Interleukin-24 mediates apoptosis in human B-cells through early activation of cell cycle arrest followed by late induction of the mitochondrial apoptosis pathway

Abstract

Interleukin (IL)-24 has death-promoting effects on various proliferating cells including B-cells from chronic lymphocytic leukemia (CLL) and germinal center B-cells, but its molecular mechanisms are poorly understood. Using a B-cell differentiation model and mRNA profiling, we found that recombinant (r)IL-24 stimulated genes of the mitochondrial apoptotic pathway (Bax, Bid, Casp8, COX6C, COX7B) after 36 h, whereas the transcription of genes involved in DNA replication and metabolism was inhibited within 6 h. Unexpectedly, insulin-like growth factor 1 (IGF1), a hormone known to promote cell growth, was stimulated by IL-24. Activated B-cells express receptor for IGF1, to which they become sensitized and undergo apoptosis, a mechanism similar in this respect to IL-24-induced cell death. Furthermore, inhibition of the IGF1 pathway reversed the effects of IL-24. IL-24-mediated apoptosis was also antagonized by pifithrin-alpha, an inhibitor of p53 transactivation. Altogether, these results disclose sequential molecular signals generated by IL-24 in activated B-cells.

Keywords::

• IL-24
• apoptosis
• B-cells
• gene arrays

Acknowledgements

We thank Mélanie Durand for technical help, and the Communauté Urbaine du Grand Nancy (CUGN) and Société Française d’Hématologie for financial support. This work is part of the fulfillment of a PhD thesis of N.H.

Potential conflict of interest

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