CpG oligodeoxynucleotide CpG-685 upregulates functional interleukin-21 receptor on chronic lymphocytic leukemia B cells through an NF-κB mediated pathway
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Rebekah L. Browning1, Xiaokui Mo2, Natarajan Muthusamy1,*, John C. Byrd1,*
1Division of Hematology, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
2Center for Biostatistics, The Ohio State University, Columbus, Ohio, United States of America
*These authors have contributed equally to this work
John C. Byrd, e-mail: [email protected]
Keywords: chronic lymphocytic leukemia, interleukin-21, CpG ODN, NF-κB
Received: December 30, 2014 Accepted: February 05, 2015 Published: March 26, 2015
CpG oligodeoxynucleotides (ODNs) upregulate the interleukin-21 receptor (IL21R) and enhance IL-21-mediated cytotoxicity in chronic lymphocytic leukemia (CLL) B cells. We demonstrate that treatment of CLL B cells with the ODN CpG-685 leads to increased IL21R expression, and that this increased expression enhances the effects of IL-21 treatment as evidenced by increased phosphorylation of JAK1, STAT1, and STAT3, as compared to IL-21 treatment without prior CpG stimulation. Induction of IL21R by CpG-685 also enhanced IL-21-mediated cytotoxicity. The mechanism by which CpG ODNs upregulate IL21R has not been elucidated, although IL21R regulation in T cells has been shown to be linked to T cell receptor-induced Sp1 binding to the IL21R promoter. Here, we demonstrate that luciferase reporter constructs containing the Sp1 binding site have increased basal luciferase activity compared to constructs lacking the Sp1 binding site, but fail to increase luciferase activity with CpG-685 stimulation in CLL B cells. By treating CLL cells with an NF-κB inhibitor, we inhibit the CpG ODN-mediated induction of IL21R, thus demonstrating that CpG-685 upregulates IL21R through an NF-κB mediated pathway. These findings suggest an alternative mechanism for induction of IL-21 receptor in CLL B cells and provide a basis for creation of future combination therapies.
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