Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.3 (topoisomerase)
 9,911 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously shown that the DNA topoisomerase II alpha (topo II alpha) gene is down-regulated in VP16/VM26-resistant cells at the transcriptional level. To determine the DNA elements responsible for down-regulation, the transcriptional activities of luciferase reporter constructs containing various lengths of the promoter sequences were investigated by transient transfection of two resistant cell lines, KB/VP2 and KB/VM4. The transcriptional activities of the full-length promoter (-295 to +85) and of three deletion constructs (-197, -154 and -74 to +85) were significantly down-regulated in resistant cells. In contrast, the transcriptional activity of the minimal promoter (-20 to +85) in resistant cells was similar to that in parental KB cells. Furthermore, introduction of a mutation in ICE1 abolished the down-regulation of the topo II alpha promoter activity in drug-resistant cells. In vivo footprinting analysis of topo II alpha gene promoter revealed several specific protein-binding sites, a GC box, ICE1, ICE2 and ICE3. In vivo footprinting analysis also identified a cluster of hypersensitive sites. However, there was no marked difference in protein-binding sites between parental and resistant cells. To confirm our previous results, we have established the VP16-resistant cell lines T12-VP1 and T12-VP2 from T12 cells derived from human bladder cancer T24 cells stably transfected with the chloramphenicol acetyltransferase reporter gene driven by the topo II alpha gene promoter. The expression to topo II alpha was down-regulated in both cell lines. We also found that CAT gene expression was significantly decreased to one-fifth of that in T12 parental cells. These results suggest that the expression of the topo II alpha gene requires the binding of multiple factors to the core promoter and is down-regulated at the transcriptional level, probably through binding of a negative factor to ICE1 in drug-resistant cells.
 ...
PMID:Structural and functional analysis of the control region of the human DNA topoisomerase II alpha gene in drug-resistant cells. 1040 35

The inhibition of cell proliferation by 1,4-bis (1-naphthyl)-2,3-dinitro-1,3-butadiene (Naph-DNB) was evaluated in vitro against 4 cell lines (L1210/DDP, A2780/DX3, HCT-8/FU7dR, A549-T12) selected for their resistance to cisplatin, doxorubicin, 5-fluorouracil and taxol, and their wild-type counterparts. Naph-DNB is a novel anti-cancer compound obtained years ago within a research project of Organic Chemistry aimed at synthesizing 2,3-dinitrobutadiene derivatives. Because of its chemical structure, Naph-DNB was suggested to interact with nucleic acids, in particular DNA, and the other cellular macromolecules. This hypothesis made us consider Naph-DNB as a candidate for studies concerning its antitumour activity. We used the MTT assay to test the inhibition of cell proliferation after incubation of the cell lines with Naph-DNB for 72 h. For comparison, resistant and wild-type cell lines were also tested against those anticancer drugs used in vitro for their selection. In these culture conditions Naph-DNB retained its inhibiting activity against all resistant cells with IC50 values similar to those obtained in corresponding wild-type cell lines. Moreover, Naph-DNB was twice as effective as 5-fluorouracil against wild-type HCT-8 cells. Our previous findings about the interaction of Naph-DNB with DNA through the formation of interstrand cross-links suggested a mechanism of action similar to that of platinum/alkylating agents or topoisomerase inhibitors (intercalating agents). Our present data obtained by the K-SDS precipitation assay in A2780 and A549 cells showed that Naph-DNB is not able to form a stable topoisomerase-DNA complex as is the case for topoisomerase inhibitors. In conclusion, our results indicate that Naph-DNB is able to overcome some of the classical mechanisms of resistance selected by some anticancer drugs mainly used in clinical setting.
 ...
PMID:1,4-Bis(1-naphthyl)-2,3-dinitro-1,3-butadiene a novel anticancer compound effective against tumor cell lines characterized by different mechanisms of resistance. 1520 65