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)

The role of DNA topoisomerase (Topo) IIbeta in cancer chemotherapy remains unclear, although this particular isoform has been implicated in drug resistance. In this study, we investigated Topo IIbeta as a target for 2-[4-(7-chloro-2-quinoxalinyloxy)phenoxy]-propionic acid (XK469), a novel synthetic quinoxaline phenoxypropionic acid derivative, in a Waldenstrom's macroglobulinemia (WM) model. In vitro, the WSU-WM cell line was exposed to 1.0, 2.0, 5.0, 8.0, and 10 microM XK469. Our results demonstrate a concentration-dependent cell growth inhibition with a concentration-independent inhibition of Topo IIbeta, as determined by band depletion assay. The cell growth inhibition of cells correlated well with increase in Bax:Bcl-2 ratio and poly(ADP-ribose) polymerase (PARP) cleavage. We used our established WSU-WM severe combined immunodeficient mouse xenograft model to test the efficacy and effect of XK469 on Topo IIbeta in vivo. Topo IIbeta was inhibited equally using two different dose schedules (20 and 40 mg/kg, i.v., for a total of 120 and 240 mg/kg, respectively); however, there was no significant decrease in tumor weight. Western blot analysis of cells isolated from s.c. tumors showed no induction of the Bax protein and a very low Bax:Bcl-2 ratio of approximately 0.3 in correlation with minimum PARP cleavage. Our study shows that XK469 inhibits Topo IIbeta in WSU-WM cells both in vitro and in vivo at or below the maximum tolerated dose in severe combined immunodeficient mice. However, there was no change of apoptosis-related molecules such as PARP, Bax, and Bcl-2 or reduction in tumor weight in association with Topo IIbeta inhibition. We conclude that Topo IIbeta inhibition by XK469 as a target is not sufficient for therapeutic effects in WSU-WM.
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PMID:2-[4-(7-chloro-2-quinoxalinyloxy)phenoxy]-propionic acid (XK469) inhibition of topoisomerase IIbeta is not sufficient for therapeutic response in human Waldenstrom's macroglobulinemia xenograft model. 1251 64

This study is to observe the effect of N-(3-phenylallylidene)-6-fluoro-1, 8-(2, 1-propoxy)-7-(4-methylpiperazin-1-yl)-quinolin-4(1H)-one-3-carbonyl hyarazine (FQ16) on apoptosis of hepatocarcinoma SMMC-7721 cells in vitro. With different concentrations of FQ16 at different times used to treat SMMC-7721 cells in vitro, the proliferation of the cells and the inhibition effect of FQ16 on the cell proliferation were examined by MTT assay. Cell apoptosis was determined by Hoechst 33258/PI fluorescence staining, TUNEL and agarose gel electrophoresis method. The effect of FQ16 on topoisomerase II activity was measured by agarose gel electrophoresis using Plasmid pBR322 DNA as the substrate. Mitochondrial membrane potential (MMP, delta psi m) was measured by high content screening image system. The reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the expression changes of Bcl-2 mRNA and Bax mRNA. The caspase-9, caspase-8, caspase-3, p53, Bcl-2 and Bax protein expressions were detected by Western blotting analysis. The results showed that the cell proliferation was inhibited by FQ16 at 0.625 - 10 micromol L(-1) in a time-dose dependent manner. Treatment of SMMC-7721 cells with different concentrations of FQ16 for 24 h increased the percentage of the apoptosis cells obviously (P<0.05), the typical ladder DNA in apoptotic cells and a concomitant dissipation of the mitochondrial membrane potential. Compared with control group, FQ16 influenced obviously DNA topoisomerase II activity, stimulated DNA cleavage and inhibited DNA reunion mediated by topoisomerase II. In addition, FQ16 (3 - 7.39 micromol L(-1)) increased mRNA expression of Bax and protein expression of p53, Bax, caspase-9, caspase-3, separately, and induced cytosolic accumulation of activities caspase-9 and caspase-3, whereas the mRNA and protein expression of Bcl-2 decreased with no change of caspase-8. Therefore it can be concluded that the effects of inhibited topoisomerase II and mitochondrial-dependent pathways were involved in FQ16 induction of apoptosis of SMMC-7721 cells.
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PMID:[Cinnamaldehyde ofloxacin-3-ylhydrazone induces apoptosis of human hepatocarcinoma SMMC-7721 cells]. 2135 66


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