A distinct "side population" of cells in human tumor cells: Implications for tumor biology and therapy

C. Hirschmann-Jax, A. E. Foster, G. G. Wulf, M. A. Goodell, M. K. Brenner

Research output: Contribution to journalShort surveypeer-review

98 Scopus citations


Stem cells have an extensive capacity to proliferate, differentiate and self-renew. In many mammals, including humans, an adult stem cell subpopulation termed the "side population" (SP) has been identified. SP cells can rapidly efflux lipophilic fluorescent dyes to produce a characteristic profile based on fluorescence-activated flow cytometric analysis. Previous studies have demonstrated SP cells in bone marrow obtained from patients with acute myeloid leukemia, suggesting that these cells might be candidate leukemic stem cells, and recent studies have found a SP of tumor progenitor cells in human solid tumors. These new data indicate that the ability of malignant SP cells to expel anticancer drugs may directly improve their survival and sustain their clonogenicity during exposure to cytostatic drugs, allowing disease recurrence when therapy is withdrawn. Identification of a tumor progenitor population with intrinsic mechanisms for cytostatic drug resistance might also provide clues for improved therapeutic intervention.

Original languageEnglish (US)
Pages (from-to)206-208
Number of pages3
JournalCell Cycle
Issue number2
StatePublished - Feb 2005


  • Cancer stem cell
  • Drug resistence
  • Hoechst 33342
  • Side population

ASJC Scopus subject areas

  • Cell Biology
  • Biochemistry
  • Molecular Biology


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