Enhanced targeting of stem-like solid tumor cells with radiation and natural killer cells

Erik Ames, Robert J Canter, Steven K. Grossenbacher, Stephanie Mac, Rachel C. Smith, Arta M Monjazeb, Mingyi Chen, William J Murphy

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Natural killer (NK) cells are innate lymphocytes postulated to mediate resistance against primary haematopoietic but not solid tumor malignancies. Cancer stem cells (CSCs) are a small subset of malignant cells with stem-like properties which are resistant to chemo- and radiotherapies and are able to repopulate a tumor after cytoreductive treatments. We observed increased frequencies of stem-like tumor cells after irradiation, with increased expression of stress ligands on surviving stem-like cells. Ex vivo NK cells activated by low dose IL2 in vitro and IL15 in vivo displayed an increased ability to target solid tumor stem-like cells both in vitro and in vivo after irradiation. Mechanistically, both upregulation of stress-related ligands on the stem-like cells as well as debulking of non-stem populations contributed to these effects as determined by data from cell lines, primary tumor samples, and most relevant patient derived specimens. In addition, pretreatment of tumor-bearing mice with local radiation prior to NK transfer resulted in significantly longer survival indicating that radiation therapy in conjunction with NK cell adoptive immunotherapy targeting stem-like cancer cells may offer a promising novel radio-immunotherapy approach in the clinic.

Original languageEnglish (US)
Pages (from-to)1-11
Number of pages11
Issue number9
StatePublished - Jan 1 2015


  • Adoptive immunotherapy
  • Cancer stem cell
  • Natural killer cells
  • Radiotherapy

ASJC Scopus subject areas

  • Immunology and Allergy
  • Oncology
  • Immunology


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