Ectopic expression of inactive forms of yeast DNA topoisomerase II confers resistance to the anti-tumour drug, etoposide.

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serval:BIB_4531
Type
Article: article from journal or magazin.
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Publications
Institution
Title
Ectopic expression of inactive forms of yeast DNA topoisomerase II confers resistance to the anti-tumour drug, etoposide.
Journal
British Journal of Cancer
Author(s)
Vassetzky Y.S., Alghisi G.C., Roberts E., Gasser S.M.
ISSN
0007-0920
Publication state
Published
Issued date
1996
Volume
73
Number
10
Pages
1201-1209
Language
english
Abstract
Drug resistance to anti-tumour agents often coincides with mutations in the gene encoding DNA topoisomerase II alpha. To examine how inactive forms of topoisomerase II can influence resistance to the chemotherapeutic agent VP-16 (etoposide) in the presence of a wild-type allele, we have expressed point mutations and carboxy-terminal truncations of yeast topoisomerase II from a plasmid in budding yeast. Truncations that terminate the coding region of topoisomerase II at amino acid (aa) 750, aa 951 and aa 1044 are localised to both the cytosol and the nucleus and fail to complement a temperature-sensitive top2-1 allele at non-permissive temperature. In contrast, the plasmid-borne wild-type TOP2 allele and a truncation at aa 1236 are nuclear localised and complement the top2-1 mutation. At low levels of expression, truncated forms of topoisomerase II render yeast resistant to levels of etoposide 2- and 3-fold above that tolerated by cells expressing the full-length enzyme. Maximal resistance is conferred by the full-length enzyme carrying a mutated active site (Y783F) or a truncation at aa 1044. The level of phosphorylation of topoisomerase II was previously shown to correlate with drug resistance in cultured cells, hence we tested mutants in the major casein kinase II acceptor sites in the C-terminal domain of yeast topoisomerase II for changes in drug sensitivity. Neither ectopic expression of the C-terminal domain alone nor phosphoacceptor site mutants significantly alter the host cell's sensitivity to etoposide.
Keywords
Amino Acid Sequence, Binding Sites, Casein Kinase II, Culture Media, DNA Topoisomerases, Type II/metabolism, Drug Resistance, Etoposide/pharmacology, Gene Expression, Genetic Complementation Test, Molecular Sequence Data, Phosphoproteins/metabolism, Protein-Serine-Threonine Kinases/metabolism, Saccharomyces cerevisiae/enzymology, Sequence Deletion, Structure-Activity Relationship
Pubmed
Web of science
Open Access
Yes
Create date
19/11/2007 12:40
Last modification date
20/08/2019 13:49
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