Measuring cytotoxicity: A new perspective on LC50

Ming Zhang, Dolly Aguilera, Chandra Das, Hernan Vasquez, Peter Zage, Vidya Gopalakrishnan, Johannes Wolff

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Background: Cytotoxicity in cell culture is typically expressed as LC 50, the concentration of a given agent which is lethal to 50% of the cells. This number is dependent on the incubation time with the agent. Previously, a two-term exponential model has been proposed to describe cell growth after a cytotoxic event: y(t) = k1 * exp(-d 1*t) + k2 * exp(d2*t). A dose-response relationship was observed between the parameter k2 in this formula and the concentration of the cytotoxic agent etoposide, in high-grade glioma cells was independent of incubation time. Materials and Methods: In order to test if the model can be applied more generally, DAOY medulloblastoma cells treated with MS275, a histone deacetylase inhibitor, were used. Results: The observed data fit the model well. Conclusion: The concentration at which k2 is reduced by 50% is called KC 50. It provides a far better description of the cytotoxicity of an agent in a specific cell line than the traditional LC50.

Original languageEnglish (US)
Pages (from-to)35-38
Number of pages4
JournalAnticancer Research
Issue number1 A
StatePublished - Jan 2007


  • Cytotoxicity
  • LC
  • Lethal concentration

ASJC Scopus subject areas

  • Cancer Research
  • Oncology


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