP treatment/the caspase-1 activity of untreated cells). Further, we examined the correlation between caspase-1 activity and apoptosis induced by CDDP in two cell lines that have very different CDDP sensitivities; OCUM-2M and OCUM-2M/DDP (IC50; 0. 85+/-0.4 microg/ml and 9.0+/-1.2 microg/ml, respectively). The apoptotic index of OCUM-2M was significantly higher than that of OCUM-2M/DDP (19.8+/-3.8% vs. 4.5+/-1.2%, respectively; p=0.0005). In both cell lines, caspase-1 activity began to increase immediately after exposure to CDDP and peaked at approximately 4 h after cessation of exposure to CDDP, and gradually decreased thereafter. The caspase-1 activity of OCUM-2M was approximately 1.8-times higher than that of OCUM-2M/DDP at 4 h after exposure to CDDP. Taken together, our results indicate that evaluating the changes of caspase-1 activity after exposure to CDDP may be useful to predict apoptosis following CDDP treatment in gastric cancer cells.
 ...
PMID:Caspase-1 activity as a possible predictor of apoptosis induced by cisplatin in gastric cancer cells. 1102 23

The human apurinic/apyrimidinic endonuclease 1/redox enhancing factor-1 (APE1/Ref-1), an essential multifunctional protein involved in the repair of oxidative deoxyribonucleic acid (DNA) damage and transcriptional regulation, is often overexpressed in tumor tissues and cancer cells. Moreover, APE1/Ref-1 (APE1) overexpression has been linked to chemoresistance in human tumors. Thus, inhibiting APE1 function in cancer cells is considered a promising strategy to overcome resistance to therapeutic agents. Gossypol is a Bcl-2 homology 3 (BH3)-mimetic agent and is able to bind to the BH3 domain of B-cell lymphoma 2 (Bcl-2) family members. Other studies demonstrated that Bcl-2 directly interacted with APE1 via its BH domains. Using apurinic/apyrimidinic (AP) endonuclease assays, we found that gossypol inhibits the repair activity of APE1. Electrophoretic mobility shift assays and dual luciferase assays showed that gossypol could also inhibit the redox function of APE1. Using dual polarization interferometry technology, we show that gossypol can directly interact with APE1. Furthermore, addition of gossypol, in conjunction with APE1 overexpression, leads to cancer cell death. The addition of gossypol also enhances the cell killing effect of the laboratory alkylating agent methyl methanesulfonate and the clinical agent cisplatin (DDP). Administration of gossypol significantly inhibited the growth of xenografts. Furthermore, the combined treatment of gossypol and DDP resulted in a statistically higher antitumor activity compared with DDP alone in vivo. In conclusion, we have demonstrated that gossypol effectively inhibits the repair and redox activity of APE1 through a direct interaction.
...
PMID:Identification of a novel potential antitumor activity of gossypol as an APE1/Ref-1 inhibitor. 2487 79

Gastric cancer (GC) is one of the most common types of malignant tumor. Due to the lack of effective drugs and the emergence of chemotherapy resistance, patients with GC exhibit a poor prognosis and low survival rate. MicroRNAs (miRNAs/miRs) serve an important role in drug resistance of different types of cancer. They may be suitable for use as biomarkers in the diagnosis, treatment and prognosis of tumors. The present study aimed to investigate the molecular mechanism underlying the ability of miR-200c-3p to reverse drug resistance in a SGC7901/DDP GC cell line, particularly its effects on the ERCC excision repair 3, TFIIH core complex helicase subunit (ERCC3) and ERCC excision repair 4, endonuclease catalytic subunit (ERCC4) proteins in the nucleotide excision repair (NER) pathway. Reverse transcription-quantitative polymerase chain reaction demonstrated that miR-200c-3p expression in cisplatin-resistant SGC7901/DDP cells was lower than in parental SGC7901 cells, whereas the protein expression levels of ERCC3 and ERCC4 in these cells were higher by western blot analysis. In SGC7901/DDP-derived miR-200c-3p overexpressing cells, ERCC3 expression, ERCC4 expression and cisplatin resistance were decreased compared with in parental SGC7901/DDP cells and SGC7901/DDP-derived vector control cells. In SGC7901-derived miR-200c-3p knockdown cells, ERCC3 expression, ERCC4 expression and cisplatin resistance were increased compared with in parental SGC7901 cells and SGC7901-derived vector control cells. In conclusion, overexpression of miR-200c-3p may reverse drug resistance in the SGC7901/DDP GC cell line via downregulation of ERCC3 and ERCC4, which suggested this may be part of a mechanism involving the NER pathway.
 ...
PMID:MicroRNA-200c reverses drug resistance of human gastric cancer cells by targeting regulation of the NER-ERCC3/4 pathway. 3128 83