Topoisomerase levels determine chemotherapy response in vitro and in vivo.
Topoisomerase poisons are chemotherapeutic agents that are used extensively for treating human malignancies. These drugs can be highly effective, yet tumors are frequently refractory to treatment or become resistant upon tumor relapse. Using a pool-based RNAi screening approach and a well characterized mouse model of lymphoma, we explored the genetic basis for heterogeneous responses to topoisomerase poisons in vitro and in vivo. These experiments identified Top2A expression levels as major determinants of response to the topoisomerase 2 poison doxorubicin and showed that suppression of Top2A produces resistance to doxorubicin in vitro and in vivo. Analogously, using a targeted RNAi approach, we demonstrated that suppression of Top1 produces resistance to the topoisomerase 1 poison camptothecin yet hypersensitizes cancer cells to doxorubicin. Importantly, lymphomas relapsing after treatment display spontaneous changes in topoisomerase levels as predicted by in vitro gene knockdown studies. These results highlight the utility of pooled shRNA screens for identifying genetic determinants of chemotherapy response and suggest strategies for improving the effectiveness of topoisomerase poisons in the clinic.
Cold Spring Harbor Laboratory and Howard Hughes Medical Institute, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
Darren J
DJ
Burgess
Jason
J
Doles
Lars
L
Zender
Wen
W
Xue
Beicong
B
Ma
W Richard
WR
McCombie
Gregory J
GJ
Hannon
Scott W
SW
Lowe
Michael T
MT
Hemann
D000818:Animals; D000951:Antigens, Neoplasm / Q000378:metabolism*; D045744:Cell Line, Tumor; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy* / Q000201:enzymology*; D000075223:Poly-ADP-Ribose Binding Proteins; D034622:RNA Interference / Q000187:drug effects; D034741:RNA, Small Interfering / Q000378:metabolism; D012008:Recurrence
D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D034741:RNA, Small Interfering; D004317:Doxorubicin; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; C000618811:TOP2A protein, human; C000618812:Top2a protein, mouse