Protection and sensitization of normal and malignant cells by a naturally occurring compound in a model of photochemical damage

Yuan Hao Lee, Neeru Kumar, Randolph D. Glickman

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Certain phytonutrients are known to confer protection and immunosuppression against radiation insults. Radiation-induced reactive oxygen species (ROS) can either lead to the destruction of normal tissue cells, or induce tumor radioresistance by activating ROS scavenging proteins. To identify whether the triterpene phytonutrient, ursolic acid, reduces radiation-induced damage in normal cells and promotes the apoptosis of malignant cells, we investigated the biologic mechanisms and effect of radiation-cell interaction with or without treatment with ursolic acid in human skin melanoma cells (ATCC CRL-11147™) and transformed human retinal pigment epithelial (hTERT-RPE) cells. UV-VIS light was employed to investigate the efficacy of ursolic acid in altering cellular viability by modulations of p53 and NF-κB p65 signaling. Cell response was investigated by changes in proliferative activity and free radical generation assessed by 2′,7′-dichlorofluorescin liquid chromatography. Ursolic acid pretreatment strongly increased the level of p53 and decreased the level of phosphorylated p65 leading to enhanced cell death of skin melanoma cells in response to UV-VIS exposure. In contrast, ursolic acid appeared to downregulate p53 levels without disturbing NF-κB activation along with an increase of oxidative stress in hTERT-RPE cells. These findings indicate that ursolic acid may beneficially increase the radiosensitivity of tumor cells while potentiating a photoprotective effect on benign cells through differential effects on the NF-κB and p53 signaling pathways.

Original languageEnglish (US)
Title of host publicationOptical Interactions with Tissue and Cells XXIII
StatePublished - Apr 2 2012
EventOptical Interactions with Tissue and Cells XXIII - San Francisco, CA, United States
Duration: Jan 23 2012Jan 25 2012

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherOptical Interactions with Tissue and Cells XXIII
Country/TerritoryUnited States
CitySan Francisco, CA


  • NF-κB
  • p53
  • radiation
  • sensitization
  • ursolic acid

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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