Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Beta-lapachone (beta-lap) affects a number of enzymes in vitro, including type I topoisomerase (Topo I); however, its exact intracellular target(s) and mechanism of cell killing remain unknown. We compared the cytotoxic responses of MCF-7:WS8 (MCF-7) human breast cancer cells after 4-h pulses of beta-lap or camptothecin (CPT), a known Topo I poison. A direct correlation between loss of survival and apoptosis was seen after beta-lap treatment (LD50 = 2.5 microM). A concentration-dependent, transient sub-2 N preapoptotic cell population was observed at 4-8 h. Estrogen deprivation-induced synchronization and bromodeoxyuridine-labeling studies revealed an apoptotic exit point near the G1-S border. Apoptosis activated by beta-lap was closely correlated with cleavage of lamin B but not with increases in p53/p21 or decreases in bcl-2. Loss of hyperphosphorylated forms of the retinoblastoma protein was observed within 5 h, but cyclins A, B1, and E levels were unaltered for up to 72 h after 5 microM beta-lap. Topo I and Topo IIalpha levels decreased at > 24 h. Logarithmic-phase MCF-7 cells were not affected by < or = 1 microM beta-lap. In contrast, dramatic and irreversible G2-M arrest with no apoptosis was observed in MCF-7 cells treated with 1 microM CPT, monitored for 6-10 days posttreatment. MCF-7 cells treated with supralethal doses of CPT (5 microM) resulted in only approximately 20% apoptosis. No correlation between apoptosis and loss of survival was observed. MCF-7 cells exposed to > 5 microM CPT arrested at key cell cycle checkpoints (i.e., G1, S, and G2-M), with little or no movement for 6 days. Ten-fold increases in p53/p21 and 2-5-fold decreases in bcl-2, Topo I, Topo IIalpha, and cyclins A and B1, with no change in cyclin E, were observed. Temporal decreases in bcl-2 and cleavage of lamin B corresponded to the minimal apoptotic response observed. Beta-lap activated apoptosis without inducing p53/p21 or cell cycle arrest responses and killed MCF-7 cells solely by apoptosis. In contrast, concentration-dependent increases in nuclear p53/p21 and various cell cycle checkpoint arrests were seen in MCF-7 cells after CPT. Despite dramatic p53/p21 protein induction responses, CPT-treated MCF-7 cells showed low levels of apoptosis, possibly due to protective cell cycle checkpoints or the lack of specific CPT-activated apoptotic pathways in MCF-7 cells.
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PMID:Induction of apoptosis in MCF-7:WS8 breast cancer cells by beta-lapachone. 958 28

The Crithidia fasciculata KAP1 gene encodes a small basic protein (p21) associated with kinetoplast DNA. The p21 protein has a nine amino acid cleavable presequence closely related to those of several other proteins targeted to the kinetoplast and binds non-specifically to kinetoplast minicircle DNA. The p21 protein also has a calculated pI of 13 with two amino acids (lysine and alanine) accounting for more than 50% of the residues and with 25 out of 28 lysine residues contained in the C-terminal half of the protein. Immunolocalization of p21 shows that the protein is found exclusively in the kinetoplast with a localization distinctly different from the antipodal localization of kinetoplast DNA topoisomerase and DNA polymerase. The KAP11 gene is a single copy gene and the KAP1 mRNA is present at a constant level throughout the cell cycle. This highly basic protein may play a role in the condensation or segregation of the kinetoplast DNA.
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PMID:The Crithidia fasciculata KAP1 gene encodes a highly basic protein associated with kinetoplast DNA. 971 9

To determine whether cell cycle regulation or alteration plays a role in oncogenesis and cytodifferentiation of odontogenic epithelium, cell cycle-related factors, including cyclin D1, p16INK4a, p21(WAF1/Cip1) and p27Kip1 proteins, DNA topoisomerase IIalpha and histone H3 mRNA, were examined in 8 tooth germs and 31 ameloblastomas. Cyclin D1 was expressed in epithelial cells near the basement membrane in tooth germs and ameloblastomas, suggesting that this protein participates in cell proliferation in odontogenic epithelium. Immunoreactivity for p16 protein was observed in most epithelial cells in tooth germs and ameloblastomas. Expression of p21 protein was detected in most epithelial cells in tooth germs and ameloblastomas, but not in keratinizing or granular cells in variants of ameloblastomas. Expression of p27 protein was chiefly found in central polyhedral cells and keratinizing cells in tooth germs and ameloblastomas. These cyclin-dependent kinase inhibitors were well preserved in ameloblastomas as compared with tooth germs, suggesting that the odontogenic epithelium is strictly regulated by these factors. The cell cycle phase/cellular proliferation markers, DNA topoisomerase IIalpha and histone H3 mRNA, were localized in scattered epithelial cells attached to the basement membrane in tooth germs and ameloblastomas.
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PMID:Detection of cell cycle-related factors in ameloblastomas. 1133 68

We examined the immunohistochemical expressions of cell-cycle- and apoptosis-related factors to investigate the possible role of these factors in odontogenic keratocyst (OKC). Expression of cyclin D1 and p16 protein was detected in the basal and parabasal cells in lining epithelium of OKCs and was found more frequently in basal cell nevus syndrome (BCNS)-associated OKCs than in primary or recurrent OKCs. Positivity for p21 protein was detected in basal to superficial cells, whereas that for p27 protein was detected in parabasal to superficial cells in lining epithelium of OKCs. DNA topoisomerase IIalpha reacted with nuclei in basal and parabasal cells of the lining epithelium of OKCs, and positive cells were observed in BCNS-associated OKCs significantly more frequently than in primary or recurrent OKCs. Expression of Fas in suprabasal to superficial cells and expression of Fas-L in basal and parabasal cells were detected in lining epithelium of OKCs. Immunoreactivity for caspase-3 was detected in basal to suprabasal or superficial cells in lining epithelium of OKCs. Single stranded (ss)DNA-positive nuclei were detected in superficial cells in lining epithelium of OKCs. Fas was more broadly distributed in BCNS-associated OKCs than in primary OKCs, and ssDNA-positive cells were observed in BCNS-associated OKCs significantly more frequently than in primary or recurrent OKCs. These results suggest that BCNS-associated OKCs might be a distinguishable entity from solitary OKCs.
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PMID:Immunohistochemical analysis of cell-cycle- and apoptosis-related factors in lining epithelium of odontogenic keratocysts. 1148 22

Apo2L/TRAIL exhibits enhanced apoptotic activity in tumor xenograft models when used in combination with the topoisomerase 1 inhibitor CPT-11. To investigate the cellular mechanisms involved in this increased tumor-killing activity, a series of in vitro experiments were conducted using the human colon carcinoma cell line (HCT116). Apo2L/TRAIL induced a transient upregulation of DR5 mRNA, while CPT-11 increased both death and decoy receptor expression. Upregulation of decoy receptors by CPT-11 was partially inhibited by co-administration of Apo2L/TRAIL. CPT-11 treatment resulted in accumulation of cells at G(2)M-phase and correlated with a substantial increase in the protein levels of the cyclin-dependent kinase inhibitor p21. However, cells co-treated with CPT-11 and Apo2L/TRAIL, or pretreated with CPT-11 for up to 24 h followed by 2 h Apo2L/TRAIL, resulted in a caspase-dependent degradation of p21, reversal of G(2)-M phase arrest with a concomitant increase in apoptosis. The sequential treatment produced the greatest induction of DR5 and DR4, caspase-3-like cleavage/activation and p21 degradation, as well as increased apoptosis. These data indicate that the up-regulation of Apo2L/TRAIL ligand and its death receptors as well as cleavage of p21 protein in the Apo2L/TRAIL plus CPT-11 treatment contributes to the positive cooperation between these agents in enhancing tumor cell apoptosis.
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PMID:Enhanced tumor killing by Apo2L/TRAIL and CPT-11 co-treatment is associated with p21 cleavage and differential regulation of Apo2L/TRAIL ligand and its receptors. 1203 63

The etiology and pathogenesis of Hodgkin lymphoma (HL) are not yet known. There are implications of genes involved in programmed cell death (apoptosis), and there have been repeated suggestions of an association with Epstein-Barr virus (EBV). The aim of this study was to investigate the protein expression patterns of key cell cycle-related genes, together with evidence of apoptosis and EBV status, in relation to clinical stage in HLs. A double immunohistochemical and in situ hybridization technique was used to detect the expression of bcl-2, p53, retinoblastoma (Rb), p21, Ki67 (MIB 1), and topoisomerase IIalpha (TopoIIalpha), together with latent membrane protein-1 and EBER for EBV status and TdT-mediated dUTP-FITC nick end-labeling (TUNEL) as a measure of apoptosis, on tissue microarray sections of 62 cases of classic HL (35 NS, 17 MC, 8 LR, and 2 LD). A panel of phenotypic markers was used to facilitate recognition of Hodgkin and Reed-Sternberg (H-RS) cells: CD3, CD20, CD30, CD15, and EMA. The H-RS cells of 62 classic Hodgkin lymphomas were bcl-2-positive in 35 cases (56.45%), p53-positive in 14 (22.58%), and positive for both EBV latent membrane protein-1 and EBER in 37 (59.68%); there was complete concordance of results for EBV by both procedures. No correlation was found between expression of bcl-2, p53, or EBV markers in H-RS cells and clinical stage (P > 0.05). Expression of Rb, Ki67, p21, and TopoIIalpha did, however, show significant differences with clinical stage. Expression of Rb and p21 in CD30-positive H-RS cells decreased with more advanced stage (P < 0.001). In contrast, Ki67 and ToPoIIalpha expression increased with later stage (P < 0.01). No correlation was found between expression of any of these markers in H-RS cells and the subtypes of nodular sclerosis HL, mixed cellularity HL, and LRHL (P > 0.05). TUNEL was found in the nonneoplastic cellular background in all cases and in H-RS cells in only 10 of 62 cases (16.12%) (8 nodular sclerosis HL, 1 mixed cellularity HL, and 1 LRHL). There was a significant correlation between high expression of bcl-2 and a low score by TUNEL (P < 0.05). These data are consistent with the notion that overexpression of bcl-2 may be linked to blockage of apoptosis-mediated death of H-RS cells in classic HL. Abnormal expression of p53-related protein may not play a major role in HL, because it is present in H-RS cells in only a minority of cases. Increased expression of Ki67 and TopoIIalpha by H-RS cells is significantly associated with advanced stage and may indicate aggressive disease. Adverse clinical outcome in HL also is associated with loss of Rb and p21 protein expression, consistent with the possible roles of Rb and p21 in inhibition of the growth of H-RS cells. Within the limitations of the methods used, almost two thirds of cases of HL provide evidence of an association with EBV. The tissue microarray technique is valuable not only for examination of large numbers of cases of a disease by a complex panel of markers but also potentially as a control for staining quality in immunohistochemistry and in situ hybridization.
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PMID:Apoptosis and cell cycle-related genes and proteins in classical Hodgkin lymphoma: application of tissue microarray technique. 1296 46

The PI3K/Akt signaling pathway is constitutively activated in various leukemias. In the present study, the topoisomerase inhibitor, 3EZ, 20Ac-ingenol, was more effective in inhibiting the growth of BALL-1 cells than that of normal lymphocyte cells. ATM/ATR protein levels were increased, PTEN protein was upregulated, and p-Akt protein was downregulated at early time points after treatment with 3EZ, 20Ac-ingenol. In further experiments, p53 protein expression was increased, and H2AX phosphorylation and p21 protein expression were induced after treatment with 3EZ, 20Ac-ingenol. Moreover, the activation of caspase 3 followed decrease in the Bcl-2/Bax ratio after treatment with 3EZ, 20Ac-ingenol, and accumulation of sub-G1 phase cells was observed in flow cytometry analyses. These data suggest that 3EZ, 20Ac-ingenol-induced DNA damage downregulates p-Akt and upregulates ATR leading to cell cycle arrest and increased apoptosis in BALL-1 cells.
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PMID:Mechanism of the inhibition of leukemia cell growth and induction of apoptosis through the activation of ATR and PTEN by the topoisomerase inhibitor 3EZ, 20Ac-ingenol. 2619 99