Characterization of ARC-111 as a Novel Topoisomerase I-Targeting Anticancer Drug

Tsai Kun Li, Peter J. Houghton, Shyamal D. Desai, Parima Daroui, Angela A. Liu, Eszter S. Hars, Alexander L. Ruchelman, Edmond J. LaVoie, Leroy F. Liu

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101 Citations (Scopus)


8,9-Dimethoxy-5-(2-N,N-dimethylaminoethyl)-2,3-methylenedioxy-5 H-dibenzo[c,h][1,6] naphthyridin-6-one (ARC-111, topovale) is a new synthetic antitumor agent. In the current study, we show that ARC-111 is highly potent in scid mice carrying human tumor xenografts. ARC-111 was shown to be as active as camptothecin (CPT)-11 in the HCT-8 colon tumor model, and compared favorably with CPT-11 and topotecan in the SKNEP anaplastic Wilms' tumor model. In tissue culture models, ARC-111 exhibited low nM cytotoxicity against a panel of cancer cells. ARC-111 cytotoxicity as well as ARC-111-induced apoptosis was reduced >100-fold in CPT-resistant topoisomerase I (TOP1)-deficient P388/CPT45 cells as compared with P388 cells. Similarly, ARC-111 cytotoxicity was greatly reduced in CPT-resistant CPT-K5 and U937/CR cells, which express CPT-resistant mutant TOP1, suggesting that the cytotoxic target of ARC-111 is TOP1. Indeed, ARC-111, like CPT, was shown to induce reversible TOP1 cleavage complexes in tumor cells as evidenced by specific reduction of the TOP1 immunoreactive band in a band depletion assay, as well as elevation of small ubiquitin modifier-TOP1 conjugate levels and activation of 26S proteasome-mediated degradation of TOP1. Unlike CPT, ARC-111 is not a substrate for the ATP-binding cassette transporter breast cancer resistance protein. In addition, ARC-111 cytotoxicity was not significantly reduced in the presence of human serum albumin. These results suggest that ARC-111 is a promising new TOP1-targeting antitumor drug with a different drug resistance profile than CPT.

Original languageEnglish
Pages (from-to)8400-8407
Number of pages8
JournalCancer Research
Issue number23
Publication statusPublished - Dec 1 2003
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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