Human interleukin 24 (MDA-7/IL-24) protein kills breast cancer cells via the IL-20 receptor and is antagonized by IL-10

Cancer Immunol Immunother. 2007 Feb;56(2):205-15. doi: 10.1007/s00262-006-0175-1. Epub 2006 May 19.


The melanoma differentiation-associated gene-7 (mda-7/IL-24) is a unique member of the interleukin 10 (IL-10) family of cytokines, with ubiquitous tumor cell pro-apoptotic activity. Recent data have shown that IL-24 is secreted as a glycosylated protein and functions as a pro-Th1 cytokine and as a potent anti-angiogenic molecule. In this study, we analyzed the activity of Ad-mda7 and its protein product, secreted IL-24, against human breast cancer cells. We show that Ad-mda7 transduction of human breast cancer cells results in G(2)/M phase cell cycle arrest and apoptotic cell death, which correlates with secretion of IL-24 protein. Neutralizing antibody against IL-24 significantly inhibited Ad-mda7 cytotoxicity. IL-24 and IL-10 both engage their cognate receptors on breast cancer cells resulting in phosphorylation and activation of STAT3, however, IL-10 receptor binding failed to induce cell killing, indicating that tumor cell killing by IL-24 is independent of STAT3 phosphorylation. Treatment with exogenous IL-24 induced apoptosis in breast cancer cells and this effect was abolished by addition of anti-IL-24 antibody or anti-IL-20R1, indicating that bystander cell killing is mediated via IL-24 binding to the IL-20R1/IL-20R2 heterodimeric receptor complex. Co-administration of the related cytokine IL-10 inhibited killing mediated by IL-24 and concomitantly inhibited IL-24 mediated up-regulation of the tumor suppressor proteins, p53 and p27(Kip1). In summary, we have defined a tumor-selective cytotoxic bystander role for secreted IL-24 protein and identified a novel receptor-mediated death pathway in breast cancer cells, wherein the related cytokines IL-24 and IL-10 exhibit antagonistic activity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / immunology
  • Breast Neoplasms / immunology
  • Breast Neoplasms / metabolism*
  • Cell Line, Tumor
  • Cell Proliferation
  • Female
  • Flow Cytometry
  • Fluorescent Antibody Technique
  • Gene Transfer Techniques
  • Humans
  • Interleukin-10 / immunology
  • Interleukin-10 / metabolism*
  • Interleukins / antagonists & inhibitors
  • Interleukins / immunology
  • Interleukins / metabolism*
  • Receptors, Interleukin / immunology
  • Receptors, Interleukin / metabolism*


  • Interleukins
  • Receptors, Interleukin
  • interleukin-20 receptor
  • interleukin-24
  • Interleukin-10