The arylstibonic acid compound NSC13746 disrupts B-ZIP binding to DNA in living cells.
The inhibition of DNA binding of basic leucine zipper (B-ZIP) transcription factors is a clinically relevant molecular target. Our laboratory has previously reported two methods of inhibiting B-ZIP DNA binding in solution: 1) an arylstibonic acid compound that binds to the basic region, stabilizes the B-ZIP dimer, and prevents B-ZIP DNA binding and 2) dominant negative proteins, termed A-ZIPs, that heterodimerize with B-ZIP domains in a leucine zipper-dependent manner. To determine if these two agents also inhibit DNA binding in live cells, GFP-tagged B-ZIP domains and mCherry-tagged A-ZIP domains were transfected into NIH3T3 cells to assess protein localization and Fluorescence Recovery After nuclear Photobleaching (FRAP). FRAP, showed that all six GFP-B-ZIP domains examined recovered faster in the nucleus in the presence of drug that we interpret represents an inhibition of DNA binding. Faster recovery in the presence of the A-ZIP was leucine zipper dependent. The arylstibonic also induced a cytoplasmic localization of all B-ZIP domains while the A-ZIPs induced a leucine zipper-dependent cytoplasmic localization. Thus, the change in cellular localization of B-ZIP domains could be used as a high-throughput assay for inhibitors of B-ZIP DNA binding. Additionally, the arylstibonic acid compound was cytostatic in clear cell sarcoma cells, which express a chimera between the B-ZIP domain of ATF-1 and N-terminal activation domain of EWS but not in K562 cells that express a non-B-ZIP containing chimeric protein BCR-ABL. These studies suggest that arylstibonic acid compounds or other small molecules capable of inhibiting B-ZIP DNA binding could be valuable anticancer agents.
Heyerdahl
Sarah L
SL
Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Rozenberg
Julian
J
Jamtgaard
Louis
L
Rishi
Vikas
V
Varticovski
Lyuba
L
Akah
Kelly
K
Scudiero
Dominic
D
Shoemaker
Robert H
RH
Karpova
Tatiana S
TS
Day
Richard N
RN
McNally
James G
JG
Vinson
Charles
C
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001557:Benzenesulfonates / Q000494:pharmacology*; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D004247:DNA / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D016350:Leucine Zippers / Q000502:physiology*; D051379:Mice; D041681:NIH 3T3 Cells; D009942:Organometallic Compounds / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D055503:Protein Multimerization; D014157:Transcription Factors / Q000378:metabolism*
D000970:Antineoplastic Agents; D001557:Benzenesulfonates; C551445:NSC 13746; D009942:Organometallic Compounds; D014157:Transcription Factors; D004247:DNA