Amino acid Asp181 of 5′-flap endonuclease 1 is a useful target for chemotherapeutic development

Harekrushna Panda, Aruna S. Jaiswal, Patrick E. Corsino, Melissa L. Armas, Brian K. Law, Satya Narayan

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


DNA alkylation-induced damage is one of the most efficacious anticancer therapeutic strategies. Enhanced DNA alkylation and weakened DNA repair capacity in cancer cells are responsible for the effectiveness of DNA-alkylating therapies. 5′-Flap endonuclease 1 (Fen1) is an important enzyme involved in base excision repair (BER), specifically in long-patch BER (LP-BER). Using the site-directed mutagenesis approach, we have identified an important role for amino acid Asp181 of Fen1 in its endonuclease activity. Asp181 is thought to be involved in Mg2+ binding in the active site. Using structure-based molecular docking of Fen1 targeted to its metal binding pocket M2 (Mg 2+ site), we have identified a potent low-molecular weight inhibitor (LMI, NSC-281680) that efficiently blocks LP-BER. In this study, we have demonstrated that the interaction of this LMI with Fen1 blocked its endonuclease activity, thereby blocking LP-BER and enhancing the cytotoxic effect of DNA-alkylating agent Temozolomide (TMZ) in mismatch repair(MMR)-deficient and MMR-proficient colon cancer cells. The results further suggest that blockade of LP-BER by NSC-281680 may bypass other drug resistance mechanisms such as mismatch repair (MMR) defects. Therefore, our findings provide groundwork for the development of highly specific and safer structure-based small molecular inhibitors targeting the BER pathway, which can be used along with existing chemotherapeutic agents, like TMZ, as combination therapy for the treatment of colorectal cancer.

Original languageEnglish (US)
Pages (from-to)9952-9958
Number of pages7
Issue number42
StatePublished - Oct 27 2009
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry


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