Related Experiment Videos
Modulation of DNA-protein interactions in the P1 and P2 c-myc promoters by two intercalating drugs
1Departamento de Biología Molecular y Celular, Centro de Investigación y Desarrollo, CSIC, Barcelona, Spain.
Abstract:
Regulation of transcription from the oncogene c-myc has an important role in the genesis of various tumors. Therefore, c-myc is a potential target for chemotherapy by drugs which are able to modify its activity directly. In this article, we identify the binding sites in the P1 and P2 promoter regions of c-myc for the intercalating antibiotics actinomycin D and elsamicin A. Gel retardation experiments indicate that actinomycin D or elsamicin A binding can inhibit the formation of several DNA-protein complexes. However, relatively low concentrations of elsamicin A, but not actinomycin D, appear to increase the level of binding to the P1 promoter of a protein factor. Using pure Sp1 transcription factor and an oligonucleotide containing the Sp1 putative binding site, we determined that the binding enhancement induced by small amounts of elsamicin was on the Sp1-DNA complex. Run-off transcription experiments in vitro showed that the effect of elsamicin A on Sp1 binding is followed by the maintenance or a relative rise in transcription levels from the P1 promoter of c-myc, while actinomycin D always inhibited the transcription from the P1 c-myc promoter in a concentration-dependent manner. Higher concentrations of elsamicin acted as an inhibitor of the transcription from the P1 start site but not from the P2.
Insights
The oncogene c-myc is crucial in tumor development, making it a chemotherapy target. Researchers found that elsamicin A, unlike actinomycin D, can enhance Sp1 transcription factor binding to the c-myc P1 promoter, potentially altering transcription.
Area of Science:
- Molecular Biology
- Cancer Research
- Pharmacology
Background:
- The oncogene c-myc plays a critical role in tumor genesis.
- Targeting c-myc activity directly offers a potential chemotherapy strategy.
- Understanding drug interactions with c-myc promoter regions is key for drug development.
Purpose of the Study:
- To identify binding sites of actinomycin D and elsamicin A in the c-myc P1 and P2 promoter regions.
- To investigate the effects of these antibiotics on DNA-protein complex formation and transcription factor binding.
- To elucidate the impact of these drugs on c-myc transcription.
Main Methods:
- Gel retardation assays to detect DNA-protein complex formation.
- Experiments using purified Sp1 transcription factor and specific oligonucleotides.
- In vitro run-off transcription assays to measure c-myc promoter activity.
Main Results:
- Both actinomycin D and elsamicin A binding inhibited several DNA-protein complexes.
- Low concentrations of elsamicin A enhanced Sp1 binding to the c-myc P1 promoter, while actinomycin D did not.
- Elsamicin A at low concentrations maintained or increased P1 transcription, whereas actinomycin D inhibited it; higher elsamicin A concentrations inhibited P1 transcription.
Conclusions:
- Elsamicin A exhibits differential effects on c-myc transcription, potentially enhancing Sp1-mediated transcription at low doses.
- Actinomycin D consistently inhibits c-myc transcription.
- These findings highlight distinct mechanisms of action for intercalating antibiotics on oncogene promoters, suggesting therapeutic potential for elsamicin A.