DNA topoisomerase II in therapy-related acute promyelocytic leukemia.
BACKGROUND
Chromosomal translocations leading to chimeric oncoproteins are important in leukemogenesis, but how they form is unclear. We studied acute promyelocytic leukemia (APL) with the t(15;17) translocation that developed after treatment of breast or laryngeal cancer with chemotherapeutic agents that poison topoisomerase II.


METHODS
We used long-range polymerase chain reaction and sequence analysis to characterize t(15;17) genomic breakpoints in therapy-related APL. To determine whether topoisomerase II was directly involved in mediating breaks of double-stranded DNA at the observed translocation breakpoints, we used a functional in vitro assay to examine topoisomerase II-mediated cleavage in the normal homologues of the PML and RARA breakpoints.


RESULTS
Translocation breakpoints in APL that developed after exposure to mitoxantrone, a topoisomerase II poison, were tightly clustered in an 8-bp region within PML intron 6. In functional assays, this "hot spot" and the corresponding RARA breakpoints were common sites of mitoxantrone-induced cleavage by topoisomerase II. Etoposide and doxorubicin also induced cleavage by topoisomerase II at the translocation breakpoints in APL arising after exposure to these agents. Short, homologous sequences in PML and RARA suggested the occurrence of DNA repair by means of the nonhomologous end-joining pathway.


CONCLUSIONS
Drug-induced cleavage of DNA by topoisomerase II mediates the formation of chromosomal translocation breakpoints in mitoxantrone-related APL and in APL that occurs after therapy with other topoisomerase II poisons.
Mistry
Anita R
AR
Department of Medical and Molecular Genetics, Guy's, King's, and St. Thomas' School of Medicine, London.
Felix
Carolyn A
CA
Whitmarsh
Ryan J
RJ
Mason
Annabel
A
Reiter
Andreas
A
Cassinat
Bruno
B
Parry
Anne
A
Walz
Christoph
C
Wiemels
Joseph L
JL
Segal
Mark R
MR
Adès
Lionel
L
Blair
Ian A
IA
Osheroff
Neil
N
Peniket
Andrew J
AJ
Lafage-Pochitaloff
Marina
M
Cross
Nicholas C P
NC
Chomienne
Christine
C
Solomon
Ellen
E
Fenaux
Pierre
P
Grimwade
David
D
D000970:Antineoplastic Agents / Q000009:adverse effects / Q000494:pharmacology; D004249:DNA Damage; D004260:DNA Repair; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000187:drug effects / Q000378:metabolism*; D004317:Doxorubicin / Q000009:adverse effects; D005047:Etoposide / Q000009:adverse effects; D006801:Humans; D066298:In Vitro Techniques; D015473:Leukemia, Promyelocytic, Acute / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics*; D008942:Mitoxantrone / Q000494:pharmacology; D016609:Neoplasms, Second Primary / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics*; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D059005:Topoisomerase II Inhibitors; D014178:Translocation, Genetic
D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D059005:Topoisomerase II Inhibitors; D005047:Etoposide; D004317:Doxorubicin; D008942:Mitoxantrone; D004250:DNA Topoisomerases, Type II