5-Ethynyl-2'-deoxycytidine as a new agent for DNA labeling: detection of proliferating cells

Anal Biochem. 2011 Oct 1;417(1):112-21. doi: 10.1016/j.ab.2011.05.037. Epub 2011 May 30.


The labeling of newly synthesized DNA in cells to identify cell proliferation is an important experimental technique. The most accurate methods incorporate [(3)H]thymidine or 5-bromo-2'-deoxyruidine (BrdU) into dividing cells during S phase, which is subsequently detected by autoradiography or immunohistochemistry, directly measuring the newly synthesized DNA. Recently, a novel method was developed to detect DNA synthesis in proliferating cells based on a novel thymidine analog, 5-ethynyl-2'-deoxyuridine (EdU). EdU is incorporated into DNA and subsequently detected with a fluorescent azide via "click" chemistry. This novel technique is highly sensitive and does not require DNA denaturation. However, it was also found that EdU exhibits time-dependent inhibition effects on cell growth. Therefore, here we report a novel deoxycytidine analog, 5-ethynyl-2'-deoxycytidine (EdC), that can be used to detect DNA synthesis in vitro and in vivo at a similar sensitivity level compared with EdU. Furthermore, the EdC-induced cytotoxicity is much less than that of EdU when combined with thymidine. This will be a potential application for the long-term detection of proliferating cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Death / drug effects
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • DNA / biosynthesis
  • DNA / metabolism*
  • Deoxyuridine / analogs & derivatives*
  • Deoxyuridine / chemistry
  • Deoxyuridine / metabolism
  • Deoxyuridine / toxicity
  • Flow Cytometry
  • Humans
  • Mice
  • Organ Specificity / drug effects
  • Staining and Labeling / methods*
  • Thymidine / metabolism
  • Time Factors


  • DNA
  • 5-ethynyl-2'-deoxyuridine
  • Thymidine
  • Deoxyuridine