Cancer Chemotherapy and Pharmacology

, Volume 62, Issue 4, pp 689–697

BRCA1 modulates sensitivity to 5F-203 by regulating xenobiotic stress-inducible protein levels and EROD activity

  • Hyo Jin Kang
  • Hee Jeong Kim
  • Sang Hoon Kwon
  • Brian DongHoon Kang
  • Thomas E. Eling
  • Sang Han Lee
  • Insoo Bae
Original Article

DOI: 10.1007/s00280-007-0657-7

Cite this article as:
Kang, H.J., Kim, H.J., Kwon, S.H. et al. Cancer Chemother Pharmacol (2008) 62: 689. doi:10.1007/s00280-007-0657-7



We have investigated the effects of BRCA1 over-expression and knockdown on 5F-203-induced gene expression and cytotoxicity in human breast cancer cells. 5F-203 is a chemotherapeutic prodrug that both induces a p450 enzyme, CYP1A1, and is metabolically activated by CYP1A1.


We used several molecular biological techniques to confirm our findings. BRCA1 regulates sensitivity to 5F-203 by regulating the expression of CYP1A1 mRNA and its EROD activity. XRE-Luc reporter assays, semi-quantitative RT-PCR, Western blot analysis, EROD activity measurements, gene knockdown and MTT cell survival assays were used for this study.


Our results show that the ability of 5F-203 treatments to increase CYP1A1 mRNA level and CYP1A1 enzymatic activity (EROD activity) are affected by BRCA1 protein levels. In addition, the ability of 5F-203 treatments to induce proteins, P53 and P53 target genes such as P21, is significantly decreased in BRCA1 knockdown cells, suggesting that BRCA1-related effects could at least partially explain why BRCA1 knockdown increases resistance to 5F-203-mediated cytotoxicity. We also observed altered expression of the two major transcription factors (AhR and ARNT) that affect CYP1A1 expression when BRCA1 protein levels are altered.


BRCA1 is an important protein, which affects 5F-203-mediated cytotoxicity. Our findings are potentially clinically significant; they suggest that those patients most likely to respond to this new prodrug will have tumors containing normal amounts of BRCA1.


BRCA1 5F-203 AhR CYP1A1 P53 EROD activity 



Aryl hydrocarbon receptor


Breast cancer susceptibility gene-1


Dulbecco’s modified Eagles’ medium


Dimethyl sulfoxide


Fetal bovine serum


Standard error of mean

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Hyo Jin Kang
    • 1
  • Hee Jeong Kim
    • 1
  • Sang Hoon Kwon
    • 1
    • 3
  • Brian DongHoon Kang
    • 4
  • Thomas E. Eling
    • 5
  • Sang Han Lee
    • 1
    • 6
  • Insoo Bae
    • 1
    • 2
  1. 1.Department of OncologyLombardi Comprehensive Cancer Center, Georgetown UniversityWashington DCUSA
  2. 2.Department of Radiation MedicineLombardi Comprehensive Cancer Center, Georgetown UniversityWashington DCUSA
  3. 3.Department of Obstetrics and GynecologyKeimyung University, School of MedicineDaeguKorea
  4. 4.Department of BiochemistryUniversity of MichiganAnn ArborUSA
  5. 5.Molecular CarcinogenesisNational Institute of Environmental Health Sciences, National Institute of HealthResearch Triangle ParkUSA
  6. 6.Department of Biochemistry, College of MedicineSoonchunhyang UniversityCheon-AnKorea

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