UV or X-irradiation increases the cytoplasmic accumulation of rhodamine 123 in various cancer cell lines

Ingrid Dumitriu, Franz Roedel, Thomas D Beyer, Udo S Gaipl, Joachim R Kalden, Martin Herrmann

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


PURPOSE: Previous studies indicated that ATP-binding cassette (ABC) membrane transporters protect against UV-induced apoptosis. We investigated the effect of UVB and X-ray irradiation on the export function of these ABC transporters in primary lymphocytes and various cancer cell lines.

MATERIAL AND METHODS: We used rhodamine accumulation assays in various human malignant cell lines and peripheral blood lymphocytes (PBL). Cells were irradiated with up to 960 mJ/cm2 and up to 50 Gy of UVB and X-ray, respectively.

RESULTS: We demonstrated that UVB as well as X-ray irradiation inhibit the export function of the ABC transporters in a dose-dependent fashion. For PBL, this effect did not correlate with an apoptotic phenotype. In the case of the tumor cell lines, even though the irradiation-induced inhibition of membrane transporters was accompanied by phosphatidylserine exposure, only a minority of cells had lost their mitochondrial membrane potential during the observation period. Furthermore, we demonstrated that the inhibition of membrane transporters is not a general feature of apoptosis.

CONCLUSION: Irradiation inhibits the export function of ABC transporters. Although some of the irradiated cells undergo apoptosis following irradiation, the inhibition is an unique feature accompanying irradiation and not a general hallmark of apoptotic cell death. The inhibition of drug export by irradiation may offer new potential for reverting multidrug resistance of cancer cells.

Original languageEnglish
Pages (from-to)564-70
Number of pages7
JournalStrahlentherapie und Onkologie
Issue number8
Publication statusPublished - Aug 2003


  • ATP-Binding Cassette Transporters/drug effects
  • Apoptosis/genetics
  • Cell Death/radiation effects
  • Cell Line
  • Cyclosporine/pharmacology
  • Cytoplasm/metabolism
  • Flow Cytometry
  • Humans
  • Lymphocytes/metabolism
  • Phenotype
  • Probenecid/pharmacology
  • Radiation Dosage
  • Radiation, Ionizing
  • Rhodamines/metabolism
  • Sulfinpyrazone/pharmacology
  • Tumor Cells, Cultured/metabolism
  • Ultraviolet Rays
  • Verapamil/pharmacology
  • X-Rays


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