Modulation of topoisomerase IIalpha expression by a DNA sequence-specific polyamide.
Topoisomerase IIalpha (topo IIalpha) is an important target for several chemotherapeutic agents, including etoposide and doxorubicin. Confluent cells express low levels of topo IIalpha and are resistant to etoposide treatment. Repression of transcription in confluent cells is mediated by binding of the transcription factor NF-Y to inverted CCAAT motifs within the topo IIalpha promoter. To block the repressive binding of NF-Y, a polyamide (JH-37) was designed to bind to the flanking regions of selected CCAAT sites within the topo IIalpha promoter. Electrophoretic mobility shift assays and DNase I footprinting assays showed occupancy of the inverted CCAAT sites by JH-37. Chromatin immunoprecipitation assays confirmed in vivo inhibition of NF-Y binding to the topo IIalpha promoter. Following incubation of confluent NIH3T3 cells with JH-37, increased expression of topo IIalpha mRNA and protein was detectable. This correlated both with increased DNA double-strand breaks as shown by comet assay and decreased cell viability following exposure to etoposide. Polyamides can modulate gene expression and chemosensitivity of cancer cells.
Hochhauser
Daniel
D
Department of Oncology, Royal Free and University College Medical School, University College London, 91 Riding House Street, London W1W 7BS, United Kingdom. d.hochhauser@ucl.ac.uk
Kotecha
Minal
M
O'hare
Caroline
C
Morris
Peter J
PJ
Hartley
Janet M
JM
Taherbhai
Zarmeen
Z
Harris
Dorothy
D
Forni
Claudia
C
Mantovani
Roberto
R
Lee
Moses
M
Hartley
John A
JA
D000818:Animals; D000951:Antigens, Neoplasm / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D047369:Chromatin Immunoprecipitation; D004250:DNA Topoisomerases, Type II / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D005047:Etoposide / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects*; D051379:Mice; D041681:NIH 3T3 Cells; D009757:Nylons / Q000737:chemistry / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; D009757:Nylons; D012333:RNA, Messenger; D014157:Transcription Factors; D005047:Etoposide; D004250:DNA Topoisomerases, Type II