Characterization and immunological identification of cDNA clones encoding two human DNA topoisomerase II isozymes.

Chung, Thomas D.Y.; Drake, Fred H.; Tan, K. B.; Per, Steven R.; Crooke, Stanley T.; Mirabelli, Christopher K.

doi:10.1073/pnas.86.23.9431

Cited by 205 publications

(116 citation statements)

References 37 publications

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“…Human topoisomerase is biochemically differentiated into two isoforms, the ␣ and the ␤ subtypes. The ␣ isoform predominates mainly in the proliferating cells, whereas the ␤ isoform is seen in resting cells (23,24). It has been proposed that topo II analysis can be used as a marker for cell proliferation (13)(14)(15)(16).…”

Section: Discussionmentioning

confidence: 99%

Expression of DNA Topoisomerase IIα in Thyroid Neoplasia

2000

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Section: Discussionmentioning

confidence: 99%

Expression of DNA Topoisomerase IIα in Thyroid Neoplasia

2000

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“…The molecular weights of these bands were 170 ± 3 kDa and 179 ± 3 kDa (mean ± s.e. ; n = 5), corresponding to previously characterised topoisomerase IIa and topoisomerase II,B isoforms of this enzyme respectively (Chung et al, 1989;Drake et al, 1989 …”

Section: Resultsmentioning

confidence: 99%

“…Samples containing 10 jig were electrophoresed through 6% SDS-polyacrylamide gel (Laemmli, 1970) and electroblotted at 400 mA overnight to nitrocellulose (Towbin et al, 1979) using a Hoefer (San Franscisco, CA, USA) Transfor apparatus. Blots were incubated with human topoisomerase II-specific rabbit antiserum, IID3 (from L.F. Liu), affinity-purified topoisomerase IIa-specific antibody FHD22 or affinity-purified topoisomerase IIP-specific antibody FHD21 (Chung et al, 1989). The affinity-purified, isoform-specific antibodies were provided by F.H.…”

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confidence: 99%

Altered stability of etoposide-induced topoisomerase II-DNA complexes in resistant human leukaemia K562 cells

Ritke

Roberts²,

Allan³

et al. 1994

Br J Cancer

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Summary K562 leukaemia cells were selected for resistance using 0.5 tiLM etoposide (VP-16). Cloned K/VP.5 cells were 30-fold resistant to growth inhibition by VP-16 and 5-to 13-fold resistant to m-AMSA, adriamycin and mitoxantrone. K/VP.5 cells did not overexpress P-glycoprotein; VP-16 accumulation was similar to that in K562 cells. VP-16-induced DNA damage was reduced in cells and nuclei from K/VP.5 cells compared with K562 cells. Topoisomerase II protein was reduced 3-to 7-fold and topoisomerase IIa and topoisomerase IIP mRNAs were each reduced 3-fold in resistant cells. After drug removal, VP-16-induced DNA damage disappeared 1.7 times more rapidly and VP-16-induced DNA-topoisomerase II adducts dissociated 1.5 times more rapidly in K/VP.5 cells than in K562 cells. ATP (I mM) was more effective in enhancing VP-16-induced DNA damage in nuclei isolated from sensitive cells than in nuclei from resistant cells. In addition, ATP (0.3-5 mM) stimulated VP-16-induced DNA-topoisomerase II adducts to a greater extent in K562 nuclei than in K/VP.5 nuclei. Taken together, these results indicate that resistance to VP-16 in a K562 subline is associated with a quantitative reduction in topoisomerase II protein and, in addition, a distinct qualitative alteration in topoisomerase II affecting the stability of drug-induced DNA-topoisomerase II complexes.DNA topoisomerase II (topoisomerase II) is a nuclear matrix-associated DNA-binding protein responsible for transient cleavage of DNA, allowing the passage of DNA double strands through formed DNA breaks to relieve torsional stress during replication and transcription (Wang, 1985;Liu, 1989;Osheroff, 1989). Topoisomerase II also allows for separation of daughter DNA strands during mitosis and is thought to play a role in recombinational events (Wang, 1985). Topoisomerase II is a target for a number of clinically effective antineoplastic agents including m-AMSA, doxorubicin, mitoxantrone, VM-26 and VP-16 (Chen et al., 1984; Tewey et al., 1984a,b;Zwelling, 1985;Minford et al., 1986;Zhang, 1990). These drugs interfere with topoisomerase II activity by stabilising topoisomerase II/DNA binding and strand breakage, a result of blockade of the religation/ resealing reaction which follows topoisomerase 1I-mediated strand breakage (Chen et al., 1984;Nelson et al., 1984). Drug resistance associated with alterations in the level, activity and/or phosphorylation state of topoisomerase II has been reported in both murine and human malignant cell lines selected for resistance in the presence of topoisomerase II inhibitors (Glisson et al

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“…Hybridisations were carried out as described previously (Keith et al, 1992). The probe SPI was used to detect topoisomerase IIa sequences (Chung et al, 1989), pHPKC-alpha 7 to detect PKCcx (Parker et al, 1986), p63 to detect RARx and pHJi was used as a control for DNA loading (Keith et al, 1992 [21][22] (Tsai-Pflugfelder et al, 1988;Mattei et al, 1988). The PKCa locus has been mapped to chromosome 17q 22-24, (Parker et al, 1986).…”

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confidence: 99%

Expression of topoisomerase II alpha and beta in an adenocarcinoma cell line carrying amplified topoisomerase II alpha and retinoic acid receptor alpha genes

Coutts¹,

Plumb²,

Brown³

et al. 1993

Br J Cancer

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Summary Human topoisomerase II enzymes are targets for a number of widely used anticancer agents. We have analysed a lung adenocarcinoma cell line CALU3, which has co-amplified topoisomerase IIax and ERBB2 sequences, for the structure of the amplicon and for expression of both topoisomerase Ila and P. The al., 1989;Woessner et al., 1991). Recent studies have also indicated that the alpha and beta enzymes are sublocalised within the nucleus to the nucleoplasm and nucleoli respectively (Negri et al., 1992).Interest in topoisomerase II is due both to its essential catalytic activity in normal cells and that it is a key target for a group of anticancer agents including etoposide, doxorubicin and mAMSA (Takano et al., 1992;Liu, 1989 (Muggia & Gill, 1991) the levels of expression in tumours may be important in determining the success of the treatment. Molecular changes at topoisomerase loci which result in altered expression are therefore important and recently it has been shown that the topoisomerase II alpha gene is co-amplified along with ERBB2 in a subset of breast adenocarcinomas (Keith et al., 1993).We have previously shown that the lung adenocarcinoma cell line CALU3, has co-amplification of ERBB2 and topoisomerase Ilcc, (Keith et al., 1992). This cell line therefore provides a model to examine the role of topoisomerase Ila amplification and expression in drug sensitivity. We have now investigated the expression, localisation and enzymatic activity of both topoisomerase Ila and P in CALU3 and further characterised the amplicon containing the topoisomerase Ila gene. We show here that the amplified topoisomerase II alpha gene in CALU3 is expressed at a high level and that enzyme activity is inhibited by a topoisomerase II interactive drug. Immunofluorescence studies using antibodies against topoisomerase II alpha and beta show the alpha product to be expressed heterogeneously within the cell population. In contrast, the beta isoform is expressed in all cells and localised to the nucleolus. In addition, we show by fluorescence in situ hybridisation (FISH)

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Characterization and immunological identification of cDNA clones encoding two human DNA topoisomerase II isozymes.

Abstract: ABSTRACT

Cited by 205 publications

References 37 publications

Expression of DNA Topoisomerase IIα in Thyroid Neoplasia

Expression of DNA Topoisomerase IIα in Thyroid Neoplasia

Altered stability of etoposide-induced topoisomerase II-DNA complexes in resistant human leukaemia K562 cells

Expression of topoisomerase II alpha and beta in an adenocarcinoma cell line carrying amplified topoisomerase II alpha and retinoic acid receptor alpha genes

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